Glossary of Terms

-- All definitions -- Ataxia / Olivopontocerebellar atrophy Bradykinesia Choreoathetosis Conditions associated with movement disorders Corticobasal degeneration Dyskinesias, paroxysmal Dystonia Essential tremor - See Tremor Hemiballismus Hemifacial spasm Hereditary Spastic Paraplegia Huntington's disease Multiple system atrophy Myoclonus Parkinson's disease Paroxysmal Dyskinesias Progressive supranuclear palsy Restless legs syndrome Rett syndrome Spasticity Stiff-person syndrome Sydenham's chorea Tardive dyskinesia / Dystonia Tics / Tourette's syndrome Tremor Wilson disease

---

Ablation: Ablation is a surgical procedure that removes or destroys tissue, or a specific part of an organ.

Accelerometer: An accelerometer is a device used to measure change in speed or rate of increasing speed. In medicine, it can be used to measure the change in speed of a tremor.

Acetylcholine (ACh): Acetylcholine is a type of neurotransmitter. It is a chemical that is used by neurons to communicate with other neurons and with parts of the body. It is also used by the part of the nervous system that is responsible for resting and digesting. It lowers blood pressure and slows down heart rate and breathing rate.

Action tremor: An action tremor is a tremor that happens when a person moves, or begins a movement.

Activities of daily living (ADL): ADLs are basic activities that a person does on a daily routine. These include dressing, bathing, eating, and using the bathroom.

Acute: Acute is a word that describes symptoms that come on quickly, and are extremely severe or intense.

Adenosine triphosphate (ATP): ATP is the molecule that provides the energy in the cells of all living things.

Adverse event: According to the United States Food and Drug Administration (FDA), an adverse event is any undesirable experience associated with the use of a medical product in a patient. The event is serious and should be reported to the FDA when the patient outcome is death or is life-threatening; results in hospitalization, disability, or defects in developing fetuses; or requires intervention to prevent permanent impairment or damage.

Agonist: An agonist describes a group of muscles. When any movement occurs, there are two sets of muscles working around a joint. The muscles on one side of the joint must relax so that the muscles on the other side can contract. Agonist refers to the group of muscles that contract. For example, when a person bends his arm at the elbow, the biceps and triceps are working in this way. The biceps are the agonists.

Akathisia: Akathisia is a neurologic condition where the person has restlessness in their muscles. There are a number of different ways that people experience akathisia. In some people, it feels as though their muscles are quivering. In others, they feel the urge to constantly move around and cannot sit still.

Akinesia: Akinesia is an absence of movement. It comes from two Greek words—a and kinçsis—a means without, and kinçsis means movement.

Akinetic: Akinetic is an absence of movement. It comes from two Greek words—a and kinçsis—a means without, and kinçsis means movement. This can mean loss of movement in part of or all of the body.

Alpha 2-adrenergic agonist: An alpha 2 adrenergic agonist is a drug that has an effect within the central nervous system (CNS). There are two systems within the CNS that have the opposite effects. One system acts to speed up the heart rate, breathing, and increase blood pressure during times of stress. This system is controlled by a neurotransmitter called norepinephrine. An Alpha 2-adrenergic agonist decreases the activity of norepinephrine. They therefore may cause a slower heart rate and lower blood pressure.

Alpha synuclein: Alpha synuclein is a protein found in the brain. Nobody knows what the function of this protein is. In some diseases, it is found in large quantities clumped together. It is found in the brains of people with Parkinson’s disease, and other diseases like Lewy Body Dementia and multiple system atrophy.

Alzheimer disease: Alzheimer disease is a disease of the nervous system in which abnormal proteins (tangles and plaques) develop in the brain, and brain tissue shrinks. Over time, the accumulation of these proteins leads to problems with normal thought processes and the ability to make decisions (abstract thinking and judgment) impaired abstract thinking and judgment, personality changes, abnormal behavior, and memory problems. Alzheimer disease is one of the leading causes of dementia.

Ambulant (ambulatory): To be ambulant means a person is able to walk. This term may be used to describe patients who do not need a wheelchair or are not confined to bed.

Ambulation: Ambulation is the act of walking without any devices such as canes or walkers.

Amino acid: An amino acid is the basic building block of life. In the body, proteins are made up of amino acids. There are 20 different amino acids that are used in different combinations to make up all the proteins in the body. Some amino acids, called essential amino acids, cannot be made by the body. A person has to get these amino acids from food in their diet. Other amino acids, called nonessential amino acids, can be made by the body.

Amniocentesis: Amniocentesis is a procedure performed on some pregnant women. It is used to screen for or diagnose different conditions of the fetus. A doctor will use a needle guided by ultrasound to take a sample of the fluid that surrounds the fetus within the uterus. This fluid, called amniotic fluid may be used to detect certain genetic disorders, metabolic diseases, chromosomal abnormalities, or developmental defects. Amniocentesis is usually performed between the 14th and 18th week of pregnancy.

Amplitude: The amplitude is the "size" or "height" of a tremor.

Analog (Analogue): Analog has two different definitions. (1) As a chemical compound, an analog is a man-made chemical substance that is similar in structure to a chemical found naturally in the body. The analog can have either the same or a different action within the body. (2) As a tissue, organ, or other bodily structure, an analog has the same function or organization as another. The only difference in this case is that the two come from different evolutionary origins.

Animal model: An animal model is a laboratory animal that is used in research. Scientists can create an animal with specific characteristics or the animal may naturally have specific characteristics that resemble a human disease or condition.

Anosmia: Anosmia is a lack of sense of smell. People who have complete anosmia are not able to detect any odors. People who have partial anosmia are not able to detect one or more odors.

Antagonist: Antagonist has two definitions. (1) As a drug, an antagonist blocks a receptor, which doesn’t allow a normal body function (biological process) to occur. (2) In a group of muscles, an antagonist refers to the muscles that relax. When any movement occurs, there are two sets of muscles working around a joint. An antagonist describes a group of muscles on one side of a joint must relax so that the muscles on the other side can contract. For example, when a person bends his arm at the elbow, the biceps and triceps are working in this way. The triceps are the antagonists.

Antibodies: Antibodies are a key part of the immune system. They are specialized proteins that fight things in the body that aren’t supposed to be there. By doing this, antibodies destroy anything in the body shouldn’t be there. Any foreign substance such as a bacteria, virus, or foreign tissue is destroyed.

Anticholinergic agents: Anticholinergic medications are drugs that block the action of acetylcholine. Acetylcholine is a neurotransmitter that has an effect opposite to that of dopamine. By blocking the action of acetylcholine, these drugs increase the ability of dopamine to control movement. Examples of anticholinergic drugs used in the treatment of Parkinson disease include trihexyphenidyl, benztropine, and ethopropazine.

Anticholinesterase: Anticholinesterase is an agent that blocks the action of acetylcholinesterase (AChE). AChE is an enzyme that breaks down acetylcholine, a neurotransmitter. By blocking the activity of AChE, acetylcholine levels increase.

Anticonvulsant medication: Anticonvulsant medications prevent or stop seizures from occurring.

Antiemetic: An antiemetic is a drug that reduces nausea or vomiting.

Antigen: An antigen is any substance that may cause the body’s immune system to act (an immune response). Antigens may be microorganisms (e.g., viruses, bacteria), toxins, or foreign tissue cells (e.g., used in transplantation).

Antihistamine: Antihistamine is a drug that is commonly taken during allergic reactions. The drug opens airways and narrows blood vessels to return breathing and blood pressure to normal.

Antioxidants: Antioxidants are agents that prevent molecules called free radicals from destroying nerves and other cells in the body.

Aorta: The aorta is the main artery of the body. The aorta receives blood filled with oxygen (oxygenated) from the heart and delivers it to the rest of the body.

Apomorphine: Apomorphine is a type of drug that is being studied to treat severe Parkinson’s disease. It is made from morphine but does not actually contain morphine. It increases the levels of dopamine available in the brain.

Apoptosis: Apoptosis is the process a cell in the body goes through when it dies. Apoptosis is a scheduled process, controlled by the body.

Apraxia: Apraxia is a condition where a person can no longer do movements when asked to do so. There is nothing wrong with the muscles themselves. The person understands the command, and wants to make the movement, but cannot physically do it. Usually there is a problem in the brain. Apraxia can affect almost any movement, including those required for eye movement, walking, speaking, or writing.

Archimedes spirals: Archimedes spirals is a simple test used to determine how severe a tremor is. During this test, the patient is asked to draw increasingly wider circles on a piece of paper.

Asterixis: Asterixis is a type of tremor where the hands make jerking or flapping movements, like a bird flapping its wings. When the person’s hand is bent backwards at the wrist, the tremor starts. It usually happens in people who have severe liver disease.

Astrocyte: An astrocyte is a type of cell found in the central nervous system. It holds together and protects nerves. Astrocytes also form the blood brain barrier that keeps chemicals from entering into the brain.

Ataxia: Ataxia is caused by damage to a part of the brain called the cerebellum that is responsible for movement and balance. Therefore, the symptoms of the disease are problems with these things. A person with Ataxia will have difficulty with balance and holding their posture. Also, a person’s manner or way of walking is damaged, causing them to stagger and lurch around. He will also have problems with speech and focusing his eyes on what he wants to look at.

Ataxia-telangiectasia (AT): AT is a disease that first shows up in childhood and becomes worse over time. AT is caused by damage to a part of the brain called the cerebellum that is responsible for movement and balance. Therefore, the symptoms of the disease are problems with these things. A person with AT will have difficulty with balance and holding their posture. Also, a person’s manner or way of walking is damaged causing them to stagger and lurch around. He will also have problems with speech and focusing his eyes on what he wants to look at. This disease also causes permanent widening of groups of blood vessels, especially on the skin that receives a lot of sunlight. AT is a disease that is passed down from one generation to the next, as an autosomal recessive trait.

Athetosis: Athetosis is a slow, writing movement that a person cannot control. These movements flow into one another, so it looks almost like a dance. A person usually has athetosis in the head, neck, tongue, or hands, but any part of the body can be affected.

Atrophy: Atrophy is when a tissue or organ slowly wastes away. It can be caused by a number of things such as disease, malnutrition, damage to the nerves, or not enough blood flow.

Attention-deficit/hyperactivity disorder: ADHD is a disease that affects both children and adults. A person with ADHD has a certain set of symptoms and behaviors that develop as the person ages. These behaviors fall into three different: inattention, hyperactivity, and impulsivity.

Atypical: Atypical means something that is irregular or not ordinary.

Atypical neuroleptics: Atypical neuroleptics are a group of antipsychotic drugs. They are newer drugs used to treat psychosis that do not have as many side effects as the older drugs. The main benefit for the atypical neuroleptics is that they do not have parkinsonian side effects.

Auditory: The word auditory refers to the sense of hearing.

Augmentation: Augmentation is something that happens after taking certain medications. After using these medications, including levodopa, a person will have worsening symptoms earlier in the day. This usually happens in people who have severe symptoms or who take high doses of the medication.

Autoimmune: Autoimmune refers to the body reacting against its own tissue or organs. Usually the body fights infections (e.g., bacteria and viruses) that invade it. This is called an immune response. In an autoimmune response, the body reacts against itself, fighting or attacking its own tissues or organs and causing damage. There are many different types of autoimmune diseases.

Automatic behavior: Automatic behaviors are behaviors that a person does without being aware of it, such as mirroring someone else speech or movements.

Autonomic dysregulation: Autonomic dysregulation is condition where there is a problem with the autonomic nervous system (ANS). The ANS is responsible for functions in the body that are not under conscious control, such as the heart beating, breathing, and digestion.

Autonomic nervous system: The autonomic nervous system controls most of the involuntary reflexive activities of the human body such as the rate of breathing and movements of the intestines as food moves through the colon. The system is constantly working to regulate the glands and many of the muscles of the body. The autonomic nervous system is made up of two primary parts: the sympathetic and parasympathetic systems. The sympathetic nervous system prepares the body for emergencies or times of stress and is responsible for the body's "fight or flight" response when faced with a dangerous situation. During this response, the heart rate and blood pressure increase, the pupils of the eye dilate, and the digestive system slows down. The parasympathetic system helps the body's functions return to normal after they have been stimulated by the sympathetic nervous system and also has some responsibility for keeping the body's immune system properly functioning.

Autonomic testing: Your autonomic nervous system controls a variety of functions in your body, including blood pressure, heart and breathing rates, and sweating. Autonomic testing is used to see of your autonomic nervous system is working as it should be or if you have had damage to nerves in this system. Testing usually involves measuring your blood pressure, blood flow, heart rate, the amount of sweat you produce, and your skin temperature.

Autosomal dominant: Human traits, including eye color, hair color, and disorders, are passed down from one generation to the next through genes. A person has two genes for each trait—one from the father and one from the mother. For a disorder that is autosomal dominant, one disease gene is needed to have the trait of the disorder appear in their children. If an individual has an autosomal dominant disorder, there is a 50% chance that their child will inherit the abnormal (mutated) disease gene.

Autosomal recessive trait: Human traits, including eye color, hair color, and disorders, are passed down from one generation to the next through genes. A person has two genes for each trait—one from the father and one from the mother. For a disorder that is autosomal recessive, both disease genes are needed to have the trait of the disorder appear in their children. When only one of their genes carries the disease, the person will usually not be affected by the disorder. If an individual has an autosomal recessive disease, each of his or her children has a 25% chance of inheriting the abnormal (mutated) disease gene.

Axons: An axon is a part of a neuron. A neuron is made up of three parts: a dendrite, cell body and axon. An axon takes information from the cell body and carries it to the other end of the neuron in order to share the information with other neurons.

Baclofen: Baclofen is a drug used to treat spasticity by inhibiting or slowing down muscle activity.

Ballismus: Ballismus is a condition where the arm and leg muscles jerk violently around, making what looks like flinging or throwing movements. The person cannot control these movements. Sometimes it only affects one side of the body (hemiballismus).

Basal ganglia: The basal ganglia are structures located deep inside the brain. They are responsible for normal movements, such as walking. The basal ganglia comprise three parts—the caudate nucleus, putamen, and globus pallidus.

Baseline: In medical research, the baseline is the starting point for gathering information. The baseline information is then compared with information collected at other times throughout the research study.

Behavior therapy: Behavior therapy is a method of treating psychiatric disorders. It focuses on getting rid of unusual, unwanted or abnormal behaviors. This form of therapy reinforces desired behaviors and loss of unwanted behaviors.

Benign myoclonus of infancy: Benign myoclonus of infancy is a neurologic condition that starts showing up in infants around four months old. Babies will have muscle spasms that look like a shock. These usually affect the muscles of the head, neck, trunk and arms. By two or three years old, the muscle spasms typically disappear.

Benzodiazepines: Benzodiazepines are a class of medications that lower the activity in the brain. They are used for a number of different reasons, including reducing anxiety or stress, promoting sleep, relaxing muscles and reducing restlessness.

Beta-adrenergic receptor: A receptor is the part of a neuron that receives information from other neurons in the form of neurotransmitters. A beta-adrenergic receptor receives only norepinephrine, a specific type of neurotransmitter. When a receptor receives norepinephrine it can cause that neuron to send signals of its own to other neurons.

Bilateral: Bilateral refers to something that has or affects two sides. In the body, the word bilateral means that both sides of the body are affected.

Biosynthesize: Biosynthesize means that the body is able to make or produce something itself.

Biphasic: Biphasic refers to a process that has two separate stages or phases.

Bipolar disorder: Bipolar disorder is a psychiatric disease characterized by mood swings. The moods include mania, during which the person has lots of energy or is excessively irritable, and depression, during which the person feels sad and hopeless. The person with bipolor disorder can also have normal moods between the swings but may also switch quickly or slowly between the highs and lows.

Blood-brain barrier: The brain is a very important and delicate organ in the body. The blood-brain barrier protects the brain from being damaged by anything that can get into the blood system. The barrier keeps chemicals and toxins out. Many drugs that people take get into the blood system but cannot reach the brain unless they are specifically designed to do so.

Body mass index: The body mass index is a measure of body fat and is based on a person’s height and weight.

Botulinum toxin (BTX): Botulinum neurotoxin or BoNT any one of seven toxins, designated A through G, which produced by Clostridium botulinum bacteria. Injections of very small amounts of commercially prepared BoNT may help to relax an overactive muscle. BoNT acts by blocking the release of acetylcholine, a neurotransmitter responsible for the activation of muscle contractions.

Bowel: The bowel is the last part of the digestive tract. It is also called the intestines. There is a large and a small bowel. Nutrients and water are absorbed from the small bowel into the body. The left over waste moves through to the large bowel. It is stored here until the waste is emptied from the body by a bowel movement in to form of stool or feces.

Bradykinesia: Bradykinesia simply means abnormally slow movement. It comes from two Greek words—bradys and kinçsis—bradys means slow or slowly, and kinçsis means movement.

Brainstem: The brain stem is a part of the brain that controls basic actions in the body such as breathing, regulating the heart beat and swallowing. It also serves as the connection to send signals between the spinal cord and other parts of the brain.

Branched-chain amino acids: Branched-chain amino acids are a specific type of amino acid found in the body. These amino acids have a structure that branches, like a tree. (Amino acids are the building blocks of proteins.)

Bruxism: Bruxism is present when people grind or clench their teeth without even realizing it. This usually happens when a person is sleeping or stressed. If a person does not use a protective device, like a mouth guard to wear at night, the teeth can become worn down and damaged. Bruxism is also associated with certain medical conditions.

Burke-Fahn-Marsden Dystonia Rating Scale (BFMDRS): The BFMDRS is a physician evaluation tool that measures the severity and provoking factors for dystonia in nine body areas, including the eyes, mouth, speech or swallowing, neck, right and left arms, trunk and right and left legs.

Cabergoline: Cabergoline is an ergotamine-based dopamine-receptor agonist. In the United States, it is marketed as Dostinex for the treatment of the rare disorder hyperprolactinaemia, or high levels of the hormone prolactin.

Carbidopa: Carbidopa is a drug that, when combined with levodopa, slows the breakdown of the levodopa in the body, thereby allowing more of the levodopa to enter the brain and thus providing more effective relief of symptoms.

Carbonic anhydrase inhibitors: Carbonic anhydrase inhibitors are a class of medications used to treat a variety of conditions. These drugs work in the kidney to increase the amount of certain substances excreted in the urine. Carbonic anhydrase inhibitors are used to increase urine production, lower fluid pressure in the eyes of people who have glaucoma and treat epilepsy.

Carnitine: Carnitine is a natural substance found in muscle, the heart and liver. Carnitine is important for energy production and the breakdown of fatty acids.

Cataplexy: Cataplexy is a sudden loss of voluntary muscle control, usually triggered by emotions such as laughter, surprise, fear or anger. Cataplexy occurs most often during times of stress or tiredness. The loss of muscle control may vary from a feeling of weakness to total body collapse. Although people having a cataplectic attack may appear to be asleep, they are actually awake, just unable to move.

Catecholamine: Catecholamine refers to a group of hormones made from a similar substance called catechol. Adrenaline and noradrenaline are two types of catecholamines.

Caudate: The caudate is a part of a structure in the brain known as the basal ganglia. The caudate receives information from the brain and sends it to other areas responsible for controlling complicated motor functions such as walking or voluntary arm movements.

Caudate nuclei: Caudate nuclei are specialized nerve cells found within the caudate. The caudate is a part of a structure in the brain known as the basal ganglia. The caudate receives information from the brain and sends it to other areas responsible for controlling complicated motor functions such as walking or voluntary arm movements.

Central nervous system (CNS): The central nervous system (CNS) is made up of the brain and spinal cord. It coordinates and controls activities and functions of the entire body. It does this by sending signals to the body to move and receives signals from the body about the surrounding environment.

Central oscillators: Central oscillators are nerve cells that send signals along tracts in the central nervous system. When these nerves fire their signals, it causes changes (fluctuations) in the electricity down the tracts.

Cerebellum: The cerebellum is a two-part region of the brain located behind the brainstem. The cerebellum receives messages about balance, posture, muscle tone and muscle contraction or extension. It also sends messages from the brain to the muscles.

Cerebral cortex: The cerebral cortex is the outer layer of the brain. It is made up of four different lobes, or parts: the frontal, temporal, occipital and parietal lobes. It is responsible for integrating higher mental processes (such as decision-making and judgment), conscious thoughts, sensations and movements.

Cerebrospinal fluid (CSF): CSF flows through and around the brain and spinal cord. It provides a cushion to the brain and spinal cord to protect it from injury. A lumbar puncture is a procedure that removes a small amount of CSF for laboratory examination. The fluid is removed by a physician from the area around the spinal cord in the lower back.

Chemodenervation: Chemodenervation is the chemical “silencing or interruption” of a nerve or group of nerves. A nerve sends a signal down a pathway. Chemodenervation happens when this pathway is “interrupted” after injecting a chemical, such as botulinum neurotoxin (BoNT). For example, when BoNT is injected into a muscle, the muscle relaxes because the BoNT slows the release of a certain chemical that allows communication between nerve cells—telling them to move or contract.

Chorea: Chorea is a jerky, rapid and irregular movement of the face, arms, or legs. People with chorea cannot control these movements. Choreic movements can be relatively simple or highly complex in nature. Several different choreic movements can be present at the same time, so the movement looks slow and writhing, like another movement called athetosis. Chorea can be present in neurodegenerative diseases or as a result of certain medications.

Chorionic villus sampling (CVS): CVS is a screening and diagnostic procedure performed where a needle is used to take tissue from the placenta of a pregnant woman. The placenta is a blood-rich organ attached to the lining of the uterus and links the blood supplies of the developing fetus and the mother. Tissue samples obtained during chorionic villus sampling are analyzed to detect certain genetic or chromosomal abnormalities.

Chromosome: A chromosome is a thread-like structure made up of DNA and proteins. Each chromosome is like a string of beads, where each bead represents a different gene. There are normally 46 chromosomes or 23 pairs in the nucleus of human cells.

Circadian: Circadian is a rhythm or repeated pattern of biological functions, occurring in a 24-hour periodic cycle (e.g., sleeping, eating, etc.).

Clinical Global Impression (CGI): The CGI is a tool used by a physician to evaluate a patient’s response to treatment. The first time the CGI is usedthe doctor rates how much the disease or illness impacts a patient’s life; this is called the “baseline.” The patient then receives treatment or, in some cases, a certain amount of time passes, and the doctor again rates the impact of the disease or illness while noting the changes such as very much improved, much improved, minimally improved, no change, minimally worse, much worse, or very much worse.

Clinical trial: A clinical trial is a research study that tests how safe or how well a drug or treatment works in humans.

Clonus: Clonus is a movement characterized by rapid, alternate contractions and relaxations of a muscle. Clonus is frequently observed in conditions such as spasticity and certain seizure disorders.

Co-contraction: When any movement occurs, there are two sets of muscles working around a joint. Normally, the muscles on one side of the joint must relax so that the muscles on the other side can contract. In co-contraction both sets of muscles contract.

Cognition: Cognition involves thinking skills such as perception, memory, awareness, reasoning, judgment, intellect and imagination.

Cognitive impairment: Cognitive impairment is a decrease in the ability to process, learn and remember information.

Cognitive therapy: Cognitive therapy is a method of treating psychiatric disorders that focuses on revising a person's thinking, perceptions, attitudes and beliefs.

Cogwheel rigidity: Cogwheel rigidity is stiffness of muscles around a joint. If a person has cogwheel rigidity of the elbow, and another person tries to bend and straighten his elbow, it will not move smoothly. It will be a jerky movement. Imagine the wheels of a clock moving against each other. They don’t glide past each other. Instead they move one notch at a time, and then stop. This is what cogwheel rigidity looks like. It is a motor symptom of Parkinson’s disease.

Complementary and alternative medicine: Complementary and alternative medicine, as defined by National Institutes of Health, is a group of diverse medical and health care systems, practices and products that are not presently considered to be part of conventional clinical medicine.

Composite Autonomic Scoring Scale: The Composite Autonomic Scoring Scale is a group of validated, sensitive and specific tests to meaure the various functions of the autonomic nervous system.

Computerized tomography (CT) imaging or scanning: CT scanning is an advanced diagnostic scanning technique. X-rays are taken of the body in cross sections at different angles. In some cases, a contrast medium (e.g., a dye) may be injected into the veins to produce enhanced images of certain tissues, organs or blood vessels.

COMT inhibitors: COMT inhibitors are drugs that block catechol-O-methyltransferase, an enzyme that breaks down dopamine. COMT inhibitors include entacapone and tolcapone and are used to treat Parkinson’s disease.

Congenital: The word congenital means that something existed or was present at birth.

Constipation: Constipation is a change in bowel movements from normal. Bowel movements are infrequent and the stool may become hard and dry. Bowel movements become difficult for people with contipation. Constipation may occur as a side effect of medications or because of a condition such as Parkinson’s disease.

Contractures: Contractures are “frozen joints,” and occur when a limb or body part cannot be stretched or moved (when another person tries to moves it about its joint). Contractures may develop because the muscles were shortened or wasted away (atrophy), or from the development of scar tissue (fibrosis) formed over the joints.

Contralateral: Contralateral means the opposite side. For example, during brain surgery for essential tremor, if the surgery is performed on the right side of the brain, the left side of the body will be affected.

Controlled-release formulation: Controlled-release formulations are forms of a drug (e.g., L-dopa) that are absorbed slowly by the digestive system. This means that the beneficial effects and side effects of the drug last longer.

Conversion disorder: A conversion disorder is a condition in which people have neurologic symptoms such as numbness, paralysis or seizures, but no neurologic cause of the symptoms can be found. These symptoms typically begin in response to difficulties in the person's life. A conversion disorder is considered to be a psychiatric disorder.

Corticobasal degeneration (CBD): CBD is a neurologic movement disorder that becomes worse over time. Certain parts of the brain are damaged and loss their ability to function, leading to the symptoms seen in affected people. Symptoms can include stiffness, slow movements and loss of the ability to coordinate movements. People can also experience sensory problems such as the feeling that a limb is not their own. As the disease progresses, people can develop slurred speech, dystonia, and "shock-like" contractions of certain muscle groups, particularly of the hands and forearms.

Corticospinal: Corticospinal refers to the connection between the outer region of the brain (cerebral cortex) and the spinal cord.

Corticosteroid agents: Corticosteroid agents are man made medications similar to corticosteroid hormones, which are naturally made in the body. Corticosteroid agents may be prescribed to: treat inflammatory conditions; as long-term therapy to suppress the immune system (immunosuppressive therapy) in order to prevent rejection of a transplanted organ; as hormone replacement therapy for those with insufficient levels of natural corticosteroid hormones; or as therapy for other conditions. High-dose, long-term corticosteroid therapy can result in various adverse effects, including an increased susceptibility to infection; progressive loss of bone mass (osteoporosis); high blood pressure (hypertension); tissue swelling (edema); or retarded bone growth in children.

Cranial: Cranial refers to the cranium or skull.

Cranial nerve nuclei: Nerve nuclei are specialized groups of nerve cells (nuclei). In the brain, there are 12 pairs of cranial nerves that send and receive information. The nerves are responsible for sensing taste, smell, hearing, and vision. They also send messages to muscles to control eye movements, chewing, swallowing, and facial expressions.

Cranial neuropathy: Cranial neuropathy is disease or damage of a cranial nerve or nerves. In the brain, there are 12 pairs of cranial nerves that send and receive information. The nerves are responsible for sensing taste, smell, hearing and vision. They also send messages to muscles to control eye movements, chewing, swallowing and facial expressions. Cranial neuropathy may result in muscle weakness, abnormal sensations, such as numbness, tingling, or pain, or other findings. Specific symptoms depend upon the specific nerve(s) affected.

Creutzfeldt-Jakob disease (CJD): A rare, degenerative, life-threatening brain disorder, CJD is characterized by severe, progressive dementia; visual disturbances; muscle weakness; and abnormal involuntary movements, such as sudden, brief, "shock-like" muscle spasms (myoclonus), tremor, and relatively slow writhing motions that appear to flow into one another (athetosis). Although CJD usually appears to occur sporadically, about 10 percent of cases are familial, potentially suggesting a hereditary predisposition to the disease. In rare cases, CJD can also result from exposure to contaminated surgical instruments during brain surgery and was reported in the past due to therapy with pituitary-derived human growth hormone. In addition, a variant form of CJD (V-CJD) has been reported primarily in the United Kingdom; V-CJD has been potentially linked to consumption of beef from cows with bovine spongiform encephalopathy or BSE (so-called "mad cow disease"). Evidence suggests that CJD may be caused by abnormal changes (mutations) in the human prion* protein gene or contamination with abnormal prion protein. (*The term "prion" was named for "protein infectious agent.") Changes in the prion protein appear to lead to distinctive neurodegenerative abnormalities, i.e., relatively small, round, "sponge-like" (spongiform) cavities or gaps in certain brain regions. CJD and bovine spongiform encephalopathy or BSE belong to a group of related neurodegenerative disorders categorized as "transmissible spongiform encephalopathies."

Crossreact: When the body encounters a foreign substance (antigen), such as bacteria or virus, it produces an antibody to fight that antigen. Crossreact refers to when an antibody reacts with an antigen that did not specifically or originally trigger its production.

Cytokine: Cytokines are small proteins that regulate the body’s immunity, inflammation and blood-cell production responses.

Cytoplasm: The cytoplasm is the part of the cell that surrounds the nucleus.

DC inhibitors: DC inhibitors are drugs that block decarboxylase, one type of enzyme that breaks down dopamine. Also called AADC inhibitors, they include carbidopa and benserazide.

Decarboxylase: Decarboxylase is a type of enzyme that breaks down or removes a part of another chemical substance. This stops the substance from working in the body. Decarboxylase breaks down levodopa in the body, keeping it from working in the brain. Carbidopa stops the decarboxylase from working. This allows levodopa to get to the brain without being broken down.

Deep brain stimulation: Deep brain stimulation (DBS) involves an operation during which a neurosurgeon (a medical doctor who specializes in surgery on the brain, spine, and other parts of the nervous system) places very thin wires through tiny holes in the skull. These wires, called leads or electrodes, go into the area of the brain that controls movements. The leads arre then connected to an insulated wire (extension) that is tunneled under the skin and connected to a battery-operated device called a neurostimulator. The surgeon sews the neurostimulator, which is about the size of a stopwatch, under the skin of the chest or abdomen. The device sends electrical pulses or signals through the wires to targeted areas deep within the brain. These signals block the abnormal nerve signals causing the symptoms of Parkinson disease, essential tremor, or dystonia. A physician or nurse uses a remote controller to transmit radio signals that can adjust the electrical pulses generated by the neurostimulator.

Degenerative: Degenerative refers to loss of function or form (deterioration). It usually refers to the slow loss of function or structure of tissues.

Delirium: Delirium is a abnormal mental state of frenzied excitement or wild enthusiasm.

Delusion: A delusion is a false belief that a person has about himself or the world. The key to a delusion is that the person believes it no matter what. Even when someone shows evidence that the belief is not true, this does not change the person’s belief.

Dementia: Dementia is not a disease in and of itself; rather, it is a term used to describe a group of symptoms. It is a loss of mental processes such as memory, language, or the ability to think. The loss is significant enough to cause problems with daily functions, and becomes worse over time. Dementia is also characterized by personality changes.

Dendrites: A dendrite is a part of a nerve cell (neuron). A neuron is made up of three parts: a dendrite, cell body and axon. A dendrite is like a tree branch or long rod—a projection from the cell body. It receives information from other neurons and sends the information to the cell body.

Dentatorubropallidoluysian atrophy: Dentatorubropallidoluysian is a rare genetic disorder that is most commonly described in Japan. Associated symptoms may become apparent in adolescence or adulthood. Early-onset disease is characterized by rapidly progressive neurodegenerative changes, including seizures, cognitive impairment and brief, "shock-like" muscle spasms of certain muscles or muscle groups (myoclonus). Late-onset disease is associated with progressively impaired control of voluntary movement (ataxia) and symptoms often seen in Huntington's disease (HD), including chorea (jerky, rapid, irregular movements) and gradual loss of thought processing and acquired intellectual abilities (dementia). Brain imaging studies typically reveal degenerative changes of the globus pallidus and specialized nerve cell clusters within the cerebellum (dentate nucleus). Similar to HD, the disorder may result from abnormally long "repeats" of particular coded instructions within a gene (located on chromosome 12).

Depression: Depression is a disease. A person with depression cannot talk themselves out of the disease. Depression is characterized by many symptoms including either a depressed mood or loss of interest in things that normally give pleasure. A person with depression also experiences weight loss or gain, fatigue, and feelings of worthlessness or guilt. Depression also causes a person to sleep and move around either too much or not at all.

Detoxification: Detoxification is the process of removing toxins or making them harmless in the body

Diaphragm: The diaphragm is a large dome-shaped muscle that separates the chest and abdomen. The diaphragm plays an essential role in breathing, contracting when air is drawn into the lungs and relaxing upon exhalation.

Differential diagnosis: A differential diagnosis is a list of two or more diseases and conditions with similar symptoms. Doctors compare and order certain tests to determine the correct diagnosis for their patients. The physician will use physical signs and symptoms as well as laboratory tests or imaging studies (e.g., x-ray, MRI, etc.) to help make a diagnosis.

Diuretics: Diuretics are medications that encourage the elimination of urine from the body (urination). These medications are often prescribed to help reduce abnormally high fluid levels in the body. Heart failure, high blood pressure (hypertension), kidney or liver diseases can cause excess fluid in the body.

DNA: DNA stands for deoxyribonucleic acid. DNA is a spiraling, ladder-like molecule that contains the body’s genetic code. DNA is the main “ingredient” of the chromosomes within the core or nucleus of the body’s cells. DNA is also found in mitochondria; these are rod-like structures outside the nucleus of a cell that function as a main supplier of cellular energy.

Dopamine: Dopamine is a chemical neurotransmitter. Neurotransmitters help relay messages from one nerve cell to another. Dopamine is especially important in relaying messages about the body’s movement.

Dopamine agonist (DA): A dopamine agonist is a chemical substance that behaves or acts like dopamine. When used in medications, DAs produce the same effects in the brain as naturally occuring dopamine.

Dopamine autoreceptor: A dopamine autoreceptor is a type of dopamine receptor that acts like a thermostat. It prevents dopamine from being released when there are already high levels of dopamine present.

Dopamine receptor: A dopamine receptor is a molecule on a nerve cell (neuron). When dopamine or a medication containing a dopamine agonist interacts with this receptor, the nerve cell responds in a particular way. There are at least five types of dopamine receptors including D1, D2, D3 receptors and the dopamine autoreceptor.

Dopamine receptor antagonist: A dopamine receptor anatagonist is a medication that works together with dopamine receptors. When the antagonist interacts with the receptor, the antagonist blocks dopamine from connecting with its receptor. When this happens, the nerve cell cannot send or respond to its messages, even if dopamine is present.

Dopamine transporter: Dopamine is a chemical in the body that allows one nerve cell to send a message or signal to another nerve cell and helps to control movement. After dopamine finishes sending its message, a substance called a dopamine transporter carries the dopamine back from the nerve ending to the cell that produced it so that the dopamine can be reused. The number of dopamine transporters is a sign of the number of nerve endings that produce or release dopamine.

Dopaminergic: Dopaminergic is a word used to describe a chemical or a drug that either acts like or involves dopamine.

Dopaminergic drug: A dopaminergic drug is any drug that acts like dopamine in the brain, having the same effects as dopamine. Levodopa is converted in the body to dopamine, and dopamine agonists mimic the effects of dopamine at the receptors.

Dopaminergic dysfunction: Dopaminergic dysfunction occurs when there is a problem with the dopamine receptors.

Double-blind trial: A double-blind trial is a clinical experiment in which neither the patients nor the researchers are aware of which patients are receiving the active treatment (the drug or device that is being tested) and which are receiving inactive treatment (placebo), like a “sugar pill.”

Duodenum: The duodenum is the upper part of the small intestine. It is connected to the stomach.

Dysarthria: Dysarthria is difficulty forming words or speaking them. It can be caused by problems in the brain or with the muscles used for speech. As a result, speech can be slurred or slowed and difficult to understand.

Dysesthesias: Dysesthesias are unpleasant sensations that are produced in response to normal stimuli such as intense pain when the skin is lightly touched.

Dyskinesias: Dyskinesia is difficulty with movement. It comes from two Greek words—dys and kinçsis—dys means difficulty, and kinçsis means movement.

Dyskinesias while awake (DWA): DWA are uncontrolled, unexpected movements of the legs and sometimes the arms. These movements can be very rapid or explosive (myoclonic) or they can be quite slow and prolonged (dystonic). Dyskinesia can disappear when a person goes to perform a voluntary action. Some researchers suspect that DWAs may be a wakeful form of periodic limb movements in sleep (PLMS).

Dysphagia: Dysphagia means difficulty in swallowing. Dysphagia may be associated with blockage of the esophageal or with certain neurodegenerative or motor disorders involving the esophagus.

Dyspraxia: Dyspraxia means the loss or partial loss of the ability to coordinate and perform certain purposeful movements such as driving, grooming, etc. The key in dyspraxia is that there is no motor or sensory impairment.

Dystonia: Dystonia is a neurologic movement disorder characterized by lasting muscle tightening or contractions. The contractions result in repeated twisting or writhing movements and unusual postures or positioning that the person with dystonia cannot control. Dystonia may be limited to specific muscle groups (focal dystonia), such as dystonia affecting muscles of the neck (cervical dystonia or spasmodic torticollis) or the eyes, resulting in closure of the eyelids (blepharospasm). Dystonia is associated with certain underlying genetic disorders, such as dystonia musculorum deformans, dopa-responsive dystonia, and paroxysmal kinesigenic and paroxysmal non-kinesigenic dystonic choreoathetosis. The condition may result from the use of certain medications, lack of oxygen during or immediately after birth, or other causes of brain trauma.

Dystonic: Dystonic refers to dystonia.

DYT-1 dystonia: The DYT-1 gene regulates or "encodes" production of a protein called torsinA. Although its specific function is not known, torrsinA appears to be related to a class of proteins that enable cells to recover from injury or stress. The change or mutation that causes DYT-1 dystonia involves one of a pair of three basic chemical "building blocks" of DNA. These are called guanine, adenine, and guanine, or "GAG" trinucleotides and are part of the genetic code within the DYT-1 gene. The specific mutation that occurs in DYT-1 dystonia is an absence, or deletion, of GAG. This relatively tiny change in the blueprint for torsinA apparently causes critical changes in the function of the protein and may lead to the symptoms of dystonia.

Echocardiogram: An echocardiogram is a medical test that is used to study the structure and function of the heart. A computer captures echoes that are created from sound waves, which are bounced off of the heart.

Economic burden: Economic burden involves both direct medical costs such as money paid for drugs and doctor’s appointments as well as indirect costs due to lost wages from illness, premature death and disability.

Edema: Edema is fluid accumulation in the tissues of the body, which causes swelling.

Edentulousness: Edentulousness is the lack of permanent teeth.

Effector organs: Effector organs cause something to happen. They produce an effect after the nerve has been stimulated, such as a muscle contracting or a gland secreting a substance.

Electrical stimulation (ES): ES is a test in which a small electrical charge is applied to a muscle via a needle. This determines the level of muscle responsiveness by looking at what happens when the electricity is delivered to the muscle.

Electrocardiogram (ECG, EKG): An EKG is a non-surgical, diagnostic test that looks at the electrical activity of the heart muscle (myocardium). The test may be administered while a patient is at rest or while performing certain designated exercises. ECGs may help to detect or characterize cardiac conduction defects (the movments of the electrical signals within the heart), abnormal heart rhythms (arrhythmias), enlargement (cardiac hypertrophy), or localized damage in heart muscle.

Electroencephalography (EEG): An EEG is a non-surgical, diagnostic technique that records the electrical impulses produced by the brain. An EEG reveals typical brain wave patterns that may assist in the diagnosis of particular neurologic conditions, such as seizure disorders, impaired consciousness and brain lesions or tumors.

Electromyography (EMG): An EMG is a diagnostic test that records the electrical responses of skeletal muscles while at rest and during voluntary action and electrical stimulation. During this test, a small needle is inserted into a muscle to record the level of activity.

Electron microscopy: An electron microscope beams electrons, instead of light beams, to magnify an object, providing very detailed images that are approximately 1,000 times the magnification of a typical light-beam microscope.

Electrophysiologic recording : Electrophysiologic recordings include the study of the electrical activity associated with a specific body function, such as muscle function during an electromyogram or brain waves during an electroencephalogram.

Electrophysiologic studies: An electrophysiologic study is the study of the electrical activity associated with a specific body function (e.g., EMG, EEG, etc.).

Encephalitis: Encephalitis is inflammation of the brain. It is most commonly caused by viral infections. Usually, symptoms include fever, headache, irritability, listlessness (lethargy), and weakness. Some affected individuals may also develop confusion, disturbances of speech and memory, abnormal involuntary movements, paralysis of one side of the body, seizures and/or coma.

Encephalopathies: Encephalopathies are any abnormal conditions or diseases of the structure or function of the brain, particularly disorders involving ongoing loss of brain structure and function (chronic, degenerative conditions).

Endogenous opiate system: Endogenous means produced in the body. Endogenous opiate is a morphine-like substance that is produced within the body.

Endoplasmic reticulum (ER): The ER is a system of membranes within a cell.

Endoscopy: Endoscopy is an in-office procedure during which the doctor looks inside the stomach or intestine using a hollow, thin, flexible tube. The tube has a lens or miniature camera on the end of it.

Endotoxin: An endotoxin is a poisonous substance that is released from bacteria after the bacteria die or break apart.

Enzyme: An enzyme is a protein made by the body’s cells. There are chemical reactions that occur all the time in the body. Enzymes either speed up or slow down these reactions. Enzymes are not used up or permanently changed during the process.

Epidemiological study: An epidemiological study is a study that looks at the patterns and causes of disease in a group of people. This type of study will try to determine factors that relate to a specific disease or to identify health problems in a specific population.

Epidemiology : Epidemiology is the study of the patterns and causes of disease in groups of people.

Epworth Sleepiness Scale (ESS): The ESS is a paper-and-pencil test. In this test, patients record how likely they are to fall asleep during seven different situations: sitting and reading, watching TV, sitting inactive in a public place (such as at a theater or in a meeting), as a passenger in a car for an hour without a break, lying down to rest in the afternoon when circumstances permit, sitting and talking with someone, sitting quietly after a lunch without alcohol, while driving a car that is stopped for a few minutes in traffic.

Eradication: Eradication is the process of permanently eliminating something.

Ergot: Ergot is a plant substance that contains nitrogen. The pH of an alkaloid is basic, or non-acidic. Ergots are produced by a certain type of fungus.

Ergot-derived medication: Ergot-derived medications have a chemical structure similar to an on ergot, a plant substance that contains nitrogen and produced by a certain fungus. Pergolide and bromocriptine are examples of ergot-derived medications that may be used to treat certain neurologic movement disorders. Ergot medications have been associated with a risk for the development of heart value defects.

Esophageal atony: Esophageal atony is a lack of normal muscle tone within the esophagus, the muscular tube that transports food from the throat to the stomach.

Essential tremor (ET): ET is a common neurologic movement disorder that becomes worse over time. It is characterized by a rhythmic back and forth movement of a body part of parts that a person cannot control. A tremor can either be postural or kinetic, or both. Postural means that when people try to hold one position, such as sitting or standing, they will have a tremor. A kinetic tremor is when a person tries to do a specific action, such as reaching a hand out towards an object, they will experience the tremor. ET can affect the hands or head commonly, less commonly, the voice, tongue or roof of mouth. The cause of ET is not known, and it can either occur randomly or be passed down from one generation to the next as an autosomal dominant trait.

Estrogen: (1) Estrogen is a female sex hormone that promotes female development and the proper functioning of the reproductive system; (2) Estrogen is also a compound chemically produced to treat a variety of conditions. It is found in birth control pills and medication to treat the symptoms of menopause. It also is used to reduce bone mass loss in osteoporosis and to treat breast and prostate cancer.

Eukaryotic: Meaning literally "true nucleus," eukaryotic organisms include microorganisms, plants, animals and fungi, all of which have separate membrane-bound nuclei that contain genetic material (mDNA).

Excessive Daytime Sleepiness (EDS): EDS is more than the normal amount of sleepiness during the day along with a lack of energy, even after a normal night's rest. EDS may be measured using the Epworth Sleepiness Scale.

Executive function: Executive function refers to a person’s ability to establish a goal and then make decisions and put into action activities to meet that goal.

Exon: An exon is a region of a gene that contains part of the code for producing the gene's protein. Each exon codes for a specific portion of the complete protein. Exons are separated by long regions of DNA (called introns or sometimes "junk DNA") that have no apparent function.

Extrapyramidal system: Extrapyramidal system refers to central nervous system structures that control motor functions. Extrapyramidal disturbances may result in problems maintaining posture and muscle tone. It can also lead to involuntary movements.

Fatigue: Fatigue is a feeling of tiredness or a sense of having low energy that may lead to a decrease in a person's ability to perform work or daily activities.

Feldenkrais: Feldenkrais is a method of improving the body’s ability to function, learn, and change by increasing awareness of movement, posture, and breathing.

Ferritin: Ferritin is a protein that stores iron inside your cells so that your body can use the iron when it is needed. A serum ferritin level is a blood test that measures the amount of ferritin in the cells. The amount of ferritin stored, or the serum ferritin level, reflects the amount of iron that is stored in the body. Symptoms of RLS have been shown to be increased in people who have low ferritin levels.

Festinating Gait: People with a festinating gate will take very small steps. Their feet never come all the way off the floor, so it looks like the person is shuffling along. People cannot control the shuffling or take bigger steps.

Fibrosis: Fibrosis is the build up of fibrous tissue in an abnormal place in the body. One example is scar tissue.

First-, second- and third-degree relatives: First-degree relatives include a person’s mother, father, brothers, sisters, sons, and daughters who are related by blood and not through adoption or marriage. Second-degree relatives include aunts, grandmothers, uncles, and grandfathers. Third-degree relatives include great-grandmothers, great-aunts, great-uncles, and first cousins.

Flexion: Flexion is the act of bending (as opposed to extending) a joint.

Focal dystonia: Focal dystonia is a type of dystonia that is limited to a specific group of muscles. Some types of focal dystonia involve muscles that control movement of the neck (cervical dystonia), eyes (blepharospasm), hand (writer’s cramp or musician’s dystonia), or vocal cords (spasmodic dysphonia).

Food and Drug Administration (FDA): The FDA is a federal agency charged with ensuring that the food supply in the United States is safe and wholesome, that cosmetics are not harmful, and that medicines, medical devices, and radiation-emitting consumer products are safe and effective.

Free radicals: Free radicals are unstable molecules that can damage cells.

Freezing: Freezing is when motion is halted. It looks like the person is nailed to the floor and cannot move forward.

Frequency: Frequency is the number of cycles or repetitions within a fixed unit of time such as the number of cycles per second (Hertz or Hz). For example, essential tremor is typically 4 to 12 Hz.

Friedreich's ataxia: Friedreich's ataxia is the most common autosomal recessively inherited type of ataxia. The main symptoms are loss of coordination and unsteadiness of gait. Other systems may also be affected and people with Friedreich's ataxia should be monitored for heart disease and diabetes. The affected protein is called frataxin, and is thought to be involved in iron metabolism.

Froment's sign: Froment’s sign is a maneuver that a physician can perform to check for muscle resistance. Here is an example of a positive Froment’s sign. A person is told to move one part of the body, for example the leg. While he or she does this, the doctor moves another part, the arm. If the arm is stiff and resists movement, this is Froment’s sign.

Functional Magnetic Resonance Imaging (fMRI): An fMRI is a non-surgical, diagnostic scanning procedure that produces detailed, computerized images. The use of a "contrast agent" or dye enhances the detail of the images. Watching the images in the order in which they were taken can help physicians visualize the body's functioning, thus aiding differential diagnosis.

Gait: Gait is a manner or way of walking. Gait disturbances are associated with certain neurologic or neuromuscular disorders, orthopedic conditions, inflammatory conditions of the joints such as arthritis and other abnormalities.

Gait apraxia: Gait apraxia is the loss of ability to coordinate and execute walking. Gait apraxia may result in unsteady walking patterns, toe-walking, a widely based, jerky gait and balance difficulties.

Gamma knife radiosurgery: Gamma knife radiosurgery is a highly specialized technique to produce an area of damage known as a lesion. This procedure uses a device that focuses a beam of high intensity irradiation to a targeted area. It is used as localized therapy to treat individuals with certain brain diseases such as brain tumors, certain movement disorders, etc.

Gamma-aminobutyric acid (GABA): GABA is an amino acid neurotransmitter that inhibits or decreases the electrical activities of nerve cells. GABA is the primary neurotransmitter in the brain that decreases electrical activity.

Gastroesophageal reflux: Gastroesophageal reflux occurs when the stomach contents flow backwards into the esophagus. Another name for this is acid reflux or heartburn. It can be a chronic condition caused by weakness in the muscle that is supposed to keep the contents in the stomach.

Gastrointestinal: Gastrointestinal refers to the stomach and small and large intestines as well as to the mouth, esophagus, anus and related organs.

Gastrostomy tube: A plastic tube inserted into the stomach through a surgical incision in the abdomen. A gastrostomy tube is used to deliver liquified food to the digestive system when swallowing becomes dangerous or difficult.

Gene: Genes, or units of heredity, are found in all cells of the body. The information from all the genes together makes up the blueprint or plan for the human body and its functions. A gene is a short segment of DNA, which is interpreted by the body as a plan or template for building a specific protein.

Generic drug: A generic drug is a medication that has the same active ingredients as its comparable brand-name drug. It works the same way a brand-name drug works, but is usually less expensive. Generic drugs meet the same FDA standards as brand-name drugs.

Genetic anticipation: Genetic anticipation refers to the appearance of the symptoms of a hereditary disease at an earlier age in each generation. In some hereditary disorders, such as Huntington’s disease, genetic anticipation has been identified.

Genetic heterogeneity: Genetic heterogeneity means that damage to different genes can produce the same characteristic or trait.

Germline mosaicism: Germline mosaicism is an abnormal change in a gene (mutation) in some but not all of a person’s reproductive cells (i.e., egg cells in the ovaries or sperm cells testes. This gene mutation is passed down to the children, but the parent doesn’t have the condition.

Gland: A gland is a structure or organ in the body that makes a substance, such as a hormone or chemical, which is used elsewhere in the body. Some hormones include insulin, bile, growth hormone, estrogen and testosterone.

Gliosis: Gliosis is an abundance of certain cells (astrocytes) in damaged areas of the central nervous system (CNS). Astrocytes are relatively large glial cells, which are the connective tissue cells of the CNS. Gliosis and neuronal loss in certain brain regions are findings seen in various neurodegenerative disorders.

Globus pallidus: The globus pallidus is a part of a structure in the brain known as the basal ganglia. The globus pallidus receives information from the brain and sends it to other areas responsible for controlling complex motor functions.

Glottis: The glottis is the slit-like opening between the vocal cords.

Glutamate: Glutamate is a chemical messenger (neurotransmitter) that “excites” other nerve cells in the central nervous system.

Gram staining: Gram staining is a method used to classify bacteria. In the first step of the process, bacteria are stained with gentian violet and then treated with Gram solution (named after Dr. Gram, the inventor of the technique). After the bacteria are treated with alcohol to remove the stain and then treated with a red organic dye called safranine, they are washed in water. Those bacteria that keep the gentian violet are gram-positive and those that do not are gram-negative.

Gray matter: Neurons are made up of three parts: the cell bodes, dendrites and axons. Axons can be covered in a sheath of fat called myelin to help the signals travel faster. Some neurons are covered in myelin and others are not, called unmyelinated axons. Gray matter is the portion of the nervous system that is made up of the cell bodies, dendrites and unmyelinated axons. White matter, on the other hand, is made up of axons that are coated in myelin.

Half life: The half life of a drug is the time it takes for the blood level to decrease by half after a drug is stopped.

Hallervorden-Spatz disease: Hallervorden-Spatz disease is a rare hereditary disorder where large amounts of iron gather in certain regions of the brain (i.e., basal ganglia). This autosomal recessive disorder typically becomes apparent during late childhood or adolescence. People with this disease experience rigidity, dystonia, choreoathetosis and other problems. The symptoms become gradually worse with time (progressive).

Hallucination: An hallucination is something that a person sees, smells, touches, hears or tastes but it is not really there. The hallucination is only present in the mind of the person. No one else experiences a hallucination because it is not a part of the environment.

Heat pain: Heat pain arises from warm or hot temperatures.

Hemichorea: Chorea is a jerky, rapid, irregular movement that a person cannot control in the face or arms and legs. Choreic movements can be relatively simple or highly complex in nature. Hemichorea are movements that involve only one side of the body or muscle groups that are only on one side of the body.

Hemidystonia: Hemidystonia is a form of dystonia that affects one side of the body or is characterized by one-sided involvement of the upper and lower limbs.

Hemizygote: Normally in humans, every cell has two pairs of genes. A hemizygote refers to a cell, organism or individual with only one of a pair of genes for a specific trait. This term is often used to describe males who inherit one copy of an X-linked disease trait.

Hereditary: Hereditary means inherited. A genetic trait, condition or disorder that is hereditary means that it is passed down from one generation to the next through the genes.

Hereditary spastic paraplegia (HSP): Hereditary spastic paraplegia or HSP is a group of genetic disorders that affects the spinal cord and results in weakness and stiffness of the legs. HSP is progressive, meaning that the symptoms become worse the longer you have HSP.

Heredodegenerative: Heredodegenerative is a term used to describe disorders that are passed down from one generation to the next. These disorders, which become gradually worse with time (progressive), affect the nervous system (neurodegenerative disorders).

Hertz (Hz): Hertz is the number of cycles per second.

Heterogeneity: Heterogeneity means that something has different forms or variations. For example, in the United States there is a heterogeneous population because there are people here from all over the world.

Heterozygous carriers: Every person has two copies of every gene. These copies can be the same, homozygous, or different, heterozygous. A heterozygous carrier has two different copies at a specific gene. This gene is responsible for a disease trait. Because the person has one good copy and one bad copy, usually he or she will not have the disease. They pass the gene to their offspring, however, and their child could have the disease.

Hoehn and Yahr Scale: The Hoehn and Yahr Scale is a commonly used physician-administered rating of the severity of the motor symptoms of Parkinson's disease. Scores range from 0, no signs of disease, to 5, wheelchair bound or bedridden without assistance.

Homeopathy: Homeopathy is a system of medicine that is based on the Law of Similars. According to this law, substances that cause healthy people to have certain symptoms can also be used to restore the body to health.

Homeostasis: Homeostasis exists when an organism’s internal state is in balance, even when the outside environment is changing.

Homocystinuria: Homocystinuria is a rare metabolic condition where an amino acid, called homocystine, is found in abnormally high levels in the urine. It is an autosomal recessive trait. People with homocystinuria experience developmental delays and worsening mental retardation. They may have dislocated eye lens, weak muscles and skeletal defects and blood clots in the blood vessels.

Huntington disease: Huntington disease (HD) is a rare disorder that causes a specific type of nerve cell in the brain to stop functioning and die off. In the early stages of the disease, symptoms can include slight personality changes, forgetfulness, clumsiness and fidgeting movements of the fingers, eyes or toes. As HD becomes worse, it can cause memory, thinking, behavior and planning problems, as well trouble talking, swallowing and walking. HD is an autosomal dominant, heriditary disoder. This means that if one parent has HD, a child will have a 50-50 chance of developing HD. A genetic blood test can determine if the child has the HD gene and will eventually develop the disease. Genetic counseling can help people to decide if they want to be tested for HD, weighing the risks and benefits of taking the test. There is no cure for HD, but some medicines can help with the symptoms.

Huntington’s Disease-like 2 (HDL2): This rare disease strongly resembles Huntington’s disease in its inheritance and symptoms, which include abnormal movements, personality changes, and changes in the ability to think and process information. HDL2 is due to damage to the same parts of the brain as in HD; however, HDL2 is caused by a change (mutation) of a different gene.

Hyperactivity: Hyperactivity means too much muscle activity. Typical behaviors may include fidgeting or constant moving, wandering, too much talking, and difficulty participating in quiet activities.

Hyperglycemia: Hyperglycemia is an abnormally high level of glucose in the blood.

Hyperkalemic: Hyperkalemia is an abnormally high level of potassium in the blood. Potassium is important in contolling fluid balance in the body, contracting muscles and sending messages along nerves. Hyperkalemia can lead to various signs and symptoms, such as diarrhea, nausea, abdominal cramps, weakness and, with increasing severity, abnormal heart rhythms and muscle paralysis.

Hyperkinetic: Hyperkinetic means excessive movement. Usually it is caused by a problem in motor activity or function. Certain movement disorders are termed "hyperkinetic" such as tics or essential tremor.

Hypersexuality: Hypersexuality is a psychological disorder in which the affected person has a desire to take part in sexual activities at a level that is considered to be abnormally high in relationship to normal development or culture. The hypersexuality occurs at a level that causes distress or serious problems for the affected person or for people associated with the affected person.

Hypertension: Hypertension, also referred to as high blood pressure, is an abnormal increase in the pressure of blood against the walls of the arteries. Hypertension can be essential, meaning that it has no known cause, or can be related to another disease such as kidney disease or diabetes.

Hyperthyroidism: Hyperthyroidism is a condition caused by the effects of too much thyroid hormone in the body.

Hyperventilation: Hyperventilation is when a person breathes very rapidly. When a person hyperventilates, it can cause changes in the body’s oxygen and carbon dioxide balance. Sometimes, a person can hyperventilate so strongly that they lose consciousness.

Hypnagogic hallucinations: Hypnagogic hallucinations are vivid, realistic, often frightening dreams that occur while the person is falling asleep or immediately upon awakening.

Hypocretin: Hypocretin (also known as orexin) 1 and 2 are protein-like molecules (neuropeptides) found in the brain that act like hormones or neurotransmitters. They are involved in the regulation of sleep and wakefulness.

Hypokalemic: Hypokalemia is abnormally low level of potassium in the blood. Potassium is important in regulating fluid balance, contracting muscles and sending messages along nerves. Hypokalemia may result in confusion, fatigue, weakness and, in severe cases, paralysis and heart rhythm abnormalities.

Hypokinesia: Hypokinesia is abnormally decreased movements. It comes from two Greek words—hypo and kinçsis—hypo means decreased, and kinçsis means movement.

Hypomimia: Hypomimia is reduced facial expressions. This can be caused by weakness or paralysis of facial muscles.

Hypoparathyroidism: Hypoparathyroidism is a condition associated with low levels of a hormone produced by the parathyroid glands. Parathyroid hormone regulates calcium levels in the body. With hypoparathyroidism, there are low levels of calcium in the body that causes symptoms. It can cause tetany, which results in uncontrollable, painful muscle spasms and cramps. It can also cause chorea, spasms of the larynx, and seizures. Calcium can also be deposited in areas where it is not supposed to be including the basal ganglia in the brain or the lens of the eye. The skin can become dry and scaly and the teeth enamel can become weakened.

Hyposmia: Hyposmia refers to a decreased sense of smell.

Hypotension: Hypotension is low blood pressure. It comes from two Greek words—hypo and tension—hypo means low and tension means pressure.

hypoxia: Hypoxia is an abnormally low level of oxygen.

Iatrogenic: Iatrogenic is a disease or disorder that is caused not deliberately by a physician or surgeon, or by medical treatment or diagnostic procedures.

Idiopathic: Idiopathic is a disorder or condition of that occurs on its own, for no apparent cause. The term comes from the prefix "idio-" meaning one's own and "pathos" indicating disease.

Idiopathic epilepsy: Idiopathic epilepsy is a disease with repeated seizures of unknown origin or cause. There is no detectable area of damage in the brain, but the person keeps having seizures. Another name for this is essential or primary epilepsy. These conditions are often thought to have a genetic component.

Illusions: Illusions occur when a person sees something that is real but misinterprets what it is. For examples, heat waves on the desert floor can look like waves of water.

Immunofluorescence: Immunoflorescence is a laboratory technique that uses antibodies linked to a light-emitting or fluorescent dye in order to study foreign substances in a tissue sample.

Immunogenicity: When the body detects a foreign substance such as a virus or bacteria, it begins an immune response. Immunogenicity is the ability or strength to which this substance launches the immune response.

Implantable Pulse Generator (IPG): IPG is a device that is placed under the skin, usually near the collarbone, as part of a surgical procedure known as deep brain stimulation. Wire leads from electrodes implanted in the brain are connected to the pulse generator, which then delivers continuous high frequency electrical stimulation to the thalamus via the implanted electrodes. This form of stimulation probably "jams" the nucleus, changing the electrical messages in the movement control centers of the brain. These changed message help to control or suppress tremor.

Incontinent: Incontinent usually means that people have lost control over their bladder. People can urinate or “dribble” urine while not using the toilet. Some people can lose control of their bowels (fecal incontinence).

Inflammation: Inflammation is the body’s response to injury or irritation. The classic signs of inflammation are pain, heat, redness, swelling and loss of function.

Inheritance patterns: Inheritance patterns are the different ways that a person inherits genes from their parents. For example, autosomal dominance is a specific pattern of inheritance. Each person inherits two copies of almost every gene, one from the mother and one from the father. Some diseases develop when only one copy of a gene is changed or mutated, even if the other copy is completely normal. Such a gene is passed from parent to child in an autosomal dominant inheritance pattern. A parent who has the abnormal, “disease” gene (mutation) may be affected by the disease. Each child of that parent has a 50% chance of inheriting the mutation and likely developing the disease. Other diseases develop only when both copies of a gene are mutated. In this case, the mutated gene is passed from both parents in an autosomal recessive inheritance pattern. Parents carrying one copy of the mutated gene are typically unaffected by the disease. Each parent must contribute one disease gene to a child for that child to develop the disease. Each child has a 25% chance of inheriting both mutations and developing the disease.

Inhibition: Inhibition is when a process or action in a cell or organ is stopped or restrained. It can also be slowing down or stopping of a chemical reaction. The term "reciprocal inhibition" refers to the restraint or "checking" of one group of muscles upon stimulation (excitation) and contraction of their opposing (antagonist) muscles.

Inhibitor: An inhibitor is a substance that blocks, restricts or interferes with a particular chemical reaction or other biologic activity.

Innervate: To innervate is to supply a body part, tissue, or organ with nerves or nervous stimulation.

Insidious: Insidious means that something develops slowly or gradually. If a disorder is insidious, this means that the symptoms develop so slowly that the people may not that they have a disorder until it is full blown.

Insomnia: Insomnia is not being able to fall asleep or stay asleep for the night.

Intestine: The intestine is sometimes called the bowel or the gut. It is the part of the digestive system that extends from the stomach to the rectum. It is made up of the small and large intestines and serves to absorb water and nutrients from the food and liquids that we drink and eat. The small intestine extends from the stomach to the large intestine and is made up of three segments: the duodenum, the jejunum and the ileum.

Intravenous: Intravenous means within a vein or veins. Substances such as fluids, nutrients, or medications, can be given intravenously, meaning directly into a vein.

Involuntary: Involuntary means that a person does not have control over something. In the body, it means the things that a person does not have conscious control over.

Ion: An ion is an electrically charged atom or group of atoms. Positively charged ions, known as cations, include potassium, calcium, sodium, hydrogen, ammonium, and magnesium. Negatively charged ions, called anions, include chloride, phosphate, and bicarbonate.

Ischemia: Ischemia occurs when the flow of oxygen-rich blood to tissue in the body is reduced or stopped.

Isoleucine: Isoleucine is an essential amino acid, meaning that the body does not make this amino acid, so it must be obtained through diet.

Jejunostomy tube: The jejunostomy tube is similar to a gastrostomy tube, although this tube is longer and inserted through the abdominal wall into the jejunum, the middle section of the small intestine.

Joint contractures: The abnormal and mostly permanent shortening of a muscle resulting in the loss of normal joint movement. When muscle fibers are shortened (due to injury, scar tissue or muscle overactivity), the nearby joint can remain fixed in one position.

Juvenile myoclonic epilepsy: Juvenile myoclonic epilepsy is a form of idiopathic epilepsy or recurrent seizures of unknown origin. Symptoms usually first appear around 12 to 16 years of age. The condition is characterized by sudden, involuntary, "shock-like" muscle jerks (myoclonus) that primarily occur during the morning or with stress, fatigue or alcohol consumption. Patients can eventually develop generalized seizures that are associated with loss of consciousness and rhythmic contractions and relaxations of all muscle groups (tonic-clonic).

Kinesigenic: Kinesigenic means something is caused by movement. This term is often used to describe abrupt episodes of uncontrolled and unintended movement that are provoked by sudden motions or unexpected stimuli. For example, exercise can cause abnormal movements in some people who have paroxysmal kinesigenic dykinesia (PKD).

Lafora's disease: A progressive myoclonic encephalopathy (PME) that is inherited as an autosomal recessive trait. Symptoms begin in childhood or early adolescence. These symptoms include frequent seizures characterized by loss of consciousness and rhythmic contraction and relaxation of all muscle groups (generalized tonic-clonic seizures); sudden, involuntary, "shock-like" muscle jerks (myoclonus); and rapidly progressive deterioration of thought processing and acquired intellectual abilities (dementia). When tissue is examined with a microscope, there are abnormal clumps of proteins and carbohydrates within the fluid part of the cells. These are called Lafora bodies.

Lance-Adams syndrome: Lance-Adams syndrome is a rare condition characterized by the development of chronic action myoclonus due to lack of oxygen to the brain. This is called posthypoxic or postanoxic action myoclonus. Patients with action myoclonus experience sudden, involuntary, "shock-like" muscle contractions that may be triggered or aggravated by voluntary movement. Lance-Adams syndrome is also often associated with cerebellar ataxia or lack of coordination and balance.

Laryngoscope: A laryngoscope is a long, thin, flexible tube that has a light and a small camera attached to the end. A doctor uses a laryngoscope to look at the larynx or voice box.

Lateral: Lateral means sideways or towards the side.

Leigh disease: Leigh disease is a rare disorder of infancy that is caused by abnormal function of mitochondria. Mitochondria are special parts of the cell that act like tiny power plants, providing energy to the rest of the cell. Affected infants have problems with feeding and swallowing, vomiting, muscle weakness, low muscle tone and delayed muscle and language skills. Infants and children can also have seizures, ataxia, abnormal eye movements (nystagmus), tremor, and dystonia. There are specific areas in the brain that lose tissue as well.

Leucine: Leucine is an essential amino acid. Essential means that the body does not make this amino acid, so it must be obtained through diet. Amino acids are the building blocks of proteins.

Levodopa: Levodopa is a drug used to treat Parkinson's disease and other movement disorder. It is also called L-dopa; in the United States, it is sold as Sinemet. Levodopa crosses the blood-brain barrier and is converted by the body into dopamine.

Lewy body: A Lewy body is a mass of protein found in dying nerve cells in the brain.

Lewy Body Disease: Lewy body disease (LBD), also called diffuse Lewy body disease or Lewy body dementia, is a common cause of dementia. LBD accounts for approximately 15-20% of all cases of dementia. The age of onset is typically in the late 50s through the 70s. It is more common in men than women. Lewy body disease is characterized by more daily changes in symptoms than Alzheimer's disease, as well as more prominent severe psychiatric problems (e.g., psychosis). People with LBD frequently experience troublesome side effects to drugs used to treat psychosis. Patients also have parkinsonian features early in the disease, including slowed movements and rigidity. Tremor is usually absent. The Lewy body is a protein clump found in dying neurons of the brain. In Lewy body disease, the Lewy bodies are most prominently found in the cortex or surface of the brain. In people with Parkinson’s disease, Lewy bodies are typically found in the midbrain, not the cortex.

Lipopolysaccharide: A lipopolysaccharide is a molecule made up of a fat with a complex sugar. In most circumstances, the terms lipopolysaccharide and endotoxin can be used interchangeably.

LRKK2: LRRK2 is an abbreviation that stands for “leucine-rich repeat kinase 2.” It is the name of a gene that is responsible for providing instructions for making a protein called dardarin. The gene is thought to be active in the brain. Although little is known about the LRRK2 gene or dardarin protein, researchers do know that part of the LRRK2 gene provides instructions to make a protein segment that is rich in a protein building block (amino acid) called leucine. Proteins with leucine-rich regions appear to play a role in activities that require protein-protein interactions, such as transmitting signals from nerve cell to nerve cell or helping to assemble the cell's structural framework (cytoskeleton).Researchers also suspect that the dardarin protein has an enzyme activity known as kinase, which may help to turn many cell activities on and off.

Lumbar puncture: Lumbar puncture is a procedure during which some cerebrospinal fluid (CSF) is removed from around the spinal cord. A needle is used to take the CSF from the fluid-filled space around the spinal cord in the lower back. The fluid can be sent to a laboratory for testing about infections, tumors and other neurologic disorders. Sometimes, a lumbar puncture is used to inject medication, such as anticancer drugs or pain medications into the CSF.

Lysosomal: Lysosomal refers to lysosomes. Lysosomes are small structures within cells that contain chemicals (enzymes) that aid in digestion with the cell.

Lysosomal storage diseases: In normal cells, lysosomes break down certain substances using enzymes. Enzymes speed up chemical reactions in the body. In lysosomal storage diseases, there are either not enough enzymes or the enzymes don’t work. This leads to a build up of that substance. This can affect various tissues and organs in the body. Most lysosomal storage disorders are thought to be inherited as a recessive genetic trait.

Machado-Joseph disease: Machado-Joseph disease, also known as spinocerebellar ataxia (SCA) type III, is a rare disorder but probably the most common dominant form of SCA. In addition to unsteadiness of walking (ataxia), symptoms can involve parkinsonism, dystonia and chorea. The abnormal protein that causes Machado-Joseph disease is called ataxin-3; however, its function is not yet known.

Magnetic resonance imaging (MRI): An MRI is a non-surgical diagnostic scanning or imaging study. The scans create detailed images in cross section of the body. MRI is a valuable tool for the neurologist to examine the brain and spinal cord; it can scan images from various angles. Sometimes a dye may be used to improve the images, providing strong contrast between healthy and abnormal tissues.

MAO inhibitors: MAO inhibitors are a group of medications that prevent the action of an enzyme called monoamine oxidase (MAO). This enzyme helps to break down dopamine. When MAO is inhibited, dopamine acts in the brain for a longer period of time. Examples of MAO inhibitors that are used in the treatment of Parkinson disease include rasagiline and selegiline.

MAO-B inhibitors: MAO-B inhibitors are medications that prevent the action of an enzyme called monoamine oxidase B (MAO-B). This enzyme helps to break down dopamine. When MAO is inhibited, dopamine acts in the brain for a longer period of time. MAO-B is a specific type of MAO inhibitor.

Matched control subjects : Matched control subjects are people in a study group or clinical trial who have similar characteristics, such as age, height, weight, education, sex or other characteristics, as the patients being studied, but they do not have the disease. An example would be control subjects that were matched with regard to age and sex to each person who had PD, but the control subjects did not have PD, parkinsonism or any other form of tremor.

Mean: The mean is the average of a set of numbers.

Mechanical pain: Mechanical pain arises from pressure or touch.

Media impression: A media impression is the interaction between a web site, radio spot, television program, or newspaper or magazine article and a single member of the audience who is exposed to that medium.

Medially: Medially means towards the middle or midline. The "median plane" refers to the imaginary line that divides a body into two identical halves.

Medication: Medication is a drug that has an effect on the body. It is usually used to treat a certain illness or condition.

Melanoma: Melanoma is a serious and potentially life-threatening type of skin cancer. The tumor cells develop in the melanocytes, the cells that give skin its color.

Membrane: A membrane is a thin wall or film that allows only some substances to pass through it or that prevents the mixing of two substances.

Membrane lipid peroxidation: Membrane lipid peroxidation is the breakdown of certain fatty acids into another form of fatty molecules.

Memory: Memory is how information is processed. It requires that a person is able to gather information. That information is then stored and held onto for a period of time. The final step is to recall the information when the person wants it.

Meningitis: Meningitis is an infection of the meninges, the thin three-layer membranes that cover and protect the brain and spinal cord.

MERFF syndrome (myoclonus epilepsy with ragged-red fibers): MERFF is a rare disorder passed down from one generation to the next. In MERFF, mitochondria that provide the energy to cells have defective genetic material. This causes neurologic and muscle problems. When the muscle fibers are examined using a microscope, the mitochondria are abnormal and look like “ragged-red fibers.” People with MERFF experience muscle weakness, myoclonus, seizures, ataxia, and dementia. Some people may also have hearing loss, breakdown of the nerves that send information from the retina of the eye to the brain, short stature and heart muscle disease.

Metabolism: Metabolism is a group of activities in the cells that use food to make energy or other compounds that are essential to life. There are two types of metabolism, catabolism and anabolism. Catabolism is when chemicals are broken down into simpler substances. This process gives off energy. Anabolism is when chemical compounds are build up into more complex substances. This process requires energy.

Methylphenidate: Methylphenidate is a drug that is used to speed up the functions of the central nervous system (a stimulant). This drug is usually used to treat symptoms of attention-deficit/ hyperactivity disorder or narcolepsy. It acts like caffeine but has a more powerful effect; however, it is not as potent as amphetamines.

Metoclopramide: Metoclopramide is a medication used to treat nausea and vomiting or migraine headaches and to help with emptying the stomach for people with specific medical conditions. It works by blocking dopamine receptors.

Micrographia: Micrographia is unusually small writing. It comes from two Greek words—micro and graph—micro means small, graph means to write.

Mini-Mental State Examination : This short, doctor-administered test measures the ability to think, calculate and reason (cognition). This test is used to measure the presence of impaired cognition or a change in cognition over time.

Mitochondrial: Mitochondria are structures found in cells that produce and regulate energy. They are the main energy source of cells. Mitochondria convert nutrients into energy and also perform many other specialized tasks.

Mitochondrial dysfunction: Dysfunction means that something is not working or functioning in the correct way. Mitochondrial dysfunction refers to a situation in which the mitochondria are not working properly.

Monoamine: A monoamine is a molecule that contains one amine group. An amine is an organic compound containing nitrogen. Monoamines that are found naturally in the body are called biogenic monoamines. The body uses these as neurotransmitters. They include dopamine, serotonin, noradrenaline and epinephrine.

Monotherapy: Monotherapy refers to the use of a single drug to treat a disease. The opposite of this is combination therapy, where more than one medication is used.

Motor fluctuations: Motor fluctuations occur when levodopa is used to treat Parkinson’s disease. As the disease becomes worse, the number of cells in the brain that store dopamine decreases, the symptoms of Parkinson’s disease worsen, and levodopa is not as effective in controlling the symptoms. When this happens, a person is said to have “on” and “off” episodes.

Motor symptoms: The motor symptoms of Parkinson's disease include tremor, stiffness (called rigidity), slowness or absence of movement (called bradykinesia or akinesia, respectively), and difficulty maintaining balance or unstable posture.

Multiple sclerosis (MS): MS is a disease of the central nervious system that becomes worse over time (progressive). In people with MS, the fatty coating that insulates nerves is destroyed. Myelin is a fatty substance that wraps around axons, which are the part of the nerve cell that carries information from one nerve cell to another neuron. The loss of myelin decreases the speed with which neurons can send information to other nerves. People with MS may develop paresthesias, such as numbness or tingling; muscle weakness and stiffness; impaired coordination; abnormal reflexes; an inability to control urination (urinary incontinence); slurred speech; and visual disturbances.

Multiple Sleep Latency Test (MSLT): The MSLT is used to measure how likely a person is to fall asleep. The test takes place over a seven-hour period during the day. Every two hours, for 20 minutes, the patient lies in a quiet dark room and is hooked up to a machine that measures brain waves, heart rate, muscle activity, and eye movements. This recording allows the doctor to see how quickly the patient falls asleep in this situation or if the patient falls asleep at all.

Multiple System Atrophy: MSA is a rare, neurodegenerative movement disorder. The main symptoms include ataxia, and problems with the autonomic nervous system.

Muscle tone: Muscle tone is the amount of tension or resistance to movement in a muscle.

Mutated: Changed

Mutation: A mutation is a change in a gene, such as loss, gain, or substitution of genetic material. This change alters the gene’s function or expression. This change is passed along with subsequent divisions of the affected cell. Gene mutations may occur randomly for unknown reasons or may be inherited.

Myelin: Myelin is a fatty substance that wraps around axons. Myelin insulates the axons which allow nerve signals to be sent more rapidly.

Myelinated: Myelinated means that an axon or long nerve fiber is covered in myelin, which is a fatty insulator. Myelin insulates the axons, helping them to send rapid nerve signals.

Myoclonic: Myoclonic refers to myoclonus or irregular, involuntary, shock-like contractions or spasms of a muscle or muscle group.

Myoclonus: Myoclonus is a neurologic movement disorder characterized by brief, involuntary, twitching or "shock-like" contractions of a muscle or muscle group. Myoclonus can be found along with other neurologic disorders or it can be present by itself. Depending on its cause, the muscle jerks can occur repeatedly or infrequently. They also may tend to occur only during specific circumstances. The muscle jerks can affect any body region or regions.

Narcolepsy: Narcolepsy is a sleep disorder marked by sudden, uncontrollable urges to sleep that cause a person to fall asleep at inappropriate times.

Nasoduodenal tube: A nasoduodenal tube is a flexible rubber tube that is inserted through the nose and into the section of the small intestine closest to the stomach (duodenum) via the esophagus and stomach. It can be used to remove the contents of the small intestine or to provide nutrition support or medication.

Nasolaryngoscopy: Nasolaryngoscopy is an in-office procedure during which the doctor looks at the larynx or voice box. During this procedure, the doctor inserts a laryngoscope through the patient’s nose into the throat.

National Institutes of Health (NIH): The NIH is one of the world’s foremost medical research centers and the federal focal point for medical research in the United States. The NIH, comprising 27 separate Institutes and Centers, is one of eight health agencies of the Public Health Service, part of the U.S. Department of Health and Human Services.

Nausea: Nausea is a feeling of discomfort in the stomach that people feel before they vomit. A person does not have to vomit though in order to have nausea.

Necrosis: Necrosis means cell death. Necrosis may result from a loss of blood supply (ischemia), infection, excessive exposure to harmful radiation, certain chemicals, or extreme temperatures.

Neoplastic: Neoplastic refers to the formation of a neoplasm, which is another word for a tumor. A neoplasm is simply uncontrolled growth of cells. Neoplasms may be benign (non-cancerous) or malignant (cancerous).

Nerve conduction velocity (NCV) test: A NCV test is a diagnostic study during which both sensory and motor nerves are repeatedly stimulated with electricity. This measures the speed at which nerve impulses are conducted. Unusually slow speeds or conduction velocities suggest damage to nerve fibers.

Nervous system: The nervous system of the human body is divided into two interconnected systems: the central nervous system, which is made up of the brain and spinal cord, and the peripheral nervous system. The peripheral nervous system is further divided into the somatic nervous system (made up of peripheral nerve fibers that send sensory information to the central nervous system and motor nerve fibers that connect to skeletal muscle) and the autonomic nervous system.

Neuroacanthocytosis: Neuroacanthocytosis, also known as choreoacanthocytosis, is a rare, genetic disorder that most often becomes apparent between the ages of 25 to 45 years. The disorder is usually transmitted as a recessive trait. Symptoms include chorea; dystonia affecting muscles of the mouth and tongue; potentially mutilating lip- and tongue-biting; and sudden, involuntary, repetitive muscle movements (motor tics) and vocalizations (vocal tics). Patients may also develop personality changes and declines in the ability to think and reason, seizures, parkinsonism, loss or wasting (atrophy) of muscle tissue (amyotrophy), and difficulties speaking and swallowing.

Neurochemical: Neurochemical refers to the chemical and its biochemical processes of the nervous system. This includes activities that involve neurotransmitters, which are chemical messenger made by the body. Neurotransmitters enable nerve cells (neurons) to communicate.

Neurodegenerative: Neurodegenerative is a term that means neurologic degeneration. Neurologic degeneration is when the tissue in the nervous system is destroyed.

Neuroimaging: Neuroimaging is any technique that produces images of the brain and spinal cord. These images can be used to do research or help make a diagnosis or a treatment decision. Neuroimaging includes CT scanning, MRI, and PET scanning.

Neuroleptic: A neuroleptic is a drug used to treat psychiatric disorders, especially psychotic behavior.

Neuroleptic malignant syndrome: Neuroleptic malignant syndrome is a life-threatening neurologic disorder. It is usually caused by a reaction to neuroleptic drugs. Symptoms include high fever, sweating, unstable blood pressure, coma-like state, muscular rigidity, and problems with the autonomic nervous system. In most people, the disorder develops within the first two weeks of treatment with the drug; however, the disorder may develop any time during the therapy period.

Neurologic: Neurologic refers to the nervous system. The nervous system is made up of the brain, spinal cord and nerves throughout the body. It can also refer to neurology. This is the medical specialty that deals with disorders of the nervous system.

Neurologist: A neurologist is a doctor who diagnoses and treats diseases of the nervous system. The nervous system is made up of the brain, spinal cord and all the nerves in the body.

Neuron: A neuron is a nerve cell. It is the smallest unit within the nervous system, which is made up of the brain, spinal cord and all the nerves in the body. A neuron can send and receive information by using either electrical or chemical signals. This information is passed from one neuron to another neuron or to a body part using these signals.

Neuronal: Neuronal is a term that means something involves a neuron or neurons.

Neuropathology: Neuropathology is the study of diseases in the nervous system. The nervous system is made up of the brain, spinal cord and all of the nerves in the body.

Neuroprotection: A neuroprotective effect means that something has the ability to prevent or slow down the death of neurons—thus protecting the nervous system.

Neuroreceptor: A neuroreceptor is a specific place on a neuron. This is where neurotransmitters attach themselves or bind. After the neurotransmitters bind, they cause signals to be sent to other neurons.

Neurotoxin: A neurotoxin is a substance that interferes with the electrical activity or functioning of nerve cells (neurons). This prevents them from communicating with each other.

Neurotransmitter: A neurotransmitter is a chemical substance that is made in the body, allowing for nerve cells to communicate. It is the chemical messenger sent from one nerve cell to another.

Neutralizing antibodies: Neutralizing antibodies are proteins made by the body's immune system to fight off foreign substances, such as bacteria or foreign proteins. They bind to and inactivate the foreign substance. Some people may develop them in response to injection with BoNT. Some of these may cause BoNT to be ineffective or neutralized, since they neutralize the effect of the toxin.

Nigrostriatal system: Nigrostriatal system refers to a system that connects two areas in the brain. These two areas are called the substantia nigra and the striatum.

Nocardia asteroides: Nocardia asteroides are gram-positive bacteria that are found in soil throughout the world. Infections usually occur in the skin following contamination of a scrape or scratch; the infection can spread when a person with a compromised immune system inhales the bacteria. The primary site of infection is typically the lungs, where abscesses form. The infection may spread to other parts of the body, including the brain, liver and kidneys.

Nocturnal Sleep Dysfunction: Nocturnal means at night. Sleep dysfunction refers to basically anything that affects or interrupts sleep. Nocturnal sleep dysfunction can be caused by Parkinson disease, for example. It can also be caused by sleep disorders such as insomnia, restless legs syndrome, rapid eye movement sleep behavior disorder or sleep apnea.

Nomenclature: Nomenclature is a system of names used in a particular scientific field. This allows scientists to order or classify the things in their field. By using nomenclature, people can avoid confusion and misunderstandings.

Non-ergotoline medication: A non-ergotoline medication is a dopamine agonist that acts like a drug made from an ergot, although it is not an ergot. They are used to treat neurologic movement disorders.

Non-kinesigenic: Non-kinesigenic means that movement does not cause something. This term often refers to abrupt episodes of involuntary movement that occur spontaneously or may be worsened by fatigue, stress, alcohol or caffeine intake, heat or cold, fasting or other factors.

Nonmotor symptoms: Non-motor signs and symptoms of Parkinson disease include general lack of interest (apathy), anxiety, bladder problems, constipation, dementia, depression, fatigue, excessive sweating, numbness, pain, psychosis, sexual dysfunction, excessive drooling and sleep disorders.

Noradrenaline (norepinephrine): Noradrenaline is a hormone and neurotransmitter made in the body. When it is released noradrenaline acts in the sympathetic nervous system. The release of noradrenaline causes breathing to deepen, and blood pressure and heart rate to rise. It also plays a role in regulating mood.

NREM sleep: Non-REM (non-rapid eye movement) sleep is one phase of the sleep cycle. NREM sleep is a lighter sleep where there are no dreams. The majority of sleep is spent in NREM sleep.

Nuclear envelope: The nuclear envelope is a membrane that surrounds the nucleus in cells, separating the DNA in the nucleus from the rest of the cell.

Nucleic acids: Nucleic acids are molecules that carry human genetic information. The most common nucleic acids are DNA and RNA. These molecules were named nucleic because scientists first found them in the nucleus of the cell. More recently, however, scientists have also found these molecules outside the nucleus of cells.

Nucleus: The nucleus is the part of the cell that contains the genetic material; it is surrounded by the nuclear envelope.

Obsessive-compulsive behaviors: Obsessive-compulsive behaviors are repetitive actions or rituals that a person must perform because of persistent thoughts or impulses. For example, obsessions may consist of repeated doubts, such as wondering whether the stove was left on; a need for routine; or impulses to perform certain inappropriate actions. Compulsions frequently include repeated checking and rechecking, such as ensuring that the stove is indeed off; touching particular objects in a specific pattern or sequence; or repetitive hand washing. These compulsions are performed in an attempt to prevent or relieve anxiety, distress, or a feeling of dread. These behaviors can interfere with the normal activities of daily living and quality of life.

Obstructive sleep apnea: Obstructive sleep apnea is a sleep disorder characterized by the temporary stopping of breathing, along with blockage of the airway (usually by soft tissue in the throat). These episodes occur throughout the night. People with sleep apnea are frequently tired during the day, as their sleep is interrupted by these episodes.

Oculomotor: Oculomotor refers to movement of the eyes.

Off episodes: Off episodes is a term used to describe the times when people with Parkinson's disease have a decrease in the ability to move (hypomobility) and other symptoms that can cause difficulty rising from a chair, speaking, walking or performing their usual activities. Off episodes occur because the person's dose of levodopa and its beneficial effects have “worn off” too soon or have suddenly and unexpectedly stopped providing benefit.

Off time: Off time is a term used to describe those times when people with Parkinson's disease have a decrease in the ability to move (hypomobility) and other symptoms that cause difficulty rising from a chair, speaking, walking or performing their usual activities. Off episodes occur because the person's dose of levodopa and its benefical effects have worn off too soon or have suddenly and unexpectedly stopped providing benefit.

Olivopontocerebellar atrophy (OPCA): OPCA is a group of rare hereditary disorders characterized by neurodegenerative changes of certain brain regions, including the cerebellum and specialized groups of nerve cells in the brainstem (e.g., olivary and pontine nuclei). With most forms of OPCA, initial symptoms become apparent from adolescence to mid-adulthood; however, a rare form has been identified that may be obivious at birth. Depending upon the type of OPCA, symptoms may include progressively impaired coordination, postural instability, slurred speech (dysarthria); parkinsonism; rapid, involuntary, rhythmic eye movements (nystagmus); and/or problems with the eyes (retinal degeneration). Some affected individuals may also have additional symptoms and findings, such as involuntary, rapid, jerky movements (chorea); relatively slow, writhing motions that appear to "flow" into one another (athetosis); increased muscle stiffness (rigidity) with twisting or distorted positions of affected muscles (dystonia); and/or other abnormalities. Most forms of OPCA are inherited as dominant traits; however, recessive forms have also been identified.

On time: Motor fluctuations occur when levodopa is used to treat Parkinson’s disease. As the disease becomes worse, the number of cells in the brain that store dopamine decreases, the symptoms of Parkinson’s disease worsen and levodopa is not as effective in controlling the symptoms. When this happens, a person is said to have “off” episodes. The times in which the levodopa is effective and the person with Parkinson’s disease is able to function normally is called “on time.”

On-off phenomenon: On-off phenomenon is a change that occurs because of Levodopa treatment. There is a sudden change in a person’s ability to move around. A person goes from being able to move with ease, “on”, to having difficulty with movement, “off.” It is very difficult to predict when this change will occur.

Opiate: An opiate is any preparation of opium.

Opioids: Opioid means "like or similar to opium" and refers to medications with opium-like effects. This term is used to describe any man-made drug that possesses the properties of opiate narcotics but is not actually made from opium.

Organic: An organic disease or disorder is caused by a problem with the function or structure of tissue or one or more organs of the body.

Orthostatic hypotension: Orthostatic hypotension is a particular kind of blood pressure drop. It happens when a person is lying or sitting down. When the person stands up then, the blood pressure drops a lot. This can cause dizziness or even fainting.

Otolaryngology: Otolaryngology is a medical specialty that studies and treats diseases of the ear, nose and throat.

Oxidative stress: Oxidative stress is a process in which substances called free radicals build up in the cells as the cells convert nutrients into energy. The free radicals damage different parts of the cells in a process that is similar to the way in which rust builds up on metal. The free radicals can be counteracted by antioxidants, but if your cells do not have enough antioxidants, the free radicals accumulate and cause damage. Coenzyme Q10 acts as a hunter of free radicals.

Palate: The palate is the bony and muscular structure that forms the roof of the mouth and separates the mouth and nose cavities.

Pallidotomy: A pallidotomy is a surgical procedure that destroys the globus pallidus, a structure in the brain. Pallidotomy can be used to treat tremor and rigidity in Parkinson’s disease. It is rarely recommended anymore, and has been largely replaced by deep brain stimulation.

Parallel-group study: In a parallel-group study, each participant is assigned to receive a single treatment. This is opposed to a cross-over study, in which participants receive some or all of the treatments.

Paranoia: Paranoia is elaborate and overly suspicious thoughts and feelings of being bullied or singled out.

Parasympathetic nervous system: The parasympathetic nervous system is part of the nervous system that, together with the sympathetic nervous system, forms the autonomic nervous system (ANS). The ANS controls the functioning of involuntary structures, including the heart, glands and smooth muscle (like in the wals of the intestines, for example). The parasympathetic nervous system controls organs under normal conditions, as opposed to times of stress. It serves to "steady" involuntary activities and conserve or restore energy. Parasympathetic responses include slowing of the heart and breathing rates, contraction of the pupils, increase in glandular activity, and speeding up of the rate of digestion.

Parathyroid glands: The parathyroids are two pairs of glands located in the neck at the back of the thyroid gland. The parathyroid glands produce parathyroid hormone. The sole function of parathyroid hormone is to increase the level of calcium in the blood. When blood calcium levels are high, the parathyroid glands reduce their production of parathyroid hormone, essentially reversing the process.

Paresthesias: Paresthesias are abnormal sensations that occur spontaneously or in response to stimulation. Paresthesias may include prickling, tingling, burning, or tickling feelings; numbness; "pins and needles"; or cramp-like sensations. Various neurologic movement disorders may be characterized by paresthesias, including restless legs syndrome (RLS), paroxysmal kinesigenic dyskinesia (PKD), and paroxysmal non-kinesigenic dyskinesia (PNKD).

Parkinson's disease (PD): PD is a disorder of the central nervous system characterized by slowness of movement (bradykinesia), rigidity, difficulty with balance and a tendency to fall, and tremor primarily while at rest. Additional characteristic findings include a shuffling, unbalanced manner of walking; forward bending or flexion of the trunk; a fixed or "mask-like" facial expression; weakness of the voice; abnormally small, cramped handwriting (micrographia); depression; anxiety; musculoskeletal pain; or other symptoms and findings. PD is a progressive disease, meaning it gets worse over time. Loss of nerve cells (called neurodegeneration) in a part of the brain called the substantia nigra is thought to cause most of these abnormalities. Because of the damage to the substantia nigra, there is a decrease in the amount of dopamine, a neurotransmitter, available in the brain. Other parts of the brain may also be affected in later stages of the disease, including those responsible for thinking and planning. Loss of nerve cells in these areas may lead to dementia.

Parkinsonism: Parkinsonism is a term that refers to a group of symptoms: tremor, rigidity, bradykinesia, and postural instability. These are usually seen in Parkinson’s disease, but there are other diseases that cause parkinsonism. Certain drugs can also cause this, and are usually reversible once the drug is stopped.

Paroxysmal: Paroxysmal refers to paroxysms, which are sudden, recurrent episodes. Paroxysm usually describes an episode of involuntary, abnormal movement that comes and goes. It can also describe ataxia, where a person loses the ability to coordinate voluntary movements.

Paroxysmal movement disorders: Certain neurologic movement disorders characterized by abrupt, temporary episodes of abnormal involuntary movements, such as chorea, athetosis, dystonia, and/or ballismus (i.e., the paroxysmal dyskinesias), or impaired coordination of voluntary actions and other associated findings (i.e., paroxysmal ataxias). Depending upon the specific disorder present, episodes may be brought on or worsened by different factors such an environmental stress, sudden noises, exercise, etc.

Pathogenesis: Pathogenesis refers to the origin and development of a disease.

Pathophysiology: Pathophysiology is the study of how disease affects body functions.

Patient registry: A patient registry is a list of people who have a specific disease. This list allows researchers and doctors to contact people who have an illness or disease to see if they want to participate in clinical studies. The information on a patient registry is not available to anyone other than the researchers, and patient privacy is always protected.

Penetrance: Penetrance is the regularity or frequency with which a specific gene produces its effect or "is expressed." For example, if a specific gene produces a disease in all individuals who carry the gene, it is termed 100% penetrant. If a gene produces the disease less than 100% of the time, it is not fully penetrant.

Peptide: Peptides are short chains of amino acids, the building blocks of protein.

Pericardium: The pericardium is the two-layered sac that surrounds and protects the heart. If the pericardium becomes fibrotic or filled with fluid, it limits the motion of the heart and its ability to efficiently pump blood to the rest of the body.

Periodic apnea: Periodic apnea is a disease where people experience episodes during which they stop breathing.

Periodic limb movements in sleep (PLMS): Periodic limb movements of sleep are regular rhythmic twitches of the limbs that occur during sleep. The twitches usually affect the legs but they also sometimes affect the arms. The twitches usually last between half a second and five seconds and usually occur every five to 90 seconds. The diagnosis of periodic limb movement disorder is based on the results of an overnight sleep study. If the person has five or more series of limb movements per hour of sleep, a diagnosis of periodic limb movement disorder is confirmed.

Perioperative setting: The perioperative setting is the time before, during and after an operation.

Peripheral edema: Peripheral edema is an unusual fluid accumulation, resulting in swelling of the arms or legs.

Peripheral nervous system: The peripheral nervous system is that portion of the nervous system outside of the brain and spinal cord (central nervous system)

Peripheral neuropathy: Peripheral neuropathy is inflammation, gradual loss of funcition or damage of nerves of the peripheral nervous system (PNS). The PNS includes nerves that extend from the brain and spinal cord (central nervous system) to various parts of the body. Peripheral neuropathy may involve motor nerves, causing muscle weakness, and/or sensory nerves, resulting in pain, abnormal sensations, such as numbness or tingling.

Peristalsis: Peristalsis is the rhythmic, wave-like contractions of smooth or involuntary muscle fibers that propel food through the digestive tract.

Phenomenology: Phenomenology is the classification based on a scientific explanation.

Phenylalanine: Phenylalanine is an essential amino acid that is converted in the body to tyrosine.

Phenylketonuria: PKU is an inherited disorder that, if untreated, causes profound mental retardation as well as other medical problems.

Phonation: Phonation is the production of speech.

Physiatrist: A physiatrist is a physician specializing in physical medicine and rehabilitation.

Physiologic tremor: A physiologic tremor is a form of rapid tremor that may occasionally occur in any individual. Physiologic tremor is typically the result of fear, anxiety or excitement. Physiologic tremor may affect the arms, legs, and, in some patients, the face or neck.

Pill-rolling tremor: To understand what a pill-rolling tremor looks like, imagine a person holding a pill between her first finger and thumb and slowly moving it back and forth. People with Parkinson disease have this type of tremor when their hands are at rest. At first, it may affect only one hand, but over time, it may affect both hands or may alternate, at times affecting one and then the other hand.

Pittsburgh Sleep Quality Index: This 24-item, self-administered questionnaire is designed to provide a brief clinically useful assessment of a variety of sleep disturbances that might affect sleep quality.

Placebo: A placebo is a substance that appears to be identical to a medication or treatment but that has no drug effects in the body (physiologic effects) of a medication or treatment.

Placebo-controlled trial: A placebo-controlled trial is a clinical experiment in which patients have been randomly assigned to receive either the treatment under study or placebo, an alternative that has no effects.

Pleura: The pleura are the two-layer membranes that cover the outside of the lungs and line the chest cavity.

Polymerase chain reaction (PCR): PCR is a highly sophisticated laboratory technique during which a known sequence of DNA is copied rapidly over a short period, such as millions of copies over a few hours. PCR testing assists in diagnosing certain genetic disorders, helps identify individuals through analysis of a single cell or so-called "DNA fingerprinting" or characterizes certain strains of infectious microorganisms.

Positron emission tomography (PET): PET is an advanced, computerized imaging technique that uses radioactively labeled substances such as glucose to demonstrate chemical and metabolic activities in the brain functions. Brain structures are also visualized on PET scans.

Positron emission tomography (PET) scanning: PET scanning is a non-surgical, diagnostic procedure used to record the uptake and distribution of certain substances in the tissues and organs of the body. Thus, PET assists in evaluating various functions or activities in the body. PET scanning may help to detect abnormal biochemical patterns associated with certain neurologic conditions, such as Parkinson’s disease, brain tumors, seizure disorders and psychiatric abnormalities.

Postural instability: Postural instability is a difficulty with balance.

Postural tremor: Postural tremor is any tremor that is present while an individual voluntarily maintains a position against gravity, such as holding the arms outstretched.

Precursor: Precursor is something that comes before another. For example, amino acids are the building blocks of proteins.

Prenatally: Prenatally means before birth.

Prevalence: Prevalence refers to the number of people in a given group or population who have a disease.

Probe: A genetic probe is a single string of genetic material that can be used during laboratory tests to detect the presence of specific genetic material in cells that are being tested.

Progressive supranuclear palsy (PSP): PSP is a progressive neurologic disorder characterized by long-term changes of certain areas of the brain, including particular areas of the basal ganglia and the brainstem. Symptom onset most often occurs in the sixth decade of life. Symptoms may include balance difficulties, sudden falls, stiffness (rigidity), slowness of movement (bradykinesia), an impaired ability to perform certain voluntary eye movements and visual disturbances. Affected individuals may also develop slurred speech; swallowing difficulties; personality changes; dystonia; sudden, involuntary, "shock-like" muscle contractions (myoclonus); or other abnormalities. PSP usually occurs randomly for unknown reasons (sporadically); however, there are some reports of families with multiple affected members, suggesting a possible hereditary component to the disease.

Prophylactic: Prophylactic refers to preventive treatment (i.e., prophylaxis). A prophylaxis can either be a medication, procedure, or device that serves as a preventive against disease.

Prophylaxis: Prophylaxis is something that protects against or prevents disease.

Proteasome inhibitor: A proteasome inhibitor is a chemical that interferes with, or inhibits, the action of proteasomes—the recyclers of proteins in the cells.

Protein: Proteins are large complex molecules made up of amino acids. Each protein starts out as a chain of amino acids. Proteins serve many different roles within the body, including providing structure (collagen), allowing movement (actin and myosin), increasing the rate of a chemical reaction (enzymes), transporting substances (hemoglobin); regulating processes within the cells (insulin); and responding to the stimuli (receptor proteins on surface of all cells).

Proxy: A proxy is someone who is permitted to make decision on behalf of another person. This person may be a relative or friend.

Psychogenic: A psychogenic disorder has a mental or emotional origin. Psychogenic also refers to a symptom, condition, or disorder that is caused by mental, psychological or emotional factors rather than physical illness.

Psychosis: Psychosis is a thought disorder characterized by impaired ability to distinguish reality from fantasy, personality changes and deterioration of normal social functioning. People with psychosis may experience hallucinations, illusions, or delusions or they may be paranoid or have distorted thinking.

Pulmonary: Pulmonary refers to the lungs.

Pulmonary fibrosis: Pulmonary fibrosis is a condition in which excessive scar tissue forms in the lungs, making them stiff, decreasing the amount of surface area that is available to provide gas exchange and interfering with their function.

Putamen: The putamen is a part, along with two others, of a structure in the brain known as the basal ganglia. The putamen receives information from the brain and sends it to other areas responsible for controlling complicated motor functions.

Randomized controlled : In a randomized controlled trial or study, participants are randomly assigned to different treatments or conditions to study the effectiveness of the treatment or condition.

Range of motion (ROM): ROM is how far a joint can move freely. The normal ROM of the elbow, for instance, moves the forearm through a half-circle. Passive ROM is tested while the limb is relaxed, and another person moves the joint. Active ROM is movement controlled by the patient.

Receptor: A receptor is one end of the nerve cell; it receives messages from other nerve cells. These messages are usually neurotransmitters sent by other nerve cells. Drugs, however, can affect receptors directly without using neurotransmitters.

Reduced penetrance: Reduced penetrance means that a genetic disorder may not appear (be fully expressed) as frequently as would be expected. . The term penetrance refers to the frequency with which a specific genetic mutation produces its effect (a genetic disorder, for example) in those with the genetic abnormality. If fewer than 100 percent of individuals who inherit a gene mutation for an autosomal dominant disorder develop the disease, the specific trait is said to have "reduced penetrance."

Reflex: A reflex is an involuntary, predictable response to a particular stimulus.

Refractory: Refractory means that something is resistant to treatment.

Regurgitation: In reference to the heart, regurgitation is the backward flow of blood through a defective heart valve.

REM sleep: Rapid Eye Movement (REM) sleep is one part of a sleep cycle. The eyes move around quickly, hence the name. This is the phase where dreaming occurs. During this phase, the body is paralyzed so that a person does not act out his dreams. Adults spend about 20% of their time in this phase.

REM sleep behavior disorder (RBD): During REM sleep, a person is normally paralyzed while dreaming. In RBD, a person is not paralyzed so he acts out his dreams. This can put the person or bed partner in danger of injury.

Resistance: Resistance means that the person receiving the injection is not obtaining the expected benefit from the treatment. This is also called treatment failure or non-response. There may be several reasons for this to happen. For example, the muscle being injected may not the one causing the biggest problems or the dose may be too low, or perhaps the patient may have developed neutralizing antibodies to some part of the BoNT molecules.

Restless legs syndrome (RLS): RLS is a neurologic movement disorder characterized by unusual, uncomfortable sensations (paresthesias/dysesthesias) deep within the calves and/or thighs. These sensations cause an irresistible urge to move the legs and motor restlessness an effort to alleviate discomfort. In some patients, the arms may also be affected. Symptoms become obvious or worse during periods of relaxation or inactivity; occur most frequently during the evening or the early part of the night; and may be temporarily relieved by voluntary movements of the affected area. Most patients experience associated sleep disturbances, including difficulties drifting off to and remaining asleep. RLS is also often associated with periodic limb movements of sleep (PLMS).

Restorative sleep: Restorative sleep is refreshing sleep. This means that a person receives a sufficient amount of rest to feel refreshed and to engage in the activities of daily living without experiencing excessive daytime sleepiness (EDS).

Retina: The retina is the nerve-rich membrane that forms the innermost region of the eye. As light passes through other areas of the eye (including the cornea, pupil, and lens), it is bent to focus on the retina, which contains nerve cells that respond to light (photoreceptors). Images formed on the retina are converted into nerve impulses that are transmitted to the brain via the optic nerve.

Retinal: Referring to the retina, which is the nerve-rich membrane forming the innermost region of the eye. As light passes through the eye, it is bent (refracted) to focus on the retina, which contains photoreceptors or specialized nerve cells that respond to light. Images formed on the retina are converted into nerve impulses, which are then transmitted to the brain by the optic nerve.

Retrocollis: Retrocollis is spasmodic torticollis in which the head is drawn backward.

Retroperitoneum: The retroperitoneal area is the area behind peritoneum, the covering of the intestines. The kidneys and the adrenal glands lie in the retroperitoneal area.

Reye syndrome: Reye syndrome is a potentially life-threatening disease characterized by a sudden inflammation and swelling of the brain and fat accumulation in organs. It normally occurs in children and adolescents who have certain viral infections. A component of aspirin can cause Reye syndrome so doctors advise that aspirin should never be given to babies, children, or adolescents.

Rhythmical myoclonus: Rhythmic myoclonus is an involuntary, shock-like contractions or spasms of a muscle or muscle group that occur in a predictable pattern. This usually occurs as a result of damage in the central nervous system.

Ribonucleic acid (RNA): RNA is a chemical that is found in the nucleus and fluid into cells (cytoplasm); it plays an important role in the manufacturing of proteins and other chemical activities of the cell.

Ribosomes: Ribosomes are small structures within a cell that are the site of protein manufacturing.

Rigidity: Rigidity is stiffness or resistance to movement. It is one of several motor symptoms in Parkinson’s disease.

Rush Hallucination Inventory: This standardized clinician-administered questionnaire assesses the presence or absence of false visual (see), auditory (hear), tactile (touch), or gustatory (taste) experiences.

Sandhoff's disease: A rare, neurodegenerative metabolic disorder that is characterized by symptoms and findings similar to those associated with Tay-Sachs disease, along with abnormal enlargement of the liver and spleen (hepatosplenomegaly). Sandhoff's disease is a storage disease in which certain fats build up in particular tissues of the body called lysosomes. The disorder is transmitted as an autosomal recessive trait

Schizophrenia: Schizophrenia is a psychiatric disorder characterized by hallucinations, delusions, disordered thinking, unusual speech or behavior and social withdrawal. This disease impairs the person’s ability to interact with others.

Scoliosis: Scoliosis is a sideways curving of the spine. Normally the spine is arranged in a vertical line. The severity of this deformity varies, depending upon the degree of weakness, the underlying disease that may have caused the condition, or other factors.

Seborrhea: Seborrhea is an increased amount of the oily substance that is produced in the sweat glands of the skin. It causes the skin to glisten or appear shiny.

Sedation: Sedation is a state of quiet or sleep that is brought on by medications, for example.

Seizures: Seizures are episodes of uncontrolled electrical activity in the brain. These abnormal electrical disturbances may lead to involuntary jerking, spasms, or rhythmic contraction and relaxation of certain muscle groups and impaired control of involuntary functions such as breathing or bladder or bowel control. There may also be loss of consciousness or sensory or behavioral abnormalities.

Sensorimotor: Sensorimotor relates to both the sensory and motor aspects of a bodily function.

Sequelae: Sequelae is the plural form of the word sequela. Sequela is any abnormal condition that is caused by disease, injury or treatment.

Sequence: As a noun, a sequence is a series of chemical bases—adenine (A), thymine (T), cytosine (C) and guanine (G)—in DNA or a string of amino acids in a protein. As a verb, sequence refers to the process of determining the order of the bases or amino acids.

Serotonin (3-[2-aminoethyl]-5-indolol): Serotonin functions as a neurotransmitter, regulating the delivery of messages between certain nerve cells. This neurotransmitter is thought to play some role in regulating consciousness and mood states. Serotonin also causes blood vessels to constrict (as opposed to expand) and found in relatively high concentrations in parts of the central nervous system. Serotonin is also present in other tissues of the body such as the intestines and blood platelets.

Serotype: Serotype refers to a form of a substance, distinguished by certain kinds of lab tests. Part of the word refers to blood serum, and indicates that the different forms of the substance provoke different reactions in the bloodstream involving the body's immune system.

Sexual dysfunction: Sexual dysfunction is any problem with sexual activity. It could be a problem with desire, arousal or orgasm. In men, it usually means having problems with erections.

Sialidosis: Sialidosis is a type of “storage disease” (lysosomal storage disease) where a unusual lack or deficiency of a certain enzyme causes accumulation of complex carbohydrates in tissues and organs. Symptoms include a cherry red spot in the middle layers of the eye and “shock-like” contractions (myoclonus) of the arm and leg muscles. Sialidosis is an autosomal recessive trait.

Sialorrhea: Sialorrhea means having too much saliva. It causes a person to drool. It could be because a person makes too much saliva. It could also be because a person has problems swallowing, and the saliva stays in the mouth.

Side effect: A side effect is a consequence or one possible end result of a drug, but not the main or intended effect. Side effects may be of no concern, or they may be bothersome or even dangerous. They may limit the amount of a drug (upper dose) that a person can take at one time. Side effects are also called adverse effects.

Single photon emission computed tomography (SPECT): SPECT is a noninvasive scanning procedure during which a radioactive substance known as a radionuclide is introduced into the body to help evaluate the function and structure of certain organs or tissues. The amount of the substance taken up by particular tissues may depend upon the amount of blood flow within such regions. By evaluating the blood supply to particular tissues, SPECT may be particularly helpful in detecting certain changes within the central nervous system or the heart.

Sinus bradycardia: Sinus bradycardia is an abnormally slow heart rate (i.e., of less than 60 beats per minute).

Sleep fragmentation: Sleep fragmentation is a continual disruption or interruption of sleep, which often leads to excessive daytime sleepiness. This disruption can occur as the result of a variety of factors, including sleep disorders, the need to get up to use the bathroom, pain and a noisy or uncomfortable sleeping environment.

Sleep latency: Sleep latency is the period of time between "settling in" to go to sleep and the beginning of actual sleep

Sleep maintenance: Sleep maintenance is once asleep, the ability to stay asleep.

Sleep paralysis: Sleep paralysis is a total inability to move that occurs while a person is falling asleep or immediately upon awakening.

Sodium Oxybate: Sodium oxybate is also known as gamma hydroxybutyrate or GHB. This clear odorless liquid was approved by the US Food and Drug Administration in 2002 for the small number of people who have narcolepsy with cataplexy. Because of the high potential for abuse and misuse, the drug is only available from a single central pharmacy and its distribution is tightly controlled.

Somatization disorder: A person with a somatization disorder has symptoms that mimic or look like those of a disease or injury but for which there is no physical cause or basis. Although somatization disorders are likely caused by a psychological factor(s), these disorders are not the result of the person deliberately producing or exaggerating symptoms.

Spasm: A spasm is an uncontrollable and sudden tightening of a muscle or group of muscles.

Spasmodic dysphonia (SD): SD is a type of dystonia. SD involves the muscles of the voice box (larynx) and the surrounding muscles. Speech is affected. . In people with SD, speech is blocked or strained by intermittent spasms of the voice box.

Spasmodic torticollis (ST): ST is a type of dystonia involving the muscles of the neck; it is also known as cervical dystonia. Abnormal, involuntary muscle pulling or contractions of the neck muscles can cause the head to be turned, tilted, leaning forward toward the chest, pulled back toward the back, or any combination of these postures.

Spasmolytic: Spasmolytic is also known as an antispasmodic. These refer to drugs that help stop or relieve muscle spasms.

Spasticity: Spasticity is an abnormal increase in muscle tone that may be caused by damage to the nerve pathways that control muscle movements. Spasticity is common in children and adults with cerebral palsy, brain injuries, spinal cord injuries, multiple sclerosis and stroke. Spasticity can lead to lack of coordinated, loss of function, difficulties with activities of daily living and self-care, discomfort and pain, and possible positioning of a joint in a fixed position (contracture).

Speech pathologist: A speech pathologist is a person who diagnoses and treats problems with speech and language. This includes disorders that affect voice, swallowing or communication.

Speech therapist: A speech therapist is a professionally trained person who helps people with speech, language, communication and swallowing problems.

Spinal cord: The spinal cord is a bundle of nerve tissue that is protected by the spinal column. The spinal cord and brain together make up the central nervous system. The spinal cord is made up of a core of gray matter surrounded by bundles of nerve fibers wrapped in a fatty insulator known as myelin. These bundles are arranged into tracts that carry sensory information up to the brain and motor information down from the brain. Nerves come out from both sides of the spinal cord through gaps in the spinal column. These spinal nerves contain both motor and sensory nerve cells.

Spinocerebellar ataxias (SCA): SCA is a group of disorders in which each is inherited as an autosomal dominant genetic trait. All types of SCA involve degeneration of the cerebellum, causing impaired balance, walking, and coordination. Each type of SCA has its own typical pattern of symptoms; however, these may vary greatly from person to person. Some forms of SCA affect eye movements, swallowing, thinking, reflexes, or cause parkinsonism, chorea, or dystonia. In most types of SCA, the onset of symptoms occurs during adulthood. Symptoms slowly become worse over the years.

Sporadically: Sporadically means that something occurs intermittently, randomly, or in isolation.

SSRIs: SSRIs are antidepressant agents that increase the concentration of serotonin within the central nervous system.

Statistician: A statistician is a mathematician who studies data, analyzes it, and interprets it. This allows people to make sense of information collected.

Stereotactic: Stereotactic refers to use of precise coordinates to identify deep structures of the brain. The coordinates are obtained using a special frame fitted to the patient’s head. Then, an MRI or CT scan is taken to produce a three dimensional image. These methods are used during brain surgery for tremor, Parkinson’s disease, and dystonia.

Stereotypic: Stereotypic means inappropriate, persistent repetition of particular bodily postures, actions, or speech patterns. These are typically involuntary, rhythmic, coordinated, and purposeless movements, postures, or vocalizations that may appear like a habit or purposeful in nature. Stereotypies may be associated with a variety of neurologic and behavioral disorders, such as Tourette syndrome, obsessive-compulsive disorders, Rett syndrome, restless legs syndrome, schizophrenia, and autism.

Stereotypical: Something that is stereotypical means that there is a recurring repetitive pattern as in repetition of particular movements or gestures.

Stimulus: A stimulus is something that creates a response in a muscle, nerve, gland or other excitable tissue or organ of the body. The plural is stimuli.

Stretch reflex: Stretch reflex is when a muscle is rapidly stretched and this causes tightening or contraction of that muscle. It is a reflex, not under voluntary control.

Stretch-loop circuits: Stretch-loop circuits are pathways of electrical signals along specific nerve fibers. These nerve fibers are arranged so that when a muscle is stretched, the nerves fire triggering a reflex contraction of the muscle.

Striatum: The striatum is an area of the brain that controls movement and balance. It is connected to and receives signals from the substantia nigra.

Study group: A study group can also be called a working group. The members of the study group meet regularly to discuss a specific topic. They also work together to design research studies.

Substantia nigra: The substantia nigra is a dark band of gray matter deep within the brain where cells manufacture the neurotransmitter dopamine for movement control. Loss of cellular function in this region may lead to a neurologic movement disorder such as Parkinson's disease.

Substrate: A chemical substance that is broken down or changed by an enzyme is called a substrate.

Subthalamic nucleus: The subthalamic nucleus is part of the brain consisting of an oval mass of gray matter located beneath the thalamus.

Sydenham's chorea: Sydenham’s chorea is a rare disorder condition where unwanted jerking movements develop, usually after the onset of an inflammatory disease called rheumatic fever, which is caused by a specific type of bacteria. If rheumatic fever involves the central nervous system, Sydenham’s chorea may develop. It most commonly affects children from 5 to 15 years old or pregnant women. In most people, the condition spontaneously resolves in weeks or months.

Sympathetic nervous system: The sympathetic nervous system is part of the nervous system that along with the parasympathetic nervous system forms the autonomic nervous system (ANS). The ANS regulates the functioning of involuntary structures, such as the glands, smooth muscle and heart. The sympathetic nervous system regulates certain responses during times of strong emotion, such as fear, anger, exercise or other forms of stress. These responses, sometimes referred to as the "fright-or-flight response," include widening of the pupils; increased heart and breathing rates; constriction of most blood vessels, raising blood pressure; widening of those blood vessels that supply skeletal muscles; and reduction in the rate of digestion.

Synapse: A synapse is the space between two neurons or between a neuron and the organ that it influences (effector organ).

Synthesis: Synthesis is the “making” or formation of a complex chemical compound through the union of simpler substances.

Systemic lupus erythematosus (SLE): SLE is an inflammatory disease involving the attack by the body’s immune system on one’s own organs. Some symptoms and findings are common to most people who are diagnosed with SLE (e.g., butterfly rash on the face). SLE is also associated with specific antibodies.

Tardive dyskinesia: Tardive dyskinesia is a movement disorder that may result from long term therapy with certain powerful drugs used to treat psychiatric disorders, such as haloperidol. The condition is characterized by involuntary, rhythmic movements of the face, jaw, mouth and tongue, such as lip pursing, chewing movements, or protrusion of the tongue. Facial movements are sometimes accompanied by involuntary, jerky or writhing motions (choreoathetoid movements) of the trunk, arms and legs. In some patients, symptoms discontinue months or years after withdrawal of their medication. However, in others, the condition may not be reversible.

Tardive dystonia: Tardive dystonia is a form of tardive dyskinesia characterized by chronic dystonia due to administration of certain powerful drugs used to treat psychiatric conditions. Dystonia is a neurologic movement disorder characterized by sustained muscle contractions that often result in repetitive twisting motions or unusual postures or positions. Tardive dystonia is the most common form of secondary dystonia, i.e., dystonia that results from certain environmental factors.

Tauopathy: Tauopathy refers to any group of diseases that cause dementia related to a problem with tau, a protein that is important in maintaining the structure of brain cells.

Tay-Sachs disease: Tay-Sachs disease is a storage disease, meaning that there are abnormal accumulations of certain unwanted substances within the cells (e.g., within the lysosomes). Tay-Sachs disease results from deficiency of a specific enzyme, which leads to an abnormal accumulation of certain fats in particular tissues, particularly nerve cells of the brain. An autosomal recessive disorder, Tay-Sachs disease primarily affects individuals of northeastern European Jewish (Ashkenazi Jewish) ancestry.

Tendon: A tendon is a tough fibrous cord of tissue that attaches muscle to bone.

Teratogenic: Teratogenic means that something has the ability to disrupt normal fetal development and causing fetal abnormalities.

Thalamotomy: A thalamotomy is a surgical procedure that destroys the thalamus, a structure in the brain. The thalamus is found deep inside the brain. Thalamotomy can be used to treat tremor and rigidity in Parkinson’s disease. It is rarely recommended anymore, and has been replaced by deep brain stimulation.

Thalamus: The thalamus is an area of the brain that relays information from most sensory organs (like sensors in the skin of the hands and feet) to the outer region of the brain. It receives and processes messages from the body concerning heat, cold, pain, pressure, and touch. The thalamus also influences motor activity of the cerebral cortex, the outer portion of the brain.

Threshold: A pain threshold is the point at which a feeling or sensation becomes painful.

Tics: Tics are involuntary, compulsive, repeated (stereotypical) muscle movements or vocalizations that abruptly interrupt normal movements, i.e., motor activities. These repetitive, purposeless motions (motor tics) or utterances (vocal tics) may be simple or complex in nature. A person feels the urge to perform a tic and finds temporary relief after the tic occurs. A person can temporarily suppress the tics until the urge becomes too great.

Tone: The tone of a muscle is the amount of tension or resistance in a muscle when it is moved around the joint by another person.

TorsinA: TorsinA is a protein that, when defective, may cause DYT-1 dystonia. Although its exact function is not known, TorsinA is believed to be related to a series of compounds that enable cells to recover from stress and injury.

Toxic metabolites: Toxic metabolites are potentially harmful substances formed as the result of normal body functions.

Toxin: A toxin is a poisonous substance that is produced by a plant or animal

Transdermal: Transdermal means, literally, through the skin.

Transient: Transient means temporary.

Tremor: A tremor is a rhythmic motion involving a specific part of the body--the hands, arms, neck, head, vocal cords, trunk or legs. The motion involves the muscles going back and forth, like a rocking chair. A person with a tremor cannot control it.

Tropical spastic paraparesis (HTLV-1-associated myelopathy): Tropical spastic paraparesis is a rare disorder characterized by slowly progressive weakness (paraparesis), stiffness (rigidity), and spasticity of the leg muscles due to infection with the human T-cell lymphotropic virus-1 (HTLV-1). Modes of transmission include sexual contact, mother-to-child transmission (e.g., via breastfeeding), and blood transfusion.

Tryptophan: Tryptophan is an essential amino acid.

Tyrosine: Tyrosine is a nonessential amino acid, which means the body can make it. From tyrosine, the body can make other biological compounds such as melanin, which gives skin its color.

Unified Parkinson Disease Rating Scale (UPDRS): The UPDRS is the most commonly used to tool to rate the symptoms of Parkinson disease. This scale is intended to be used to follow the course of Parkinson disease in patients over a period of time. It is made up of four parts: (1) mentation (the process of thinking), behavior, and mood; (2) activities of daily living; (3) motor symptoms, and (4) complications of therapy.

Unilateral: Unilateral refers to only one side, as in one side of the body.

Unverricht-Lundborg's disease (Baltic myoclonic epilepsy): Unverricht-Lundborg’s disease is a form of progressive myoclonic encephalopathy (PME). It is characterized by the development of repeated seizures or episodes of uncontrolled electrical activity of the brain (epilepsy); sudden, "shock-like" muscle contractions that may begin because of voluntary movements or in response to certain external stress or stimuli; and eventual impairment of coordination, instability while holding posture against gravity (standing, getting up), and other associated findings (e.g., cerebellar ataxia). The disease is inherited as an recessive trait. The disorder is slowly progressive; however, the degree of disease progression and disability may be extremely variable among affected family members. Symptom onset typically begins from about age 6 to 13.

Upper motor neurons: Upper motor neurons are nerve cells extending from the brain to the spinal cord. These neurons control movement.

Vaginosis: Bacterial vaginosis is an infectious disease associated with an abnormally increased growth of certain bacteria in the vagina.

Valine: Valine is an essential amino acid.

Variable expressivity: Variable expressivity refers to a genetic trait that changes how that trait will appear an individual. If a person has a disorder that has variable expressivity, the symptoms could range from mild to severe.

Vascular: Vascular refers to blood vessels.

Vasoconstrictor: A vasoconstrictor is a chemical that causes blood vessels to narrow. This will raise blood pressure.

Vasodilator: A vasodilator is a chemical that causes blood vessels to widen. This will lower blood pressure.

Vasomotor: Vasomotor is a term used to describe the system of nerves and muscles that control the diameter of blood vessels. Nerves send signals to muscles that surround blood vessels to narrow or widen the vessels. This will cause blood pressure to raise or lower.

Ventral intermediate (VIM) nucleus: VIM nucleus is a specific region of the thalamus. This area of the brain is involved in the control of movement. It is the "target" area for surgical removal of the thalamus (thalomotomy) and for deep brain stimulation when treating patients with tremor.

Ventriculography: Ventriculography is a brain imaging method that uses an injected dye and X-rays to visualize the brain's ventricles.

Virulent: Virulent refers to what degree a microorganism is able to produce disease. If a bacterium or virus is strongly virulent, it could either mean it is able to invade bodily tissues or cause severe disease.

Visual-analog scale: In this scale, there is a line that has numbers from one to ten. For example, patients may be asked, “On a scale of one to 10, how bad is your pain today.”

Washout: In a cross-over study, participants begin taking a placebo (like a sugar pill) or the study medication and then switch to the alternate “treatment.” To remove the effects of the first substance from the participants’ bodies, a period in which the participants receive no treatment is commonly used between the two treatments. This is called the washout period. A washout period may also be used at the beginning of a study in which participants have already been using a treatment for the condition under study to remove the effects of that treatment.

Wearing off: Wearing off is the return to PD symptoms earlier than expected after a dose of levodopa or other similar drug (dopaminergic agent). For example, a dose of levodopa might usually relieve your PD symptoms for six hours; wearing off occurs when the same dose lasts for only four hours. As time passes, the “on time” when the drug is working to relieve symptoms is shortened.

Wearing-off phenomenon: Wearing-off phenomenon is a decrease in how long levodopa works to relieve the symptoms of PD. Over time, the ON time, when the drug is working, is shortened. The OFF time, when the drug benefits are not present, comes back quicker the more times a person takes the drug.

White matter: Neurons are made up of three parts, the cell bodes, dendrites and axons. Axons can be covered in a sheath of fat, called myelin, to help the signals travel faster. Some neurons are covered in myelin and others are not, called unmyelinated axons. White matter is made up of axons that are coated in myelin. Gray matter contains unmyelinated axons.

Wilson disease: Wilson disease is a rare genetic disorder of copper metabolism, or its breakdown in the body. This causes excessive accumulation of copper in certain tissues and organs, including the liver, brain, kidneys, or corneas of the eyes. Neurologic findings may include tremor; involuntary, rapid, jerky movements combined with relatively slow, writhing movements (choreoathetosis); impaired muscle tone and sustained muscle contractions, producing repetitive movements and abnormal posturing; increasingly slurred speech; and difficulties swallowing.

X-linked dominant trait: Human traits, such as an individual's specific blood group, eye color, or expression of certain diseases, result from the interaction of one gene inherited from the mother and one from the father. In X-linked dominant disorders, the gene mutation for the disease trait is transmitted as a dominant gene on the X chromosome and therefore may "override" the instructions of the normal gene on the other chromosome, resulting in appearance/symptoms of the disease. Females often have less severe symptoms than affected males, because the second X chromosome “protects” females from having the full-blown version of the disease. In contrast, males have one X chromosome from the mother and one Y chromosome from the father; those who inherit an X-linked dominant disease trait typically have the full-blown version of the disease, with all its symptoms. The mutated gene on the X chromosome, therefore, causes a more severe form of the disorder. Fathers with an X-linked dominant trait transmit the gene to their daughters but not to their sons. Mothers with a single copy of an X-linked dominant gene have a 50 percent risk of transmitting the gene to their daughters as well as to their sons.

X-linked recessive trait: Human traits, such as a person's eye color, specific blood group, or expression of certain diseases, result from the interaction of one gene inherited from the mother and one from the father. In X-linked recessive disorders, the gene mutation for the disease trait is located on the X chromosome. Because males have one X chromosome from the mother and one Y chromosome from the father, those who inherit an X-linked recessive disease trait typically have most or all of the symptoms associated with the mutated gene on the X chromosome. Some females who carry a single copy of the disease gene (heterozygous carriers) may have certain symptoms associated with the disorder; however, such findings are usually more variable and less severe than those seen in affected males. Fathers with an X-linked recessive trait may transmit the gene to their daughters but not to their sons. Mothers with an X-linked recessive gene have a 50 percent risk of transmitting the gene to their daughters and their sons.

Zydis: Unlike drugs that are incorporated into pills or capsules that must be swallowed, Zydis drugs are incorporated into fast-dissolving, freeze-dried wafers that "melt" on the tongue. The term Zydis refers to the vehicle that is used for drug delivery and not to the drug itself.