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Dystonia is characterized by involuntary sustained muscle contractions that may make people freeze in the middle of an action or make the entire body, the trunk, or another part of the body twist or turn.
Causes
Dystonia seems to result from overactivity in several areas of the brain—the basal ganglia, thalamus, cerebellum, and cerebral cortex. Dystonia may result from a genetic mutation (called primary dystonia) or from a disorder or drug (called secondary dystonia). Antipsychotic drugs can cause various types of dystonia, including shutting of the eyelids, twisting of the neck (spasmodic torticollis) or back, grimacing, puckering of the lips, protrusion of the tongue, and writhing of the arms or legs.
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Causes of Dystonias |
Type
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Examples
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Disorders
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Cerebral palsy
Genetic disorders, such as generalized dystonia and dopa-responsive dystonia
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Multiple sclerosis
A severe lack of oxygen to the brain (which may occur at birth or later in life)
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Stroke
Toxicity due to accumulation of certain metals (such as copper in Wilson's disease)
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Drugs
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Antiemetics (such as metoclopramide and prochlorperazine)
Antipsychotic drugs (such as chlorpromazine, fluphenazine, haloperidol, and thiothixene)
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Types and Symptoms
Dystonias may affect one part (focal dystonias) or several parts (segmental dystonias) of the body. Sometimes they affect the whole body (generalized dystonias).
Focal and Segmental Dystonias:
Dystonias that affect one or several body parts typically start in a person's 30s or 40s and affect women more often. Initially, spasms may occur randomly or only during stress. Certain movements of the affected body part may trigger the spasms, which may disappear during rest. Over days, weeks, or many years, spasms may become more frequent and may continue during rest. Eventually, the affected body part remains distorted, sometimes in a painful position. Severe disability results. The following are examples of focal and segmental dystonias:
Generalized Dystonias:
Dystonias that affect the whole body include the following:
Treatment
Correcting or eliminating the cause of dystonia, if known, usually reduces the spasms. For example, drugs used to treat multiple sclerosis may reduce spasms related to that disease. When dystonia is due to use of an antipsychotic drug, promptly taking diphenhydramine by injection or by mouth usually stops the spasms quickly, and the antipsychotic is stopped.
For generalized dystonia, a drug with anticholinergic effects (such as trihexyphenidyl or benztropine) is most commonly used. These drugs reduce spasms by blocking specific nerve impulses involved in causing the spasms. However, anticholinergic effects also include confusion, drowsiness, dry mouth, blurred vision, dizziness, constipation, difficulty urinating, loss of bladder control, and tremor, which are troublesome, especially in older people. A benzodiazepine (a mild sedative) such as clonazepam, baclofen (a muscle relaxant), or both are also usually given. Baclofen may be given by mouth or by a pump implanted in the spinal canal. If generalized dystonia is severe or does not respond to drugs, tiny electrodes may be surgically implanted in the basal ganglia (a procedure called deep brain stimulation).
Some people, especially children with dopa-responsive dystonia, improve dramatically when they are treated with levodopa plus carbidopa.
If one or a few body parts are affected, botulinum toxin (a bacterial toxin used to paralyze muscles or to treat wrinkles) is injected into the overactive muscles. Botulinum weakens the muscle contraction but does not affect the nerves. These injections are particularly useful for blepharospasm and spasmodic torticollis.
Physical therapy helps some people, especially those who are treated with botulinum.
Last full review/revision August 2007 by David Eidelberg, MD; Michael Pourfar, MD
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