[dys- + tono- + -ia]
Prolonged involuntary muscular contractions that may cause twisting (torsion) of body parts, repetitive movements, and increased muscular tone. These movements may be in the form of rhythmic jerks. The condition may progress in childhood, but progression is rare in adults. In children the legs are usually affected first.
Many childhood dystonias are genetically inherited. Drugs used to treat psychosis, Parkinson disease, strokes, brain tumors, toxic levels of manganese or carbon dioxide, and viral encephalitis may produce dystonia.
Offending drugs are withdrawn, and the patient may be treated with diphenhydramine, or, in the case of dystonias caused by neuroleptic drugs, benztropine. Focal dystonias, such as blepharospasm or torticollis, may be treated with injected botulinum toxin, which paralyzes hypertonic muscle groups. Other treatments include physical therapy, deep brain stimulation, and pallidotomy.
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