Systemic therapy of dystonia.

A number of pharmacologic agents have been found to be effective for the dystonias. Anticholinergic drugs have been shown to be the most effective in terms of percentage of subjects who receive moderate to marked benefit. About 50% of children and 40% of adults obtain such improvement. Peripheral adverse effects are usually overcome by pyridostigmine. It may be necessary to utilize pilocarpine eyedrops for blurred vision. Central adverse effects, such as forgetfulness, can be reduced only by a reduction in dosage of the anticholinergic. In comparing trihexyphenidyl and ethopropazine, we found that children tend to have better tolerance of the former and adults tend to have better tolerance of the latter. The antidopaminergics are the group of drugs that were found to be the next most effective agents in terms of percentage of patients who respond. However, these drugs, particularly the dopamine receptor blockers, have the capacity to induce tardive dyskinesia and tardive dystonia. Tardive syndromes are difficult to treat and can persist indefinitely. Other agents that have shown usefulness in controlling dystonia are levodopa, baclofen, carbamazepine, and the benzodiazepines, either alone or in combination with each other and with the anticholinergics. Stereotactic thalamotomy is particularly useful in contralateral hemidystonia. The risk of adverse effects is less than with bilateral thalamotomy, which may need to be employed when generalized dystonia is severely disabling and not responsive to pharmacotherapy.