Hemidystonia: a report of 22 patients and a review of the literature.

Hemidystonia defined as involuntary, sustained posturing of the unilateral arm, leg, and face was studied in 12 male and 10 female patients. Hemidystonia was caused by cerebrovascular disease in eight patients, perinatal trauma or childhood injury in four, head trauma and its sequelae in three, neuronal storage disorders in two, neurodegenerative disease in two, lesions after thalamotomy in two, and presumed encephalitis in one. Sixteen patients (73%) had CT evidence of contralateral basal ganglia damage, history of hemiparesis, or both. Brain damage before 7 years of age produced contralateral hemidystonia with a mean delay of 9-7 years. In older patients hemidystonia appeared within 6 months after injury. Hemidystonia may result from a disconnection between the striatum and the thalamus with relative preservation of the corticospinal pathways.