Hemiballism and tremor due to ependymal cyst.

A 21-year-old woman was admitted with right hemiballism and tremor. She had tremor since the age of 6 years. At age 12, an intracerebral, left paraventricular space-occupying lesion was found and treated with 4,500 rads. Increasing tremor was associated with mass enlargement. By age 20, there was insidious presentation of right hemiballism. At age 21, she had craniotomy and a large septate cyst was opened and drained. Biopsy of the cyst wall revealed that it was consistent with ependymal cyst. Postoperatively the hemiballism resolved and the tremor improved. This case is unusual due to the presentation of hemiballism caused by ependymal cyst.