Epidermoid cysts of the fourth ventricle.

Epidermoid tumors located in the fourth ventricle are exceedingly rare. Seven cases of this pathological condition were observed during a 10-year period. Patients were mostly middle-aged men, with a clinical history of relatively short duration (5 months). Clinical symptoms consisted of vertigo and ataxia, followed by incoordination, dysmetria, and tremor at a later stage. Computed tomography scanning represented the main diagnostic technique for these lesions, and typically showed a highly hypodense, round-shaped area within the fourth ventricle, occasionally accompanied by hydrocephaly. Subtotal surgical removal of the cysts produced excellent results in 86% of the cases. The implications of these findings are discussed.