Epidermoid cyst of the fourth ventricle.

The case of a 52-year-old patient with a fourth ventricle epidermoid is reported. The initial presentation included long-standing headaches, progressive anomalies of gait and slight impairment of mentation. CT showed a hypodense mass enhancing peripherally after contrast infusion. Brain auditory evoked responses (BAER) showed asymmetric increased latencies. At operation, total removal of an extensive fourth ventricle epidermoid was achieved. A delayed meningitis occurred postoperatively. Physical examination was normal at the 2 year follow-up and BAER were improved. The etiological and clinical features of fourth ventricular epidermoids are briefly reviewed. The diagnostic value of CT is emphasised but the possibility of CT-dense epidermoid cysts deserves a special mention. Total removal of the neoplasm is the theoretical aim of operative treatment, but this purpose may be harmful when the ventricular floor is involved by the capsule.