[A case of symptomatic interhemispheric arachnoid cyst in the elderly].

The incidence of interhemispheric cyst is rare. There have been only 12 cases reported in adults since the advent of CT. We encountered a case of an interhemispheric arachnoid cyst in a 54-year-old patient who had developed paraparesis. Excision of the cystic wall produced a satisfactory result. The CT and MRI scans were not contributory to histological differentiation of the lesions. According to the literature, however, it is highly likely that these patients are suffering from an arachnoid cyst, when the interhemispheric cyst without agenesis of the corpus callosum occurs in adults.