Arachnoid Cyst with Ictal Presentation.

Arachnoid cysts are benign cystic cavities surrounded by membranes that arc indistinguishable from the arachnoid membrane They contain cerebrospinal fluid in contact with the subarachnoid space They arc frequently asymptomatic and incidentally diagnosed in the adult Their clinical onset is variable and depends on their size and possible triggering factors We report a case in which a big arachnoid cyst presented in an unusual way. not finding a background or any triggering factors that might Justify this clinical presentation It is necessary to perform a differential diagnosis from other common affections of sudden onset Surgical treatment by cystoperitoneal shunting resulted in a complete resolution of symptoms.