ARACHNOID CYST OF THE LATERAL VENTRICLE

BACKGROUND Arachnoid cysts rarely occur within the lateral ventricles, with only 10 reported cases in the literature. They may arise from th e arachnoid layer that is present in the choroidal fissure. CASE DESCR IPTION This 25-year-old man with headache and a left jacksonian seizur e had an intraventricular arachnoid cyst of the right occipital horn a nd trigone found on radiologic examination by computed tomography (CT) and magnetic resonance imaging (MRI), He was successfully treated by evacuation of the cyst and removal of its wall through a right parieto occipital craniotomy. Histologic studies of the cyst wall confirmed th e presence of arachnoid cells and connective tissue, CONCLUSIONS Arach noid cysts of the lateral ventricles occur in the occipital horns and trigone (all but 1 of 10 cases) in young patients with symptoms of int racranial hypertension. MRI well defines the relationship of the cyst with the ventricular wall, Surgical removal of the cyst wall or cystop eritoneal shunt have been successfully performed in the reported cases ; however, endoscopic fenestration of the cyst must be considered toda y as the treatment of choice. (C) 1997 by Elsevier Science Inc.