Arachnoid cyst rupture with concurrent subdural hygroma

Arachnoid cysts (ACs) are relatively common intracranial mass lesions, whic h occur most often in the middle cranial fossa, While these lesions can pre sent as a mass lesion, many are asymptomatic, Rarely, posttraumatic or spon taneous rupture of ACs can result in intracystic hemorrhage, subdural hemat oma or subdural hygroma, We have encountered two cases of ruptured arachnoi d cysts that resulted in subdural hygromas. Both patients harbored middle c ranial fossa cysts and suffered mild closed head injuries. The presentation , radiographic findings and surgical management of these patients as well a s the association between ACs and subdural hygromas are described, Copyrigh t (C) 2000 S.Karger AG, Basel.