Arachnoid cyst rupture with concurrent subdural hygroma.

Arachnoid cysts (ACs) are relatively common intracranial mass lesions, which occur most often in the middle cranial fossa. While these lesions can present as a mass lesion, many are asymptomatic. Rarely, posttraumatic or spontaneous rupture of ACs can result in intracystic hemorrhage, subdural hematoma or subdural hygroma. We have encountered two cases of ruptured arachnoid cysts that resulted in subdural hygromas. Both patients harbored middle cranial fossa cysts and suffered mild closed head injuries. The presentation, radiographic findings and surgical management of these patients as well as the association between ACs and subdural hygromas are described. Copyright 2000 S. Karger AG, Basel