Nontraumatic Subdural Hematoma and Intracystic Hemorrhage Associated with a Middle Fossa Arachnoid Cyst.

Intracranial arachnoid cysts (ACs) are relatively common findings that can be seen in up to 2% of patients. They are generally found incidentally with a benign clinical course and can be usually managed by observation. We report an unusual case of a middle fossa AC presenting with spontaneous intracystic hemorrhage along with subdural hematoma (SDH) causing significant mass effect and midline shift requiring surgical treatment.