Huge Arachnoid Cyst of the Occipital Cerebral Convexity

A 68-year-old woman presented with a rare huge right occipital cystic lesion manifesting as progressive left hemiplegia. Cranial computed tomography revealed a 4 × 7 cm right occipital lobe thin-walled cyst with midline shift and compression of the ipsilateral ventricle. The patient underwent a single burr hole operation for cystography and delineation of the cyst anatomy, then a separate right parieto-occipital craniotomy with complete cyst evacuation, corticotomy, and ventriculostomy. The presumptive diagnosis was arachnoid cyst. The symptoms had completely resolved by 4 months after surgery with nearly normal neuroimaging appearance after 7 months. Cystography followed by craniotomy and ventriculostomy may be effective for supratentorial arachnoid cysts.