An acoustic neuroma is a benign tumor of the 8th cranial nerve (hearing nerve). In most cases these are slow growing tumors. These typically occur in middle-aged adults, and affect women twice as often as men. Acoustic neuomas are relatively rare and account for 7.5% of all brain tumors
Meningiomas arise from the arachnoid matter, one of the layers of the meninges that line the brain. These tumors account for about 27% of all primary brain tumors, and are seen most frequently in middle-aged women. The majority of meningiomas are benign, slow-growing tumors that are localized and noninfiltrating.