craniotomy /krā″nē·ot″əmē/ [Gk, kranion, cranium, temnein, to cut] , any surgical opening into the skull, performed to relieve intracranial pressure, to control bleeding, or to remove a tumor. X-ray films of the skull are taken before surgery, and a computed tomographic (CT) scan or an electroencephalogram is done to establish the diagnosis. The operative site is shaved and cleansed. Parenteral corticosteroids are given to reduce cerebral edema. Mannitol is administered to decrease intracranial pressure. A semicircular skin incision is made just above the hairline, a series of burr holes is made and connected with a cut, and the flap of bone is removed. The meninges are incised, and the brain is exposed. The flap may be replaced after surgery or left off temporarily to prevent the buildup of pressure from cerebral edema.
