A craniotomy is a procedure in which an opening is made in the skull to access the brain. These openings can range from the size of a dime to a very large portion of the skull. Craniotomies are done for many reasons including providing access for a biopsy of a brain tumor, repairing skull fractures, inserting pressure monitors, removal of a blood clot, removal of bullets, clipping aneurysms or relieving pressure caused by injury or bleeding in the brain. When removing brain tumors, imaging modalities including Stealth MRI is used to map the brain and the diseased tissue targeted for resection. Intra-operative nerve monitoring is also used, if indicated. When the necessary treatments have been completed, the piece of skull is replaced to close the opening.