Definition

An operation in which a small hole is made in the skull or a piece of bone from the skull is removed to show part of the brain. A craniotomy may be done to remove a brain tumor or a sample of brain tissue. It may also be done to remove blood or blood clots from the brain, relieve pressure in the brain after an injury or stroke, repair a skull fracture or brain aneurysm (a bulge in a blood vessel wall), or treat other brain conditions. The piece of bone that is removed from the skull is usually put back in place after the surgery has been done.