This was a cylindrical drill with circumferential saw teeth, similar to modern hole saws, which was used
to drill a large hole into the patient’s skull. The drill was rotated by a bow string or a usually wooden handle. The
drill was used to perform trepanations (its use is dated to the Paleolithic Age) to treat migraines, epilepsy and
other mental disorders. Several patients survived trepanation, according to evidence supported by numerous
healed trepanned skulls.