Also known as trephining, this involves drilling a hole in the patient's head. It is believed this technique was used in prehistory to allow evil spirits a route out of the patient's head, to allow the patient to communicate with the spirit world, or to cure a headache! We know that some people survived these operations because there is evidence of healing in the skulls.

Modern evidence shows that repanning can lead to altered mental sensations, and some people have tried it for non-medical reasons. It's sometimes done by doctors when head injury has led to build-up of pressure within the skull.