http://en.wikipedia.org/wiki/TrepanningTrepanning, also known as trephination, trephining or making a burr hole, is a medical intervention in which a hole is drilled or scraped into the human skull, exposing the dura mater in order to treat health problems related to intracranial diseases. It may also refer to any "burr" hole created through other body surfaces, including nail beds. It is often used to relieve pressure beneath a surface. A trephine is an instrument used for cutting out a round piece of skull bone.
Modern medical practices
Trepanation is a treatment used for epidural and subdural hematomas, and for surgical access for certain other neurosurgical procedures, such as intracranial pressure monitoring. Modern surgeons generally use the term craniotomy for this procedure. The removed piece of skull is typically replaced as soon as possible. If the bone is not replaced, then the procedure is considered a craniectomy. Trepanation instruments are now available with diamond coated rims (Diamond Bone Cutting System), which are less traumatic than the classical trephines with sharp teeth. They are smooth to soft tissues and cut only bone.
Prehistoric evidence
Trepanation is perhaps the oldest surgical procedure for which there is forensic evidence,<4> and in some areas may have been quite widespread. Out of 120 prehistoric skulls found at one burial site in France dated to 6500 BC, 40 had trepanation holes.<5> Many prehistoric and premodern patients had signs of their skull structure healing; suggesting that many of those subjected to the surgery survived
Pre-modern Europe
Trepanation was also practiced in the classical and Renaissance periods. Hippocrates gave specific directions on the procedure from its evolution through the Greek age, and Galen also elaborates on the procedure. During the Middle Ages and the Renaissance, trepanation was practiced as a cure for various ailments, including seizures and skull fractures. Out of eight skulls with trepanations from the 6th to 8th centuries found in southwestern Germany, seven skulls show clear evidence of healing and survival after trepanation suggesting that the survival rate of the operations was high and the infection rate was low.<2>