Evolution of understanding.

From the time of Hippocrates to the early 19th century, knowledge advanced but that was an uneven process. Anatomy was basically defined by Galen and remained cast in stone until the early 16th century. Neuroanatomy was described by Galen but had little practical value, as brain surgery was not possible. The anatomy of the cranium was known and was largely correct. Care was taken to avoid the frontal air sinuses and the venous sinuses and the temporal region. The role of the brain in consciousness was not understood. It was considered the seat of the soul but there was a lack of understanding that damage to it could induce clinical symptoms such as stupor or paralysis. These were variously attributed to injuries to the meninges or the bone. This error was finally corrected in the 18th century when the brain was identified as responsible for much of the clinical disturbance following cranial trauma. All awareness that post traumatic neurological deficit was contralateral was ignored until the late 18th century, although several authors noted it. Likewise, the presence of CSF had to wait until the 18th century until it was recognized. Fissures were treated with trepanation, because of a perceived risk of infection developing between the bone and the dura. Depressed fracture fragments were elevated, replaced, or removed according to the details of the injury. Finally, for centuries surgeons blocked patients ears to reduce the sound of drilling, despite the fact that such a blocking would amplify the noise.