The enlightenment.

The period begins with the work of Richard Wiseman who was associated with royalists in the English Civil War. A little later Dionis was the first to note a relationship between a disturbance of consciousness and extravasation of blood. This notion was continued and expanded by Le Dran, Pott, and Benjamin Bell, with Pott providing a pathophysiological explanation of the phenomenon. Daniel Turner commented on how confusing Galenic teaching was on the topic of consciousness. Heister further emphasized the relationship between clinical disturbance and the extravasation of blood. Le Dran stated that symptoms following cranial trauma related to cerebral injury, an opinion supported by Pott and never subsequently challenged. Latta noted the importance of meningeal arteries in the development of hematomas. Benjamin Bell considered trepanation only appropriate for a clinical deterioration consistent with hemorrhagic extravasation. The two Irish surgeons made it clear that the presence of periosteal separation was not in fact a reliable indicator of an extravasation. The most striking change of instruments was disappearance of simple straight trepans with non-perforating tips for making small holes safely. The use of scrapers gradually declined as did that of lenticulars. There was a great debate about the value of a conical rather than a cylindrical crown. The former was said to be safer. But this opinion faded and the cylindrical crown became preferred. Another improvement in technique involved the use of constant probing to check the depth of the drilled groove.