Existing comment:
Techniques of Surgery:
Four basic techniques were used by prehistoric surgeons: scraping, grooving, drilling, and cutting.
The scraping technique consisted of gradually scraping the bone with a sharp or abrasive stone until the outer, middle, and lower layers of the skull were worn away, exposing the membrane that covers the brain. This technique produced a hole with a sloping edge.
The grooving technique was accomplished using a sharp stone point to carve a circular piece of bone from the skull. The groove was drawn and redrawn until the central piece of bone was loose.
The drilling technique had two steps. First, a circle of holes was drilled with a sharp instrument. This required great skill, as the holes had to be drilled to just the right depth so that the membrane covering the brain was not punctured. Then the tiny bridges of bone between the holes were cut with a stone knife and the disc of bone was pried out to expose the membrane covering the brain. This method was rare -- probably because it was difficult to control drill depth and pressure.
The cutting technique usually consisted of four straight cuts at right angles (tic-tac-toe style) to remove a rectangular piece of bone. The cuts were made with a sharp stone knife and were deeper in the center than on either end. Variations included openings with five or more sides and curved cuts which opened large areas.
In modern surgical procedures, trephination is used to treat epidural and subdural hematomas, and for surgical access for other neurosurgical procedures. Modern surgeons use the term craniotomy for this procedure, and the removed piece of skull is usually replaced as soon as possible. |