ncient Peruvians vs. modern Americans

The researchers suggest that one reason why skull-drilling practices during the Civil War may have had such dismal outcomes was the subpar hygiene involved in such operations, wherein surgeons used unsterlized tools and their bare — perhaps unclean — hands.

“If there was an opening in the skull [Civil War surgeons] would poke a finger into the wound and feel around, exploring for clots and bone fragments,” Dr. Kushner says of the gruesome practice.

At the same time, he admits, “We do not know how the ancient Peruvians prevented infection, but it seems that they did a good job of it.”

Dr. Kushner also believes that the Peruvians may have used something akin to anesthetic to make the procedure more bearable, and his first guess is coca leaves — which have been used for medicinal purposes by Andean populations for centuries.

“[We still do not] know what they used as [anesthetic], but since there were so many [cranial surgeries] they must have used something — possibly coca leaves,” Dr. Kushner surmises, though he concedes that other substances may also have been employed.

The fact that the ancient Peruvians were clearly doing something well when it came to trepanation is supported by the evidence of over 800 prehistoric skulls bearing between one and seven precision holes.

All of these skulls were discovered along the coasts or in the Andean regions of Peru, with the earliest skulls dated as early as 400 B.C.

Very high survival rates for ancient patients

Combined evidence — detailed by John Verano and colleagues in a book published 2 years ago, Holes in the Head: The Art and Archaeology of Trepanation in Ancient Peru — suggests that the ancient Peruvians had spent many a decade perfecting their trepanation knowledge and skills.

At first, in around 400–200 B.C., the survival rates following a trepanation weren’t all that high, and about half of the patients did not survive, the researchers argue. The team was able to assess the outcomes by looking at how much — if at all — the bone surrounding the trepanation holes had healed after the procedure.

Where no healing seemed to have occurred, the team thought it safe to conclude that the patient had either survived for a short period of time or had died during the procedure.

When, to the contrary, the bone showed extensive remodeling, the researchers took it as a sign that the person operated upon had lived to tell the tale.

Dr. Kushner and team found that, based on these signs, in 1000–1400 A.D., trepanation patients saw very high survival rates, of up to 91 percent in some cases. During the Incan period, this was 75–83 percent, on average.

This, the researchers explain in their paper, is due to ever-improving techniques and knowledge that the Peruvians acquired over time.

One such important advance was understanding that they should be careful not to penetrate the dura mater, or the protective layer found just under the skull, which protects the brain.

“Over time,” says Dr. Kushner, “from the earliest to the latest, they learned which techniques were better, and less likely to perforate the dura.” He continues, “They seemed to understand head anatomy and purposefully avoided the areas where there would be more bleeding.”

Based on the evidence offered by the human remains uncovered in Peru, the researchers saw that other advances in trepanation practice also occurred.

Dr. Kushner goes on to explain, “[The ancient Peruvians] also realized that larger-sized trepanations were less likely to be as successful as smaller ones. Physical evidence definitely shows that these ancient surgeons refined the procedure over time.”

He calls this ancient civilization’s progress when it came to this risky procedure “truly remarkable.”

It is these and similar practices that — directly or indirectly — have shaped modern neurosurgery, which has a high rate of positive outcomes.

“Today, neurosurgical mortality rates are very, very low; there is always a risk but the likelihood of a good outcome is very high. And just like in ancient Peru, we continue to advance our neurosurgical techniques, our skills, our tools, and our knowledge,” says Dr. Kushner.