"South America’s Inca civilization was better at skull surgery than Civil War doctors"

Trepanation likely started as a treatment for head wounds, says David Kushner, a neurologist at the University of Miami in Florida. After a traumatic injury, such surgery would have cleaned up skull fractures and relieved pressure on the brain, which commonly swells and accumulates fluid after a blow to the head. But not all trepanned skulls show signs of head injuries, so it’s possible the surgery was also used to treat conditions that left no skeletal trace, such as chronic headaches or mental illnesses. Trepanned skulls have been found all over the world, but Peru, with its dry climate and excellent preservation conditions, boasts hundreds of them... 

Techniques also seemed to improve over time, resulting in smaller holes and less cutting or drilling and more careful “grooving,” which would have reduced the risk of puncturing the brain’s protective membrane called the dura mater and causing an infection. “What we’re looking at is over 1000 years of refining their methods,” says Corey Ragsdale, a bioarchaeologist at Southern Illinois University in Edwardsville who wasn’t involved in the study. “They’re not just getting lucky. … The surgeons performing this are so skilled.” Several patients appear to have survived multiple trepanations; one Inca-era skull showed five healed surgeries.

Kushner and Verano then compared those success rates with cranial surgeries on soldiers in the American Civil War, which used similar methods. Battlefield surgeons also treated head wounds by cutting away bone while trying not to puncture the brain’s delicate dura mater membrane. According to Civil War medical records, some 46% to 56% of cranial surgery patients died, compared with just 17% to 25% of Inca-era patients."

http://www.sciencemag.org/news/2018/06/south-america-s-inca-civilization-was-better-skull-surgery-civil-war-doctors?utm_source=sciencemagazine&utm_medium=facebook-text&utm_campaign=incasurgery-19850

I'm also imagining if some American found descriptions of these surgeries, or if the practice had survived Spanish genocide in a small pocket of practitioners and they taught someone who brought it to American doctors. Like, it would have been described as "an ancient mystical practice" instead of an advanced surgical technique.