Trepanning is an ancient (back to Bronze Age) surgical procedure (the earliest attested) that involves cutting a one inch or so circular hole through a person's cranium, to relieve pressure from a brain bleed, or perhaps to vent evil spirits, or for other for other ritual reasons. There’s a substantial body of archeological evidence for the practice,
But I can’t help thinking the patients (subjects?) would have found it tedious. They must have been bored out of their skulls.
Early surgical intervention was the top explanation about 60 years ago (such a persuasive notion) but I don’t buy it. I need more research.