I cannot look at this line drawing from Hadywarke of Surgeri, 1525, without getting a little sick. It depicts a trepanation — the drililng of a hole in the skull for therapeutic reasons. Disturbingly, it is not an uncommon process. Though occasionally done today for “legitimate” medical purposes — in the case of brain swelling, for instance, after traumatic brain injury — it is also practiced by quacks, as in the 2000 case of two men from Cedar City, Utah, who were prosecuted for practicing medicine without a license for trepanning a woman to treat her depression and chronic fatigue syndrome.
M. Christian first alerted me to this practice, thankfully through an article he wrote for Gothic.net years ago and not with a pair of handcuffs and a drill in the manner of, say, Dr. Phibes.