Hemiglossectomy
Today we are familiar with hemiglossectomy as a procedure that involves the removal of part of the tongue, which is most often performed in such cases as oral cancer. However, some people who lived during the 18th and 19th centuries were subjected to this barbaric treatment as an attempt to correct their stutter. Doctors believed that the tongue was to blame for their speech problems, so they came up with a highly ineffective and sometimes even deadly method of correcting it with surgery.
#18 The idea is that of sympathetic (imitative) magic : mices have good teeth, so they are good for ailing teeth... the same kind of "reasoning" is always used nowadays in... homeopathy !
#19 Some trepanated prehistoric patients have survived long enough for the bone to grow again around the opening !
#1 Maybe one was supposed to have masturbated with a handful of cornflakes. That certainly would have made it a lot less fun. (Cream on your cornflakes, anyone?)