Follow-up: the 'playing banjo in surgery' thing is because that's what the surgeons wanted. The operation was "deep brain stimulation (DBS)," and the patient needs to help the doctors find the exact spot where the treatment will do the most good. In his case, since it was his right hand and tremors that needed correcting, he had to play to let them know what worked and what didn't. He called it 'the most painful thing I ever undured,' but it seems to have been successful.

Bob