It's common for brain surgery patients to stay awake. That's how surgeons know everything is going smoothly, after all. When concert violinist Roger Frisch started suffering from tremors that are only a problem when he's playing, however, Mayo Clinic doctors had to resort to some rather unusual technology to find out if they were installing the necessary brain pacemaker correctly. The surgical crew gave Frisch a bow equipped with a motion-tracking sensor and asked him to fiddle during the operation; the team knew it had electrodes in the right spot when the musician's performance was steady.
As you can see in the video below, the procedure was a success. Frisch can now play smoothly simply by flicking on the pacemaker, and his musical career remains intact. A case like his is unlikely to come up often, but the invention hints that motion tracking could be handy for any surgery where motor skills are at stake -- you might not have to worry about less-than-perfect implants and repeat hospital visits.