Cease your twittering, listen & learn:
Your Brain surgeon is probably past his prime and no doubt suffers from a
midlife crisis, a divorcing wife, a demanding mistress, Parkinson's disease
(hand tremors), feelings of inadeqequacy, short/log sightedness, and is
having it off with the anaesthetist, and has just had a screeching brawl
with management, and is the recipient of 54 margin calls.

If I were his patient I would insist he down a bottle of scotch just before
he makes the first cut!

In my humble experience Surgeons (including the dental variety) should be
treated as plumbers and electricians.