A word used by doctors and nurses to imply that a patient's problems are all in their mind. The tentorium is a membrane just under
the brain, so "supratentorial" refers to what is above that, namely the brain. This term can be used in front of
the patient or patient's family because it sounds like
technical jargon.
Patient: "Every time Dr Phil comes on TV, my arms and legs start
twitching!"
Doctor, quietly to nurse: "Seems to be a supratentorial
problem."
Then to patient, condescendingly: "Sorry, dear, we're just
talking shop. Go on."