My friend is in a deep coma after brain surgery. she feel hard on her head on a metal ramp. she suffered severly from headaches, went to the doctor, they did a mri, saw a blood clot, and operated. she has brain stem injury, and in a coma since?

Attempting to interpret your post, in the absence of temporal duration, age, prior health, medications being used, and "brain stem" signs, it would be fair to state that prognosis would be guarded at best. An EEG at this point might objectify underlying brain function. Ongoing conferences with the medical team are advised. Wish you and the family the best outcome.