Differences between coma, vegetated stage, & brain dead. . .

A person is considered "in a coma" when his or her GCS is 8 or lower. The way PVS (persistent vegetative state) was explained to me is that a person is considered to be in a PVS when his or her GCS is less than 8 for 3 months or more. Brain death = GCS 3 with: absence of cerebral blood flow (via CBF scan), no primitive reflexes (corneal, gag, cough), flat EEG, negative cold calorics exam, etc. In Texas, where I practice, a person is legally dead when he or she is pronounced brain dead. Hope this helps.

Glasgow Coma Scale.

http://www.unc.edu/~rowlett/units/scales/glasgow.htm