Definition: unarousable unresponsiveness in which pts lies /w eyes closed. ± reflexes (such as vestibulo-ocular reflex) and withdrawal from noxious stimulus. ± abnormal EEG.
Coma implies dysfunction of:
Ascending reticular activating system - Central brainstem structures (bilaterally) from caudal medulla to rostral midbrain - This can result from compression due to swelling or herniation;
Both cerebral hemispheres - usually will require very extensive lesions.