[Physiopathologic mechanisms of coma].

The occurrence of coma betrays a deficiency of the ascending reticular activating system (ARAS) of the brain stem, which constitutes the neurophysiological support of wakefulness. Multiple factors, acting separately or jointly, may be responsible for coma. They include diffuse lesions or circumscribed lesions with repercussions on the ARAS metabolic and toxic factors, intracranial hypertension, cerebral oedema, epileptic activity, and so forth. Owing to the influence it exerts on the management of coma, the physiopathological approach is as necessary as the aetiological approach.