The comatose patient

Consciousness and wakefulness require normal functioning of the cerebral cortex, as well as of the midbrain reticular formation and its ascending projections. Bilateral structural lesions or functional disturbances of these brain areas can impair consciousness and can produce coma. The bodily posture and brainstem reflexes of the comatose patient provide clues as to whether the lesion lies in the brainstem or in the cerebral hemispheres. Brainstem reflexes are usually preserved in coma due to bilateral hemispheric dysfunction, including metabolic, anoxic, and toxic coma. Ancillary tests are used to answer specific diagnostic questions. The treatment of coma depends on its etiology.