Coma

Abstract

Coma is a state of eyes-closed unresponsiveness that usually reflects serious and sometimes irreversible brain pathology. The site of coma can be localized by directed examination of the cerebral cortex and all three levels of the brainstem. In most cases, coma is due to a medical condition rather than to a mass lesion. Prognostication of comatose patients is most accurate for those who have sustained cardiac arrest, and in most cases should wait until 72 h after the inciting event. Patients in the persistent vegetative state show roving or tracking eye movements, an irregular sleep–wake cycle, and an inability to interact with the environment in a meaningful way. The minimally conscious state differs from the persistent vegetative state in that patients are able to respond to external stimuli in a limited manner, make basic verbalizations, hold objects appropriately, and follow simple commands. Brain death examination should follow a strict protocol to establish the absence of brain function and to exclude the possibility of an alternative diagnosis. Increased intracranial pressure is the most serious neurologic emergency and should be approached in an organized but expedient fashion in an attempt to obtain the best possible outcome.