Unconsciousness

A state of unresponsiveness to external stimuli, absent awareness, and inability to maintain purposeful, voluntary behavior, typically resulting from dysfunction of the cerebral hemispheres or ascending reticular activating system. Possible causes are hypoglycemia, dehydration, sedatives, illicit drugs, alcohol poisoning, cardiovascular (vasovagal syncope, cardiac arrhythmia, orthostatic hypotension), neurological (seizure, stroke, traumatic brain injury, meningitis or encephalitis).