Imaging the Unconscious "Found Down" Patient in the Emergency Department.

Unconsciousness may be due to severe brain damage or to potentially reversible causes. Noncontrast head computed tomography (CT) helps identify acute ischemic and hemorrhagic lesions as well as certain patterns of toxic encephalopathy. MR imaging plays an important role in the assessment of acutely encephalopathic patients who may show no significant abnormality on CT. This review describes some of the common and infrequent entities that can lead to unconsciousness, including epilepsy and vascular, traumatic, metabolic, and toxic disorders.