Evaluation of the comatose patient.

This article has emphasized a basic approach to coma. First, the patient must have airway, breathing, and circulation protected. If the etiology of coma is in doubt, a broad metabolic screen is necessary. Table 5 demonstrates the major differences between structural and metabolic coma. Usually, history alone is sufficient to make an accurate diagnosis. If history or neurologic examination suggests a structural cause for the coma, then a cranial CT scan is mandatory. An electroencephalogram is often helpful, particularly in metabolic coma, and at times may even show structural abnormalities not demonstrated by CT scan. Rapid assessment and treatment is critical because coma is the clinical manifestation of brain failure, and often irreversible injury will occur if treatment is slow or incorrect.