Coma

Comatose patients are unresponsive to all external stimuli, noxious or othe rwise. The eyes are closed, but there may be nonpurposeful movements or pos turing of the limbs. Coma may be caused by a number of insults, including h erniation, hy drocephalus, intracranial hemorrhage, hypoxicischemic injury, trauma, infection, and toxic/ metabolic insults. The neuroanatomic correla tes of coma include either (1) direct brain stem-diencephalic involvement d isrupting the reticular formation or nuclei or (2) bilateral cerebral dysfu nction.(2) When neurosurgeons in the emergency department evaluate individuals with un explained coma, their ability to differentiate between structural and toxic /metabolic causes heavily influences diagnostic and treatment consideration s. The history often provides the most important clues, especially when tra uma or drug ingestion is suspected. Often, the history is unavailable, howe ver, and the examination findings may offer the initial clues. Furthermore, daily assessment of comatose patients in the critical care setting require s a working knowledge of examination techniques and clinicoanatomic correla tion.