Prognostic factors in severe head injury.

Head injury is a significant economic, social and medical problem in the United States. For this reason, prognostic factors in head injury are of major importance to all surgeons who treat severely injured patients. Outcome of severe head injury is frequently determined at the time of impact, and surgical and medical treatment is often ineffective. Prediction of outcome of severe head injury should be based upon early neurologic signs, including degree of coma as measured by the Glasgow Coma Scale, brain stem reflexes, central nervous system lesion type, presence of increased intracranial pressure and multimodality evoked responses. The Glasgow Coma Scale is a standardized measurement of coma which numerically rates the response of eye opening, verbal response and motor response of the patient with head injury. The Glasgow coma score, the sum of the three response ratings, correlates with mortality of head injury, although the correlation between the coma score and morbidity has not been conclusively established. Because injury to the brain stem is generally irreversible, absence of oculocephalic reflexes, oculovestibular reflexes and pupillary response and the presence of decerebrate rigidity indicate an unfavorable outcome. Patients with focal brain injuries, especially subdural hematomas, generally have a higher mortality than patients who have diffuse brain injuries, regardless of the Glasgow coma score. Elevated intracranial pressure indicates an unfavorable outcome, especially if not reducible. Increased age and hypotension also subject patients with head injury to greater risk. Multiple injuries do not affect mortality of head injury. Multimodality evoked responses are a noninvasive prognostic technique which predicts outcome with a high degree of certainty. For optimal accuracy, prognosis should be based upon a combination of factors, including age, Glasgow coma score, pupillary response, eye movements, presence of surgical lesion, motor posturing and multimodality evoked responses. Decisions regarding surgical and medical treatment of patients with head injury should be based upon these prognostic factors.