Sensory evoked responses in head injury.

Abstract

Head trauma is a significant source of morbidity in the United States each year. Approximately 700 patients were admitted to our surgical intensive care unit with some degree of head trauma in a 24-month period. Glasgow Coma Score (GCS) was 8 or less in 90% of this group, and 3 or 4 in 43%. Sensory evoked responses were recorded in over 500 patients. This study is reported to demonstrate that optimum care of the injured brain depends on titration of care aimed at maintaining normal neuronal function. In our series, 25% of the patients with GCS of 3 or 4 returned home or to a rehabilitation unit, a significant decrease in morbidity over other reported series. Chemical paralysis and barbiturate coma were a factor in the decision to monitor in 50-60% of the series. In these patients, the auditory brainstem evoked response (ABR), a monitor of brainstem neuroelectrical function, and the somatosensory evoked response, a monitor of brainstem and cortical function, were used to follow the effectiveness of medical and surgical management in these patients, since neurologic examination was of limited value. Case reports are presented to demonstrate that even at high barbiturate levels, access to the integrity of the central nervous system is still possible. Relations among GCS, computerized tomography (CT), intracranial pressure (ICP), ABR, pupillary response, and outcome were studied for a subgroup of 114 patients. All of these clinical parameters, except CT findings, were significantly correlated with outcome using Chi-square analysis. When the data were further analyzed with linear regression analysis, however, the only parameters that significantly correlated with outcome were pupil reactivity and ABR. The principal conclusion of this report is that the main application of serial monitoring of the sensory central pathway in the head-injured patient is not in the prediction of outcome but in the titration of care of the patient for the preservation of neuronal function.