A PHYSIOLOGICAL COMA SCALE - GRADING OF COMA BY COMBINED USE OF BRAIN-STEM TRIGEMINAL AND AUDITORY-EVOKED POTENTIALS AND THE GLASGOW COMA SCALE

Forty-five comatose patients were prospectively studied by means of cl inical examination and evoked potentials. In each patient, clinical da ta included Glasgow Coma Scale (GCS) score, age, pupillary response to light, corneal reflex, and eye movements. Neurophysiological evaluati on was based on brain-stem trigeminal evoked potentials (BTEPs) and br ain-stem auditory evoked potentials (BAEPs). For each physiological te st, a progressive grading system was designed. This system was based o n the evaluation of central conduction times along the trigeminal and the auditory pathways within the brain-stem. The accuracy of the clini cal and the neurophysiological indicants in predicting ''favorable'' o r ''unfavorable'' outcome was assessed singly and in combination. Of t he clinical indicants, the GCS provided the most accurate prognosis (8 0%). Similar results were provided by the BAEP and the BTEP, with sign ificant improvement in the confidence of outcome prediction. No signif icant difference in the accuracy of outcome predictions could be found between combined clinical data and neurophysiological data. However, the combination of clinical and neurophysiological data markedly incre ased both the accuracy and the confidence of outcome prediction, reach ing 86% correct predictions at the over 90% confidence level with only 2% false pessimistic errors. According to these findings, a clinical- physiological coma scale, the trigeminal-auditory Glasgow (Coma Scale) score (TAG score) was designed. The TAG score demonstrated the highes t accuracy at each confidence level as compared to other single indica nts. We concluded that the TAG score may improve the evaluation of dee p comatose patients and assist the physician in the management of such patients.