The relationship among auditory brainstem responses, electroencephalograms and light reflexes in comatose patients

The relationship among auditory brainstem response (ABRs), elecrtoencephalograms (EEGs) and light reflexes in 70 comatose patients was ecamined. The patients were divided into three groups, i.e. primary brain disorders, hypoxic brain disorders and multiple organ failure (MOF). To evaluate the grade of abnormality of ABRs and EEGs, ABRs were classified into 8 types (A : normal-H : flat) and EEGs were classified into five types (I : normal- V : flat). When calssifying ABRs, the normal values obtained in 80 healty subjects were referred. In the primary brain disorders, most of the patients who survived showed normal ABRs (A, B) and EEGs (I) at the time of discharge from ICU, though, functional disability was observed in 31%. The patients who died showed marked abnormalities of ABRs (E, F, G, H) and EEGs (IV, V). In hypoxic brain desorders, marked abnormalities of EEGs preceded the abnormalitied of ABRs in the patients who either died or recorvered with moderate or severe disabikity. In both groups, light reflexes were normal in the survived patients, while, in the patients who died, light reflexes dissappeared before the occurrence of abnormalities in ABRs. In the MOF group, the ABR consisting of single wave at the latency of wave V (type G) was observed in 85%. When this type of ABR was observed in association with abnormal EEG, the prognosis was poor. The light reflexes in the patients who died with MOF remained to be observed (at least 5-13 hours before death) even after the ABR and EEG became flat. In conclusion, there are differences in the relationship among ABRs, EEGs and light reflexes depending on the different brain disorders. The assessment of the neurologic condition and prediction of prognosis of eaminations of ABRs, EEGs and clinical neurologic signs including light reflexes.