Clinical and electrophysiological study on the prognosis of comatose patients with severe brain damage in the acute or subacute stage
依田, 啓司 徳島大学
七條, 文雄 徳島大学
multimodality evoked potentials
patient outcome assessment
It is difficult to assess the prognosis of comatose patients with severe brain damage in the acute or subacute stage. CT scan, or even MRI still have limitations in the evaluation of potential brain function in such patients.
In this study, multimodality evoked potentials were used to predict the clinical outcome of comatose patients. We have studied 36 comatose patients with various disorders and with Glasgow coma scale scores of 5 or less. In all patients we examined multimodality evoked potentials ; short latency somatosensory evoked potentials (SSEP), auditory brainstem response (ABR), slow vertex response (SVR), visual evoked potentials (VEP), motor evoked potentials (MEP) as well as EEG within 14 days of the onset of coma. According to the electrophysiological findings, the patients were divided into four groups : group 1, global brain damage, in which all electrophysiological findings were severely abnormal ; group 2, severe cerebral damage, in which all electrophysiological findings except ABR were severely abnormal; group 3, mild cerebral damage, in which ABR findings were normal or mildly abnormal, but the other findings were varied ; and group 4, brainstem damage, in which ABR or SSEP findings showed severe abnormality but VEP and EEG findings were normal or mildly abnormal. The outcome of each patient was categorized according to the Glasgow outcome scale (GOS). Group 1 consisted of twelve patients who all died. Three patients in group 2 had an unfavorable outcome, two patients remained in a vegetative state and the third died. There were 16 patients in group 3. Of these seven died from secondary brain damage or as a result of the original disease, such as pneumonia, heart failure, or pulmonary embolism. None of the patients in this group died of primary brain damage. Of the surviving 9 patients, three had good recovery, two had moderate disability, two had severe disability, and two entered a persistent vegetative state. The differences in clinical outcome correlated well with the results of VEP, SVR, the P25 wave of SSEP, and EEG. In group 4, four out of the 5 patients had severe disability, and one died as a result of disseminated intravascular coagulation.
A reliable prediction of the clinical outcome was obtained from multimodality evoked potentials and EEG. It is expected that such classification on brain damage based on electrophysiological findings will be useful. For comatose patients, ABR findings were the most useful for successfully predicting a poor prognosis. This study has indicated that the cortical response should be fully evaluated in order to predict favorable outcomes. In particular, SVR, VEP, the P25 wave of SSEP and EEG results were found to be important. In view of the clinical aspects, patients with mild cerebral damage who have the chance of making a good recovery must not been overlooked.
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