重症意識障害患者の臨床電気生理学予後推定

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

BPNN法によるてんかん原性焦点の推定に関する研究

Localization of the epileptogenic focus is essential in surgical treatment for intractable epilepsy. Intracranial electrical recording is now one of the accurate but invasive methods for preoperative investigation. As a possible non-invasive method for estimation of the epileptogenic focus, we have developed a topographic mapping method for two dimensional localization and the distribution of epileptic spikes (spike voltage topography : SVT). Recently, a new computer-aided method was developed to estimate the location of brain electric sources by Abeyratne et al. In this method, artificial neural network trained with a back propagation algorithm (back propagation neural network : BPNN) was used for single dipole estimation of epileptic spikes. In this paper, our clinical experiences with the BPNN method as a dipole estimation of epileptic spikes are presented and discussed. The interictal spike discharges from 11 patients (6 with partial seizures and 5 with generalized seizures) were analyzed by SVT for two dimensional localization of the epileptic spikes and the BPNN method for three dimensional localization of the dipole. The EEG of 11 patients with epilepsy was recorded from 16 channel electrodes of international 10-20 system. These data were displayed with Signal processor 7T18 for SVT, and were analyzed with the BPNN method. In five cases with partial seizure, we were able to estimate the dipole localization corresponding to the intraoperative findings with the BPNN method. On the other hand, the dipole moments of each spike showed the same direction. The dipoles of epileptic spikes in four patients of generalized seizures were estimated in the deep and central cerebral structure and the dipole moments were rotated in a clockwise or counterclockwise direction with the BPNN method. However, in another patient, the dipole existed in the left frontal region and propagated to the contralateral fronto-temporal region, and the dipole moments showed the anterio-superior direction. This finding might be implied secondary generalized seizure. Although further studies are necessary to explain the electrophysiological significance of the dipole estimation with the BPNN method, it has so far been possible to identify the three dimensional localization of epileptic spikes in most cases with partial seizure