椎骨脳底動脈系脳動脈瘤手術における術中モニタリング(<特集>脳動脈瘤手術update)  [in Japanese] Intraoperative Neurophysiological Monitoring During the Operation of Vertebro-basilar Artery Aneurysms(<Topic>Surgical Approach for Cerebral Aneurysm)  [in Japanese]

The efficacy of intraoperative neurophysiological monitoring in vertebro-basilar artery aneurysm (VB-AN) was clinically examined. Since June 2001, intraoperative monitoring was performed in 12 operations for VB-AN. Five operations were for vertebral artery aneurysms: 4 through the lateral suboccipital route and 1 endovascular surgery. Among 5 operations for basilar bifurcation aneurysms, 3 were through the subtemporal route and 2 were by the anterior temporal approach. The other 2 operations were for the posterior cerebral artery aneurysms by the subtemporal approach. Auditory brain stem responses (ABR) were recorded in 5 operations, somatosensory evoked potential in 1 operation, and motor evoked potential (MEP) in 9 operations by 7 of 300〜600 (400 in general) V bipolar transcranial (TC) stimulations or 7 of 3〜10mA brain stem direct (BSD) stimulations. In 5 operations, both TCMEP and BSDMEP were used together. Glasgow outcome scales of 12 patients were divided into 6 good recoveries, 2 moderate disabilities, 3 severe disabilities and 1 persistent vegetative state. Among 3 patients with BA aneurysms who had a significant decrease or disappearance of the amplitude of MEP by the temporally occlusions of the BA or both VA, 2 patients have never suffered from the prolonged motor palsy. ABR monitoring seems to be essential in the operation by lateral suboccipital approach since it is very easy and sensitive. It is also applicable in endovascular surgery. TCMEP seems to be useful in VB-AN surgery in which the primary motor cortex connot always be exposed. BSDMEP was successfully recorded in 5 of 7 operations tried and it seems to be a more effective way to monitor motor functioning than TCMEP.