抄録
Extracranial-intracranial (EC/IC) bypass as surgical treatment for ischemic cerebrovascular diseases has been performed since 1973. The reliability of the authors' mehtods of selecting candidates for EC/IC bypass were evaluated through long-term follow-up of 14 patients (mean age, 54 years) who underwent bypass surgery for 50% to 95% stenosis in the intracranial portion of the internal carotid artery (ICA) and/or the middle cerebral artery (M1 or M2) . The interval from the last stroke to bypass surgery ranged from 22 hours to 6 months (mean, 42 days). Computed tomography, cerebral angiography, cerebral blood flow (CBF), and somatosensory evoked potentials (SEP) were evaluated preoperatively. Seven patients were considered candidates for EC/IC bypass because they had decreased hemispheric or regional CBF. In 3 of these 7, improvement or worsening were shown by electroencephalography (EEG) and measurement of SEP during druginduced hypertension or hypotension (drug-induced EEG and SEP test: DEE test). In the other 7 patients bypass surgery was felt to be indicated on the basis of the angiographic findings and the preoperative clinical course. The bypass was patent in 12 patients and not patent in 2. The term of follow-up averaged 4.4 years. One patient experienced a transient ischemic attack in the ICA on the affected side, and another suffered an additional reversible ischemic neurological deficit (RIND) in the vertebrobasilar (VB) system; the latter patient died of a stroke in the VB system 1.5 years after the RIND. Nine of the 14 patients were leading an independent, useful life at the last follow-up visit, and 5 had died, 1 of a stroke and 1 of purulent meningitis. In 3 cases the cause of death was unknown. EC/IC bypass appears somewhat effective in preventing cerebral ischemia, although the mortality rate in this study was rather high (42%). Considering the results of the Cooperative EC/ IC Bypass Study, selecting candidates on the basis of clinical symptoms and angiographic evidence of steno-occlusion of the main trunk of the carotid system is not satisfactory. The patients most likely to benefit from EC/IC bypass will be those in whom the procedure improves CBF and cerebral metabolism. Measurement of CBF and cerebral metabolism, as well as DEE testing, are indispensable in determining whether or not EC/IC bypass is indicated.
