Embolization法による中大脳動脈閉塞に対するembolectomy : 神経症状, 局所脳血流, evoked potentialに与える影響

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This experiment was performed to study the pathophysiology of cerebral infarctions produced by segmental embolization of the trunk of the middle cerebral artery (MCA) of dogs and effects of embolectomy 3 or 6 hours after embolization. A silicone rubber cylinder was injected into the cerevical internal carotid artery and segmental occlusion of MCA was produced (embolization group). In a separate group microsurgical embolectomy was performed 3 (3 hour embolectomy group) or 6 hours (6 hour embolectomy group) after embolization. The animals in the three groups were kept alive for 4 to 7 days and neurological deficits were evaluated according to Smith's neurological evaluation score. After macroscopic observation of the involved brain, the infarct volume was calculated by the average end area method. Regional cerebral blood flow (rCBF) was measured in the cortex of the anterior sylvian gyrus and posterior sylvian gyrus and in the basal ganglia on the affected side by a hydrogen clearance method. Sensory evoked potential (SEP) was also recorded in response to contralateral median nerve stimulation. The measurements of rCBF and SEP were repeated at intervals of an hour for 6 hours after embolization in the embolization group and 3 hour embolectomy group. In the embolization group the animals exhibited severe neurological deficits and the neurological evaluation score was 2.7 ± 0.34 (mean ± SE). Infarcts involved the lobus pyriformis, thalamus and caudate nucleus. These infarct volumes reached 4.6 ± 0.5 (mean ± SE) cm^3. The rCBF decreased signiticantly in all measured regions. In the basal ganglia rCBF decreased most remarkably from the original value of 53.9 ± 13.0 (mean±SD) ml/100 g/min to 21.5±8.9 ml/100 g/min 6 hours after embolization. The amplitude of SEP decreased progressively from the resting value of 100% to 53.0 ± 7.6 (mean ± SE) % 3 hours after embolization. In the 3 hour embolectomy group all animals were able to walk and the neurological evaluation score was 1.1 ± 0.45. The infarct volume was 1.1 ± 0.47 cm^3. The rCBF was restored to the original value in the three measured regions 1 hour after embolectomy. The amplitude of SEP increased from 87.8 ± 4.3% one hour after embolization to 110-120% after embolectomy. In the 6 hour embolectomy group five out of 10 dogs could walk but the other five dogs exhibited severe neurological deficits and the mean neurological evaluation score was 2.1 ± 0.44. The infarct volume was 2.9 ± 0.54 cm^3 and seven out of 10 dogs demonstrated hemorrhagic infarction or intracerebral hematoma. This study suggests that early restoration of the perforating arteries of MCA prevents deep cerebral infarction in this model. Development of ischemic brain edema seems to be the most severe risk factor in the prognosis in this embolectomy. Measurements of rCBF and SEP are beneficial for the evaluation of reversibility of the function after ischemia.
日本脳神経外科学会の論文
1980-06-15

Embolization法による中大脳動脈閉塞に対するembolectomy : 神経症状, 局所脳血流, evoked potentialに与える影響

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