Change of Motor Cortical Representations and Hemodynamics inPatients with Severe Middle Cerebral artery Stenosis afterSuperficial Temporal Artery - Middle Cerebral Artery Anastomosis

Abstract

Background & purpose : There have been few reports about the change of hemodynamics and excitability of the cortex in the patients with severe middle cerebral artery stenosis after superficial temporal artery - middle cerebral artery anastomosis(SMA). Intracranial stenosis is more prevalent in Korea than in western countries, and SMA is considered as an important method for improving the cerebral blood flow. We investigated the hemodynamic & functional changes of cortex after SMA using transcranial magnetic stimulations(TMS), perfusionweighted magnetic resonance imaging(PWI) and 99mTC-HMPAO-SPECT with acetazolamide. Methods : TMS mapping was used to evaluate the motor map of abductor digiti minimi(ADM) in the motor cortex on both sides, with recording motor map and threshold. Four patients with chronic middle cerebral artery stenosis(one man and three women; age: 45~67 years) and two patients with internal carotid artery stenosis(two men, 65 and 58 years old, respectively) were examined with TMS, 99mTC-HMPAO-SPECT and PWI with acetazolamide before vascular surgery. The tests were performed 6 months after operation. We evaluated the motor power of lesion-sided ADM simultaneously. Results : Prior to the surgery, the ADM representation area in the affected hemisphere was smaller than in the non-affected side but it was not statistically significant. After SMA, the size of cortical motor output map to the paretic ADM became significantly larger and this enlarged area was bigger in patients with improved ADM power than those without. However, motor thresholds did not change in patients with severe MCA stenosis in the affected hemisphere before and after surgery. In two patients with carotid endarterectomy(CEA), there were no changes of TMS mapping and motor thresholds. Pre- and post-acetazolamide 99mTC-HMPAO-SPECT and PWI showed the similar pattern of the hemodynamic change after STA-MCA anastomosis. Conclusion : These findings suggest that improved hemodynamics produced by SMA are correlated with enlarged motor cortical reorganization and also with an improvement of motor function. Korean Journal of Stroke 2002;4(2):111~116