Neuromodulatory Role of Revascularization Surgery in Moyamoya Disease

Abstract

To evaluate the effectiveness of bypass surgery for moyamoya disease, electrocorticography was first evaluated. A total of 13 hemispheres in 9 patients with moyamoya disease were included in this study. To record the spectral power of electrocorticography continuously during the bypass procedure, a 4× 5 subdural electrode grid was placed on the middle frontal gyrus. The changes in spectral power before and after bypass surgery were evaluated and compared with those in a control group. The correlation between changes in spectral power and regional cerebral blood flow was analyzed. The average spectral power ratio of the beta band per total band in moyamoya disease before bypass surgery was lower than that of controls (P= 0.027), and the significance disappeared after bypass surgery (P=0.800). The spectral power levels of the beta band and gamma band were increased in moyamoya disease after bypass surgery (P < 0.001). Changes in spectral power of the beta band correlated with changes in regional cerebral blood flow (P= 0.002). The spectral power of the beta band on electrocorticography was focally suppressed in patients with moyamoya disease, and the suppression was reversible by revascularization surgery. Steno-occlusive ischemic changes in moyamoya disease might cause suppression of neurophysiologic activity, and the present results provide insight into the potential neuromodulatory role of revascularization surgery.