Abstract WP171: Surgical Strategy And Results Of Additional Bypass For Patients With Moyamoya Disease Refractory To Previous Surgery

Introduction —It is well known that surgical revascularization can improve cerebral hemodynamics and prevent further ischemic cerebrovascular events in moyamoya disease. However, a certain subgroup of patients repeats ischemic attacks even after surgery because of insufficient surgery or disease progression during follow-up periods. Hypothesis —Relevant designs and techniques in additional bypass surgery can resolve ischemic cerebrovascular events in patients with moyamoya disease refractory to previous bypass surgery. Methods —This study included totally 7 patients (9 hemispheres) with moyamoya disease refractory to previous bypass surgery. There were 5 children and 2 adults. They underwent previous bypass surgery in Japan and Europe 6 to 240 months before admission. Based on precise clinical and radiological analysis, cerebrovascular events were considered to occur because of insufficient bypass surgery in 5 patients and disease progression in the ipsilateral posterior cerebral artery in 2. Surgical strategies included wide craniotomy to cover the area where cerebral hemodynamics is still impaired and appropriate bypass procedures such as STA-MCA anastomosis, OA-PCA anastomosis, and indirect bypass. Using [123]I-IMP SPECT or [15]O-gas PET, cerebral hemodynamics was precisely examined before and after surgery Results —Postoperative course was uneventful and cerebral hemodynamics significantly improved in all 7 patients. Postoperative cerebral angiography revealed that additional bypass provided collateral blood flow to ischemic area before surgery. Ischemic cerebrovascular events rapidly resolved in 5 patients and gradually decreased in 2. Conclusion —This study strongly suggests adequate surgical design and procedures can resolve ischemic cerebrovascular events in patients with moyamoya disease refractory to previous bypass surgery.