Long-term outcome of superficial temporal artery-middle cerebral artery bypass for patients with moyamoya disease in the US

Object. The authors report the long-term results of a series of direct superficial temporal artery-middle cerebral artery (STA-MCA) bypass procedures in patients with moyamoya disease from the western US. Methods. All patients with moyamoya disease treated at the University of Washington from 1990 through 2004 (39 patients) were included in this study. Patients underwent pre- and postoperative evaluation of cerebral perfusion dynamics. Surgical revascularization procedures were performed in all patients with impaired cemtal blood flow (CBF) findings. Results. The mean age of patients at diagnosis was 34 years (range 10-55 years). An 39 patients had impaired CBF and/or vasomotor reserve and underwent revascularization procedures: 26 patients underwent bilateral operations, 13 unilateral (65 total procedures). An STA-MCA bypass was technically possible in 56 procedures (86.2%); saphenous vein interposition grafts were required in 3 procedures (4.6%); encephaloduroarteriosynangiosis was performed in 6 procedures (9.2%). Three patients died due to postoperative complications, yielding a procedure-related mortality rate of 4.61%, and 8 experienced non-life threatening complications (for a procedure-related rate of 12.3%). Long-term follow-up appeared to indicate a reduction in further ischemic events in surviving patients compared with the natural history. Cerebral perfusion dynamics improved postoperatively in all 36 surviving patients. Conclusions. Moyamoya disease may differ in the US and Asia, and STA-MCA bypass procedures may prevent future ischemic events in patients with this condition.