OBJECTMoyamoya disease/syndrome (MMD/S) is a progressive, occlusive vasculopathy of the intracranial vasculature that leads to ischemic and hemorrhagic strokes. Significant debate exists regarding the role of indirect cerebrovascular bypass surgery in its management. The authors review their institution's experience with indirect bypass in the surgical management of patients with MMD/S.METHODSThe authors conducted a retrospective review of patients with MMD/S who underwent encephaloduroarteriosynangiosis (EDAS), a form of indirect bypass, from 1996 to 2013.RESULTSA total of 37 patients (52 hemispheres) underwent an EDAS procedure for MMD/S; 21 patients received revascularization of both hemispheres. Patients presented with the following: 49% with stroke, 35% with transient ischemic attack, 13% with hemorrhage, and 3% with seizure. The mean Suzuki grade was 3.46. The number of patients with a modified Rankin Scale score of 0-1 improved from 21 to 29 (p = 0.002) from the time of surgery to the time of last follow-up. The number of neurological events (i.e., transient ischemic attacks, strokes, and hemorrhages) decreased from a mean of 1.7 events per patient to 0.14 (p < 0.001). The mean length of follow-up was 32.8 months.CONCLUSIONSThis series demonstrates that EDAS is an effective procedure for MMD/S in a North American cohort of patients.