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Purpose: Bypass surgery is regarded as the standard treatment option for symptomatic and hemodynamically unstable moyamoya disease (MMD). However, there is ongoing debate about the most effective type of bypass surgery. We aimed to analyze the long-term outcomes of combined and indirect bypasses for MMD patients through intra-individual comparisons., Methods: Of the 896 patients who underwent 1084 bypass surgeries between 2007 and 2021, 24 patients with MMD who underwent combined bypass on one side and indirect bypass on the other side were ultimately enrolled in this study. Clinical, angiographic and hemodynamic outcomes were retrospectively evaluated., Results: Three asymptomatic strokes (12.5%) occurred within 30 postoperative days in each group. Postoperative strokes after 30 days occurred in 3 patients (12.5%) with 3 hemorrhagic events and 1 cerebral infarction, only in indirect bypass, while no stroke occurred in hemispheres treated with combined bypass. The revascularization area relative to supratentorial area was significantly greater in combined bypass than in indirect bypass, both in short-term and long-term periods (64.9% versus 43.9% in short-term and 75.7% versus 54.9% in long-term; P < .001, respectively). Hemodynamic outcomes showed significantly greater increases in acetazolamide-challenged cerebral blood flow (CBF acz ) during short-term follow-up (P = .04) and in both basal CBF (CBF bas ) and CBF acz during long-term follow-up (P = .014 and P = .009, respectively) in combined bypass than in indirect bypass., Conclusion: Combined bypass may be a more effective treatment option for MMD based on its higher revascularization area and favorable hemodynamic results compared to indirect bypass in the same patient., Competing Interests: Declarations. Competing interests: The authors declare no competing interests., (© 2025. The Author(s).)

Previous studies have suggested that enlarged perivascular spaces (EPVSs) are potential radiological markers of cerebral ischemia in moyamoya disease (MMD). However, serial changes in EPVSs after surgical revascularization have not yet been clarified. We aimed to elucidate the postoperative changes in EPVSs in adult patients with MMD, clinical and radiological factors affecting the number of EPVSs, and the degree of postoperative changes. We counted the EPVSs in the centrum semiovale in each hemisphere on a T2-weighted MRI performed before surgery. EPVSs were quantified 3 months and 2 years after combined bypass surgery in surgically treated patients and compared with the number of EPVSs before surgery. We performed multivariate logistic regression analysis to identify the clinical and radiological factors associated with the number of EPVSs. This study included 120 hemispheres of 65 adults with MMD. Older age (P < 0.01), posterior cerebral artery (PCA) involvement (P < 0.01), and cerebral blood flow (CBF) impairment (P = 0.02) were significantly associated with a large number of EPVSs. The number of EPVSs markedly decreased at 3 months and 2 years after surgery compared with that before surgery (P < 0.01). PCA involvement (P = 0.04) and CBF impairment (P = 0.02) were independent predictors of the regression of EPVSs after surgery. The number of EPVSs in the centrum semiovale was closely associated with age, PCA involvement, and CBF impairment in adult patients with MMD, which remarkably regressed after surgical revascularization, especially in the hemispheres with PCA involvement and CBF impairment. EPVSs are reversible radiological markers reflecting impaired cerebral hemodynamics in adult patients with MMD., (© 2024. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)