Comparing Outcomes of Moyamoya Disease and Moyamoya Syndrome in a Real-World Scenario: A Cohort Study

Background: Moyamoya disease (MMD) and moyamoya syndrome (MMS) are rare cerebrovascular conditions with unclear distinctions in clinical presentation and prognosis. Aim: This study assessed potential differences between MMD and MMS patients using real-world data on clinical manifestations, surgical outcomes, and stroke risk factors. Methods: This multicenter, retrospective cohort study examined patients with MMD or MMS treated at three tertiary academic hospitals in China, with a mean follow-up of 11.2 +/- 3.1 years. Clinical differences were compared between MMD and MMS, and postoperative cerebrovascular events were compared between patients who underwent surgery and those with conservative management. Primary outcomes were postoperative ischemic and hemorrhagic strokes. Risk factors were evaluated via multivariate Cox regression analysis. Results: Of the 2565 patients, 2349 had MMD and 216 had MMS. After 1:1 propensity-score matching, no significant differences were observed between these two cohorts. Surgical patients had fewer cerebrovascular events than those who received conservative treatment (HR, 0.487; 95% CI, 0.334-0.711; p < 0.001). Preadmission modified Rankin scale scores > 2 (HR, 3.139; 95% CI, 1.254-7.857; p = 0.015) and periprocedural complications (HR, 8.666; 95% CI, 3.476-21.604; p < 0.001) were independent stroke risk factors in patients with MMD. Periprocedural complications (HR, 31.807; 95% CI, 10.916-92.684; p < 0.001) increased stroke risk in patients with MMS. Conclusions: This real-world study revealed substantial clinical overlap between MMD and MMS. Both groups derived significant benefits from surgical revascularization, suggesting distinction may not be necessary to guide surgical management decisions. Optimizing preoperative status and preventing periprocedural complications may improve outcomes in these rare cerebrovascular conditions.