Introduction: Bypass surgery is the major treatment for Moyamoya disease (MMD), but which surgical modality is superior still remains controversial.
Methods: This prospective cohort study screened a series of 696 consecutive MMD patients from 2009 to 2015. Patients without revascularization surgeries or with different surgical modalities on bilateral hemispheres were excluded. Finally, 529 patients who were followed up for with at least 12 months were included, with 438 patients undergoing unilateral surgeries and 91 patients undergoing bilateral surgeries. Of these, 241 patients received direct bypass (DB), 81 patients received combined bypass (CB) and 207 patients received indirect bypass (IB). Three clinical outcomes were evaluated and compared between different surgical groups, including recurrent stroke events, modified Rankin Scale (mRS) scores and change of main symptoms.
Results: The mean follow-up period was 40 months. During the follow-up period, recurrent stroke events were observed in 43 patients, including 15 patients with hemorrhage, 26 patients with ischemia (TIA in 19 and infarction in 7) and 2 patients with both hemorrhage and cerebral infarction. Kaplan-Meier analysis showed that patients receiving CB and DB had longer ischemia-free time compared to patients with IB (p=0.013). But there was no significant difference in hemorrhage-free time between different surgical modalities (p=0.534). A good neurological status (mRS=2) was achieved in 495 patients (93.6%), which was significantly more common in children (98.2%) than in adults (92.3%; p=0.022). Surgical modalities were not significantly associated with neurological status outcome (p=0.860). Moreover, improvement of symptoms was observed in 449 patients (84.9%), which was also significantly more common in children (93.0%) than in adults (82.7%; p=0.006). No significant difference was observed between different surgical modalities, either (p=0.548).
Conclusions: CB and DB are more effective to prevent recurrent ischemic strokes than IB. However, there is no evidence that these three surgical modalities had significant difference in preventing recurrent hemorrhage.
Patient Care: For ischemic-type moyamoya disease, combined bypass and direct bypass are suggested to prevent ischemic events when it is available; for hemorrhagic patients, indirect bypass might be considered for its feasibility.
Learning Objectives: By the conclusion of this session, participants should be able to identify an effective treatment that combined bypass and direct bypass are better than indirect bypass for ischemic-type moyamoya disease; and for hemorrhagic patients, indirect bypass might be considered for its feasibility.