Long-Term Hemorrhagic Morbidity for Children With Moyamoya Treated With Revascularization Surgery in a Single Center Retrospective Cohort.

Background: Children with moyamoya arteriopathy have reduced subsequent ischemic risk after revascularization surgery and it is also suggested that hemorrhagic risk may also be reduced by minimizing hemodynamic stress on collateral vasculature recruited within the brain parenchyma, but this has been studied only in intermediate follow-up or follow-up for more than a decade in East Asian populations. We aimed to evaluate the incidence of hemorrhagic stroke in long-term follow-up and identify at-risk subpopulations. Methods: A single surgeon's personal case series with decades of follow-up was reviewed for children (18 years or younger) treated with revascularization surgery. This included medical records and the surgeon's personal correspondence. Results: Hemorrhagic stroke occurred in 2.6% of 302 children followed for a median of 21 years after surgery. Occurring at a median of 19 years (interquartile range 14-22.75) after surgery, these hemorrhages would not be recognized in series that discontinue follow-up at transition from pediatric to adult neurosurgical care. There was a higher proportion (5.5-fold hazard, 95% CI, 1.1-27.6) of patients who had prior radiation therapy in the group with hemorrhagic stroke compared with the overall group. Close retrospective evaluation of vascular imaging suggests aneurysms of the collateral periventricular vessels as a common culprit. Conclusion: Children who have moyamoya treated with revascularization surgery remain at long-term risk of hemorrhagic stroke during adulthood, even though their ischemic stroke risk is significantly mitigated. These patients would benefit from continued clinical and radiological follow-up, potentially with advanced imaging modalities.