Abstract 133: Asymmetry of Arteriopathy in Pediatric Moyamoya

Introduction: Moyamoya is a progressive steno-occlusive cerebrovascular arteriopathy of bilateral anterior circulation. The pathophysiology is elusive, and once established, moyamoya is typically inexorably progressive. Hypothesis: We hypothesized that the left-sided circulation is more vulnerable to steno-occlusive arteriopathy compared to the right, which may reflect differences in mechanical stress from blood flow. Methods: All children with moyamoya cared for between 1/1/2009 and 7/1/2024 at a single institution were identified through an IRB-approved, retrospective study. The charts and neuroimaging at the time of diagnosis were reviewed to assess symmetry of steno-occlusion. Chi-square test was used for statistical analysis, with p-value <0.05 considered statistically significant. Results: A total of 67 children (35 males) with moyamoya were identified. Steno-occlusive arteriopathy at diagnosis was assessed on head and neck MRA for all 67, as well as on cerebral catheter angiogram in the 32 patients who underwent interventional neuroimaging. Arteriopathy was more severe on the left than the right in 29 (43%), and more severe on the right than the left in 15 (22%). This left-sided predilection was statistically significant (p=0.03). Twenty-three (34%) children had complete occlusion of bilateral anterior circulation without asymmetry at diagnosis. Of the 38 (57% of the total) patients with clinical stroke at the time of presentation, 21 (55%) had right hemiplegia, 10 (26%) had left hemiplegia, and 7 (18%) presented without focal weakness. Conclusions: Moyamoya is an important cause of childhood stroke, and a risk factor for recurrent ischemic and hemorrhagic stroke throughout life. The mechanism of arteriopathy initiation and progression is unknown, and current treatment consists of palliative revascularization. The left predominance of arteriopathy with moyamoya may provide insight into underlying causes of moyamoya arteriopathy. A better understanding of moyamoya pathophysiology may also inform interventions to halt the progression of steno-occlusive arteriopathy once it has begun.