High Prevalence of Moyamoya Syndrome in Appalachia

Introduction: Moyamoya is a chronic cerebrovascular condition of unclear etiology characterized by progressive occlusion of 1 or both internal carotid arteries with neovascular collateral formation. With both an idiopathic form (moya­moya disease) and congenital condition-associated form (moyamoya syndrome), it can cause ischemic and hemorrhagic stroke. Recent findings in Kentucky have challenged traditional estimates of its incidence in US populations. Using the Kentucky Appalachian Stroke Registry (KApSR), our aim was to further characterize its incidence as a cause of stroke and to understand the patient population in Appalachia. Methods: A retrospective review of moyamoya patients was performed using the KApSR database. Data collected included demographics, county location, risk factors, comorbidities, and health-care encounters from January 1, 2012, to December 31, 2016. Results: Sixty-seven patients were identified; 36 (53.7%) resided in Appalachian counties. The cohort accounted for 125 of 6,305 stroke admissions, representing an incidence of 1,983 per 100,000 stroke admissions. Patients presented with ischemic strokes rather than hemorrhagic strokes (odds ratio 5.50, 95% CI: 2.74–11.04, p < 0.01). Eleven patients (16.4%) exhibited autoimmune disorders. Compared to the general population with autoimmune disorder prevalence of 4.5%, the presence of autoimmunity within the cohort was significantly higher (p < 0.01). Compared to non-Appalachian patients, Appalachian patients tended to present with lower frequencies of tobacco use (p = 0.08), diabetes mellitus (p = 0.13), and hypertension (p = 0.16). Conclusions: Moyamoya accounts for a substantial number of stroke admissions in Kentucky; these patients were more likely to develop an ischemic stroke rather than a hemorrhagic stroke. Autoimmune disorders were more prevalent in moyamoya patients than in the general population. The reduced frequency of traditional stroke risk factors within the Appalachian group suggests an etiology distinct to the population.