Abstract WP167: Is There a Distinct Phenotype for Non-Asian Moyamoya Patients?

Background and Purpose: Idiopathic moyamoya syndrome (IMMS) is a progressive narrowing of the anterior circulation arteries resulting in the development of a tenuous collateral blood supply which is prone to rupture or thrombosis. IMMS has mostly been studied in East Asian populations where it was first described, with limited data describing this syndrome in non-Asians. We aimed to describe IMMS patients in New York and identify differences between Asians and non-Asians in this population. Methods: Using the New York State Department of Health Statewide Planning and Research Cooperative System database from 2000-2014 we identified all newly diagnosed cases of IMMS (ICD-9 437.5) in adults aged 18 and older. We excluded patients with down syndrome, neurofibromatosis type 1 and sickle cell disease. We compared patient demographics, comorbidities and extracranial-intracranial revascularization (ECIC) rates for IMMS patients that self-identified with Asian race/ethnicity vs those who did not. Results: All IMMS diagnoses occurred in urban hospitals. There were 554 IMMS patients in total; 89.4% (n=495) were non-Asian while only 10.6% (n=59) were Asian. A smaller proportion of non-Asian IMMS patients were diagnosed in smaller, non-academic hospitals compared to Asians (3.8% vs 10.2%, p=0.03) (Table). Both groups showed comparable rates of characteristics and comorbidities. Stroke risks following IMMS diagnosis were similar for both Asians and non-Asians (13.6% vs 22.4%, p=0.1); strokes occurred later for non-Asian patients with ECIC than in those without (2.1 + 2.8 vs 1.4 + 2.1 years, p=0.04). No subsequent strokes occurred in Asians after ECIC. Conclusion: Individuals of non-Asian origin account for almost 90% of IMMS diagnoses in New York State, but they are infrequently diagnosed in small, non-academic hospitals. Further research is needed to identify a distinctive phenotype and genotypic profile of IMMS in non-Asians.