Prevalence and characteristics of concurrent down syndrome in patients with moyamoya disease

BACKGROUND: An association between moyamoya disease and Down syndrome appears to exist on the basis of reported anecdotal cases in the literature. OBJECTIVE: To determine the prevalence of Down syndrome associated with moyamoya disease in inpatients and to identify the demographic and clinical features of moyamoya disease that may be unique when associated with Down syndrome. METHODS: In this observational study, we analyzed data from the Nationwide Inpatient Sample between 2002 and 2009 using International Classification of Diseases codes for moyamoya disease and Down syndrome for patient identification. Data including patient age, sex, race/ethnicity, secondary diagnosis, procedures, hospital costs, and patient outcomes were obtained. RESULTS: From 2002 to 2009, an estimated 518 patients (mean 6 SD age, 16.2 6 1.68 years) with coexisting moyamoya disease and Down syndrome were admitted. The estimated prevalence was 3.8% (3760 per 100 000) among patients admitted with moyamoya disease and 9.5% (9540 per 100 000) among moyamoya patients ,15 years of age. Patients admitted with moyamoya disease and Down syndrome were most frequently white and Hispanic (P = .02). They were more likely to present with ischemic stroke and less commonly with hemorrhagic stroke (15.3% and 2.7%, respectively; P , .05). CONCLUSION: This is the first study to estimate the prevalence of Down syndrome in patients with moyamoya disease. The 26-fold-greater prevalence of Down syndrome in patients with coexisting moyamoya disease compared with the prevalence of Down syndrome among live births (145 per 100 000) highlights the need for a better understanding of the common pathophysiology of the 2 conditions.