Moyamoya disease (MMD) is a rare neurologic disorder caused by idiopathic stenosis or occlusion of the anterior cerebral circulation and abnormal collaterals formation. Limited studies described the prevalence and the clinical characteristics in non-Asian populations, especially African Americans (AA).

This is a retrospective cohort for adults with confirmed MMD at an urban medical center from 1998 to 2018. Demographics, clinical presentation, brain imaging, and outcomes were analyzed.

Sixty-three patients are included. Thirty-five (56%)  AA, 23% white, 5% Hispanic and 3% Asian. AA patients were slightly older at presentation (mean age 41.1 ± 10.9 years vs. 35.7 ± 11.5 years, other races; (p=0.06). AA had hypertension more often (80% AA vs. 36% other races, p<0.001), with no difference in DM, HLD, CAD, substance abuse, or smoking. AA patients presented less often with a headache with focal neurological signs (6% AA vs. 25% other races, p=0.065) and more often with stroke (71% AA vs. 39% other races, p=0.010). MMD diagnosis was delayed in 26 (41%) patients. The median delay for AA was 5 (1-19) years. AA strokes at MMD diagnosis 86.7% were ischemic, 13.3% were hemorrhagic. 71.4% of strokes were ischemic in other races, and 28.6% were hemorrhagic (p= 0.64). At the time of formal diagnosis, 91% of AA had bilateral MMD, and 31% had advanced disease; Suzuki (4-5-6). Long term complications in AA were recurrent strokes (26%), ICH (6%), seizures (14%), and TIA (9%).

In this cohort, 56% of MMD patients were AA. Ischemic stroke is the most common initial presentation. MMD diagnosis in AA can be delayed due to atypical clinical, radiographic presentation, or inadequate access to health care. MMD can be advanced in AA at the time of diagnosis; therefore, early diagnosis and interventions would improve outcomes.