To determine the proportion of ischemic stroke patients with Moyamoya disease (MMD) and Moyamoya syndrome (MMS), evaluate their impact on outcomes across TOAST subtypes after adjusting for demographics and comorbidities, and compare outcomes by socioeconomic status (SES) and race.

MMD and MMS are progressive cerebrovascular conditions that predispose to ischemic stroke through intracranial arterial stenosis. Limited national data exist on how Moyamoya-associated ischemic stroke influences outcomes across TOAST subtypes and socioeconomic and racial groups.

A retrospective cross-sectional analysis was conducted using the National Inpatient Sample (2016–2022). Adult patients (≥18 years) with ischemic stroke and either MMD or MMS were identified using ICD-10 codes. Stroke subtypes were classified as cardioembolic, large-vessel disease (LVD), or small-vessel disease (SVD). Outcomes included in-hospital mortality, discharge disposition, length of stay (LOS), and total hospital charges. Survey-weighted multivariable regression models adjusted for age, sex, income, and comorbidities (hypertension, diabetes, atrial fibrillation).

Among 578,696 ischemic stroke hospitalizations, only 1,056 (0.2%) had MMD or MMS, while cardioembolic, LVD, and SVD subtypes comprised 18.3%, 5.8%, and 48.8% of cases, respectively. In-hospital mortality occurred in 2.7%, with lower odds of death than non-Moyamoya patients (OR 0.62 [95% CI 0.42–0.90]; p = 0.011; aOR 0.69 [0.47–1.03]; p = 0.066). Moyamoya patients had longer LOS (6.46 vs 5.14 days; p < 0.001), higher charges ($116,220 vs $71,681; p < 0.001), and were less often discharged home (aOR 0.59 [0.52–0.67]; p < 0.001). No significant SES differences were found. LOS (p = 0.003) and total charges (p < 0.001) differed by race, longest and highest among Hispanic and Asian/Pacific Islander patients.

Moyamoya-associated ischemic stroke, encompassing MMD and MMS, shows lower mortality but greater healthcare utilization. Clinically, these findings emphasize the need for early detection, multidisciplinary care, and equitable rehabilitation access to optimize recovery and reduce costs.