Characteristics and Clinical Implication of White Matter Lesions in Patients With Adult Moyamoya Disease

White matter hyperintensities (WMHs) are reportedly increased in moyamoya disease (MMD); however, their clinical importance is not well-established owing to their pathophysiologic heterogeneity by distribution. This study aimed to evaluate the burden and pattern of WMHs and its clinical implications in the MMD trajectory.Adult patients with MMD without significant structural lesions were 1:1 propensity score-matched with healthy controls for sex and vascular risk factors. The total, periventricular, and subcortical WMH volumes were segmented and quantified fully automatically. WMH volumes were detrended by age and compared between the 2 groups. MMD severity based on Suzuki stage and future ischemic events were assessed for their association with WMH volumes.A total of 161 pairs of patients with MMD and controls were analyzed. MMD significantly correlated with increased total WMH volume (B [standard error], 0.126 [0.030]; p < 0.001), periventricular WMH volume (0.114 [0.027]; p < 0.001), and periventricular-to-subcortical ratio (0.090 [0.034]; p = 0.009). In the MMD subgroup (n = 187), advanced MMD had an independent association with the total WMH volume (0.120 [0.035]; p < 0.001), periventricular WMH volume (0.110 [0.031]; p < 0.001), and periventricular-to-subcortical ratio (0.139 [0.038]; p < 0.001). Periventricular WMH volume (adjusted hazard ratio [95% confidence interval], 5.12 [1.26-20.79]) and periventricular-to-subcortical ratio (3.80 [1.51-9.56]) were associated with future ischemic events in patients with medically followed up MMD. However, no demonstrable association was found between subcortical WMH volume and MMD, MMD severity, or future ischemic events.Periventricular WMHs, but not subcortical WMHs, may represent the main pathophysiology of MMD. Periventricular WMHs may be used as a marker for ischemic vulnerability in patients with MMD.