Abstract Body: Introduction:
Moyamoya disease (MMD) is a rare cerebrovascular disease causing nonatherosclerotic intracranial arterial stenosis in children and young adults. The RNF213 gene variant plays an important role in the pathophysiology of MMD, particularly among East Asian populations. However, this variant is rarely found in patients of other ethnicity. Previous studies have shown that RNF213 gene variant is related to vascular structures such as the extent of moyamoya collaterals and posterior cerebral artery involvement. In this study, we utilize an imaging-based approach to investigate vascular structural features in MMD, which may offer novel insights into the pathophysiology of MMD.
Methods:
We retrospectively reviewed 770 patients with MMD or Moyamoya syndrome (MMS) from diverse ethnic backgrounds at Stanford University Medical Center treated between 2015 and 2024 (Fig. 1). After selecting sporadic non-hemorrhagic bilateral MMD patients aged 18-50 years old, the vascular structures acquired on MRA were visually assessed to evaluate the degree of intracranial arterial stenosis and basal moyamoya collaterals. T2 weighted images were reviewed to assess negative remodeling - shrinkage of the outer diameter of middle cerebral arteries (MCA) and internal cerebral arteries (ICA) as defined by Kuroda et al.2015, Neurol Med Chir (Tokyo).
Results:
Detailed demographic and clinical characteristics of 107 patients evaluated were listed in Table 1. By reviewing MRA, we have identified a subset of patients with unique imaging features characterized by ICA stenosis localized proximal to the terminal portion of ICA, differing from the typical lesion sites seen in MMD (Fig. 2). This non-terminal ICA stenosis was more frequently observed in Caucasian than in Asian patients (17.5% vs. 5.7%, P=0.007). Compared to patients with terminal ICA and/or MCA stenosis, patients with non-terminal ICA stenosis were older (P=0.03), had less advanced disease stages (P<0.001), and displayed fewer basal moyamoya collaterals (P=0.002).
Conclusion:
Using the imaging-based approach of vascular structural features, we have identified a potential subtype of moyamoya disease characterized by non-terminal ICA stenosis. This subtype may have a different pathophysiology from patients with typical ICA terminal stenosis, potentially driven by distinct genetic and epigenetic factors. Ongoing investigations are focused on elucidating these factors and their implications in MMD.