Objective: Using high-resolution magnetic resonance imaging(HRMRI), we sought to examine the proportions of intracranial stenosis subtypes and their clinical relevance in young patients(≤45 years old).
Methods: One hundred and twenty-nine consecutive patients (mean age 36±8 years) with middle cerebral artery stenosis and without Moyamoya disease were evaluated by HRMRI. The stenosis was classified as eccentric stenosis, concentric stenosis, and mixed stenosis if both eccentric and concentric stenosis occurred in one vessel. The clinical data and vessel wall properties were analyzed among the subtypes.
Results: Eccentric stenosis was found in 86 (69.4%) patients, while concentric stenosis was found in 26 patients (21.0%) and mixed stenosis in 12(9.7%) patients. The patients with eccentric stenosis were older (p<0.001) and more likely had atherosclerosis risk factors (p=0.024). The patients with concentric stenosis were more likely female, and aged 35 years old or younger. All mixed stenosis were high-grade (>70%) stenotic. All concentric stenosis showed constrictive remodeling, while eccentric and mixed stenosis had heterogeneous remodeling types. In 34 patients with available enhanced images, ring enhancement was revealed in 8/9(88.9%) concentric stenosis and 5/5(100%) mixed stenosis, but only in 3/20(15%) eccentric stenosis (P<0.001). Ten of twelve (83.3%) patients with mixed stenosis were symptomatic, more frequently than the patients with eccentric stenosis (57.0%, p=0.072) and the patients with concentric stenosis (50%, p=0.052).
Conclusions: The distinct vessel wall features among intracranial stenosis subtypes suggest heterogeneous pathophysiology. Further studies are required to investigate whether mixed stenosis is the most vulnerable subtype in young patients (≤45 years old).