Nonatheroscleotic Isolated Middle Cerebral Artery Disease May Be Early Manifestation of Moyamoya Disease.

BACKGROUND AND PURPOSE: Middle cerebral artery steno-occlusive disease (MCAD) is not an uncommon cause of ischemic stroke in young Asians. Aside from atherosclerosis, the pathogenesis of MCAD include various nonatherosclerotic vasculopathies, most of which are yet to be defined. This study investigated the pathogenesis of symptomatic isolated MCAD in young Asian patients using high-resolution magnetic resonance imaging (HR-MRI) and mutation analysis of RNF213.

METHODS

Patients aged <60 years with stroke or transient ischemic attack caused by MCAD were prospectively enrolled. Patients with a confirmed diagnosis of moyamoya disease, dissection, and vasculitis; with significant steno-occlusion in cerebral arteries other than the MCA; or with high-risk cardioembolic source were excluded. Using high-resolution MRI, patients were classified into an atherosclerosis group and a nonatherosclerosis group.

RESULTS

Eighty-one patients were enrolled, 45 (56.6%) in the atherosclerosis and 36 (44.4%) in the nonatherosclerosis group. The nonatherosclerosis group was significantly younger (P=0.013), had a smaller number of vascular risk factors (P=0.001), showed a lower homocysteine level (P<0.001), thinner intima-media thickness (P=0.006), and had more frequent heterozygotes at RNF213 (P=0.045) than the atherosclerosis group. Diffusion-weighted image lesion pattern showed no significant differences in assumed stroke mechanisms between the 2 groups.

CONCLUSIONS

Nonatherosclerotic pathogenesis are common in young Asians with symptomatic isolated MCAD. Clinical findings, high-resolution MRI features, and results of RNF213 mutation analysis suggest that moyamoya disease is responsible etiologically for a significant portion of nonatherosclerotic lesions. Symptomatic isolated MCAD may be an early manifestation of moyamoya disease in young Asian adults.