An 8-year-old boy with vertebral artery dissection with cerebellar ataxia featuring suspected vertebral artery hypoplasia.

We report an 8-year-old boy with left vertebral artery dissection featuring cerebellar ataxia in which congenital vertebral artery hypoplasia was suspected as a predisposing factor in the dissection. The patient suddenly suffered from vertigo and vomiting while swimming, and he was brought to our department. The initial brain Computed Tomography (CT) demonstrated no abnormalities, and his symptoms disappeared the next morning. However, one month after onset, brain Magnetic Resonance Imaging (MRI) revealed ischemic changes (infarction) in the left cerebellum. Transfemoral angiography showed complete occlusion at the C2 portion of the left vertebral artery, suggesting dissection and diffuse narrowing of the proximal segment of the occlusion site. Three-dimensional CT angiography also revealed diffuse narrowing of the left vertebral artery from the bifurcation of the subclavian artery. He has since been living daily life without any difficulties. The detailed etiology of cerebral artery dissection remains unknown, but arterial anomalies should be considered as a predisposing factor.