Vertebral artery stump syndrome associated with a bihemispheric posterior inferior cerebellar artery

Background: Vertebral artery (VA) stump syndrome (VASS) is an embolic source for cerebral infarction (CI) in the posterior circulation after VA occlusion. Case Description: A 63-year-old patient with a history of hypertension presented to our emergent department with dizziness, vomiting, and gait disturbance. Head magnetic resonance imaging (MRI) showed acute CIs in the bilateral cerebellar hemispheres and the vermis. Magnetic resonance angiography revealed patency of the VA and basilar artery. Left subclavian artery digital subtraction angiography (DSA) revealed severe left VA orifice stenosis and collateral flow from the deep cervical artery into the left V2 segment. Right VA angiography showed retrograde flow to the left V4 segment, branching bihemispheric posterior inferior cerebellar artery (PICA), and to-and-flow appearance in the proximal PICA segment and VA. VASS was diagnosed, and conservative treatment with aspirin was administered. Worsened nausea and gait disturbance had developed during hospitalization. MRI revealed an enlarged posterior circulation CI. Follow-up DSA revealed proximal to-and-flow appearance translocation to the proximal V4 segment and poor PICA flow. We performed proximal V4 segment parent artery occlusion (PAO) by endovascular therapy. No recurrence of symptoms or CI was observed. The patient was discharged on day 32 of hospitalization with 1 on the modified Rankin scale. Conclusion: We reported a rare case of VASS involving bihemispheric PICA. No CI recurrence was observed after performing PAO of the proximal V4 segment. When treating acute cases of bilateral cerebellar CI due to VASS, the contribution of PICA variations should be considered.