Management of intracranial vertebral artery stenosis with ipsilateral vertebral artery hypoplasia and contralateral vertebral artery occlusion via type 2 proatlantal intersegmental artery

BACKGROUND: Proatlantal intersegmental artery (PIA) is a rare primitive carotid-basilar anastomosis. PIA may accompany with ipsilateral or bilateral vertebral arteries (VAs) agenesis. Here, we presented the case with intracranial VA stenosis supplying via PIA and demonstrated how we evaluated and managed. METHODS: Dual antiplatelet therapy and adequate hydration were given for three weeks for intracranial atherosclerotic disease (ICAD). We arranged magnetic resonance (MR) vessel wall imaging to survey both intracranial VAs. Intracranial right VA stenosis supplying via PIA with ipsilateral VA hypoplasia and contralateral intracranial VA occlusion caused multiple posterior circulation infarcts. We performed angioplasty and intracranial stenting for ICAD at the right VA V4 segment via PIA. RESULTS: National Institute of Health Stroke Scale (NIHSS) and modified Rankin scale (mRS) got improved at discharge and ten months. CONCLUSIONS: This case is the first report for ICAD management via PIA. A persistent type 2 PIA is essential for supplying posterior circulation.