Ruptured vertebrobasilar junction aneurysm coexisting with isolated interrupted aortic arch and basilar artery hypoplasia in an adult female: illustrative case.

backgroundVertebrobasilar junction (VBJ) aneurysms are frequently associated with basilar artery variations like fenestration or hypoplasia, altering hemodynamics. An interrupted aortic arch (IAA), a rare congenital malformation, may contribute to intracranial aneurysms via vascular wall defects, hemodynamic stress, and compensatory hypertension. Coexistence of IAA with cerebrovascular anomalies and VBJ aneurysms is exceptionally rare, with no prior documented cases. OBSERVATIONS: A 33-year-old female presented with a ruptured VBJ saccular aneurysm (2.0 × 4.1 × 2.9 mm). Emergency right transradial stent-assisted coiling achieved complete occlusion (Raymond-Roy Occlusion Classification class I). Associated anomalies included 1) Celoria-Patton type B IAA, 2) diffuse basilar hypoplasia, and 3) proximal basilar occlusion. Echocardiography confirmed isolated Celoria-Patton type B IAA. Postoperative MRI performed on day 4 revealed no infarction, and CT performed on day 12 confirmed subarachnoid hemorrhage (SAH) resolution. The patient was discharged neurologically intact (modified Rankin Scale score 0). Seven-month CT angiography demonstrated stable coils, an intact stent, and patent vertebral arteries. LESSONS: In adults or adolescents with aneurysmal SAH, IAA typically manifests as an isolated anomaly pathologically linked to prenatal development of robust compensatory collateral circulation supplying the descending aorta. This case demonstrates a synergistic pathogenesis involving two critical hemodynamic factors: proximal basilar artery occlusion combined with type B aortic arch discontinuity, collectively promoting VBJ aneurysm formation. Transradial endovascular intervention proved safe and effective in this anatomically complex scenario. https://thejns.org/doi/10.3171/CASE25421.