Hybrid Occipital Artery–AICA Bypass Followed by Endovascular Embolization for a Radiation-Induced Dissecting AICA Aneurysm in a Pediatric Patient

BACKGROUND AND IMPORTANCE: Pediatric anterior inferior cerebellar artery (AICA) aneurysms are rare; radiation-associated dissecting lesions require exclusion without compromising brainstem or cerebellar perforators. CLINICAL PRESENTATION: A 13-year-old boy developed a progressively enlarging right AICA a2 dissecting aneurysm after cranial irradiation for pineal nongerminomatous germ cell tumor. Because direct clipping or isolated parent vessel occlusion was considered high risk, he underwent occipital artery-AICA a3 bypass followed by endovascular coil embolization in a single hybrid session. Dual arterial access enabled transradial vertebral artery treatment and transfemoral angiographic bypass assessment. Postoperative MRI showed a small transient cerebellar ischemic lesion that resolved within 2 weeks. At 2 months, the patient was neurologically intact with patent bypass and no aneurysm recurrence. CONCLUSION: Hybrid occipital artery-AICA bypass followed by endovascular embolization is a feasible flow-preserving option for selected pediatric AICA aneurysms requiring distal perfusion preservation.