Vertebral artery pseudoaneurysm with recurrent posterior circulation transient ischemic attacks in a post-radiotherapy nasopharyngeal carcinoma survivor: a case report.

Background: Radiation-induced osteosarcoma (RIOS), osteoradionecrosis (ORN), and post-radiotherapy pseudoaneurysms are recognized late complications of radiotherapy for nasopharyngeal carcinoma (NPC). Although post-radiotherapy pseudoaneurysms usually present with life-threatening hemorrhage, associated ischemic manifestations are rarely described. Case presentation: A 50-year-old man with a history of NPC treated with radiotherapy developed a left cervical paravertebral RIOS 15 years later, with suspected coexisting cervical spine osteoradionecrosis (C-ORN). He experienced recurrent, brief, and fully reversible posterior circulation transient ischemic attacks (TIAs). Computed tomography angiography (CTA) demonstrated destructive C1-C2 changes, a partially thrombosed left vertebral artery (VA) pseudoaneurysm, and residual distal opacification extending to the V4 segment and left posterior inferior cerebellar artery. Digital subtraction angiography (DSA) performed approximately two weeks later showed no antegrade filling beyond the lesion, while right VA angiography confirmed adequate posterior circulation perfusion. Endovascular parent artery occlusion completely excluded the lesion. No further TIAs or new ischemic complications occurred during the 6-month follow-up. Conclusion: Post-radiotherapy RIOS, suspected C-ORN, and destructive upper cervical changes may compromise the VA and contribute to pseudoaneurysm formation. Progressive thrombosis of the pseudoaneurysm may be associated with recurrent posterior circulation TIAs. Careful assessment of the vertebral arteries on CTA, supplemented by DSA when indicated, is warranted in patients with otherwise unexplained posterior circulation symptoms.