A Case of Ruptured Posterior Inferior Cerebellar Artery Aneurysm Suggestive of Dissection in an Octogenarian Patient with Anti-Neutrophil Cytoplasmic Antibody-Related Vasculitis.

An anti-neutrophil cytoplasmic antibody-associated vasculitis is a systemic autoimmune disease characterized by small-vessel inflammation, with rare central nervous system manifestations such as subarachnoid hemorrhage. Cerebral artery dissection, a rare but serious condition that can lead to ischemic stroke or subarachnoid hemorrhage, predominantly affects young to middle-aged adults and is less common in elderly patients. We report the case of an 86-year-old male with anti-neutrophil cytoplasmic antibody-associated vasculitis who developed subarachnoid hemorrhage due to a ruptured posterior inferior cerebellar artery aneurysm, suggestive of dissection. Despite diagnostic challenges related to the patient's advanced age, repeated vascular imaging indicated arterial dissection, and parent artery occlusion successfully prevented re-rupture. This case highlights the importance of considering cerebral artery dissection as a potential cause of subarachnoid hemorrhage in patients with anti-neutrophil cytoplasmic antibody-associated vasculitis, even in octogenarians, and underscores the need for comprehensive vascular evaluation to ensure timely diagnosis and management.