Dissecting Aneurysm of Well-developed Posterior Inferior Cerebellar Artery: A Case Report

We report a rare case of dissecting aneurysm of the posterior inferior cerebellar artery (PICA) with vascular variation. A 38-year-old man, who had no medical, familial or traumatic histories, presented with headache, nausea and mild consciousness disturbance. Computed tomography (CT) imaging demonstrated subarachnoid hemorrhage with intra-ventricular hemorrhage. Angiography disclosed an aneurysm of left PICA, which did not involve the vertebral artery. The PICA was well developed and widely perfused the cerebellum and lower brain stem, which was accompanied by lack of ipsi-lateral anterior inferior cerebellar artery (AICA) and contra-lateral PICA. The aneurysm was successfully treated by trapping and revascularization procedure with occipital artery (OA)-PICA anastomosis. We suggest that congenital vascular variation related to well-developed PICA might lead to dissecting aneurysm, and that direct surgical treatment with bypass would be indicated for such patients to preserve hemodynamic integrity.