Ruptured Isolated Dissecting Aneurysm of the Posterior Inferior Cerebellar Artery Treated with Endovascular Coil Embolization: A Case Report

Although intracranial dissecting aneurysms frequently occur in the vertebral artery, isolated dissecting aneurysm in the posterior inferior cerebellar artery are rare. A 24-year-old male presented with a severe headache and disturbance of consciousness. Computed tomography of the head showed a diffuse subarachnoid hemorrhage at the posterior cranial fossa. Digital subtraction angiography of the left vertebral artery was performed to clearly display dilatation of the tonsillo-medullary segment at the posterior inferior cerebellar artery, which showed a strong hairpin curve. Endovascular coil embolization of the posterior inferior cerebellar artery was performed to prevent re-rupture of the dissecting aneurysm, and a subsequent small infarction in the left cerebellar hemisphere with mild truncal ataxia emerged. The patient was discharged without any abnormal neurological finding a month after onset of a subarachnoid hemorrhage. In summary, we encountered a rare case of a patient with dissecting aneurysm of the posterior inferior cerebellar artery who was treated with endovascular coil embolization. We hypothesize that the developmental mechanism of this dissecting aneurysm involves hemodynamic stress during the running of the posterior inferior cerebellar artery.