“Plugged” Anterior Inferior Cerebellar Artery Aneurysm Causing Facial Palsy, Hearing Loss, and Subarachnoid Hemorrhage Treated by a Translabyrinthine Approach

Anterior inferior cerebellar artery (AICA) aneurysms are rare, less than 1%-2% of all intracranial aneurysms. Aneurysms of the distal AICA are even less common and can present with hearing loss and facial paralysis because of their relationship with the internal auditory canal (IAC). A 65-year-old male was followed for fluctuating left facial weakness and left-sided hearing loss for over a year. Serial magnetic resonance imaging (MRI) scans showed a mass near the left IAC, thought to be a vestibular schwannoma. Just prior to his next clinic visit, the patient deteriorated suddenly from a subarachnoid hemorrhage. Cerebral angiography revealed a 5.5 mm saccular aneurysm at the distal left AICA, which was clip ligated via a translabyrinthine (TL) approach. The patient had a good functional outcome (modified Rankin Scale [mRS] 1) after 30 days despite persistent left facial weakness. Stable obliteration of the aneurysm was demonstrated by cerebral angiography postoperatively. Distal AICA aneurysms are rare and can have a similar presentation to tumors in the cerebellar pontine angle. Because of the unique anatomy of the distal AICA, open clip ligation via a TL approach is an effective method to secure these aneurysms.