Radiosurgery-Induced Anterior Inferior Cerebellar Artery Pseudoaneurysm Treated with Trapping and Bypass

Stereotactic radiosurgery (SRS) is an established modality for treatment of vestibular schwannomas (VSs). However, its long-term vascular complications have not been well studied. Among 360 patients who underwent SRS for VS in our institution and lived for >5 years thereafter, we identified only 1 patient who exhibited a complication secondary to a late-onset aneurysm for an estimated incidence of 0.3%.

A 78-year-old man who had undergone SRS 19 years previously for a right VS presented with right peripheral facial palsy. Radiographic examinations revealed a distal anterior inferior cerebellar artery (AICA) fusiform aneurysm that was embedded in the tumor and progressively enlarged over 17 months. Although the right AICA perfused a large area of the cerebellum, the aneurysm was successfully treated with AICA trapping in conjunction with an occipital artery-AICA bypass.

Distal AICA pseudoaneurysm formation is a rare but potentially severe late complication after SRS for VS. This pathology was successfully treated with AICA trapping with occipital artery-AICA bypass.