Ruptured aneurysms of anterior inferior cerebellar artery (AICA) after
radiotherapy for
vestibular schwannoma (VS) are rare, and no definite treatment has been established for distal AICA
pseudoaneurysms. We describe a 61-year-old man who underwent Gamma Knife surgery (GKS) for left VS. Follow-up magnetic resonance imaging (MRI) revealed partial regression of the
tumor. Twelve years after GKS, he suffered from
subarachnoid hemorrhage. Initial angiogram showed no vascular lesions; second left vertebral angiogram, 10 days after admission, demonstrated a
pseudoaneurysm in the lateral pontine segment of the left AICA. The proximal portion of the AICA was occluded by a coil. Postoperative MRI revealed an
infarction on the left side of the pons and brachium pontis. Although the patient suffered from mild postoperative
cerebellar ataxia and facial and
abducens nerve palsy, he was discharged 1 month postoperatively requiring no assistance with
activities of daily living. Twelve months later, he recovered satisfactorily with a modified Rankin Scale grade of 1, and no recanalization of the
aneurysm was found on MR angiography. Endovascular parent artery occlusion for
ruptured aneurysms at distal AICA carries the risk of
brain stem infarction, but should be considered when no other option is available such as after
radiotherapy for VS.