Ruptured distal anterior inferior cerebellar artery aneurysm--case report.

A 62-year-old female presented with a distal anterior inferior cerebellar artery (AICA) aneurysm showing severe involvement of the facial and acoustic nerves manifesting as progressive left hearing disturbance and left facial nerve paresis. She was admitted to our hospital 2 months after the onset. A saccular aneurysm arising from the meatal loop of AICA was found between the facial and acoustic nerves which were damaged directly by the aneurysm. Magnetic resonance imaging demonstrated a vascular anomaly, differentiating this disorder from cerebellopontine angle tumor, and evidence of an old subarachnoid clot. These characteristics were extremely helpful for the differential diagnosis. Neck clipping and aneurysmectomy were performed to achieve decompression of the cranial nerves. One year and 2 months later full function of the facial nerve returned but the hearing disturbance persisted.