Anteroinferior cerebellar artery aneurysms: Surgical approaches and outcomes - A review of 34 cases

OBJECTIVE: Anteroinferior cerebellar artery (AICA) aneurysms are rare lesions whose treatment requires expertise in vascular, endovascular, and cranial base surgery. This article presents the largest series treated at one center. METHODS: We retrospectively analyzed presenting symptoms, aneurysm characteristics, surgical approaches, postoperative outcomes, and the application of endovascular techniques. RESULTS: We found 32 patients with 34 AICA aneurysms (11 men and 21 women; age range, 6-77 yr; mean age, 51 yr). Twenty-one aneurysms had ruptured; 13 were unruptured. Seven of the unruptured aneurysms presented with brainstem compression, and six were found incidentally. Surgical approaches included the retrosigmoid, far-lateral transcochlear, translabyrinthine, and orbitozygomatic. Eighteen patients (56%) had neurological complications. Thirty aneurysms were at proximal locations, and four were distal. Intraoperative hypothermic cardiac arrest was used to clip eight giant aneurysms. Follow-up was available in 56% of the patients for a mean of 41 months. The mean Glasgow Outcome Scale scores at discharge were not significantly different from the patients' status at their initial assessment. CONCLUSION: We recommend the standard retrosigmoid approach for treating small to medium aneurysms involving the lower two-thirds of the clivus or distal AICA aneurysms. Cranial base approaches are recommended for large or giant aneurysms or for those proximal to the emergence of the AICA from the basilar trunk. Hypothermic cardiac arrest facilitates dissection of giant aneurysms. Endovascular treatment is a useful adjunct for treating residual aneurysms but did not provide definitive treatment in any of our patients.