Anatomical Variations of the Anterior Inferior Cerebellar Artery and Their Surgical Significance: A Combined Radiologic and Cadaveric Study
Abstract
Objective: To delineate the anatomical spectrum, frequency, and neurosurgical relevance of anterior inferior cerebellar artery (AICA) variations through combined radiological and microsurgical cadaveric analysis, and to explore potential associations between AICA anomalies and posterior circulation aneurysms. Material and Methods: Computed tomography angiography (CTA) scans of 400 patients (212 males, 188 females; mean age 55.9 years) were retrospectively reviewed for AICA anomalies, aneurysms, and other vascular variations. Cadaveric dissections of two formalin-fixed adult heads (four sides) were performed through retrosigmoid and far-lateral approaches under microscope magnification, with attention to cranial nerve relationships and labyrinthine artery origin. Results: AICA variations were identified in 26 patients (6.5%), totaling 27 variant arteries. The most common anomaly was AICA-PICA common trunk (2.5%), followed by early bifurcation (1.5%) and duplication (1.0%). Hypoplasia (0.75%), double origin (0.5%), aplasia (0.25%), and fenestration (0.25%) were less frequent. Posterior circulation aneurysms were present in 17 patients (4.25%); 11.5% of patients with AICA variations harbored aneurysms versus 3.7% without variations, suggesting a potential anatomical predisposition to aneurysm formation. Cadaveric dissection confirmed AICA origin from the basilar artery, looping around the CN VII–VIII complex, and consistent relationship with the labyrinthine artery and flocculus. Conclusion: AICA variations occur in ~6.5% of individuals, most commonly as an AICA-PICA common trunk or early bifurcation, and show a higher association with posterior circulation aneurysms. Accurate preoperative identification and understanding of microsurgical anatomy are essential, as these variants increase surgical complexity and potential complications in skull base and vascular procedures.