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.

Keywords

• Anterior inferior cerebellar artery
• cerebellopontine angle
• microsurgical anatomy
• vascular variations.

Supporting Institution

The authors declare that this research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.

Ethical Statement

The study was approved by the Izmir City Hospital Ethics Committee (decision number 2025/261, date 04/06/2025). This study was conducted in accordance with the Declaration of Helsinki.

Thanks

We thank Medtronic, Inc. and this company’s representation in Turkey, for providing the Midas Rex legend system (Medtronic, Inc., Minneapolis, MN, USA) to the Microsurgical Neuroanatomy Laboratory in Istanbul University–Cerrahpasa, Turkey, Department of Neurosurgery.

Anterior İnferior Serebellar Arterin Anatomik Varyasyonları ve Cerrahi Önemi: Kombine Radyolojik ve Kadavra Çalışması

Abstract

Amaç: Anterior inferior serebellar arter (AICA) varyasyonlarının anatomik spektrumunu, sıklığını ve nöroşirürjikal önemini; radyolojik ve mikrocerrahi kadavra analizinin birlikte kullanılmasıyla ortaya koymak ve AICA anomalileri ile posterior dolaşım anevrizmaları arasındaki olası ilişkileri araştırmak. Gereç ve Yöntem: 400 hastaya ait bilgisayarlı tomografi anjiyografi (CTA) görüntüleri (212 erkek, 188 kadın; ortalama yaş 55,9 yıl) AICA anomalileri, anevrizmalar ve diğer vasküler varyasyonlar açısından retrospektif olarak incelendi. İki adet formalinle fikse edilmiş erişkin kafa kadavrasında (dört taraf) retrosigmoid ve far-lateral yaklaşımlar kullanılarak mikroskop büyütmesi altında diseksiyonlar gerçekleştirildi ve kranial sinir ilişkileri ile labirentin arterinin kökeni özellikle değerlendirildi. Bulgular: AICA varyasyonları 26 hastada (%6,5) saptandı ve toplam 27 varyant arter tespit edildi. En sık görülen anomali AICA-PICA ortak trunku (%2.5) olup, bunu erken bifurkasyon (%1,5) ve duplikasyon (%1,0) izledi. Hipoplazi (%0,75), çift köken (%0,5), aplazi (%0,25) ve fenestrasyon (%0,25) daha nadir görüldü. Posterior dolaşım anevrizmaları 17 hastada (%4,25) mevcuttu; AICA varyasyonu bulunan hastaların %11.5’inde anevrizma saptanırken, varyasyonu olmayanlarda bu oran %3,7 idi ve bu durum anevrizma oluşumu açısından olası bir anatomik yatkınlığı düşündürmektedir. Kadavra diseksiyonları, AICA’nın baziler arterden köken aldığını, CN VII–VIII kompleksinin etrafında bir halka oluşturduğunu ve labirentin arter ile flokkulus ile olan ilişkisini doğruladı. Sonuç: AICA varyasyonları bireylerin yaklaşık %6.5’inde görülmekte olup, en sık AICA-PICA ortak trunkusu veya erken bifurkasyon şeklinde izlenmekte ve posterior dolaşım anevrizmaları ile daha yüksek birliktelik göstermektedir. Bu varyantların varlığı, kafa tabanı ve vasküler cerrahi girişimlerde cerrahi karmaşıklığı ve olası komplikasyonları artırabileceğinden, ameliyat öncesi doğru tanımlanması ve mikrocerrahi anatomisinin iyi anlaşılması büyük önem taşımaktadır.

Keywords

• Anterior inferior serebellar arter
• serebellopontin açı
• mikrocerrahi anatomi
• vasküler varyasyonlar.

Supporting Institution

Yazarlar, bu araştırmanın kamu, ticari veya kâr amacı gütmeyen herhangi bir finansman kuruluşundan özel bir destek almadığını beyan eder.

Ethical Statement

Çalışma, İzmir Şehir Hastanesi Etik Kurulu tarafından onaylanmıştır (karar numarası: 2025/261, tarih: 04/06/2025). Bu çalışma Helsinki Bildirgesi ilkelerine uygun olarak yürütülmüştür.

Thanks

Medtronic, Inc.’e ve bu şirketin Türkiye temsilciliğine, İstanbul Üniversitesi–Cerrahpaşa, Nöroşirürji Anabilim Dalı bünyesindeki Mikroskopik Nöroanatomi Laboratuvarına Midas Rex Legend sistemi (Medtronic, Inc., Minneapolis, MN, ABD) sağladıkları için teşekkür ederiz.

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