• Iwao Yamakami, Shunsuke Kubota, Yoshinori Higuchi, and Seiro Ito.
• Department of Neurosurgery, Seikei-kai Chiba Medical Center, Chiba, Japan; Department of Neurosurgery, Chiba Central Medical Center, Chiba, Japan. Electronic address: yamakami@seikeikai-cmc.jp.
• World Neurosurg. 2019 Jan 1; 121: e370-e378.

ObjectiveReferring to the anterior inferior cerebellar artery (AICA) traversing a cerebellopontine angle tumor during retrosigmoid vestibular schwannoma (VS) removal as a challenging AICA (c-AICA), we describe incidence, anatomic characteristics, mechanism of development of c-AICA, and surgical techniques used to remove VS while preserving the AICA.MethodsReview of surgical records and videos of 150 patients who underwent retrosigmoid VS removal revealed 10 patients (7%) with c-AICAs. Retrospective analysis of these 10 patients was performed.ResultsSurgical findings classified c-AICAs as c-AICAs with subarcuate artery (SAA) and c-AICAs without SAA. In c-AICAs with SAA (7/10), the SAA had an anchoring effect in the development of the c-AICA. The most challenging c-AICAs (i.e., c-AICAs reaching the porus acusticus, entering the internal auditory canal, and adhering to the dura) were associated with short cisternal SAAs (4/7). We preserved the most challenging c-AICA with the surrounding dura by drilling the posterior wall to preserve the posterior wall dura. AICAs adhering to the porus acusticus dura were not associated with long cisternal SAAs. Sacrificing the SAA caused no neurologic deficits. c-AICAs were preserved in all patients, and tumors were removed with no complications related to AICAs.Conclusionsc-AICAs occur more often than expected. The anatomy of the SAA is related to the development and characteristics of c-AICAs. Although preserving a c-AICA is challenging and necessitates a complex dissecting technique, understanding of anatomic characteristics and appropriate surgical management of c-AICAs enable VS removal while preserving the AICA.Copyright © 2018 Elsevier Inc. All rights reserved.

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