Sudden-Onset Hearing Loss Revealing a Terminal Unruptured Anterior Inferior Cerebellar Artery Aneurysm in the Internal Auditory Canal

Background: Sudden sensorineural hearing loss is a condition with various etiologies. Whenever it presents and a mass is seen in the internal auditory canal (IAC) on imaging it usually points toward a cerebellopontine angle (CPA) tumor most likely a vestibular schwannoma or meningioma. Yet, various etiologies including vascular causes such as aneurysms, while rare, can also be the cause of such symptomatology.

Objective: This article presents two cases from an expert (OD) aneurysm case series of patients with a labyrinthine artery (LA) aneurysm that presented with sudden sensorineural hearing loss.

Case Report: We describe two cases of patients over 60 years of age who presented with hearing loss in both patients later imaging would reveal a terminal anterior inferior cerebellar artery (AICA) aneurysm located in the IAC. A 66-year-old female presented with sudden-onset right hearing loss, headache, and vertigo. An initial physical exam revealed sensorineural hearing loss on the right side. Further imaging identified a small aneurysm within the IAC endovascular intervention was deemed necessary to prevent potential rupture and further neurological compromise ([Figs. 1]–[2]).

Fig. 1 CTA MIP reconstruction shows a round-enhancing lesion located in the right IAC.

Fig. 2 3D angio-reconstruction shows an aneurysm of a terminal branch of the AICA the labyrinthine artery also called the internal auditory artery.

Fig. 3 3D angioreconstruction shows a completely occluded aneurysm after endovascular coiling.

Discussion: Aneurysms within the IAC are rare and often present with nonspecific symptoms, making early diagnosis challenging. This case highlights the importance of considering vascular causes in the differential diagnosis. Furthermore, it underscores the utility of advanced imaging modalities. The entire inner ear receives vascular supply from the labyrinthine artery also called the internal auditory artery, which is most often a branch of the AICA such as in this case but can also branch from the basilar artery in a minority of cases. A high index of suspicion for an aneurysm in this location is required to make a prompt diagnosis.

Conclusion: Aneurysms within the IAC present unique diagnostic and management challenges due to their proximity to critical neurovascular structures. These cases emphasize the need for a high index of suspicion for vascular etiologies in patients presenting with sudden-onset hearing loss, especially when on imaging a mass is located exclusively in the IAC. Conventional management such as that for a CPA tumor would yield terrible consequences for these patients. Timely diagnosis and intervention are crucial in optimizing outcomes and preventing potentially life-threatening complications associated with aneurysmal rupture.

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Artikel online veröffentlicht:
07. Februar 2025