Vascular Loops of the Anterior Inferior Cerebellar Artery and Audio-Vestibular Dysfunction: A Report of Two Cases with Review of the Recent Literature

Abstract

Ichraq Horrane, Eden Ayele Habte, Moad El Mekkaoui, Zakaria El Hafi, Zakaria Arkoubi, Razika Bencheikh, Mohammed Anas Benbouzid and Leila Essakalli

Background: Vascular loops of the anterior inferior cerebellar artery (AICA) are a relatively common incidental finding on brain MRI, yet their actual role in causing audio-vestibular symptoms-tinnitus, vertigo, and hearing losscontinues to be debated in the literature. The relationship between these vascular structures and the vestibulocochlear nerve is complex, and differentiating a true neurovascular conflict from an asymptomatic anatomical variant remains a significant diagnostic challenge.

Objective: We present two patients with audio-vestibular complaints in whom imaging and functional testing pointed to a symptomatic AICA-nerve conflict, and we review the available evidence to guide clinicians on when and how to act on these findings.

Methods: We retrospectively analysed two patients investigated at a tertiary otology referral centre for tinnitus, vertigo, or hearing loss. Each patient underwent a full otoneurological workup including pure-tone audiometry, videonystagmography (VNG), and high-resolution MRI of the cerebellopontine angle with MR angiography. Vascular loop configuration was categorised according to Chavda's classification.

Results: In both patients, MRI identified a type II AICA loop in direct contact with the eighth cranial nerve, ipsilateral to the side with objective vestibular areflexia. Symptom profiles included intractable tinnitus, progressive sensorineural hearing loss, and episodic vertigo-findings that were consistent with a neurovascular origin rather than a purely central or peripheral labyrinthine process.

Conclusion: Although AICA loops are often asymptomatic anatomical variants, they can be clinically meaningful in patients whose subjective complaints are supported by objective vestibular deficits and concordant imaging. Highresolution MRI and comprehensive audiovestibular testing are the cornerstone of evaluation. Treatment should be tailored to the individual patient, with surgical microvascular decompression reserved for those with disabling, refractory symptoms.

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