Incidental Anterior Inferior Cerebellar Artery (AICA) Loops on MRI and Their Clinical Relevance

Incidental Findings in Imaging

AICA loops are commonly observed as incidental magnetic‑resonance imaging (MRI) findings that are not associated with sudden sensorineural hearing loss (SSNHL). This observation is based on imaging studies of patients evaluated for SSNHL, where the presence of an AICA loop did not correlate with the acute hearing deficit. 1
The American Academy of Otolaryngology–Head and Neck Surgery (AAO‑HNS) clinical practice guidelines list AICA loops among “MRI findings not directly related to SSNHL.” The guideline emphasizes that detection of an AICA loop should not be interpreted as the cause of the hearing loss. 2

Incidental AICA loops have been reported in 3–4 cases per study cohort in published series. These numbers derive from retrospective analyses of patients undergoing high‑resolution temporal bone MRI, indicating that such loops are relatively uncommon but still observed as incidental findings. 3
Similar incidence (3–4 cases per cohort) was confirmed in an independent cohort study. The replication across studies supports the notion that AICA loops, while present, are not a frequent cause of otovestibular symptoms. 4

Strength of evidence: All statements are derived from observational cohort studies and guideline documents (Level III evidence).