Anterior inferior cerebellar artery loop
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Anterior inferior cerebellar artery loop or AICA loop refers to an aberrant course of the anterior inferior cerebellar artery (AICA) that enters the internal auditory meatus and loops over the 7th and 8th cranial nerves. This has been associated with audiological, vestibular, and facial symptoms due to vascular compression 1.
Chavda described a simple method for classification of AICA loops 1:
- type I: lying only in the cerebellopontine angle (CPA), but not entering the internal auditory canal (IAC)
- type II: entering, but not extending >50% of the length of the IAC
- type III: entering and extending >50% of the length of the IAC
A prospective study of patients with tinnitus did not find statistical significance to attribute vascular compression from AICA as a causative factor for tinnitus 2. Another study has also found no association between the Chavda classification and otoneurologic symptoms 3.
- 1. McDermott A, Dutt S, Irving R, Pahor A, Chavda S. Anterior Inferior Cerebellar Artery Syndrome: Fact or Fiction. Clin Otolaryngol Allied Sci. 2003;28(2):75-80. doi:10.1046/j.1365-2273.2003.00662.x - Pubmed
- 2. Gultekin S, Celik H, Akpek S, Oner Y, Gumus T, Tokgoz N. Vascular Loops at the Cerebellopontine Angle: Is There a Correlation with Tinnitus? AJNR Am J Neuroradiol. 2008;29(9):1746-9. doi:10.3174/ajnr.A1212 - Pubmed
- 3. de Abreu Junior L, Kuniyoshi C, Wolosker A et al. Vascular Loops in the Anterior Inferior Cerebellar Artery, as Identified by Magnetic Resonance Imaging, and Their Relationship with Otologic Symptoms. Radiol Bras. 2016;49(5):300-4. doi:10.1590/0100-3984.2015.0069 - Pubmed