Presentation
Right side tinnitus
Patient Data
A vascular loop in the right internal auditory canal and crosses underneath the seventh and eighth cranial nerves. The loop only extends less than half of the canal's length. This indicates an aberrant course of the anterior inferior cerebellar artery (AICA loop).
AICA loop
Case Discussion
AICA loop indicates an aberrant course of the anterior inferior cerebellar artery (AICA) entering the internal auditory meatus and loops over the 7th and 8th cranial nerves causing symptoms due to the pressure effect.
Here is an illustration of a Type II AICA loop, where AICA extends to less than 50% of the length of the internal auditory meatus.
type I: lying only in the cerebellopontine angle (CPA), but not entering the internal auditory canal (IAC)
type II: entering, but not extending more than 50% of the IAC length
type III: entering and extending more than 50% of the IAC length
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