Anterior inferior cerebellar artery vascular loop - type III

Case contributed by Dr Amro Omar

Presentation

Right tinnitus.

Patient Data

Age: 45 years
Gender: Male

Axial 3D-FIESTA MR images through the eighth cranial nerve shows the right AICA (anterior inferior cerebellar artery) loop within the right internal acoustic canal (IAC). The vascular loop extends >50% into the IAC (type III).

Red arrow: AICA (anterior inferior cerebellar artery) loop within the right IAC. The vascular loop extends >50% into the IAC (type III).

Case Discussion

AICA loops in the cerebellopontine cistern have been implied in causing auditory and vestibular symptoms, as well as hemifacial spasm, resulting from compression of the VII and VIII cranial nerves.

The vessels can be classified according to their anatomic location: 

  • type I: lying only in the 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

In addition, it is important to evaluate the presence of vascular contact and the angulation of eighth cranial nerve at the contact point, as specific signs of vascular compression.

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Case information

rID: 26338
Published: 13th Feb 2015
Last edited: 1st Jun 2020
Inclusion in quiz mode: Included