Presentation
Episodes of right sided pulsatile tinnitus.
Patient Data
There is a vascular loop of the right anterior inferior cerebellar artery (AICA) where the artery is reaching the distal half of the internal auditory canal (IAC).
Other associated findings include partly empty sella and expanded Meckel's cave bilaterally.
Case Discussion
Tinnitus may be classified according to its nature as arterial pulse synchronous type (pulsatile) or a continuous (non-pulsatile) type.
Pulsatile tinnitus is most frequently the result of a vascular abnormality or a vascular tumor. However, in some cases, the etiology of tinnitus remains uncertain, and most of these patients have no imaging abnormalities.
Compression of the vestibulocochlear nerve by vascular structures has been proposed as a possible cause of tinnitus. However, controversial results have been reported in the medical literature about the relationship between neurovascular compression of the nerve and neuro-otologic symptoms like vertigo and tinnitus.
Magnetic resonance imaging (MRI) is the most appropriate method for noninvasive evaluation of the microvascular structures in this region, using 3D-gradient echo (GRE) sequences with high resolution such as fast imaging employing steady-state acquisition (FIESTA) and constructive interference in steady state (CISS) sequences.
The vascular loop can be divided into three anatomical groups based on location:
- Type I: CPA (cisternal segment)
- Type II: Proximal half of the IAC
- Type III: Distal half of the IAC