Is Presence of Vascular Loop in Magnetic Resonance Imaging Always Related to Tinnitus?

Prevalence of Anterior Inferior Cerebellar Artery Vascular Loop in Cerebellopontine Angle With Three-Dimensional Constructive Interference in Steady State (CISS) Sequence MRI

Background The cerebellopontine angle (CPA) cistern houses vital neurovascular structures such as cranial nerves V, VII, and VIII and the anterior inferior cerebellar artery (AICA), often leading to neurovascular compression syndromes due to its complex anatomy. Although vascular compression is a recognized cause of certain neuralgias, its association with otologic symptoms such as tinnitus, hearing loss, and dizziness remains uncertain. Hence, this study aims to determine the prevalence of the AICA vascular loop in the CPA cistern on MRI in patients with asymptomatic audiovestibular symptoms. Methodology Adult patients who underwent MRI, including the posterior fossa's high-resolution volumetric T2 sequence (three-dimensional constructive interference in steady state (3D-CISS)), were assessed. Patients with a history of audiovestibular symptoms (tinnitus/dizziness/vertigo/sensorineural hearing loss), intracranial tumor, vascular lesions, intracranial surgery, brain radiation therapy, traumatic brain injury, poor image quality, and MRI scans without 3D-CISS sequences were excluded. Two radiologists independently reviewed 114 (228 sides) MRI studies for the vascular loop of AICA in the CPA cistern and the extension of the AICA loop into the ipsilateral internal acoustic meatus which was graded by Chavda's classification. Results The prevalence of vascular loop of AICA in the CPA cistern was as high as 47.6% in asymptomatic patients. Grade I Chavda vascular loop was the most common type followed by type II, with type III being the least common type. Conclusions Knowledge regarding the high prevalence of the AICA loop in the asymptomatic population and the lack of significant correlation between the presence of the AICA loop and otovestibular symptoms should be considered in preoperative planning for decompression procedures.

The significance of vascular loops in the internal auditory meatus: a true incidental imaging finding?

PURPOSE

To determine the clinical significance of vascular loops (VL) in the internal auditory meatus (IAM) and cerebellopontine angle (CPA).

METHODS

We carried out a retrospective case series in a tertiary referral centre. Out of 6978 patients undergoing magnetic resonance imaging (MRI) of the IAM for unilateral cochleovestibular symptoms we identified the ones with VLs and reviewed their medical notes. We performed a statistical correlation between the laterality of the VL in the IAM/ CPA as graded according to the Chavda classification (type 1 in the CPA, type 2 extending in the IAM, type 3 extending to the distal IAM end), the laterality of symptoms and the patient's age.

RESULTS

A total of 77 VL were identified in 64 patients (0.9%); 39 patients had the VL on the same side of the main symptom, while 25 patients had the VL on the contralateral side. There were 37 Type 1 loops, 29 Type 2 loops and 11 Type 3 loops. The comparison between the grading of the VL and the laterality of symptoms did not reach the level of significance (p = 0.321). There was also no association between the presence of the loop and the patients' age (p = 0.5). All patients were reassured and discharged without any representation in three years follow-up.

CONCLUSIONS

We did not identify any significant correlation between the laterality of VLs and the laterality of symptoms, irrespective of the grading of the loop or the patients' age. Such VLs should be considered an incidental rather than causal findings.