The Impact of Vascular Loops in the Cerebellopontine Angle on Audio-Vestibular Symptoms: A Systematic Review

Positional nystagmus is observed in the vast majority of healthy individuals

INTRODUCTION

Benign paroxysmal positional vertigo (BPPV) is a vestibular disease characterized by brief  positional vertigo. When examined, characteristic patterns of positional nystagmus (PN) are found with specific head position changes. Previous studies have shown a high prevalence of PN among vestibular healthy subjects. Considering the current diagnostic criteria of BPPV and the potentially high prevalence of PN in healthy individuals, this raises the question of potential over diagnosing BPPV, if diagnostics are based exclusively upon objective findings. This study aims to determine the prevalence of PN within a healthy, adult population and furthermore include a characterization of the PN observed.

METHODS

This is a prospective cross-sectional study. 78 subjects were included. The subjects underwent four standardized positional tests for BPPV in a mechanical rotational chair while using a VNG-goggle to monitor and record eye movements.

RESULTS

Positional nystagmus was recorded in 70.5% (55/78) of the subjects. Of the 55 subjects, who presented with PN, 81.8% (45/55) had upbeating PN. The 95th percentile of the maximum a-SPV was found to be 10.4 degrees per second, with a median of 4. Five subjects (6.4%) in total presented with PN mimicking BPPV.

CONCLUSION

This study found PN to be a common finding within a healthy, adult population based on the high prevalence of PN in the study population. Upbeating PN mimicking posterior canalolithiasis was found in numerous subjects. The authors recommend a cautious approach when diagnosing BPPV, especially in cases of purely vertical PN (without a torsional component) and if no vertiginous symptoms are present during Dix-Hallpike and Supine Roll Test examinations.

Role of Neuroradiological Imaging in Progressive Sensorineural Hearing Loss: A Retrospective Study

Aim

Our aim was to determine prevalence and type of neuro-radiological lesions detected on screening Magnetic Resonance Imaging (MRI) of brain in patients presenting with progressive sensorineural hearing loss in otorhinolaryngology clinic.

Materials and Methods

This retrospective study included 96 screening magnetic resonance imaging MRI brain scans of patients who presented with progressive sensorineural hearing loss in department of otorhinolaryngology. The clinical and radiological data was collected and analysed.

Results

Out of 96 screening MRI brain, 19 (19.8%) had positive findings. The commonest imaging finding was presence of vascular loop around facial and vestibulocochlear nerve root complex in 9 cases (9.4%) followed by presence of a cerebellopontine angle lesions in 5 cases (5.2%). The mean age of all patients was 48.5 years and those with positive screening MRI was 40.6 years. A gender gap was noticed with female being 22 (22.9%) in number against 74 (77.1%) males.

Conclusion

This is the first retrospective study to determine prevalence and type of neuro-radiological lesions detected on screening magnetic resonance imaging in patients with progressive sensorineural hearing loss. We recommend screening MRI brain in patients with progressive SNHL aged below 60 years and all the described neuroradiological finding provide differential diagnosis. Definition and classification of progressive sensorineural hearing loss should be formulated to standardize the management. Further multi-institutional studies are required to identify social, occupational, genetic, or other factors that can cause gender disparity in patients with progressive SNHL.

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.

Vascular Loop of the Anterior Inferior Cerebellar Artery (AICA) as a Cause of Sensorineural Hearing Loss (SNHL): A Case Report

Sensorineural hearing loss (SNHL) is one of the most common causes of hearing loss worldwide. Although highly prevalent, many patients often present with SNHL of unknown cause. Related to SNHL is tinnitus, which often presents with SNHL and can have debilitating effects on patients. The idiopathic nature of SNHL and tinnitus often makes treatment difficult, however, a relatively new etiology has been suggested as a cause of SNHL and tinnitus -- vascular loops within the internal auditory canal (IAC). This report presents the case of a 36-year-old male with bilateral SNHL and tinnitus treated with oral steroids. The patient reported subjective improvement of hearing loss and tinnitus, and the audiogram demonstrated hearing improvement, except in higher frequencies. After initial treatment, MRI revealed a vascular loop of the anterior inferior cerebral artery (AICA) in the right IAC, in contact with the vestibulocochlear nerve. Thus, this case report seeks to present a conservative strategy for SNHL and tinnitus in the presence of a vascular loop of the AICA. As a controversial cause of SNHL and tinnitus, there is no standard of treatment for AICA loops of the IAC which are often treated surgically. This case highlights the importance of an initial conservative prior to surgical intervention. Thus, we seek to contribute to the growing body of literature by further elucidating the relationship between SNHL, tinnitus, and vascular loops and discussing potential pathophysiological mechanisms to guide optimal management strategies.

Radiological presence of vascular loops in the cerebellopontine angle region in patients with unilateral Ménière's disease

OBJECTIVE

The relationship between vascular compression of the vestibulocochlear nerve and audio-vestibular symptoms remains controversial. We aimed to examine the radiological features of vascular loops signs in cerebellopontine angle (CPA) and internal auditory canal (IAC) in patients with unilateral Ménière's disease (MD).

METHODS

One hundred and thirty-seven patients with unilateral definite MD and 69 control subjects (138 ears) were enrolled. All subjects received magnetic resonance imaging of CPA-IAC. The configuration of vascular loops in CPA-IAC, based on the Kazawa classification system, from MD-affected, non-affected and control ears were compared. The associations between imaging findings and Ménière's stage, electrocochleogram (EcochG) and caloric test were analyzed.

RESULTS

(1) Among the MD-affected ears, 6 cases (4.4%) were classified as Kazawa type IA, 27 cases (19.7%) as IB, 60 cases (43.8%) as IIA, and 44 cases (32.1%) as IIB. No significant interaural difference in the distribution of Kazawa's types was found ([Formula: see text] = 4.737, p = 0.578) in unilateral MD patients. (2) The distribution of Kazawa's types were not significantly different between the MD-affected ears and the control subjects ([Formula: see text] = 2.876, p = 0.411). (3) No relationship was found between Kazawa staging of the MD-affected ear and Ménière's stage (H = 2.679, p = 0.444), EcochG ([Formula: see text] = 0.827, p = 0.867) and caloric test ([Formula: see text] = 4.116, p = 0.248).

CONCLUSIONS

In patients with unilateral MD, the configuration of vascular loops in CPA-IAC region, measured by Kazawa criteria, did not correlate with the laterality, clinical stage, the results of EcochG and caloric test, suggesting that vascular loops may be natural anatomical variations for patients with MD.