Cochlear-facial dehiscence in a pediatric patient

Otic Capsule Dehiscences Simulating Other Inner Ear Diseases: Characterization, Clinical Profile, and Follow-Up-Is Ménière's Disease the Sole Cause of Vertigo and Fluctuating Hearing Loss?

INTRODUCTION

We present a series of six cases whose clinical presentations exhibited audiovestibular manifestations of a third mobile window mechanism, bearing a reasonable resemblance to Ménière's disease and otosclerosis. The occurrence of these cases in such a short period has prompted a review of the underlying causes of its development. Understanding the pathophysiology of third mobile window syndrome and considering these entities in the differential diagnosis of conditions presenting with vertigo and hearing loss with slight air-bone gaps is essential for comprehending this group of pathologies.

MATERIALS AND METHODS

A descriptive retrospective cohort study of six cases diagnosed at a tertiary center. All of them went through auditive and vestibular examinations before and after a therapeutic strategy was performed.

RESULTS

Out of 84 cases of dehiscences described in our center during the period from 2014 to 2024, 78 belonged to superior semicircular canal dehiscence, while 6 were other otic capsule dehiscences. Among these six patients with a mean age of 47.17 years (range: 18-73), all had some form of otic capsule dehiscence with auditory and/or vestibular repercussions, measured through hearing and vestibular tests, with abnormalities in the results in five out of six patients. Two of them were diagnosed with Ménière's disease (MD). Another two had cochleo-vestibular hydrops without meeting the diagnostic criteria for MD. In two cases, the otic capsule dehiscence diagnosis resulted from an intraoperative complication due to a gusher phenomenon, while in one case, it was an accidental radiological finding. All responded well to the proposed treatment, whether medical or surgical, if needed.

CONCLUSIONS

Otic capsule dehiscences are relatively new and unfamiliar entities that should be considered when faced with cases clinically suggestive of Ménière's disease, with discrepancies in complementary tests or a poor response to treatment. While high-sensitivity and specificity audiovestibular tests exist, completing the study with imaging, especially petrous bone CT scans, is necessary to locate and characterize the otic capsule defect responsible for the clinical presentation.

Facial nerve in skullbase tumors: imaging and clinical relevance

Facial nerve, the 7th cranial nerve, is a mixed nerve composed of sensory and motor fibers, and its main branch is situated in the cerebellopontine angle. Facial nerve dysfunction is a debilitating phenomenon that can occur in skullbase tumors and Bell's pals. Recovery of the facial nerve dysfunction after surgery for skullbase tumors can be disappointing, but is usually favorable in Bell's palsy. Advances in magnetic resonance imaging (MRI) allow to visualize the facial nerve and its course in the cerebellopontine angle, also when a large tumor is present and compresses the nerve. Here, we describe the anatomical, neurochemical and clinical aspects of the facial nerve and highlight the recent progress in visualizing the facial nerve with MRI.

Severe and persistent facial nerve stimulation after cochlear implantation in a patient with cochlear-facial dehiscence: a case report

Generally, cochlear implants (CIs) are effective in helping patients improve their hearing performance; however, some patients have poor hearing performance owing to facial nerve stimulation (FNS), which is often associated with cochlear anomalies. We report a case with a normal cochlea and severe and persistent FNS owing to cochlear–facial dehiscence (CFD) that affected the CI outcomes. Preoperatively, a careful review of the computed tomography images before CI surgery is necessary not only for patients with otosclerosis and inner ear malformations but also for patients with normal cochlear structures because facial nerve anomalies could be present.

Audiovestibular Quantification in Rare Third Window Disorders in Children

Third window disorders are structural abnormalities in the bony otic capsule that establish a connection between the middle/inner ear or the inner ear/cranial cavity. Investigated extensively in adults, they have hardly been studied in children. This study is a retrospective study of children (aged 5-17 years) diagnosed with rare third window disorders (third window disorders reported rarely or not reported in children) in a tertiary pediatric vestibular unit in the United Kingdom. It aimed to investigate audiovestibular function in these children. Final diagnosis was achieved by high resolution CT scan of the temporal bones. Of 920 children attending for audiovestibular assessment over a 42 month period, rare third windows were observed in 8 (<1%). These included posterior semicircular canal dehiscence (n = 3, 0.3%), posterior semicircular canal thinning (n = 2, 0.2%), X linked gusher (n = 2, 0.2%), and a combination of dilated internal auditory meatus/irregular cochlear partition/deficient facial nerve canal (n = 1, 0.1%). The majority of them (87.5%) demonstrated a mixed/conductive hearing loss with an air-bone gap in the presence of normal tympanometry (100%). Transient otoacoustic emissions were absent with a simultaneous cochlear pathology in 50% of the cohort. Features of disequilibrium were observed in 75% and about a third showed deranged vestibular function tests. Video head impulse test abnormalities were detected in 50% localizing to the side of the lesion. Cervical vestibular evoked myogenic potential test abnormalities were observed in all children in the cohort undergoing the test where low thresholds and high amplitudes classically found in third window disorders localized to the side of the defects in 28.5%. In the series, 71.4% also demonstrated absent responses/amplitude asymmetry, some of which did not localize to the ipsilesional side. Two children presented with typical third window symptoms. This study observes 2 new rare pediatric third window phenotypes and the presence of a cochlear hearing loss in these disorders. It emphasizes that these disorders should be considered as an etiology of hearing loss/disequilibrium in children. It also suggests that pediatric third window disorders may not present with classical third window features and are variable in their presentations/audiovestibular functions.