Cochlear-Internal Canal and Cochlear-Facial Dehiscence: A Novel Entity

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.

A case of cochlear-facial dehiscence revealed after bilateral cochlear implants

The cochlear implant is an implanted auditory prosthesis that can restore severe and profound hearing loss. About 20% of patients with congenital sensorineural hearing loss have a malformation of the inner ear. These abnormalities must be investigated before a cochlear implant because they can lead to intra and postoperative complications and/or anomalies. Most labyrinthine malformations are well known; some are less frequent and can be underdiagnosed at the preoperative computed tomography. This report presents the case of bilateral cochlear-facial dehiscence, bony dehiscence between the facial nerve labyrinthine segment, and cochlear basal turn. In our 56-year-old patient, this malformation was misdiagnosed before the cochlear implant and revealed afterward because of abnormal facial nerve stimulation during intraoperative electrophysiological checking.

Prevalence of otic capsule dehiscence in temporal bone computed tomography scan

PURPOSE

To investigate the radiologic prevalence of otic capsule dehiscence in temporal bone computed tomography (CT) scan.

METHODS

This was a cross-sectional study. The temporal bone CT scans of the patients presenting to a tertiary center were evaluated for possible dehiscence in any part of the otic capsule; then, all of the dehiscence were confirmed by a trained academic radiologist. For each type of otic capsule dehiscence, at least three planes were used with a specific type of reconstruction. When a dehiscence was present in at least two consecutive images in all planes, it was considered as a true dehiscence.

RESULTS

Six hundred patients (mean age: 40 ± 18.1 years) were enrolled. The prevalence of superior and posterior semicircular canal dehiscence was 6.0% and 2.7%, respectively. The prevalence of cochlear-facial dehiscence, cochlear-internal auditory canal dehiscence, and cochlear-carotid dehiscence was 6.3%, 0.7%, and 0.7%, respectively. The prevalence of vestibular aqueduct-jugular bulb dehiscence was 6.3% and the prevalence of posterior semicircular canal-jugular bulb dehiscence was 0.2%.

CONCLUSIONS

Considering different types of otic capsule dehiscence described, care should be taken in patients with vestibular and auditory signs and symptoms to diagnose these dehiscences.

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.

Cochlear Implantation in Meniere's Disease: A Systematic Review and Meta-Analysis

OBJECTIVES/HYPOTHESIS

Meniere's disease (MD) is a debilitating condition characterized by hearing loss, vertigo, and tinnitus. The objective of this study was to systematically investigate outcomes in MD after cochlear implantation (CoI), with and without labyrinthectomy.

STUDY DESIGN

Systematic review and meta-analysis.

METHODS

A systematic review of articles in Medline and Embase was performed to identify all studies of patients with MD who underwent CoI. This analysis evaluates outcomes of speech recognition, pure tone audiometry, vertigo, tinnitus, and quality of life.

RESULTS

Of 321 studies identified, 37 were included, involving 216 patients. Mean age at implantation was 61.4 years (range 27-85 years) with average length of follow-up at 1.7 years (range 0-9 years). Forty-four (20.4%) patients underwent labyrinthectomy. Meta-analysis demonstrated significant improvements in audiometric outcomes following CoI. There was a statistically significant improvement in Hearing in Noise Test performance, with a mean difference improvement of 44.7 (95% confidence interval [CI] [8.8, 80.6]) at 6 months and 60.1 (95% CI [35.3, 85.0]) at 12 months. The Freiburger Monosyllabic Test (FMT) and Consonant-Nucleus-Consonant (CNC) also improved significantly, with mean difference improvements of 46.2 (95% CI [30.0, 62.4]) for FMT and 19.3 (95% CI [8.1, 30.4]) for CNC. There was a statistically significant decrease in tinnitus, as measured by a mean difference reduction of 48.1 (95% CI [1.0, 95.2]) in the Tinnitus Handicap Index.

CONCLUSIONS

CoI with and without simultaneous labyrinthectomy is a viable treatment option for patients with MD, yielding high rates of tinnitus suppression and vertigo control. Post-CoI MD patients demonstrate similar postoperative speech perception outcomes to non-MD implant recipients. Laryngoscope, 131:1845-1854, 2021.

Cochlear-facial dehiscence in a pediatric patient

Temporal bone dehiscence is an infrequent but clinically important phenomenon. Cochlear-facial dehiscence, the rarest type, has been described only in adults. We report cochlear-facial dehiscence in a child. Knowledge of this entity is imperative for radiologists searching for anatomical markers of inner ear pathology and for cochlear implant planning.