Low Frequency Air-Bone Gap in Meniere's Disease: Relationship With Magnetic Resonance Imaging Features of Endolymphatic Hydrops

The appearance of low-frequency air-bone gaps (LFABGs) in Meniere’s disease (MD) is a recognized but relatively unexplored phenomenon. Two theories have been proposed to explain their etiology: increased perilymphatic pressure resulting in either reduced stapedial mobility or dampened transmission of acoustic energy, and direct contact between the dilated saccule and the stapes footplate. The aim of this study was to evaluate these two hypotheses by comparing delayed postgadolinium magnetic resonance imaging (MRI) features of two groups of patients with unilateral definite MD, those with and without LFABGs. DESIGN: This retrospective case-control study was conducted at a tertiary otolaryngology unit in the United Kingdom. The study included 35 patients who satisfied the 2015 Barany criteria for unilateral definite MD. The cohort was divided into two groups, those with LFABGs (LFABG+ group) and those without (LFABG− group), according to the pure-tone audiometry performed within 6 months of MRI. Alternative potential causes for the LFABGs were excluded on the basis of otologic history, otoscopy, tympanometry, and/or imaging. Using a 4-hr delayed postgadolinium 3-dimensional fluid-attenuated inversion recovery sequence, two observers evaluated the severity of cochlear and vestibular endolymphatic hydrops (EH) and the presence of vestibular endolymphatic space contacting the oval window (VESCO). The air and bone conduction thresholds, ABGs and MRI features were compared between the LFABG+ and LFABG− groups. Where any of the variables were found to be significantly associated with the presence of ABGs, further analysis was performed to determine whether or not they were independent predictors. Continuous variables were compared using the independent t test if normally distributed, and the Mann–Whitney U test or Kruskall–Wallis test if not normally distributed. Categorical variables were compared with Pearson’s Chi-squared test or Fishers/Fisher-Freeman-Halton exact tests. RESULTS: There were 10 patients in the LFABG+ group (28.6%) and 25 patients in the LFABG− group (71.4%). The mean ABGs in the symptomatic ear at 500 Hz, 1 kHz, and 2 kHz were 15.1 dB ± 6.4, 10.5 dB ± 9.0, and 4.0 dB ± 7.7, respectively, in the LFABG+ group and 2.0 ± 5.8, 2.4 ± 4.4, and −0.8 ± 4.7 dB in the LFABG− group. The differences in ABGs between the two groups were statistically significant at all three test frequencies (p < 0.001 at 500 Hz, p = 0.007 at 1 kHz, and p = 0.041 at 2 kHz). The presence of ABGs was significantly associated with both the grade of vestibular EH (p = 0.049) and VESCO (p = 0.009). Further analysis showed a statistically significant association between the grade of vestibular EH and VESCO (p = 0.007), and only VESCO was an independent variable associated with the presence of LFABGs (p = 0.045). CONCLUSIONS: The study findings add to the existing body of evidence that LFABGs are a true audiological finding in MD and allow us to propose a mechanism. Analysis of delayed gadolinium-enhanced MRI suggests that direct contact between the distended saccule and the inner surface of the stapes footplate is the more likely underlying pathophysiological mechanism for this audiometric phenomenon

An unusual clinico-radiological presentation of epithelioid haemangioma as an external ear mass

Background: Epithelioid haemangiomas are rare, benign, red-brown lesions of uncertain pathogenesis, mostly arising in the head and neck. Case reports in the literature demonstrate considerable variability in their clinical appearance, and rarely describe any associated lymphadenopathy. Case report: We report a case of a 26-year-old female who presented with a mass in the right external auditory meatus (EAM), causing progressive occlusion and conductive hearing loss. Imaging demonstrated an enhancing EAM mass with ipsilateral lymphadenopathy. The lesion was surgically excised, restoring the patient's hearing, and the final diagnosis was made on histopathology. Conclusion: This case portrays the variable clinical presentation and heterogenous macroscopic appearances of epithelioid haemangiomas, which clinicians should consider when diagnosing EAM lesions, along with radiological and histopathological features. Epithelioid haemangiomas often recur, warranting regular post-operative follow-up

The impact of the size and angle of the cochlear basal turn on translocation of a pre‑curved mid‑scala cochlear implant electrode

Scalar translocation is a severe form of intra-cochlear trauma during cochlear implant (CI) electrode insertion. This study explored the hypothesis that the dimensions of the cochlear basal turn and orientation of its inferior segment relative to surgically relevant anatomical structures influence the scalar translocation rates of a pre-curved CI electrode. In a cohort of 40 patients implanted with the Advanced Bionics Mid-Scala electrode array, the scalar translocation group (40%) had a significantly smaller mean distance A of the cochlear basal turn (p &lt; 0.001) and wider horizontal angle between the inferior segment of the cochlear basal turn and the mastoid facial nerve (p = 0.040). A logistic regression model incorporating distance A (p = 0.003) and horizontal facial nerve angle (p = 0.017) explained 44.0–59.9% of the variance in scalar translocation and correctly classified 82.5% of cases. Every 1mm decrease in distance A was associated with a 99.2% increase in odds of translocation [95% confidence interval 80.3%, 100%], whilst every 1-degree increase in the horizontal facial nerve angle was associated with an 18.1% increase in odds of translocation [95% CI 3.0%, 35.5%]. The study findings provide an evidence-based argument for the development of a navigation system for optimal angulation of electrode insertion during CI surgery to reduce intra-cochlear trauma.</p

Which is the optimally defined vestibular cross-section to diagnose unilateral Meniere’s disease with delayed post-gadolinium 3D fluid-attenuated inversion recovery MRI?

OBJECTIVES: Delayed post-gadolinium 3D fluid-attenuated inversion recovery (FLAIR) MRI is used to support a diagnosis of Ménière’s disease (MD) with the ratio of the endolymphatic space (ES) to the sum of the endolymphatic and perilymphatic spaces (SEPS) on a cross-section through the vestibule being a key diagnostic criterion. It was hypothesised that the exact definition of the vestibular cross-section would influence the ES: SEPS ratio, its ability to diagnose MD, and its reproducibility. METHODS: Following institutional approval, 22 patients (five male, 17 female; mean age 52.1) with unilateral MD and delayed post-gadolinium 3D FLAIR MRI were retrospectively analysed. Two observers measured the ES and SEPS on predefined axial (superior and inferior) and sagittal vestibular cross-sections. Receiver operating characteristic (ROC) curves, Bland-Altman plots and intraclass correlation (ICC) were analysed for the ES:SEPS ratios. RESULTS: The area under the curve (AUC) was decreased for the ES:SEPS ratios on the superior axial section through the vestibule (AUC 0.737) compared to the inferior axial (AUC 0.874) and sagittal sections (AUC 0.878). The resulting optimal thresholds (sensitivities/specificities) were 0.21 (0.66/0.75), 0.16 (0.77/0.9) and 0.285 (0.75/0.96). The reproducibility was excellent for all measures with ICCs of 0.97, 0.98 and 0.99. CONCLUSION: Inferior axial or sagittal vestibular cross-sections are more accurate for the diagnosis of MD ears and have excellent reproducibility. ADVANCES IN KNOWLEDGE: The choice of vestibular cross-section influences both the ability to distinguish MD from asymptomatic contralateral ears, and the optimum threshold ES:SEPS value