Ménière’s disease (MD) is characterized by loss of balance and hearing disorders. Although there is known to be endolymphatic hydrops involved in the pathological process, the pathogenesis of the disease is still largely unclear. Approximately half of patients with MD suffer from depressive symptoms and high levels of several stress hormones were observed in MD and depression, simultaneously. Recently, gut microbes have been shown to influence the function of the central nervous system in humans through their metabolites. We studied the intestinal microbiota of 10 patients with MD and 11 healthy donors (HD). Significant negative correlations were found between disease duration and alpha diversity indexes of gut microbes in patients with MD. The relative abundance of the species Butyricicoccus ambiguous taxa was increased in patients with MD compared with that of HD. In contrast, Oscillospiraceae UCG-002/UCG-005 ambiguous taxa and Anaerovoracaceae (Eubacterium) brachy group uncultured bacterium were increased in the relative abundance of HD than that of patients with MD. The relative abundance of the Butyricicoccus species was positively correlated with disease duration. Thus, these compositional alterations of gut microbes in patients with MD are associated with inner ear pathologies, such as endolymphatic hydrops, by changing the metabolite profiles in the intestine.

Background: The computerized rotational head impulse test (crHIT) employs whole-body impulsive rotations like the angular motion used in the video head impulse test (vHIT) to assess the function of all semicircular canals (SCCs). Objective: This study utilized vertical crHIT and vHIT among healthy subjects to evaluate the effectiveness of these tools in assessing SCC function. Methods: Thirty-five individuals with no history of vestibular disorders or traumatic brain injury were enrolled in this study. Participants underwent vHIT (ICS Impulse Otometrics) and crHIT (Neuro-Otologic Testing Center, Spryson America, Inc.). Results: Mean VOR gain was significantly higher during crHIT compared to vHIT, except for the right horizontal SCC ( p < 0.01). Coefficient of variation (CV) for crHIT was smaller than that observed in vHIT across all 6 SCCs, with significant differences in all but the LA and RP SCCs. We also computed lower limits of normal (LLN) for each condition; up to 2.9% of crHIT values fell outside the acceptable LLN compared to up to 37% of vHIT gain values. Average reduced vestibular response (RVR) for crHIT was lower than that observed in vHIT among all semicircular canal pairs and demonstrated less variability for crHIT as compared to vHIT. Conclusions: Overall, these findings support the clinical utility of crHIT for comprehensive SCC function evaluation.

Objective: The video head impulse test (v-HIT) can evaluate the function of all semicircular canals (SCCs) in a short period. In this work, we sought to compare v-HIT results among 2 commercially available devices, the ICS impulse (Otometrics, Denmark) (ICS) and Eye See Cam (Interacoustics, Denmark) (ESC), among individuals with unilateral vestibular disorders. Design: Retrospective study (n = 15). Setting: St. Marianna University School of Medicine Hospital. Patients: Fifteen patients with acute unilateral vestibular disorders. Intervention: Two v-HIT devices were conducted across patients to compare the results of the 2 models. Main Outcome Measures: Gain values and pathological saccades for each SCC were compared across the 2 models. Monothermal caloric testing was performed to compare alongside v-HIT gain values. Results: There was no difference between the 2 models for the evaluation of the horizontal SCCs. There was a significant negative correlation (ESC: r = −0.52, ICS: r = −0.53) between caloric testing and the gain values of the 2 models. In the vertical SCCs, the gain values of ESC were significantly higher than the gain values of ICS. Detection of catch-up saccades in vertical SCCs was similar across the 2 models. Conclusion: For the horizontal SCCs, there was no difference in test results between the 2 models. However, in the vertical SCCs, gain values were variable across the 2 devices. Larger scale studies are needed to develop normative ranges for the vertical canals.

Background/Objectives: Migraine is frequently comorbid with Meniere’s disease, which may complicate interpretation of inner ear imaging and clinical diagnosis. While endolymphatic hydrops has been studied in Meniere’s disease and vestibular migraine separately, comparative imaging data for Meniere’s disease patients with and without migraine remain limited. Methods: We retrospectively analyzed 78 patients with definite Meniere’s disease who underwent endolymphatic contrast-enhanced MRI (HYbriD of Reversed image of Positive endolymph signal and native image of positive perilymph signal; or “HYDROPS”). Patients were classified as Meniere’s disease only group (n = 56), or Meniere’s disease with migraine (n = 22). The degree of endolymphatic hydrops (negative, mild, or significant) was assessed separately in the inner ear, the cochlea, and the vestibule. Results: In Meniere’s disease group, the affected ear consistently showed higher rates of significant endolymphatic hydrops compared to the healthy ear across the inner ear, cochlea, and vestibule (p < 0.01). In contrast, Meniere’s disease with migraine group showed no significant interaural differences. Meniere’s disease with migraine group showed a significantly higher frequency of significant endolymphatic hydrops in the healthy cochlea (p < 0.01). Similar patterns were observed in the inner ear (p < 0.025) and vestibule (p = 0.05), although these differences did not reach statistical significance. Bilateral hydrops was significantly more frequent in Meniere’s disease with migraine group than in Meniere’s disease group among all regions investigated (p < 0.05). Conclusions: Meniere’s disease patients with migraine exhibit a distinct endolymphatic hydrops pattern, characterized by bilateral or symmetrical hydrops and involvement of the healthy ear. These findings suggest migraine-related mechanisms may contribute to endolymphatic hydrops, and bilateral endolymphatic hydrops on endolymphatic contrast-enhanced MRI in suspected Meniere’s disease cases should prompt consideration of comorbid migraine, in addition to bilateral Meniere’s disease or asymptomatic hydrops.

Hypothesis: Dysbiosis of the intestinal microflora has been reported in stress-induced depression and irritable colitis, a similar abnormality may also occur in stress-triggered Meniere’s disease. Background: Meniere’s disease is an intractable disease characterized by paroxysms of intense rotatory dizziness, hearing loss, and other auditory symptoms. It is believed to be caused by endolymphatic hydrops of the vestibule and cochlea. The diagnosis of Meniere’s disease is based on the diagnostic criteria established by the Barany Society and AAO-HNS and Journal of Vestibular Research as definite or probable cases. Endolymphatic hydrops identification using cochlear contrast-enhanced MRI (hybrid of reversed image of positive endolymph signal and native image of positive perilymph signal [HYDROPS]) is an objective test for Meniere’s disease, enabling reliable diagnosis of this disease. Methods: We investigated the gut microbiota of 10 patients (6 males and 4 females, mean age 49.6 ± 8.1 years) who met the diagnostic criteria for a unilateral definite case of Meniere’s disease using the diagnostic criteria of the Journal of Vestibular Research, and who also had significant endolymphatic hydrops on the affected side on HYDROPS. Intestinal microbiota tests were performed on these 10 patients and the results were evaluated in relation to the duration of disease, results of audiometry of the affected side, and DHI (Dizziness Handicap Inventory) score. Results: A significant negative correlation was found between the disease duration and Shannon diversity index and Faith’s phylogenetic diversity, which indicated dysbiosis of the intestinal microflora. No correlation was found between the indicators of microbial diversity and the results of audiometry or the DHI on the affected side. Dysbiosis of the intestinal microbiota worsened with increasing duration of Meniere’s disease. Moreover, Akkermansia muciniphila was not detected in any patient with Meniere’s disease. Conclusions.: Despite the small number of cases in this study (n = 10), the findings indicate the possibility of abnormalities of the intestinal microflora in Meniere’s disease.

Facial nerve decompression is a surgical procedure performed for severe facial nerve paralysis associated with conditions such as Bell’s palsy and Ramsay Hunt syndrome. Classical Western studies by Fisch first established the surgical principles of facial nerve decompression, providing the foundation for subsequent work on decompression extent and outcomes. However, the optimal extent of bony decompression of the facial nerve canal remains unclear, and a 180° removal of the surrounding bone has traditionally been performed based on empirical judgment. Nevertheless, more extensive bone removal may increase the risk of surgical complications. This study aimed to evaluate the relationship between the angle of bony decompression around the facial nerve canal and pressure reduction, in order to determine the optimal decompression angle. To achieve this, a simplified experimental model was employed to quantitatively evaluate the relationship between decompression angle and internal pressure reduction, providing mechanical insight into facial nerve decompression rather than clinical data. To evaluate this relationship, a decompression model was created, and pressure changes were measured at opening angles ranging from 30° to 180°. The results revealed that a 150° decompression provided a comparable reduction in pressure to that of a 180° decompression. These findings suggest that the extent of bone removal can be minimized while still achieving sufficient pressure reduction, potentially lowering the risk of nerve injury. We also observed significant pressure reduction at 30°, suggesting utility in regions where extensive bone removal is difficult. The finding that a 150° decompression produced an effect comparable to that of 180° is an important contribution toward improving surgical safety. Moving forward, we aim to refine the decompression model and conduct further investigations using more detailed angle settings, with the goal of establishing a practical surgical technique.