Characteristics of intestinal microflora and dysbiosis in relation to the disease duration in patients with Meniere’s disease

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.