Morphological studies of labyrinthine tissue in patients affected with Meniere's disease and vestibular schwannoma following labyrinthectomy

Background: Meniere's disease (MD) is a disabling disease of the inner ear, having a substantial effect on a patient's quality of life. While various postulations regarding its aetiology exists, due to the difficulty with accessing inner ear tissue, there have been limited histological studies in patients with active MD.

Methods: Tissue was collected during labyrinthectomy from 8 patients with intractable MD who had failed medical therapy (22 samples), and 9 patients undergoing translabyrinthine resection of vestibular schwannoma (19 samples). 20 additional samples were obtained from 2 cadavers without a history of inner ear disease. Samples were assessed with routine histology and a panel of immunohistochemical markers to assess any differences between the groups.

Results: No MD samples demonstrated significant inflammatory infiltrate, evidence of denervation of the sensory epithelium, fibrosis, or thickening of blood vessel wall stroma. Novel findings included confirmation that no lymphatic channels of usual type were present and that the subepithelial stromal cells are strongly positive for S100, suggesting possible perineurial origin. There were no consistent differences in expression of Claudin or Aquaporin between the MD and VS patient samples.

Conclusion: This is one of the largest comparative histological study utilising operative samples from inner ear of living donors with active intractable MD and control patients with VS. There were no significant morphological differences between the two groups, suggesting that the aetiology lies elsewhere within the vestibular system. Examination of endolymphatic sac tissue is therefore a priority for future work.