Induced endolymphatic flow from the endolymphatic sac to the cochlea in Meniere's disease
Objective: The aim of the present study was to verify whether drugs injected into the endolymphatic sac (ES) can reach the cochlea and possibly treat inner ear disorders. Study Design: Prospective cohort study. Setting: Tertiary referral center, Otolaryngology Department, University of Verona. Subjects and Methods: Patients with Meniere's disease (MD) who were candidates for ES decompression were selected. Nineteen subjects received dexamethasone (DEX) via injection into the ES. To objectively define whether substances administered into the ES could reach the cochlea, we added gadolinium (GD) in three patients. All subjects had intraoperative electrocorticogram recordings and an audiologic follow-up. The three subjects who underwent injection of the DEX-GD solution were followed-up with magnetic resonance imaging. The audiological data are presented during a follow-up period of 12 months. Results: Intraoperative electrocochleography recordings revealed no changes in two patients and summating potentials and compound action potential latency and wave-form modifications in all the other subjects. GD distribution was observed from 48 hours to one week after ES injection into the cochlea of the three subjects injected with DEX-GD. GD-related enhancement of inner ear structures lasted more than two weeks in all subjects. Pure tone average results showed hearing improvement of at least 20 dB HL in 42 percent of patients (8 of 19) at the 12-month follow-up. Statistically significant differences emerged between the mean pure tone average of the ES procedure subjects at one and 12 months after surgery (P = 0.0096). Conclusion: This novel approach might reveal new prospects for treating viral, metabolic, autoimmune, and genetic disorders of the cochlea.