Round window membrane vibration may increase the effect of intratympanic dexamethasone injection

Abstract

OBJECTIVES/HYPOTHESIS: We investigated whether the round window membrane (RWM) vibration can facilitate dexamethasone perfusion via the RWM in patients with sudden hearing loss. STUDY DESIGN: Prospective study. METHODS: We first performed an in vitro study using a semipermeable membrane. In the subsequent in vivo study, 20 mice were randomized into two groups: an intratympanic dexamethasone injection (ITDI)-only group, and an ITDI with RWM vibration group. Concentration of dexamethasone was investigated using high performance liquid chromatography. Third, we performed a prospective clinical study. Fifty-five refractory sudden hearing loss patients were divided into two groups: those who received ITDI only (n = 36) and those who received ITDI with RWM vibration (n = 19). Final hearing assessments were conducted 2 months after salvage treatment. RESULTS: In the in vitro study, the concentration of dexamethasone increased with vibration time with the peak concentration observed at 3 minutes of vibration. In the in vivo study, ITDI with RWM vibration resulted in a significantly higher perilymph concentration of dexamethasone (7.68 ± 3.13 µg/ml) than that in the ITDI-only group (2.66 ± 1.73 µg/ml). In a clinical setting, the overall improvement in hearing was similar between the two groups. However, when we compared the speech discrimination score between the two groups, we found that the relative discrimination gain in the ITDI with RWM vibration group (18.11 ± 23.54%) was higher than that in the ITDI-only group (7.00 ± 15.54%) (P = 0.042). CONCLUSION: RWM vibration can enhance the effect of intratympanic dexamethasone injection and is a viable treatment option for sudden hearing loss.