Oval window membrane vibroplasty for direct acoustic cochlear stimulation: treating severe mixed hearing loss in challenging middle ears

Abstract

Objective: To date, all the Vibrant Soundbridge (VSB) applications have managed to stimulate the inner ear indirectly. Our objective was to present a new VSB application for direct inner ear stimulation.

Study design: Prospective cohort study.

Settings: Tertiary, referral center

Patients: Three patients with previous middle ear surgery and moderate-to-severe ipsilateral, mixed hearing loss.

Interventions: Oval window membrane vibroplasty (OWMV) for direct acoustic cochlear stimulation. A total ossicular replacement prosthesis (TORP) was attached to the floating mass transducer (FMT). Then, the stapes footplate was perforated, and the tip of the FMT-TORP assembly was advanced approximately 1 mm into the inner ear. A silicon ring was placed around the TORP's tip to prevent it from slipping deeper into the inner ear.

Main outcome measure: Audiologic assessment involving pure-tone audiometry, aided and unaided free-field audiometry, Freiburg monosyllabic word test, and registration of any complications.

Results: OWMV resulted in an average functional hearing gain of 36.1 dB (range, 24.2-47.5 dB). Although the greatest amplification was observed in the higher frequencies, there also was a significant improvement in the lower frequencies. The surgery was not related to any difficulties; vertigo, inner ear trauma, or further complications did not occur.

Conclusion: We present a new method for direct acoustic cochlear stimulation using an active middle ear implant. The preliminary results show that OWMV is a promising and safe option for treating moderate and severe hearing loss, even in challenging cases with previous middle ear operations or fixed stapes footplate.