Vibrant Soundbridge for hearing restoration after chronic ear surgery

Middle ear surgery is primarily concerned with resolving the discharging pathology, in the case of chronic otitis media (COM), or with complete eradication, in case of cholesteatoma. Either of these procedures may require repeated surgeries, often resulting in severe mixed hearing impairment. A middle ear implant may be indicated in these cases instead of a hearing aid because the anatomical conditions in such cases often impede an adequate acoustic coupling. The objective of this study was to evaluate MED-EL Vibrant Soundbridge (VSB) implantation in patients with severe conductive and mixed hearing loss occurring after middle ear surgery for cholesteatoma or chronic otitis media (COM).

Over a 2-years period, the VSB system was implanted in 40 patients between 35 and 81 year old (mean: 59.5). Surgery was performed with comparable technique in 3 regional hospitals in Italy: Rovereto (n=16), Meran (n=12) and Tortona (n=12). The 40 candidates for implantation had a history of 1-5 previous surgeries. Of those, 20 patients suffered from COM and 20 from, cholesteatomas. The floating mass transducer (FMT) of the VSB was placed and stabilized on the round window niche in 32 cases; alternative positioning was necessary in 8 cases. Bone conduction (BC) was tested 1 day post-operatively. At 1 month post-surgery and between 6-9 months, open-field warble tones threshold in VSB-off and VSB-on conditions and open-field speech audiometry for words in quiet were conducted.

Results of BC audiometry one day post-operatively showed no significant changes in hearing. Unaided mean pure tone average (PTA4) was 82.38 dB SPL with a mean speech recognition threshold (SRT) of 94.28 dB SPL. Results obtained after a minimum of three months post-operatively were evaluated in terms of aided thresholds and functional gain. At VSB activation, the mean PTA4 was 50.63 dB SPL with a mean SRT of 61.68 dB. After 6-9 months, the group had a mean PTA4 of 47.89 dB SPL and a mean SRT of 53.33 dB SPL.

Implantation of the VSB with its direct driver of the inner ear fluids appears promising for auditory rehabilitation of severe mixed hearing loss associated with sequelae of cholesteatoma surgery. Patients' results improved over time, allowing us to assume a positive effect of consolidation of the coupling related to fibrosis. Results reported here refer to 6-9 months of observation and do not provide evidence of long term stability.