A Comparative Study on Speech in Noise Understanding with a Direct Acoustic Cochlear Implant in Subjects with Severe to Profound Mixed Hearing Loss

Abstract

The aim of this study was to investigate the efficacy of a direct acoustic cochlear implant (DACI) for speech understanding in noise in patients suffering from severe to profound mixed hearing loss (MHL) due to various etiologies compared to the preoperative best-aided condition. The study was performed at five tertiary referral centers in Europe (Belgium, Germany, Poland and Spain). Nineteen adult subjects with severe to profound MHL due to (advanced) otosclerosis, ear canal fibrosis, chronic otitis media, tympanosclerosis or previous cholesteatoma were implanted with a DACI (Codacs™ Investigational Device) combined with a conventional stapes prosthesis. Unaided and aided speech reception scores in quiet and in noise, preoperative and postoperative air and bone conduction thresholds and aided and unaided sound field thresholds were measured prospectively during the study. Subjective benefit analysis was determined through the Abbreviated Profile of Hearing Aid Benefit questionnaire. Quality of life was measured by the Health Utilities Index. All subjects were fitted preoperatively with hearing aids and/or a bone conduction implant on a headband before DACI implantation. This allows direct comparison between different hearing rehabilitation solutions. The mean speech reception threshold in noise improved significantly by 7.9 dB signal-to-noise ratio (SNR) after activation of the DACI compared to the preoperative best-aided condition. For all 19 subjects, a mean postoperative aided speech reception threshold of 2.6 dB SNR (standard deviation: 8.3 dB) was measured. On average, no significant shift in the bone conduction thresholds was noted 4-5 months after implantation. A mean sound field threshold improvement of 46 and 16 dB was measured compared to the preoperative unaided and best-aided condition, respectively. Speech perception tests in quiet showed a mean improvement of the word recognition scores by 65 and 48% at 65 dB SPL compared to the preoperative unaided and best-aided condition, respectively. In summary, DACI provides an effective improvement of the speech perception in noise compared to the best-aided condition in subjects suffering from severe to profound MHL.

Cochlear Implant Users with Otosclerosis: Are Hearing and Quality of Life Outcomes Worse than in Cochlear Implant Users without Otosclerosis?

“…These factors may result in reduced functioning of the CI itself as well as an increased probability of implant revisions or reimplantation [Calmels et al, 2007]. The impact of these potentially worse results on the CI user's quality of life (QoL) has been reported [Calmels et al, 2007;Lenarz et al, 2014].…”

A Role for Acoustic Stimulation in Advanced Otosclerosis: Direct Acoustic Cochlear Implant versus Cochlear Implant

“…Another study of the group of Hannover reported the rather long adaptation phase of 12 months in CI patients, which is the time needed for the brain to adapt to electrical stimulation [Lenarz et al, 2011]. The suggestion of a faster and less effortful rehabilitation in DACI users due to more natural acoustic sound was also reported in a previous multicenter study comparing speech performance in DACI users for different pathologies [Lenarz et al, 2014].…”

“…The DACI system provides more natural hearing in contrast with electrical stimulation, and implantation with a DACI system is reversible as the incus is preserved. Even after longer rehabilitation with a DACI system, CI surgery can still be considered in case of far advanced otosclerosis and extensive cochlear involvement [Lenarz et al, 2014]. Nevertheless, similar risks -which can occur during stapedectomy/stapedotomy or CI surgery -may result due to DACI implantation.…”

“…L. Noé and A. Dierckx, Master in Audiology, helped with the data collection of the CI subgroup. Part of DACI subjects have been implanted in a multicenter study reported in a previous publication [Lenarz and Verhaert et al, 2014] with support of Cochlear Ltd. The company did not have any additional role in the study design, data collection and analysis, decision to publish, or preparation of abstract and manuscript.…”

“…Recently, a powerful acoustic hearing implant has been introduced in Europe, named a direct acoustic cochlear implant (DACI) (Codacs, Cochlear Ltd., Syndey, NSW, Australia, not US Food and Drug Administration approved), for subjects with severe-to-profound mixed hearing loss [Lenarz et al, 2013[Lenarz et al, , 2014. In brief, the device provides vibrations through an artificial incus upon which a conventional stapes prosthesis is crimped.…”