Long-term Outcome with Direct Acoustic Cochlear Stimulation

Objective evaluation of long-term outcome of the Codacs (Cochlear Ltd., Australia) and DACS-PI (Phonak Acoustic Implants SA, Switzerland) Implants for direct acoustic cochlear stimulation, which was developed for treatment of patients with severe-to-profound mixed hearing losses.

Patients 22 subjects (23 implants) that were implanted at the Medical University of Hannover between 2009 and 2012 during three multi-center studies and continued to visit the clinic up to 9 years after implantation.

Methods the audiological protocol included pure tone thresholds presented with headphones (air and bone conduction), sound field (aided condition) and in situ stimulation with the implanted device. Speech intelligibility was measured in sound field with Freiburg monosyllable test in quiet and Oldenburg Sentence Test in adaptive S₀N₀ condition.

Results averaged over all patients, bone conduction thresholds (mean of 0.5, 1, 2 and 4 kHz) remained stable at 56 ± 8 dB HL (mean, SD) from preoperative to first fit appointment. During following visits an average decay of 0.5 ± 1.3 dB HL per year was measured. The patient with the worst decrease of bone conduction thresholds lost 23 dB HL in eight years. Speech intelligibility in quiet improved from 26 % (mean, range 0 % to 85 %) measured within the first year after implantation to 78 % (mean, range: 35 % to 100 %) after one year and remained on average unchanged until last visit.

Conclusion the clinical results with direct acoustic cochlear stimulation remain stable up to nine years after implantation. Particularly, no accelerated decrease of bone conduction by direct acoustic cochlear stimulation was observed.

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Publication History

Article published online:
10 June 2020