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Initial Clinical Experience With a Totally Implantable Cochlear Implant Research Device

Briggs, Robert J. S.*†; Eder, Helmut C.; Seligman, Peter M.†‡; Cowan, Robert S. C.*†; Plant, Kerrie L.†‡; Dalton, James; Money, David K.; Patrick, James F.*†‡

doi: 10.1097/MAO.0b013e31814b242f
Original Articles

Objective: To evaluate the effectiveness and issues associated with a research totally implantable cochlear implant (TIKI).

Study Design: Limited patient trial.

Setting: Tertiary referral center.

Patients: Three adult human subjects with severe-to-profound sensorineural hearing loss.

Interventions: Subjects were implanted with a research TIKI developed by Cochlear Limited and the Co-operative Research Centre for Cochlear Implant and Hearing Aid Innovation. The TIKI has a lithium ion rechargeable battery, a package-mounted internal microphone, and sound-processing electronics that enable the use of "invisible hearing" without the use of an external device. The TIKI also functions with an external ESPrit 3G sound processor as a conventional cochlear implant. The standard surgical technique was modified to accommodate the larger device package. Postoperatively, subjects used TIKI in both invisible hearing and the conventional ESPrit 3G modes.

Main Outcome Measures: Device use was recorded in both invisible hearing and ESPrit 3G listening modes. Performance of the internal battery and microphone was assessed over time. Psychophysical MAP data were collected, and speech perception was measured at 1, 3, 6, and 12 months postoperatively in both listening modes.

Results: There were no surgical or postoperative complications. All subjects use both invisible hearing and conventional ESPrit 3G modes. Speech perception outcomes for all patients showed improvement from preoperative scores. As a consequence of the reduced sensitivity of the implanted microphone, speech perception results using the invisible hearing mode were significantly lower than the ESPrit 3G mode. Subjects reported some body noise interference that limited use of the invisible hearing mode; however, all continue to use the invisible hearing mode on a limited daily basis. The rechargeable battery functioned well, with a cycle time indicating the low-power implant design is effective and will deliver long battery life.

Conclusion: This study demonstrates that the challenges in developing a safe and effective TIKI can be overcome. Three subjects implanted with the research TIKI all reported benefit from routine use. For each subject, hearing outcomes using invisible hearing mode were not as good as when using the external ESPrit 3G sound processor in the conventional mode.

*The University of Melbourne Department of Otolaryngology; †The Co-operative Research Centre for Cochlear Implant and Hearing Aid Innovation, Melbourne; and ‡Cochlear Limited, Sydney, Australia

Address correspondence and reprint requests to Robert J. S. Briggs, M.B.B.S., F.R.A.C.S., Department of Otolaryngology, University of Melbourne, 32 Gisbourne St., East Melbourne, Victoria 3002, Australia; E-mail:

This study was supported by the Commonwealth of Australia through the Cooperative Research Centre for Cochlear Implant and Hearing Aid Innovation and by Cochlear Limited, Lane Cove, Australia. This study was conducted under ethical guidelines as approved by the Human Research Ethics Committee of the Royal Victorian Eye and Ear Hospital.

© 2008 Otology & Neurotology, Inc.