Insertion of Cochlear Implant Electrode Array Using the Underwater Technique for Preserving Residual Hearing.

OBJECTIVE

To describe a method of cochlear implantation in which the opening of the cochlea and the electrode array insertion are performed under water (underwater technique).

STUDY DESIGN

Retrospective patient review.

SETTING

Academic tertiary referral center.

PATIENTS

Fifteen implantations in children and adult patients with residual hearing at the frequencies 250, 500, and 1000 Hz on the unaided preoperative pure-tone audiometry were included in this study.

INTERVENTION(S): Cochlear implantation with a conventional full-length electrode, in which the opening of the cochlea and the electrode array insertion are performed after the tympanic cavity was filled with body-temperature Ringer solution.

MAIN OUTCOME MEASURE(S): Changes on residual hearing 6 to 8 weeks after surgery and at subsequent follow-up appointments were analyzed. Preservation of residual hearing was defined as measurable postoperative threshold at the frequencies 250, 500, and 1000 Hz.

RESULTS

Overall postimplant hearing preservation 6 to 8 weeks after implantation was achieved in 13 of the patients (87%). Subsequent follow-up was performed on average 15.2 months after surgery (range, 7-32) in 14 out of 15 patients. At this late postoperative evaluation preservation of hearing was recorded in nine patients (64%), whereas in the remaining five patients (36%) no residual hearing was measured.

CONCLUSION

The underwater technique offers a reliable nontraumatic method for electrode array insertions during cochlear implantation. The method respects the physiology of the cochlea und minimizes the pressure variations during cochlear opening and implantation.