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Cochlear Implant Receiver-Stimulator Migration Using the Subperiosteal Pocket Technique

Objective Measurements of Early and Late Positioning

Maxwell, Anne K.; Cass, Stephen P.

doi: 10.1097/MAO.0000000000002117
COCHLEAR IMPLANTS
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Objective: Current clinical practice for fixation of the cochlear implant receiver-stimulator (RS) may not follow recommended manufacturer's guidelines. We investigated short- and long-term RS migration using a subperiosteal pocket technique via serial objective position measurements since previous literature provided only subjective or short-term evaluation.

Study Design: Retrospective review.

Setting: Tertiary referral center.

Patients: We reviewed all patients who underwent cochlear implantation by the senior author between 2012 and 2018. At least two comparison measurements were available for 73 implants in 62 patients, 72.6% adults and 27.4% children.

Interventions: RS placement using a subperiosteal pocket technique.

Main Outcome Measure: Distance between the pinna and RS magnet in the early (<6 mo) and late (>6 mo) postoperative period.

Results: In the early postoperative period, mean RS distance was 57.0 mm (SD 9.4 mm) from the pinna compared with baseline intraoperative distance of 55.8 mm (SD 8.4 mm), p = 0.44. With some shifts closer and some farther from the pinna, there was a 3.0 mm mean absolute value migration (median 2 mm, SD 3.8 mm, range 0–15 mm). Fourteen implants (25.9%) migrated >5 mm in the early period, 35.7% closer, and 64.3% farther from pinna. In the late postoperative period, mean RS final distance was 56.6 mm (SD 10.1 mm), compared with its baseline of 59.0 mm (SD 9.2 mm), p = 0.29. Seven implants (19.4%) demonstrated shifts >5 mm, with a mean 3.6 mm shift (median 2 mm, SD 4.5 mm, range 0–17 mm).

Conclusion: A subperiosteal pocket technique demonstrated objective RS migration in 20 to 25% of adult and pediatric patients, nearly all of which were not clinically apparent unless measured. Additionally, none of these patients experienced associated symptoms or device failures.

Department of Otolaryngology, University of Colorado School of Medicine, Aurora, Colorado

Address correspondence and reprint requests to Stephen P. Cass, M.D., M.P.H., Department of Otolaryngology, University of Colorado School of Medicine, 12631 East 17th Avenue, B205, Aurora, CO 80045; E-mail: stephen.cass@ucdenver.edu

S.P.C. is a consultant for Cochlear Corporation.

The authors disclose no conflicts of interest.

Copyright © 2019 by Otology & Neurotology, Inc. Image copyright © 2010 Wolters Kluwer Health/Anatomical Chart Company