Slim Perimodiolar Arrays Are as Effective as Slim Lateral Wall Arrays for Functional Hearing Preservation After Cochlear Implantation

Abstract

Objective: To compare functional hearing preservation (HP) with a slim perimodiolar array (SPA) and a slim lateral wall array (SLW) in cochlear implantation (CI). Study Design: Retrospective chart review. Setting: Tertiary referral center. Patients: All adult, post-lingual CI recipients with serviceable preoperative hearing serially implanted with SPA or SLW electrodes from July 2015 through July 2018. Interventions: Cochlear implantation. Main Outcome Measures: Hearing preservation (HP). Patients with a low frequency pure-tone average (LFPTA) (125, 250, 500 Hz) threshold less than 80 dB were considered HP candidates based on preoperative audiograms. Postoperative audiograms were obtained before activation. Successful HP was defined as retention of LFPTA less than 80 dB. The change in LFPTA (ΔLFPTA) was also calculated. Results: One hundred twenty one patients were implanted with either the SPA or SLW electrodes, 82 (42,40) of whom were HP candidates with postoperative audiograms. Average (standard deviation, SD) preoperative LFPTA was 54.86 [19.38] and 54.38 [13.58] dB for SLW and SPA respectively, with a mean ΔLFPTA of 24.6 [15.94] and 24.92 [16.66] dB. Successful HP was achieved in 21 (50%) and 22 (55%). Preoperative LFTPA, ΔLFPTA, and postoperative LFPTA were not significantly different (p = 0.89, 0.75, 0.93) between electrodes. Conclusions: The SPA is as effective at immediate functional HP after CI as a SLW.

Speech Recognition Outcomes in Adults With Slim Straight and Slim Modiolar Cochlear Implant Electrode Arrays

“…13 Prior studies have demonstrated that LFPTA <80 dB is the postoperative threshold indicative of preserved low-frequency hearing. 15 As our patients tended to have poor preoperative LFPTA (mean [SD], 75.5 [20.9] for SLW and 78.3 [17.9] for SME), very few patients in our cohort would have qualified for hearing preservation. It has been theorized that PM electrodes would allow for lower stimulation thresholds, improved dynamic range, and decreased stimulation of adjacent neural elements when compared with LW electrodes and result in improved audiologic performance.…”

“…It has been theorized that for patients with little to no residual hearing, a PM electrode should be chosen to provide greater electrode apposition to the spiral ganglion neurons, less energy usage, and greater overall speech understanding 13 . Prior studies have demonstrated that LFPTA <80 dB is the postoperative threshold indicative of preserved low‐frequency hearing 15 . As our patients tended to have poor preoperative LFPTA (mean [SD], 75.5 [20.9] for SLW and 78.3 [17.9] for SME), very few patients in our cohort would have qualified for hearing preservation.…”

“…Finally, there are anatomic and technical aspects to consider with the SME, such as the size of the facial recess, orientation of the RW, or, rarely, the level of the jugular bulb. 29 If the angle of the RW is unfavorable, extending the RW may be required to prevent tip rollover with SME. However, placement of the SLW is possible irrespective of the orientation of the RW.…”

One‐Year Hearing Preservation and Speech Outcomes Comparing Slim Modiolar and Lateral Wall Arrays

“…9 Woodson et al reported an HP rate of 53% for the CI 532 and 50% for the CI 522 at activation, but also did not report speech performance. 25 Mady et al's review of 45 patients using either CI 512 perimodiolar array or CI 422 LWE found an HP% (≤85 dB) of 17.6% and 4.3% at 1 year, respectively; although their speech data was not shown, they did not find any speech outcomes differences by electrode type or HP status. 24 Lee et al reported outcomes on 34 patients with LWE for HP and also did not find significant speech performance differences by HP status.…”

Mythbusters! The Truth about Common Misconceptions in Cochlear Implantation

“…The average patient will experience a threshold shift of approximately 20 dB after soft surgery with modern slim arrays. 17 Additionally, delayed loss of HP may occur over time, any time after activation. In the study by Mamelle et al, a large series of patients implanted with various slim arrays were noted to have a cumulative risk of 50% total HL at 7 years postoperative.…”