Long-Term Influence of Electrode Array Length on Speech Recognition in Cochlear Implant Users
Editor's Note: This Manuscript was accepted for publication on June 30, 2020.
m.w.c. was supported in part by the National Institutes of Health through a National Institute on Deafness and Other Communication Disorders training grant (T32 DC005360). MED-EL Corporation provided a research grant to support the initial study. h.c.p., k.d.b., and b.p.o. have served on the surgical advisory board for MED-EL Corporation. c.a.b. is a surgical consultant for Advanced Bionics, Cochlear, IotaMotion, and Envoy, and has equity interest in Advanced Cochlear Diagnostics, LLC. b.p.o. is a consultant for Advanced Bionics and Johnson and Johnson. e.r.k. has served on the audiology advisory board for MED-EL Corporation. m.t.d. and m.a.r. are supported by a research grant from MED-EL Corporation provided to the university. h.c.p. is a consultant for MED-EL Corporation. o.f.a. is a paid consultant for MED-EL Corporation, Advanced Bionics, Spiral Therapeutics, and AGTC Inc., receives research support from MED-EL Corporation and Advanced Bionics, has ownership in Advanced Cochlear Diagnostics, and receives royalties from Advanced Bionics.
The authors have no other funding, financial relationships, or conflicts of interest to disclose.
Abstract
Objectives/Hypothesis
Results from a prospective trial demonstrated better speech recognition for cochlear implant (CI) recipients implanted with a long lateral wall electrode array compared to subjects with a short array after 1 year of listening experience. As short array recipients may require an extended adaptation period, this study investigated whether differences in speech recognition continued through 4 years of CI use.
Study Design
Long-term follow-up of a prospective randomized trial.
Methods
Subjects were randomized to receive a MED-EL medium (24 mm) or standard (31.5 mm) array. Linear mixed models compared speech recognition between cohorts with word recognition in quiet and sentence recognition in noise at 1, 3, 6, 12, 24, and 48 months postactivation. Postoperative imaging and electric frequency filters were reviewed to assess the influence of frequency-to-place mismatch and angular separation between neighboring contacts, a metric associated with peripheral spectral selectivity.
Results
Long (31.5 mm) array recipients demonstrated superior speech recognition out to 4 years postactivation. There was a significant effect of angular separation between contacts, with more closely spaced contacts associated with poorer speech recognition. There was no significant effect of mismatch, yet this may have been obscured by changes in frequency filters over time.
Conclusions
Conventional MED-EL CI recipients implanted with 31.5-mm arrays experience better speech recognition than 24-mm array recipients, initially and with long-term listening experience. The benefit conferred by longer arrays in the present cohort can be partially attributed to more widely spaced electrode contacts, presumably a result of reduced channel interaction.
Level of Evidence
2 Laryngoscope, 131:892–897, 2021
