Otology-Neurotology

Hearing Preservation After Cochlear Implantation

Criteria for cochlear implantation (CI) have expanded to include patients with increasing amounts of residual acoustic hearing. The expectation of improved speech understanding exists with or without residual acoustic hearing; however, hearing preservation (HP) is of emerging relevance to CI surgeons. If low-frequency hearing (LFH) is preserved at aidable levels, patients typically have better performance in background noise and have a greater ability to appreciate music.¹

In 2020, Cleveland Clinic’s Hearing Implant Program used 4 different electrode arrays in hearing preservation cases: Cochlear Americas (Denver, Colorado) Cochlear™ slim perimodiolar array (Nucleus® 532 and 632), Nucleus slim lateral wall array (Nucleus 522, 622 and 624), Hybrid™ L24, and Advanced Bionics (Valencia, California) HiFocus™ Ultra 3D Midscala. The initial choice of platform was made by the patient. In cases where a Nucleus device was opted, both the perimodiolar and lateral wall arrays were available in the operating room with the choice of array made by the surgeon based on the anatomy and orientation of the round window at the time of surgery. Whenever possible a round window insertion technique was used.

The Hearing Implant Program identifies CI candidates as having potential for HP if they have an aidable low-frequency (125–500 Hz) pure-tone average (LFPTA) ≤ 80 dB HL (hearing level). The average preoperative LFPTA for HP candidates in 2020 was 53.1 dB. Postoperative hearing thresholds were assessed 4 weeks after surgery.

Average change in hearing

2020 (N=44)

HP = hearing preservation

A total of 106 CIs were performed in 2020. Of these, 91 were adults, and 52 of these were appropriate for HP (57%), of which 44 had post-operative audiograms. The COVID-19 pandemic adversely affect post-operative audiogram collection as patients desired to minimize clinic visits in the short-term after shutdowns were relaxed. Of the 44 HP candidates with post-operative audiograms, 59% of these patients retained at least one frequency of 80 dB or better HL and 48% maintained a LFPTA <80 dB. The median change in LFPTA was superior for recipients with precurved vs lateral wall arrays (22 dB vs 28 dB).

References
  1. Woodson EA, Reiss LA, Turner CW, Gfeller K, Gantz BJ. The Hybrid cochlear implant: a review. Adv Otorhinolaryngol. 2010; 67:125-134.