The aim of the study was to determine the degree of hearing preservation
(HP) and its relation to electrode array length after cochlear implantation
using different thin flexible electrode arrays (TFEA).
One hundred twenty adult patients with preoperative residual hearing received a cochlear implant with a TFEA: 46 received a TFEA20, 34 a TFEA24, and 40 a TFEA28 mm.
Main Outcome Measures:
Pure-tone audiometry (125–1500 Hz) was performed preoperatively, at initial fitting, and at 3, 6, and 12 months postoperatively. Median hearing loss (HL) was determined for each of the three array groups. The pre- to postoperative pure-tone average difference was scaled into three groups (≤15 dB, >15 to ≤30 dB, >30 dB) for array group.
At initial fitting, median HL of 17.5 dB (TFEA20), 20 dB (TFEA24), and 24 dB (TFEA28) was observed. At 12 months, medial HL of 15 dB (TFEA20), 19.4 dB (TFEA24), and 32.5 dB (TFEA28) was observed. At initial fitting, a HL of ≤15 dB was achieved in 45.6% TFEA20 subjects, 29.4% TFEA24 subjects, and 15.0% TFEA28 subjects; compared with 48.8% TFEA20 subjects, 50.0% TFEA24 subjects, and 15.8% TFEA28 subjects at 12 months.
HP is possible in the majority of subjects who are implanted with a TFEA20, 24, or 28. Using shorter arrays led to greater HP and lower median HL.