The role of hearing preservation on electrical thresholds and speech performances in Cochlear Implantation

Introduction. Candidacy criteria for cochlear implantation have evolved including patients with more residual hearing. The purpose of this study was therefore to verify the correlation between preservation of residual hearing after classic cochlear implantation in adult, electrical thresholds and speech performances. Matherials and Methods. 41 patients with CI were involved in our study. They were subdivided into 2 groups according to the average pre-operative hearing loss at the frequencies of 125 and 250 Hz (low frequency pure tone average- LFPTA). Group A included 21 patients with a mean LFPTA ≤ 90 dB HL; Group B included 20 patients with a mean LFPTA > 90 dB HL. They underwent 12 months follow up after cochlear implantation, including standard audiological investigation, speech discrimination tests and electrical measurements. Results. No significant differences were found in speech perception tests among groups. In Group A hearing was preserved in 8 (group A1) and was lost in 13 patients (group A2); the postoperative LFPTA was significantly better (p < 0,0001) in A1. Group A1 patients present significantly higher C values (p < 0,0001) than the other two groups and the dynamic range was therefore significantly wider (p