The influence of various factors on the performance of repetition tests in adults with cochlear implants

A variety of internal and external factors influence speech perception performance following cochlear implantation (CI) in adult deaf patients. The aim of this study was to evaluate the speech perception performance during repetition testing according to various factors and to identify the predictive factors associated with postoperative speech perception. The performances on speech perception under audio-only conditions were examined over time in 61 adult patients with CI. Mono- and bi-syllable and sentence repetition testing, using both the Korean version of the Central Institute for the Deaf (K-CID) and the K-Western Aphasia Battery test (K-WAB), were performed preoperatively and at 3, 6 and 12 months postoperatively. To elucidate the effect that the etiology of deafness has on postoperative outcome, patients were divided into the following four groups: Prelingual hearing loss (HL) (n = 9), Meningitis (n = 6), Progressive HL (n = 31) and Sudden HL groups (n = 15). Moreover, the duration of HL and deafness was defined as follows: (1) "age of deafness onset: AoD", (2) "number of years between the onset of profound deafness and CI: DoD" and (3) "percentage of the patient's life with moderate-to-profound hearing loss before CI: PoL". DoD and PoL were significantly different between the four groups. Although AoD appeared to be associated with performance on the sentence repetition test before standardizing for education level and age (P = 0.015), there was no association after adjusting for these factors (P = 0.719). Only PoL showed a good correlation with performance on repetition testing after CI after adjusting for AoD and DoD. However, DoD was associated with speech perception performance on the sentence repetition test only. In addition, speech perception performance results in the Progressive and Sudden HL groups were improved over the Prelingual HL and Meningitis groups. The Meningitis group showed the poorest speech perception performance among postlingually deaf adults. Consideration of age, education level, etiology and overall time with hearing loss may be necessary for predicting speech perception outcomes in CI recipients.