Audiological outcomes of cochlear implantation of adults with long term post-lingual deafness

Introduction: The literature indicates that long term deafness is a critical factor that negatively impacts the outcome after cochlear implantation. Nevertheless, we believe that this variable should not be separated from residual hearing before implantation. Objective: The aim of this study was to verify whether the residual hearing interferes in the speech perception outcomes after one year of CI use of adult patients with long term deafness. Methods: Retrospective exploratory chart review of adult patients with more than 10 years of post lingual deafness. Partial insertions were excluded. Twenty-three subjects participated in the study. Data regarding etiology, pre and post aided hearing thresholds as well as aided speech perception scores were analyzed. According to the pre operative aided thresholds, patients were separated into two groups. Group 1 (G1): 12 patients with access to speech sounds (preoperative aided thresholds equal to or better than 50 dB HL), and group 2 (G2): 11 patients without access to speech sounds (preoperative aided thresholds worse than 55 dBHL). Results: Etiology distribution was as follows: nine subjects were deaf due to unknown causes; six had meningitis, three had ototoxicity history, two otosclerosis, 1 acoustic trauma, 1 had had head trauma, and 1 had measles. Average time of deafness was 25.6 years, varying from 10 to 51 years. Fifty-seven percent of the patients presented good outcome (> 70% of open set sentence recognition) after 1 year of implant use, eight patients (35%) from group 1 and 5 patients (22%) from group 2. Although our initial hypothesis was that G1 patients would have better scores in speech perception tests than G2 group, our findings showed that even patients with long term deprivation could achieve very good outcomes after one year of implant use. Discussion and conclusion: This fact reveals that hearing deprivation is not a dictator of poor prognosis. In fact, at our service, when there are identical medical and anatomical conditions between ears to be implanted, we choose the worst residual hearing to be implanted in order to preserve the better hearing for the hearing aid use, with a bimodal stimulation. We believe that the central auditory nervous system can be stimulated when there had been at least one ear with aided access to speech sounds. We believe that factors other than residual hearing, such as auditory processing skills may impact the outcomes even in patients with long term auditory deprivation. Residual hearing not necessarily interferes in the speech perception outcomes of CI users with long term deafness.