Indications and effectiveness of adult cochlear implantation at our hospital

In 2017, the criteria for adult cochlear implantation were revised by the Oto-Rhino-Laryngological Society Japan. Cases with average hearing levels of 70-90 dB and with speech recognition scores of ≤50% were added as candidates for cochlear implantation. We conducted a retrospective examination of the data of our patients with average hearing levels of ≤90 dB who underwent cochlear implantation, and discuss the new criteria. In this study, we analyzed the data of 68 patients over the age of 18 years who had undergone cochlear implantation at our hospital between 2008 and 2018. The subjects were divided into three groups : The "conventional criteria group," consisting of patients whose preoperative hearing data corresponded to the conventional criteria, the "new criteria group," consisting of patients who fulfilled the newly added criteria, and the "special case group," consisting of patients who did not fulfill either the conventional or the new criteria. For each group, we investigated the age at operation, age at onset, cause of the hearing loss and the CI-2004 score at the final visit. In the new criteria group, all the patients had post-lingual deafness, with progressive sensorineural hearing loss of unknown etiology accounting for the majority. The postoperative CI-2004 score was almost equal between the new criteria group and the conventional criteria group, whereas that in the special case group tended to be lower as compared to the scores in the other two groups. In the special case group, two patients who had good speech recognition scores of 45% and 70% in the contralateral ear did not use the cochlear implants during all waking hours. The patients with visual impairment tended to have better speech recognition performance as compared to those without visual impairment. This study suggested that the new criteria might shorten the duration of post..lingual progressive hearing loss of unknown etiology. The speech recognition performance in the patients who fulfilled the new criteria was equal to that in the patients who fulfilled the conventional criteria. Cochlear implantation for special cases such as auditory neuropathy and patients with visual impairment is effective, if we judge the candidates adequately by a comprehensive understanding about the patients. The postoperative speech recognition performance was limited in patients with a difference between the right and left hearing levels who received cochlear implantation on the side with the worse hearing.