Is there a deafness duration limit for cochlear implants in post-lingual deaf adults?

Abstract
Conclusion: Patients with post-lingual deafness should not be excluded from cochlear implantation (CI) on the basis of duration
of deafness. We found that the prognosis was favorable in patients who developed deafness after adolescence, even in those with
extremely long-term deafness. Objectives: CI is an effective treatment for post-lingual deafness. However, it remains unclear
whether CI would benefit patients with extremely long-term deafness. We evaluated the auditory performance after CI of
patients who had been deaf for more than 30 years. Methods: The study enrolled 81 adults with post-lingual deafness. Speech
perception tests were performed preoperatively and 12 months postoperatively, and factors affecting the postoperative auditory
performance were investigated. The subjects were divided into groups according to the duration of deafness and the
postoperative speech perception scores were compared. Results: A marked improvement in the open-set speech perception
scores (mono/disyllabic words and sentences) after implantation was seen in all groups, and no significant difference in the
improvement in speech perception scores was observed among the groups. Age at onset of deafness was closely related to the
postoperative performance, and patients who had lost their hearing before adolescence performed poorly.