Performance Plateau in Prelingually and Postlingually Deafened Adult Cochlear Implant Recipients.

Objective: To characterize the performance plateau after unilateral cochlear implantation (CI) in prelingually and postlingually deafened adults and to compare their relative progress.

Study Design: Retrospective chart review.

Setting: Tertiary referral center.

Patients: Prelingually and postlingually deaf adults who received a unilateral CI and completed a minimum of 2 years of follow-up at our center.

Intervention: Unilateral CI.

Main Outcome Measures: Standard speech perception testing (consonant-nucleus-consonant [CNC] monosyllabic word test and hearing in noise test [HINT] or AzBio sentence test) were performed preoperatively and 3 and 12 months postoperatively, and annually thereafter.

Results: In postlingually deaf patients (n = 102), there was a significant improvement in word scores for 3 years postimplantation (p < 0.01). Beyond the 3 years postoperative time point, word scores continued to improve, albeit at a flatter rate. In prelingually deaf patients (n = 16) word scores improved significantly for 5 years postimplantation (p = 0.03).

Conclusions: Adults with postlingual deafness undergoing unilateral CI show significant improvement in speech perception for 3 years postimplantation, at which point their performance continues to improve, albeit at a flatter rate. The performance of adults with prelingual deafness improves significantly as late as 5 years postimplantation. These time intervals reflect a change to the currently reported 6 to 12 months period and should impact on counseling, especially in the prelingual CI candidate.