Auditory Performance and Cortical Plasticity Following Late Sequential Cochlear Implantation.

Abstract

Introduction: Bilateral cochlear implantation (CI) may be performed either simultaneously or sequentially, depending on factors such as the degree of hearing loss and the patient's age. However, a global consensus regarding the optimal timing for sequential implantation has yet to be established.

Methods: This study included 27 individuals who underwent late sequential CI. The mean chronological age of the participants was 140.93 ± 41.51 months. The mean age at the time of the first (early unilateral) CI 1 was 25.44 ± 9.25 months, with a mean interimplant interval of 115.48 ± 41.45 months before the second (late sequential) implantation (CI 2). Cortical auditory evoked potentials (CAEPs) were recorded, and P1 latency measurements were obtained at 3, 6, 9, and 12 months following CI 2 activation. Auditory performance outcomes were analyzed across five time points post-implantation.

Results: Auditory perception improved markedly within 3 months after CI 2 activation. CAEP analysis demonstrated significant enhancements in cortical responsiveness, indicating that CI 2 had a beneficial effect on central auditory system plasticity. The reduction in P1 latency was statistically significant (p < 0.001), supporting the notion of cortical reorganization following late implantation.

Conclusion: Late sequential CI can lead to substantial gains in auditory performance and may facilitate adaptive cortical plasticity in individuals with a history of early unilateral implantation. These findings support the clinical value of late second implantation, even after extended interimplant delays.