Development of P1 Response in Children with Bilateral Sequential Cochlear Implants

Purpose of the study: Bilateral pediatric cochlear implantation is becoming increasingly common in clinical practice. Besides many advantages of binaural hearing, the amelioration of the auditory deprivation is important in young cochlear implantees. The effects of auditory deprivation on the central auditory system can be examined by P1 cortical auditory-evoked response latencies as an indicator of cortical maturation in response to sound. In this study we aim to examine the development of P1 response in children who received bilateral sequential implants before the age of 4.

Materials and Methods used: 50 children with bilateral sequential cochlear implants took part in the study. The age range at the time of first implantation was 1 -3.5 years and the age range of the second implantation was 2 to 4 years. P1 latency was measured before the second implant, at the hook up of the second implant, 3 months and 6 months after the second implant.

Results: P1 latencies recorded from the first implanted ear were within normal limits at the time they received their second implant. P1 latencies from the second implanted ear were obtained at the first day of the hook up but the latencies were delayed when compared with the first implanted ear. The latency of the P1 response of the second ear decreased after one month and 3 months of CI use in all patients, most of the subjects  reached age mormative levels depending on the age of implantation at the end of 3 months of implant use. The P1 latencies measured at the 6 months after second ear activation shortened in latency, and reached the normal levels.

Conclusion: Auditory evoked potentials reflect the performance after cochlear implantation and provide an objective way to evaluate postoperative cortical auditory performance.Early bilateral implantation helps to preserve the integrity of the central auditory system.