Auditory cortical maturation in children with sequential bilateral cochlear implants.

OBJECTIVE

To assess the effect of sequential bilateral cochlear implantation on auditory, cortical maturation after various periods of unilateral cochlear implant use.

STUDY DESIGN

Prospective cohort study.

SETTING

Tertiary academic referral center.

PATIENTS

Thirty prelingually deaf children, who received their first implant at a mean age of 1.8 years and their second implant at a mean age of 5.3 years.

INTERVENTION

Sequential bilateral cochlear implantation.

MAIN OUTCOMES MEASURE

The electrically evoked auditory cortical response (EACR) was evoked by the 2 implants separately after 12 and 24 months of bilateral cochlear implant use. P1 and N2 latencies and RMS amplitudes were compared between both implant sides and were compared with those of a group of 27 age-matched children with normal hearing.

RESULTS

EACR latencies diminished over time for both implant sides. RMS amplitudes and P1 latencies elicited by the second implant were still significantly different from that of the first implant after 24 month. After 24 months, the difference in N2 latencies between both implant sides was no longer significant, although still apparent. Interimplant delay had an adverse effect on RMS amplitudes and waveform morphology. EACR latencies were age appropriate, although RMS amplitudes evoked by the second implant were smaller than those of the children with normal hearing.

CONCLUSION

Auditory cortical maturation is possible after extended unilateral cochlear implant use, although responses evoked by the second implant still lack behind that of the experienced first implant. It is not clear if the auditory cortical response will become similar on both implant sides over time, especially for the children with longer interimplant delays.