Changes in electrically evoked auditory brainstem responses in children with sequential bilateral cochlear implants

Abstract Objectives The primary aim of this study is to investigate whether the electrical stimulation of the second ear causes a difference in electrically evoked auditory brainstem responses (eABR) between two ears over time. Methods The study included thirteen subjects under the age of five who used cochlear implants for at least six months in the first ear prior to the sequential cochlear implantation. Postoperative eABRs were conducted on the 1st (first fitting of the second speech processor), 3rd, and 6th months of the second implantation in the basal, medial, and apical electrode positions. The recording was started with the second cochlear implant (CI2), and then the first cochlear implant (CI1) was tested. Sound field audiometry and receptive/expressive language assessments were also performed at 1 and 6 months after the second cochlear implantation. Results eABR results indicate that when eV wave latencies are examined for all electrodes, CI2 is significantly longer than CI1 (p  Conclusion The postoperative eABR test is a valuable test battery that provides the clinician with important ideas about the estimated threshold, comfortable and audible sound level, CI performance, and auditory pathways up to the brainstem. Since the maturation is still ongoing, an extended period longer than six months is needed to evaluate interaural differences.