Cone-beam computed tomography in children with cochlear implants: The effect of electrode array position on ECAP.

OBJECTIVES: To assess the feasibility of using cone-beam computed tomography (CBCT) in young children with cochlear implants (CIs) and study the effect of intracochlear position on electrophysiological and behavioral measurements.

METHODS: A total of 40 children with either unilateral or bilateral cochlear implants were prospectively included in the study. Electrode placement and insertion angles were studied in 55 Cochlear® implants (16 straight arrays and 39 perimodiolar arrays), using either CBCT or X-ray imaging. CBCT or X-ray imaging were scheduled when the children were leaving the recovery room. We recorded intraoperative and postoperative neural response telemetry threshold (T-NRT) values, intraoperative and postoperative electrode impedance values, as well as behavioral T (threshold) and C (comfort) levels on electrodes 1, 5, 10, 15 and 20.

RESULTS: CBCT imaging was feasible without any sedation in 24 children (60%). Accidental scala vestibuli insertion was observed in 3 out of 24 implants as assessed by CBCT. The mean insertion angle was 339.7°±35.8°. The use of a perimodiolar array led to higher angles of insertion, lower postoperative T-NRT, as well as decreased behavioral T and C levels. We found no significant effect of either electrode array position or angle of insertion on electrophysiological data.

CONCLUSION: CBCT appears to be a reliable tool for anatomical assessment of young children with CIs. Intracochlear position had no significant effect on the electrically evoked compound action potential (ECAP) threshold. Our CBCT protocol must be improved to increase the rate of successful investigations.