[Threshold dynamics of the auditory nerve electrically evoked compound action potential in implanted children]

Area of Science:

• Audiology and Speech-Language Pathology
• Biomedical Engineering
• Otolaryngology

Background:

• Cochlear implantation (CI) is a vital treatment for pediatric sensorineural deafness.
• Intraoperative and postoperative assessment of auditory nerve function is crucial for optimizing CI outcomes.
• Neural response telemetry (NRT) provides objective measures of auditory nerve response to electrical stimulation.

Purpose of the Study:

• To investigate the dynamic changes in electrically evoked compound action potential (ECAP) thresholds measured via NRT.
• To assess these threshold dynamics intraoperatively, at CI activation, and at 3 and 6 months post-activation.
• To evaluate the stability and accuracy of NRT for programming cochlear implant speech processors.

Main Methods:

• Fifty children (1-4 years) with bilateral sensorineural deafness received Nucleus CI512 Profile + CP900 systems.
• NRT thresholds were recorded intraoperatively, at CI activation, and at 3 and 6 months post-activation.
• Thresholds were assessed on electrodes 1, 6, 11, 16, and 22 of the multichannel electrode array.

Main Results:

• Significant differences (p<0.001) were observed in NRT threshold profiles between intraoperative and postoperative measurements.
• Postoperative NRT thresholds demonstrated relative stability, particularly on mid-array electrodes compared to apical/basal electrodes.
• NRT thresholds at activation, 3, and 6 months were significantly lower than intraoperative thresholds in most patients.

Conclusions:

• NRT is a stable and accurate method for objectively assessing auditory nerve function in pediatric CI users.
• The observed changes in NRT thresholds highlight the importance of serial measurements for effective CI programming.
• NRT facilitates individualized speech processor programming during the crucial rehabilitation phase post-cochlear implantation.