Objectives: This is a cross-sectional study conducted on cochlear implant recipients, to monitor changes in recorded impedance telemetry and evoked compound action potentials (ECAP) measured during surgery versus the same measures at post implant follow-up visits. An additional aim was to correlate the recorded ECAP measures with the patient ' s postoperative performance and to evaluate the incidence of abnormal intra-operative cochlear implant telemetry measurements and their changes at device activation. Study design: The present study comprised 44 subjects -12 adults and 32 children of both genders -implanted at the Cochlear Implant Unit, Cairo University. ECAP thresholds and electrode impedance measures were collected intra-operatively, at initial stimulation, and at 9 -12 months post initial stimulation. Measurements were compared at the three intervals and ECAP measures were correlated to the patient ' s post-operative performance in the form of aided sound fi eld thresholds, speech detection and discrimination for adults and language assessment for children. Results: In the absence of electrical stimulation, there was an increase of impedance on all electrodes at the initial stimulation visit, which decreased at the 9 -12 months follow-up. Open circuit fi ndings were more prevalent than short circuits. Children had higher impedance values at post implant activation compared to adult patients. No correlation existed between ECAP thresholds and post-operative patient performance at the one-year evaluation. Conclusion: At the time of surgery, telemetry provides valuable information regarding the electrical output of the implant and the response of the auditory system to electrical stimulation; however, it is not a valuable predictor of post-operative performance.

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EnAbstract Background Cortical auditory evoked potentials (CAEPs) are noninvasive measures used to quantify central auditory system function in humans. More specifically, the P1–N1–P2 cortical auditory evoked potential has a unique role in identifying the central auditory system that has benefited from amplification or implantation. P1 reflects the maturation of the auditory system in general as it has developed over time. Objective The aims of this study were to assess the CAEP in children with cochlear implants compared with age-matched controls, to study the different variables affecting the results, and to compare the pattern of P1 CAEP in cochlear implant patients compared with that in those with hearing aids. Methodology Thirty-five hearing-impaired children (using cochlear implants) were compared with 20 age-matched and sex-matched children with normal hearing. In both groups, P1 CAEP latency and waveform morphology were recorded using free-field auditory stimulation with tone bursts at 500 and 2000 Hz at 100 dB sound pressure level in two sessions that were 6 months apart. Results Children using cochlear implants exhibited prolongation of P1 latencies, indicating an overall delay in maturation when compared with that in children who could hear normally. P1 CAEP latency and amplitude improved significantly after 6 months of device use. Conclusion Standardized age-appropriate normative data on P1 CAEPs in the pediatric Egyptian population could be used to determine implantation or amplification results.