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Study of telemetry changes over time in children with a cochlear implant



Cochlear implant (CI) is an electronic device that provides direct electrical stimulation to the auditory division of the eighth cranial nerve. The integrity of the internal CI part after implantation can be assessed through objective measures, which are a widely used and valuable tool in the field of CIs. Impedance measurement and electrically evoked compound action potential (ECAP) are the most frequently used tests to facilitate programming of the implants especially in young children.


This study was carried out to compare ECAP thresholds and electrode impedance at the time of surgery, at the first stimulation session, and monthly for the next 2 months to assess whether a significant change take places with time.

Patients and Methods

Fifteen deaf children implanted unilaterally with a MED-EL Sonata Implant System with an Opus 2 speech processor were included in this study. All patients received the implant if they fulfilled the Alexandria main hospital criteria for receiving CIs. The group studied included seven males and eight females; they ranged in age from 2 to 6 years. Two of the patients had received implantation in the left ear, whereas the rest of the patients had received a CI in the right ear.


Intraoperative impedance was the lowest among all postoperative readings in all electrodes. The highest value was that measured 1 month after surgery, after which impedance values continued to decrease significantly, but not to the intraoperative values. The ECAP threshold showed no significant P values between the ECAP threshold measured in the intraoperative and the postsurgery follow-up period.


The measured impedance showed significant changes in the form of increasing values postoperatively relative to the intraoperative time. The ECAP threshold did not change significantly intraoperatively and postoperatively, showing that intraoperative ECAP can be useful in mapping as it shows no changes.


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Correspondence to Najla D. Massad MSc.

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Asal, S.I., Sobhy, O.A. & Massad, N.D. Study of telemetry changes over time in children with a cochlear implant. Egypt J Otolaryngol 34, 198–202 (2018).

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  • electrically evoked compound action potential
  • impedance
  • telemetry