Intra and Post-Operative Electrocochleography in Pediatric Cochlear Implant Recipients and in Normal Hearing Animal Model

Background:

Preservation of the cochlear structures and residual hearing are a challenging target in cochlear implantation, especially in children with congenital hearing loss. Assessing the residual hearing after CI in small children can only be done by an objective measure. Electrocochleography (ECoG) recorded directly from the CI may serve as an excellent tool both for monitoring the changes during the implantation and assessing the residual hearing post implantation.

Objectives:

Understanding the ECoG patterns observed in the "insertion phase" and in post "insertion phase" in small children and in normal hearing animals underwent cochlear implantation.

Correlating the ECoG Audiograms with the behavioral audiograms obtained in pediatric CI recipients. In addition, comparing the correlations to those obtained in post lingual adults.

Methods:

In this study, 38 Advanced Bionics cochlear implant recipients and 8 normal hearing animals participated. The ECoG was recorded using the Bionic Ear Data Collection research software. During CI surgery (n=15) extra (Round window niche) and intra cochlear ECoG was obtained. In addition, ECoG thresholds at 250 to 2000 Hz were measured and correlated to the behavioral audiometric thresholds.

Results:

Variety of ECoG insertion patterns found both in human and animals. Losses of cochlear function can occur in each step even long after insertion. Post implantation ECoG audiograms revealed "Auditory Neuropathy" and "Sensory" patterns with different correlations to the behavioral audiograms.

Conclusion:

ECoG is a valuable tool to monitor the cochlear changes during the insertion and to predict closely the behavioral thresholds of pure tone stimuli.