Estimation of the status of spiral ganglion neurons and Schwann cells in the auditory neural degeneration mouse using the auditory brainstem response.

Conclusion: The auditory brainstem response (ABR) wave I threshold, latency and amplitude are insensitive to spiral ganglion neurons (SGNs) degeneration, but are sensitive to the degeneration of Schwann cells and can estimate the status of Schwann cells in a neural degeneration mouse model. The thorough pre-operative ABR assessment would be helpful in predicting cochlear implant performance.
Objectives: This study aimed in finding a non-invasive electrophysiological method to evaluate the status of the auditory nerve and the Schwann cells in sensorineural hearing loss (SNHL) and auditory neuropathy (AN) ears, and providing useful information for candidates screening and outcome prediction in cochlear implantation.
Methods: The frequency-specific acoustic ABR was recorded in mice. The immunohistochemical staining was performed to detect the SGNs and Schwann cells in mice cochlea. The correlations between ABR wave I metrics and SGNs, Schwann cells were investigated.
Results: In SNHL and AN mice cochlea, statistically significant correlations between ABR wave I thresholds, latencies and amplitudes at 8, 16, and 32 kHz and their corresponding SGNs densities were found only in wave I amplitude at 8 kHz. While the ABR wave I metrics at all three frequencies showed strong significant correlations with their corresponding Schwann cells densities.