Longitudinal Electrocochleography as an Objective Measure of Serial Behavioral Audiometry in Electro-Acoustic Stimulation Patients.

The study was done at one institution and used custom in-house ECoG equipment, so it may not be available in ordinary clinics. Not all subjects were tested at all scheduled time points, and some were enrolled years after surgery. The number of subjects in the stable and hearing-loss groups could differ for each test frequency, so the group sizes were not fixed across analyses. Group classification depended on a behavioral threshold change greater than 5 dB between baseline and the most recent appointment, which may not capture gradual fluctuations. The CM/DIFF and ANN/SUM separation was imperfect, so some responses may contain mixed hair-cell and nerve activity. ECoG thresholds were often higher than behavioral thresholds, so ECoG values cannot be read as exact copies of audiogram thresholds. The study did not test speech understanding, hearing aid benefit, or clinical outcomes, so it does not show that ECoG monitoring improves patient care. Without post-mortem histology, the study cannot prove why delayed hearing loss occurred.

The article is listed as supported by NIH extramural research. BJG is a consultant for Cochlear Ltd. MRH is co-founder and Chief Medical Officer for iotaMotion, Inc. VDT is a consultant for iotaMotion, Inc. All other authors declare that they have no conflict of interest.

Do not conclude that ECoG can replace behavioral audiometry or identify the cause of delayed hearing loss. The recordings used custom in-house equipment, ECoG thresholds were often higher than behavioral thresholds, and the study had no post-mortem histology to confirm what damaged the cochlea.