Establishing Reproducibility and Correlation of Cochlear Microphonic Amplitude to Implant Electrode Position Using Intraoperative Electrocochleography and Postoperative Cone Beam Computed Tomography.
Andrew Soulby, Steve Connor, Dan Jiang and 3 others
PMID 33813521WHAT IT FOUND
Intraoperative cochlear microphonic recordings were reproducible and correlated with electrode position in 13 of 14 ears.
However, they did not reliably predict hearing preservation, with only 7 of 13 traces correctly forecasting the outcome. Predicted thresholds were too inaccurate for clinical use in fitting hybrid devices.
Key findings
01Cochlear microphonic responses were successfully recorded in 13 out of 14 ears and showed significant correlation between intraoperative and postinsertion measurements regarding electrode position.
02The intraoperative traces failed to reliably predict hearing preservation outcomes, correctly forecasting the result in only 7 of 13 successful recordings.
03Predicted hearing thresholds were not accurate enough to replace behavioral testing for fitting electroacoustic stimulation devices, with a 2 SD range of ±24 dB HL.
STILL TO COME
How it was doneWhat they foundWhat it means for SLPs
Read the rest of this summary
You get three full summaries a month, free, and we do not ask for a card. Search, the TL;DRs and your library stay unlimited either way.
What it does not show
The sample size was small (12 patients, 14 ears), limiting the generalizability of the findings. Stimulus intensity was not calibrated on a patient-by-patient basis, and a change in ear tip type during the study caused significant signal loss at low frequencies, affecting threshold predictions. The method for estimating electrode position during insertion assumed that the final position seen on CBCT matched the insertion trajectory, which may not be true. There is an incomplete understanding of the ECochG signal itself, particularly regarding phase interference and how amplitude changes relate to actual cochlear damage or preservation.
Declared interests
Advanced Bionics provided the recording devices on a loan basis. One author is used by Advanced Bionics. Guy’s and St. Thomas’ research and development department acted as study sponsors.
The easy way to misread this
Do not interpret the statistical correlation between CM amplitude and electrode position as evidence that the test can reliably predict hearing preservation. The study found that intraoperative traces correctly predicted the hearing outcome in only 7 of 13 cases, meaning more than half were wrong.