Intra-Cochlear Electrocochleography During Cochear Implant Electrode Insertion Is Predictive of Final Scalar Location

Abstract

Intracochlear ECochG may provide information about CI electrode location and hearing preservation.

Electrocochleography in Cochlear Implant Users with Residual Acoustic Hearing: A Systematic Review

“…This bidirectional telemetry system is available for all three major CI devices, as referred to as the Neural Response Telemetry (NRT, Cochlear Ltd.), Neural Response Imaging (NRI, Advanced Bionics), and Auditory Nerve Response Telemetry (ART, MED-EL). The intracochlear ECoG recording via the reverse telemetry system was feasible to offer the real-time feedback of cochlear responses during electrode insertion [ 23 , 24 , 25 , 27 , 41 , 42 , 47 , 48 ]. The prognostic value of intracochlear ECoG obtained in the operating room to assess insertion trauma and predict early postoperative hearing preservation is yet unclear.…”

“…Intraoperative ECoG recordings have the potential to provide information about scalar location of the electrode array during and after electrode insertion. Frequent instances of translocation (22–38%) from scala tympani (ST) to scala vestibuli (SV) during electrode insertion and its negative impact on speech outcomes were reported [ 23 , 24 ]. Subjects who had electrode arrays translocated from ST into SV showed a sizeable decrease in CM amplitudes during insertion without recovery, while this CM amplitude change was not significantly different from responses from the nontranslocation group [ 24 , 25 ].…”

“…Frequent instances of translocation (22–38%) from scala tympani (ST) to scala vestibuli (SV) during electrode insertion and its negative impact on speech outcomes were reported [ 23 , 24 ]. Subjects who had electrode arrays translocated from ST into SV showed a sizeable decrease in CM amplitudes during insertion without recovery, while this CM amplitude change was not significantly different from responses from the nontranslocation group [ 24 , 25 ]. However, the difference between intraoperative CM thresholds and postoperative audiometric thresholds for patients with electrode crossed from ST to SV was significantly lower, which suggests that scalar translocation from ST to SV was associated with significantly higher shifts in low-frequency audiometric thresholds when compared to electrodes inserted entirely within ST [ 23 ].…”

“…However, the difference between intraoperative CM thresholds and postoperative audiometric thresholds for patients with electrode crossed from ST to SV was significantly lower, which suggests that scalar translocation from ST to SV was associated with significantly higher shifts in low-frequency audiometric thresholds when compared to electrodes inserted entirely within ST [ 23 ]. In addition, a trend of smaller phase changes was observed in the translocation group compared to a larger phase shift in the nontranslocation group [ 24 ]. Therefore, incorporating phase change information during electrode insertion may enhance specificity and sensitivity when predicting scalar translocation based on intraoperative ECoG measurements.…”

“…Once hearing preservation became possible for CI users with the development of thinner, flexible electrode arrays and the use of the soft surgical techniques, there were surging interests in using ECoG to measure cochlear function in this expanded CI population. The ECoG has been increasingly used to monitor the status of hearing to mitigate possible intracochlear damage while inserting an electrode and optimize electrode placement during cochlear implant surgery [ 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 ]. Recently, noninvasive recording methods have been developed that allow ECoG responses to be measured from an intracochlear electrode [ 26 , 27 , 28 , 29 , 30 ].…”