Electrocochleographic Responses Before and After Short-Term Suprathreshold Electrical Stimulation in Human Cochlear Implant Recipients (original) (raw)
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Extra- and Intracochlear Electrocochleography in Cochlear Implant Recipients
Audiology and Neurotology, 2015
Objective: To monitor cochlear function by extra- and intracochlear electrocochleography (ECoG) during and after cochlear implantation and thereby to enhance the understanding of changes in cochlear function following cochlear implantation surgery. Methods: ECoG responses to acoustic stimuli of 250, 500 and 1,000 Hz were recorded in 9 cochlear implant recipients with presurgical residual hearing. During surgery extracochlear ECoG recordings were performed before and after insertion of the cochlear implant electrode array. After insertion of the electrode array, intracochlear ECoG recordings were conducted using intracochlear electrode contacts as recording electrodes. Intracochlear ECoG recordings were performed up to 6 months after implantation. ECoG findings were correlated with findings from audiometric tests. Results: Extra- and intracochlear ECoG responses could be recorded in all subjects. Extracochlear ECoG recordings during surgery showed moderate changes. Loss or reduction ...
Frontiers in neuroscience, 2018
The aims of this study were: (1) To investigate the correlation between electrophysiological changes during cochlear implantation and postoperative hearing loss, and (2) to detect the time points that electrophysiological changes occur during cochlear implantation.Extra- and intracochlear electrocochleography (ECoG) were used to detect electrophysiological changes during cochlear implantation. Extracochlear ECoG recordings were conducted through a needle electrode placed on the promontory; for intracochlear ECoG recordings, the most apical contact of the cochlear implant (CI) electrode itself was used as the recording electrode. Tone bursts at 250, 500, 750, and 1000 Hz were used as low-frequency acoustic stimuli and clicks as high-frequency acoustic stimuli. Changes of extracochlear ECoG recordings after full insertion of the CI electrode were correlated with pure-tone audiometric findings 4 weeks after surgery.Changes in extracochlear ECoG recordings correlated with postoperative ...
Response Changes During Insertion of a Cochlear Implant Using Extracochlear Electrocochleography
Ear and hearing, 2018
Electrocochleography is increasingly being utilized as an intraoperative monitor of cochlear function during cochlear implantation (CI). Intracochlear recordings from the advancing electrode can be obtained through the device by on-board capabilities. However, such recordings may not be ideal as a monitor because the recording electrode moves in relation to the neural and hair cell generators producing the responses. The purposes of this study were to compare two extracochlear recording locations in terms of signal strength and feasibility as intraoperative monitoring sites and to characterize changes in cochlear physiology during CI insertion. In 83 human subjects, responses to 90 dB nHL tone bursts were recorded both at the round window (RW) and then at an extracochlear position-either adjacent to the stapes or on the promontory just superior to the RW. Recording from the fixed, extracochlear position continued during insertion of the CI in 63 cases. Before CI insertion, responses...
The Journal of the Acoustical Society of America
In cochlear implant (CI) users with residual hearing, the electrode-nerve interface can be investigated combining electricacoustic stimulation (EAS) via electrocochleography (ECochG), a technique to record cochlear potentials evoked by acoustic stimulation. EAS interaction was shown in previous studies using psychoacoustic experiments. This work characterizes EAS interaction through psychophysical experiments and the amplitude growth of cochlear microphonics (CM) and auditory nerve neurophonics (ANN) derived from intracochlear ECochG recordings. Significant CM responses were recorded at psychoacoustic threshold levels. The mean difference between psychoacoustic and CM threshold was 17.5 dB. No significant ANN responses were recorded at the psychoacoustic threshold level. At the psychoacoustic most comfortable level, significant CM and ANN responses were recorded. In the presence of electrical stimulation, the psychoacoustic detection thresholds were elevated on average by 2.38 dB while the recorded CM amplitudes were attenuated on average by 1.15 dB. No significant differences in electrophysiological EAS interaction across acoustic stimulation levels were observed from CM recordings. The presence of psychophysical and electrophysiological EAS interaction demonstrates that some aspects of psychoacoustic EAS interaction can be measured via intracochlear ECochG.
Real-Time Intracochlear Electrocochleography Obtained Directly Through a Cochlear Implant
Otology & neurotology : official publication of the American Otological Society, American Neurotology Society [and] European Academy of Otology and Neurotology, 2017
Utilizing the cochlear implant to record electrophysiologic responses during device placement is a feasible and efficacious technique for monitoring near real-time cochlear physiology during and following electrode insertion. Minimizing intracochlear trauma during cochlear implantation has emerged as a highly researched area to help improve patient performance. Currently, conventional cochlear implant technology allows for the recording of electrically evoked compound action potentials (eCAPs). Acoustically evoked potentials may be more sensitive in detecting physiologic changes occurring as a result of electrode insertion. Electrocochleography obtained from within the cochlea allows hair cell and neural response monitoring along the cochlear spiral at locations where changes most likely would occur. Intracochlear electrocochleography (ECochG) was recorded from the cochlear implant during surgery in 14 subjects. A long acquisition time (54.5 ms), capable of measuring potentials from...
Trends in Hearing
The use of electrocochleography (ECochG) for providing real-time feedback of cochlear function during cochlear implantation is receiving increased attention for preventing cochlear trauma and preserving residual hearing. Although various studies investigated the relationship between intra-operative ECochG measurements and surgical outcomes in recent years, the limited interpretability of ECochG response changes leads to conflicting study results and prevents the adoption of this method for clinical use. Specifically, the movement of the recording electrode with respect to the different signal generators in intracochlear recordings makes the interpretation of signal changes with respect to cochlear trauma difficult. Here, we demonstrate that comparison of ECochG signals recorded simultaneously from intracochlear locations and from a fixed extracochlear location can potentially allow a differentiation between traumatic and atraumatic signal changes in intracochlear recordings. We meas...
Long-Term Evolution of the Electrical Stimulation Levels for Cochlear Implant Patients
Clinical and Experimental Otorhinolaryngology, 2012
The stimulation levels programmed in cochlear implant systems are affected by an evolution since the first switchon of the processor. This study was designed to evaluate the changes in stimulation levels over time and the relationship between post-implantation physiological changes and with the hearing experience provided by the continuous use of the cochlear implant. Methods. Sixty-two patients, ranging in age from 4 to 68 years at the moment of implantation participated in this study. All subjects were implanted with the 12 channels COMBI 40+ cochlear implant at
Electroencephalography and Clinical Neurophysiology/Evoked Potentials Section, 1996
Recording electrical auditory brainstem responses (EABR) provides clinical insight about responses of the residual post-cochlear neural system to electrical stimulation in profoundly deaf patients. A new strategy is presented for stimulating patients already implanted with a 15-electrode cochlear implant. Since the device is fully re-programmable via a RS-232 PC interface, it was possible to load a specific stimulating strategy designed to improve the spatial locus and the temporal structure of the impulse stimulation. Waves III to V emerge more clearly when this method is applied.
Ear & Hearing, 2017
Objectives: This study examined electrical stimulation levels over 8 to 10 years postimplantation in adult Nucleus implant users. The first aim was to investigate long-term trends and amount of change in electrical stimulation levels for each of four electrode array segments. The second aim was to determine long-term trends and amount of change for particular participants who previously showed greater change (i.e., >20% of dynamic range [DR]) in each of the threshold (T) and comfort (C) levels within the first 3 to 6 months postimplantation. The third aim was to determine whether demographic characteristics were predictive of the long-term trends and amount of change in each of the T and C levels. Design: For 128 adults implanted with Nucleus implants, T levels, C levels, and DR were extracted for the following postimplant time points: 6, 9, 12, 18, 24, 48, 72, 96, and 120 months. For each time point, the mean T levels, C levels, and DR were calculated for each of four electrode ...
PLoS ONE, 2013
Previous animal study revealed that post-implantation electrical detection levels significantly declined within days. The impact of cochlear implant (CI) insertion on human auditory pathway in terms of impedance and electrically evoked compound action potential (ECAP) variation within hours after surgery remains unclear, since at this time frequency mapping can only commence weeks after implantation due to factors associated with wound conditions. The study presented our experiences with regards to initial switch-on within 24 hours, and thus the findings about the milieus inside cochlea within the first few hours after cochlear implantation in terms of impedance/ECAP fluctuations. The charts of fiftyfour subjects with profound hearing impairment were studied. A minimal invasive approach was used for cochlear implantation, characterized by a small skin incision (<2.5 cm) and soft techniques for cochleostomy. Impedance/ECAP was measured intro-operatively and within 24 hours post-operatively. Initial mapping within 24 hours post-operatively was performed in all patients without major complications. Impedance/ECAP became significantly lower measured within 24 hours post-operatively as compared with intra-operatively (p,0.001). There were no differences between pre-operative and post-operative threshold for air-conduction hearing. A significant drop of impedance/ECAP in one day after cochlear implantation was revealed for the first time in human beings. Mechanisms could be related to the restoration of neuronal sensitivity to the electrical stimulation, and/or the interaction between the matrix enveloping the electrodes and the electrical stimulation of the initial switch-on. Less wound pain/swelling and soft techniques both contributed to the success of immediate initial mapping, which implied a stable micro-environment inside the cochlea despite electrodes insertion. Our research invites further studies to correlate initial impedance/ECAP changes with long-term hearing/speech performance.