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Oliver F. Adunka - One of the best experts on this subject based on the ideXlab platform.

  • intraoperative Electrocochleography of posterior fossa tumors producing meniere s syndrome
    Otology & Neurotology, 2020
    Co-Authors: Varun V. Varadarajan, Meghan M Hiss, Edward E Dodson, Aaron C Moberly, Oliver F. Adunka, Willian J Riggs, Jameson K Mattingly
    Abstract:

    OBJECTIVES: Intraoperative Electrocochleography (ECochG) has provided insight regarding inner ear pathophysiology during neurotologic procedures. In this study, intraoperative ECochG findings are reported in patients who presented with episodic aural and vestibular symptoms during resection of posterior fossa neoplasms. PATIENTS: Three patients with episodic vertigo who underwent resection of posterior fossa tumors. INTERVENTION: Intraoperative ECochG was performed before and after tumor resection with the active electrode at the round window. Acoustic stimuli consisted of click and tone bursts presented in alternating polarity. MAIN OUTCOME MEASURE: ECochG responses including summation potential (SP), action potential (AP), and SP:AP ratio values to evaluate for endolymphatic hydrops. RESULTS: All subjects presented with asymmetric sensorineural hearing loss (SNHL), episodic vertigo, and tinnitus. Subject 1 was a 63-year-old woman who underwent left translabyrinthine excision of an endolymphatic sac (ELS) tumor and demonstrated no measurable responses until fenestration of the lateral semicircular canal, suggesting severe hydrops relieved by labyrinthotomy. Subject 2 was a 44-year-old woman who underwent right ELS tumor resection and exhibited an elevated SP:AP ratio. Subject 3 was a 55-year-old woman who underwent right retrolabyrinthine resection of a meningioma and exhibited robust responses without hydrops. CONCLUSIONS: Endolymphatic hydrops secondary to mechanical obstruction by a posterior fossa neoplasm may be demonstrated using intraoperative ECochG. Immediate improvement of hydrops may not be demonstrated after tumor resection.

  • Electrocochleography and cochlear implantation a systematic review
    Otology & Neurotology, 2020
    Co-Authors: Eleonora M C Trecca, William J Riggs, Meghan M Hiss, Jameson K Mattingly, Michele Cassano, Oliver F. Adunka
    Abstract:

    Objective Given the heterogeneity of papers about Electrocochleography (ECochG) and cochlear implantation (CI) and the absence of a systematic review in the current literature, the aim of this work was to analyze the uses of ECochG in the different stages of CI. Data sources A search of PubMed from inception to December 8, 2019, with cross-references, was executed. Keywords were: "Cochlear Implant" OR "Cochlear Implantation" AND "Electrocochleography" OR "ECochG." The main eligibility criteria were English-language articles, investigating the use of ECochG in the different phases of CI. Study selection Literature reviews, editorials, case reports, conference papers were excluded, as were papers in which ECochG was just sporadically executed. Data extraction The quality of the included studies was assessed using "The Strengthening the Reporting of Observational Studies in Epidemiology" (STROBE) Statement. Data synthesis A total of 95 articles were identified and 60 papers were included. The included articles covered a timeframe from 2003 to 2019. Of the 60 papers, 46 were human studies, 12 animal studies, and two involved more data sets. Eleven related to the diagnostic phase, 43 described intraoperative monitoring, and 10 were regarding follow-up testing. Hearing preservation was the most discussed topic with 25 included articles. Conclusions and relevance ECochG measurements appeared to be useful in many aspects of CI, such as hearing preservation. Our review is the first that shows the evolution of the technique and how much has been achieved from the earliest experiments to the most recent signal process refinements and device implementation in CI.

  • utilizing Electrocochleography as a microphone for fully implantable cochlear implants
    Scientific Reports, 2020
    Co-Authors: William J Riggs, Meghan M Hiss, Aaron C Moberly, Jameson K Mattingly, Varun V. Varadarajan, Jeffrey Skidmore, Oliver F. Adunka
    Abstract:

    Current cochlear implants (CIs) are semi-implantable devices with an externally worn sound processor that hosts the microphone and sound processor. A fully implantable device, however, would ultimately be desirable as it would be of great benefit to recipients. While some prototypes have been designed and used in a few select cases, one main stumbling block is the sound input. Specifically, subdermal implantable microphone technology has been poised with physiologic issues such as sound distortion and signal attenuation under the skin. Here we propose an alternative method that utilizes a physiologic response composed of an electrical field generated by the sensory cells of the inner ear to serve as a sound source microphone for fully implantable hearing technology such as CIs. Electrophysiological results obtained from 14 participants (adult and pediatric) document the feasibility of capturing speech properties within the Electrocochleography (ECochG) response. Degradation of formant properties of the stimuli /da/ and /ba/ are evaluated across various degrees of hearing loss. Preliminary results suggest proof-of-concept of using the ECochG response as a microphone is feasible to capture vital properties of speech. However, further signal processing refinement is needed in addition to utilization of an intracochlear recording location to likely improve signal fidelity.

  • Enlarged vestibular aqueduct: Intraoperative Electrocochleography findings during cochlear implantation.
    International Journal of Pediatric Otorhinolaryngology, 2020
    Co-Authors: William J Riggs, Meghan M Hiss, Jameson K Mattingly, Varun V. Varadarajan, Oliver F. Adunka
    Abstract:

    Enlarged vestibular aqueduct (EVA) is the most frequent inner ear abnormality found on computed tomography in children with sensorineural hearing loss. The effects EVA abnormalities have on Electrocochleography (ECochG) are unknown. Positive deflections in summation potential evoked by tone bursts were observed in 3/5 subjects, while a large negative deflection, similar to endolymphatic hydrops (EH), was observed for 2/5 subjects. The presence of an enlarged summation potential, with and without a compound action potential, was observed in response to a broadband click stimulus. Results suggest likely effects of a third window on ECochG responses and presence of EH in EVA.

  • intracochlear Electrocochleography response patterns during cochlear implantation and hearing preservation
    Ear and Hearing, 2019
    Co-Authors: Christopher K Giardina, Kevin D. Brown, Oliver F. Adunka, Craig A Buchman, Kendall A Hutson, Harold C Pillsbury, Douglas C Fitzpatrick
    Abstract:

    Objectives Electrocochleography (ECochG) obtained through a cochlear implant (CI) is increasingly being tested as an intraoperative monitor during implantation with the goal of reducing surgical trauma. Reducing trauma should aid in preserving residual hearing and improve speech perception overall. The purpose of this study was to characterize intracochlear ECochG responses throughout insertion in a range of array types and, when applicable, relate these measures to hearing preservation. The ECochG signal in cochlear implant subjects is complex, consisting of hair cell and neural generators with differing distributions depending on the etiology and history of hearing loss. Consequently, a focus was to observe and characterize response changes as an electrode advances. Design In 36 human subjects, responses to 90 dB nHL tone bursts were recorded both at the round window (RW) and then through the apical contact of the CI as the array advanced into the cochlea. The specific setup used a sterile clip in the surgical field, attached to the ground of the implant with a software-controlled short to the apical contact. The end of the clip was then connected to standard audiometric recording equipment. The stimuli were 500 Hz tone bursts at 90 dB nHL. Audiometry for cases with intended hearing preservation (12/36 subjects) was correlated with intraoperative recordings. Results Successful intracochlear recordings were obtained in 28 subjects. For the eight unsuccessful cases, the clip introduced excessive line noise, which saturated the amplifier. Among the successful subjects, the initial intracochlear response was a median 5.8 dB larger than the response at the RW. Throughout insertion, modiolar arrays showed median response drops after stylet removal while in lateral wall arrays the maximal median response magnitude was typically at the deepest insertion depth. Four main patterns of response magnitude were seen: increases > 5 dB (12/28), steady responses within 5 dB (4/28), drops > 5 dB (from the initial response) at shallow insertion depths ( 5 dB occurring at deeper depths (5/28). Hearing preservation, defined as 0.57, maximum of 0.80 for the maximal response). Conclusions Monitoring the cochlea with intracochlear ECochG during cochlear implantation is feasible, and patterns of response vary by device type. Changes in magnitude alone did not account for hearing preservation rates, but considerations of phase, latency, and neural contribution can help to interpret the changes seen and improve sensitivity and specificity. The correlation between the absolute magnitude obtained either before or during insertion of the ECochG and the hearing threshold changes suggest that cochlear health, which varies by subject, plays an important role.

Douglas C Fitzpatrick - One of the best experts on this subject based on the ideXlab platform.

  • Electrocochleography during translabyrinthine approach for vestibular schwannoma removal
    Otology & Neurotology, 2020
    Co-Authors: William J Riggs, Douglas C Fitzpatrick, Meghan M Hiss, Shashank Rajkumar, Kevin Y Zhan, Aaron C Moberly, Jameson K Mattingly, Michael S. Harris, Kevin D. Brown, Edward E Dodson
    Abstract:

    HYPOTHESIS: Intraoperative Electrocochleography (ECochG) can differentiate hair cell and neural dysfunction caused by a vestibular schwannoma (VS) and help define the site of lesion as peripheral or central to the spiral ganglion. BACKGROUND: Hearing loss in patients with a VS can be caused by both sensory (cochlear) and neural dysfunction. METHODS: Round-window ECochG using low and high-frequency tone bursts was performed in 49 subjects with a VS. Responses were analyzed for magnitude, spectrum, and shape of the time waveform. Components examined included the cochlear microphonic, auditory nerve neurophonic, compound action potential (CAP), and summating potential (SP). RESULTS: Variability in the summed response magnitudes across frequency, or "total response" (ECochG-TR), varied from 0.1 to 100 μV. Responses were larger for lower frequencies. Subjective estimates revealed a wide range of neural contributions from the auditory nerve neurophonic to low frequencies and the CAP to high frequencies. Cases with larger CAPs had smaller SPs. The correlation of ECochG-TR, with word recognition score (WRS), was moderate (r = 0.67), as well as the correlation between pure-tone averages and ECochG (r = 0.63). The cochlea remained functional in two cases of sudden sensorineural hearing loss with 0% WRS. CONCLUSION: Reduced ECochG-TR and neural activity in many cases indicates both sensory and neural deficits. Smaller SPs when CAPs are present indicate a neural contribution to the SP. Good cochlear function with 0% WRS, and cases of sudden sensorineural hearing loss with retained cochlear function, indicate retrocochlear effects, typically proximal to the spiral ganglion cells.

  • intracochlear Electrocochleography response patterns during cochlear implantation and hearing preservation
    Ear and Hearing, 2019
    Co-Authors: Christopher K Giardina, Kevin D. Brown, Oliver F. Adunka, Craig A Buchman, Kendall A Hutson, Harold C Pillsbury, Douglas C Fitzpatrick
    Abstract:

    Objectives Electrocochleography (ECochG) obtained through a cochlear implant (CI) is increasingly being tested as an intraoperative monitor during implantation with the goal of reducing surgical trauma. Reducing trauma should aid in preserving residual hearing and improve speech perception overall. The purpose of this study was to characterize intracochlear ECochG responses throughout insertion in a range of array types and, when applicable, relate these measures to hearing preservation. The ECochG signal in cochlear implant subjects is complex, consisting of hair cell and neural generators with differing distributions depending on the etiology and history of hearing loss. Consequently, a focus was to observe and characterize response changes as an electrode advances. Design In 36 human subjects, responses to 90 dB nHL tone bursts were recorded both at the round window (RW) and then through the apical contact of the CI as the array advanced into the cochlea. The specific setup used a sterile clip in the surgical field, attached to the ground of the implant with a software-controlled short to the apical contact. The end of the clip was then connected to standard audiometric recording equipment. The stimuli were 500 Hz tone bursts at 90 dB nHL. Audiometry for cases with intended hearing preservation (12/36 subjects) was correlated with intraoperative recordings. Results Successful intracochlear recordings were obtained in 28 subjects. For the eight unsuccessful cases, the clip introduced excessive line noise, which saturated the amplifier. Among the successful subjects, the initial intracochlear response was a median 5.8 dB larger than the response at the RW. Throughout insertion, modiolar arrays showed median response drops after stylet removal while in lateral wall arrays the maximal median response magnitude was typically at the deepest insertion depth. Four main patterns of response magnitude were seen: increases > 5 dB (12/28), steady responses within 5 dB (4/28), drops > 5 dB (from the initial response) at shallow insertion depths ( 5 dB occurring at deeper depths (5/28). Hearing preservation, defined as 0.57, maximum of 0.80 for the maximal response). Conclusions Monitoring the cochlea with intracochlear ECochG during cochlear implantation is feasible, and patterns of response vary by device type. Changes in magnitude alone did not account for hearing preservation rates, but considerations of phase, latency, and neural contribution can help to interpret the changes seen and improve sensitivity and specificity. The correlation between the absolute magnitude obtained either before or during insertion of the ECochG and the hearing threshold changes suggest that cochlear health, which varies by subject, plays an important role.

  • response changes during insertion of a cochlear implant using extracochlear Electrocochleography
    Ear and Hearing, 2018
    Co-Authors: Christopher K Giardina, Kevin D. Brown, Oliver F. Adunka, Craig A Buchman, Stephen H Pulver, Harold C Pillsbury, Tatyana E Khan, Douglas C Fitzpatrick
    Abstract:

    OBJECTIVES 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. DESIGN 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. RESULTS Before CI insertion, responses to low-frequency tones at the RW were roughly 6 dB larger than when recording at either extracochlear site, but the two extracochlear sites did not differ from one another. During CI insertion, response losses from the promontory or adjacent to the stapes stayed within 5 dB in ≈61% (38/63) of cases, presumably indicating atraumatic insertions. Among responses which dropped more than 5 dB at any time during CI insertion, 12 subjects showed no response recovery, while in 13, the drop was followed by partial or complete response recovery by the end of CI insertion. In cases with recovery, the drop in response occurred relatively early (<15 mm insertion) compared to those where there was no recovery. Changes in response phase during the insertion occurred in some cases; these may indicate a change in the distributions of generators contributing to the response. CONCLUSIONS Monitoring the Electrocochleography during CI insertion from an extracochlear site reveals insertions that are potentially atraumatic, show interaction with cochlear structures followed by response recovery, or show interactions such that response losses persist to the end of recording.

  • clinical role of Electrocochleography in children with auditory neuropathy spectrum disorder
    International Journal of Pediatric Otorhinolaryngology, 2017
    Co-Authors: Tatyana E Fontenot, Kevin D. Brown, Oliver F. Adunka, Craig A Buchman, Christopher K Giardina, Holly F B Teagle, Lisa R Park, Douglas C Fitzpatrick
    Abstract:

    Abstract Objectives To assess Electrocochleography (ECochG) to tones as an instrument to account for CI speech perception outcomes in children with auditory neuropathy spectrum disorder (ANSD). Materials & methods Children ( Results On average, TR was larger in ANSD than in non-ANSD subjects. Most ANSD (73.3%) and non-ANSD (87.8%) subjects achieved open-set speech perception; TR accounted for 33% and 20% of variability in the outcomes, respectively. In the ANSD group, the PTA accounted for 69.3% of the variability, but there was no relationship with outcomes in the non-ANSD group. In both populations, nerve score was sensitive in identifying subjects at risk for not acquiring open-set speech perception, while the CAP and the ANN were more specific. Conclusion In both subject groups, the TRs correlated with outcomes but these measures were notably larger in the ANSD group. There was also strong correlation between PTA and speech perception outcome in ANSD group. In both subject populations, weaker evidence of neural activity was related to failure to achieve open-set speech perception.

  • round window Electrocochleography before and after cochlear implant electrode insertion
    Laryngoscope, 2016
    Co-Authors: Oliver F. Adunka, Craig A Buchman, Eric J Formeister, Christopher K Giardina, Baishakhi Choudhury, Douglas C Fitzpatrick
    Abstract:

    Objective/Hypothesis Previous reports have documented the feasibility of utilizing electrocochleographic (ECoG) responses to acoustic signals to assess trauma caused during cochlear implantation. The hypothesis is that intraoperative round window ECoG before and after electrode insertion will help predict postoperative hearing preservation outcomes in cochlear implant recipients. Study Design Prospective cohort study. Methods Intraoperative round window ECoG responses were collected from 31 cochlear implant recipients (14 children and 17 adults) immediately prior to and just after electrode insertion. Hearing preservation was determined by postoperative changes in behavioral thresholds. Results On average, the postinsertion response was smaller than the preinsertion response by an average of 4 dB across frequencies. However, in some cases (12 of 31) the response increased after insertion. The subsequent hearing loss was greater than the acute loss in the ECoG, averaging 22 dB across the same frequency range (250–1,000 Hz). There was no correlation between the change in the ECoG response and the corresponding change in audiometric threshold. Conclusions Intraoperative ECoG is a sensitive method for detecting electrophysiologic changes during implantation but had limited prognostic value regarding hearing preservation in the current conventional cochlear implant patient population where hearing preservation was not intended. Level of Evidence 2b Laryngoscope, 126:1193–1200, 2016

Stephen Oleary - One of the best experts on this subject based on the ideXlab platform.

  • toward a better understanding of Electrocochleography analysis of real time recordings
    Ear and Hearing, 2020
    Co-Authors: Stefan Weder, Robert Briggs, Christofer Bester, Aaron Collins, Chanan Shaul, Stephen Oleary
    Abstract:

    OBJECTIVES Real-time Electrocochleography (ECochG) has been used as a monitoring tool during cochlear implantation (CI), whereby, amplitude drops have been correlated with postoperative acoustic hearing results. However, no consensus has been reached as to how a single event of an amplitude drop should be characterized. The aim of this study was to identify ECochG events that predict loss of hearing 1 month after surgery. DESIGN Fifty-five patients were included in this prospective cohort study. Real-time ECochG measurements were performed during CI electrode insertion. Single ECochG events were characterized according to their amplitude loss and slope steepness. RESULTS Using receiver operating characteristic analyses, the most efficient cut-off criterion for a relative hearing loss of 25% was an amplitude loss of 61% at a fixed slope steepness of 0.2 µV/sec. Three-quarters of our population had at least one such event during implantation. Most events occurred shortly before full insertion. With increasing number of events, median residual hearing thresholds deteriorated for all frequencies. Larger amplitude drops trended toward worse hearing preservation. Signal recovery after an ECochG event could not be correlated to acoustic hearing outcomes. CONCLUSIONS Our data suggest that amplitude drops exceeding 61% of the ongoing signal at a slope steepness of 0.2 µV/sec are correlated with worse acoustic hearing preservation. Clearly defined ECochG events have the potential to guide surgeons during CI in the future. This is essential if a fully automated data analysis is to be employed or benchmarking undertaken.

  • intraoperative intracochlear Electrocochleography and residual hearing preservation outcomes when using two types of slim electrode arrays in cochlear implantation
    Otology & Neurotology, 2019
    Co-Authors: Angel Ramosmacias, Stephen Oleary, Angel Ramosdemiguel, Christo Bester, Juan C Falcongonzalez
    Abstract:

    Objectives:To report residual hearing preservation outcomes in patients with low frequency hearing, after cochlear implant (CI) electrode insertion with two types of electrode arrays: one straight and other perimodiolar, when using intraoperative intracochlear Electrocochleography (ECochG) during (C

  • intraoperative force and Electrocochleography measurements in an animal model of cochlear implantation
    Hearing Research, 2017
    Co-Authors: Christofer Bester, Aaron Collins, Carrie Newbold, Amy Hampson, Scott Chambers, Hayden Eastwood, Stephen Oleary
    Abstract:

    To preserve residual hearing, techniques for monitoring and reducing the effects of trauma during cochlear implant surgery are being developed. This study examines the relationships between intraoperative recordings (electrode insertion force and Electrocochleography), trauma, and hearing loss after cochlear implantation. The study also evaluated the efficacy of intravenous steroids for reducing hearing loss after implantation. Thirty-two normal-hearing guinea pigs were randomly implanted with electrode arrays of differing stiffness ('hard' or 'soft'). These arrays used an intracochlear electrode to record electrode insertion force and Electrocochleography responses to a multi-frequency acoustic stimulus during implantation. Additionally, sub-cohorts of animals were administered intravenous saline ('control') or dexamethasone ('steroid') prior to surgery. Subsequent hearing loss was assessed using Electrocochleography recordings from the round window membrane prior to surgery and 4 weeks after implantation. After 4 weeks, cochleae were harvested and imaged with thin sheet laser imaging microscopy. After 4 weeks, compound action potential (CAP) thresholds did not differ between steroid and control groups. The CAP amplitude at low-mid frequencies decreased after implantation with a hard electrode, an effect which was partly negated by administering steroids. A decrease in the 'intraoperative' CAP amplitude preceded the reporting of insertion resistance by the surgeon by 5.94 s (±4.03 s SEM). Intraoperative CAP declines were also correlated with higher grades of trauma (r = 0.56, p < 0.01) and greater hearing loss (r = 0.56, p < 0.01). This relationship was not repeated with intraoperative cochlear microphonics. A rise in intraoperative force, which preceded the reporting of resistance by 0.71 s (±0.15 s SEM), was correlated with trauma (r = 0.400, p = 0.04) but not hearing loss (r = 0.297, p = 0.27). Preserving intraoperative CAP amplitudes during implantation was predictive of an atraumatic insertion and reduced post-implantation hearing loss. A rise in force usually preceded the reporting of resistance, although by less than 1 s. These results suggest that intraoperative CAPs may offer a more robust feedback mechanism for improving hearing preservation rates than cochlear microphonic and electrode insertion force recordings, especially considering the rapid changes in insertion force and relatively slow human reaction times. Pre-operative steroids were effective in reversing loss of CAP amplitude with hard electrodes and evoked by lower frequency tones, which suggests a possible role in reducing synaptopathy.

  • characterizing Electrocochleography in cochlear implant recipients with residual low frequency hearing
    Frontiers in Neuroscience, 2017
    Co-Authors: Christopher W Bester, Aaron Collins, Luke Campbell, Adrian Dragovic, Stephen Oleary
    Abstract:

    Objective: Lay the groundwork for using Electrocochleography (ECochG) as a measure of cochlear health, by characterising typical patterns of the ECochG response observed across the electrode array in cochlear implant recipients with residual hearing. Methods: ECochG was measured immediately after electrode insertion in 45 cochlear implant recipients with residual hearing. The Cochlear Response Telemetry system was used to record ECochG across the electrode array, in response to 100- or 110-dB SPL pure tones at 0.5-kHz, presented at 14 per second and with alternating polarities. Hair cell activity, as the cochlear microphonic (CM), was estimated by taking the difference (DIF) of the two polarities. Neural activity, as the auditory nerve neurophonic (ANN), was estimated by taking the sum (SUM) of the two polarities. Prior work in humans and animal studies suggested that the expected ECochG pattern in response to a 0.5-kHz pure tone is an apical-peak in CM amplitude and latency. Results: The most prevalent pattern was a peak in the DIF amplitude near the most apical electrode, with a prolongation of latency towards the electrode tip; this was found in 21 / 39 individuals with successful ECochG recordings. The 21 apical-peak recipients had the best low-frequency hearing. A low amplitude, long-latency DIF response that remained relatively constant across the electrode array was found in 10 / 39 individuals, in a group with the poorest low- and high-frequency hearing. A third, previously undescribed, pattern occurred in 8 / 39 participants, with mid-electrode peaks in DIF amplitude. These recipients had the best high-frequency hearing and a progressive prolongation of DIF latency around the mid-electrode peaks consistent with the presence of discrete populations of hair cells. Conclusions: The presence of distinct patterns of the ECochG response with relationships to pre-operative hearing levels supports the notion that ECochG across the electrode array functions as a measure of cochlear health.

  • cochlear response telemetry intracochlear Electrocochleography via cochlear implant neural response telemetry pilot study results
    Otology & Neurotology, 2015
    Co-Authors: Luke Campbell, Arielle Kaicer, Robert Briggs, Stephen Oleary
    Abstract:

    Aim To record cochlear responses to acoustic stimulation (Electrocochleography) directly from a cochlear implant (CI) in awake recipients with residual hearing, using an adaptation of Neural Response Telemetry (NRT) that achieves a 10-ms recording window. Background Modern cochlear implants contain circuitry for recording neural responses to electrical stimulation, which is known in Cochlear Ltd systems as NRT. We adapted NRT to achieve an extended recording window long enough to record an acoustic electrocochleogram. This paper reports recordings made with this system in recipients with residual hearing. Methods Subjects were adults with CI422 CIs who retained audiometric thresholds between 75 and 90 dB HL at 500 Hz in their implanted ear. The CI was interfaced to a laptop via a Freedom speech processor connected by USB. Calibrated acoustic stimuli (clicks and tone bursts between 500 and 1,500 Hz) were presented via insert tube phones to the implanted ear. Responses were acquired through the adapted NRT system. Recordings were made from apical, mid-array, and basal electrodes. Electrocochleography responses were compared with audiometric thresholds. Results Electrocochleography could be recorded from all five subjects. The compound action potential, cochlear microphonic, and summating potentials were identified. Good quality recordings were most reliably attained from apical electrodes using 40 to 100 repetitions. Audiometric thresholds were similar to compound action potential thresholds. Conclusions Intracochlear responses to acoustic stimulation can be recorded directly from the CI in awake recipients with residual hearing. This may prove useful for monitoring postoperative hearing and for device fitting.

Craig A Buchman - One of the best experts on this subject based on the ideXlab platform.

  • hearing preservation after cochlear reimplantation using Electrocochleography a case report
    Laryngoscope, 2021
    Co-Authors: Amit Walia, Matthew Shew, Amanda J Ortmann, Craig A Buchman, Jacques Herzog
    Abstract:

    Studies have shown that hearing preservation is possible in the context of reimplantation, but residual hearing could not be predicted or expected in these cases. We describe a case in which a patient with mild to profound sensorineural hearing loss who underwent cochlear implantation with a lateral wall array and had hearing preserved postoperatively. She developed facial nerve stimulation which was unresponsive to reprogramming. Using Electrocochleography to measure intracochlear trauma during the insertion process, the patient underwent reimplantation with a perimodiolar electrode and hearing was preserved postoperatively. This case demonstrates the potential to use Electrocochleography for hearing preservation during reimplantation. Laryngoscope, 131:2348-2351, 2021.

  • intracochlear Electrocochleography and speech perception scores in cochlear implant recipients
    Laryngoscope, 2021
    Co-Authors: Carla V Valenzuela, Craig A Buchman, Kanthaiah Koka, Jeffery T. Lichtenhan, Shannon M Lefler, Amanda J Ortmann
    Abstract:

    OBJECTIVES/HYPOTHESIS Previous studies have demonstrated that Electrocochleography (ECochG) measurements made at the round window prior to cochlear implant (CI) electrode insertion can account for 47% of the variability in 6-month speech perception scores. Recent advances have made it possible to use the apical CI electrode to record intracochlear responses to acoustic stimuli. Study objectives were to determine 1) the relationship between intracochlear ECochG response amplitudes and 6-month speech perception scores and 2) to determine the relationship between behavioral auditory thresholds and ECochG threshold estimates. The hypothesis was that intracochlear ECochG response amplitudes made immediately after electrode insertion would be larger than historical controls (at the extracochlear site) and explain more variability in speech perception scores. STUDY DESIGN Prospective case series. METHODS Twenty-two adult CI recipients with varying degrees of low-frequency hearing had intracochlear ECochG measurements made immediately after CI electrode insertion using 110 dB SPL tone bursts. Tone bursts were centered at five octave-spaced frequencies between 125 and 2,000 Hz. RESULTS There was no association between intracochlear ECochG response amplitudes and speech perception scores. But, the data suggest a mild to moderate relationship between preoperative behavioral audiometric testing and intraoperative ECochG threshold estimates. CONCLUSION Performing intracochlear ECochG is highly feasible and results in larger response amplitudes, but performing ECochG before, rather than after, CI insertion may provide a more accurate assessment of a patient's speech perception potential. LEVEL OF EVIDENCE 4 Laryngoscope, 131:E2681-E2688, 2021.

  • intracochlear Electrocochleography response patterns during cochlear implantation and hearing preservation
    Ear and Hearing, 2019
    Co-Authors: Christopher K Giardina, Kevin D. Brown, Oliver F. Adunka, Craig A Buchman, Kendall A Hutson, Harold C Pillsbury, Douglas C Fitzpatrick
    Abstract:

    Objectives Electrocochleography (ECochG) obtained through a cochlear implant (CI) is increasingly being tested as an intraoperative monitor during implantation with the goal of reducing surgical trauma. Reducing trauma should aid in preserving residual hearing and improve speech perception overall. The purpose of this study was to characterize intracochlear ECochG responses throughout insertion in a range of array types and, when applicable, relate these measures to hearing preservation. The ECochG signal in cochlear implant subjects is complex, consisting of hair cell and neural generators with differing distributions depending on the etiology and history of hearing loss. Consequently, a focus was to observe and characterize response changes as an electrode advances. Design In 36 human subjects, responses to 90 dB nHL tone bursts were recorded both at the round window (RW) and then through the apical contact of the CI as the array advanced into the cochlea. The specific setup used a sterile clip in the surgical field, attached to the ground of the implant with a software-controlled short to the apical contact. The end of the clip was then connected to standard audiometric recording equipment. The stimuli were 500 Hz tone bursts at 90 dB nHL. Audiometry for cases with intended hearing preservation (12/36 subjects) was correlated with intraoperative recordings. Results Successful intracochlear recordings were obtained in 28 subjects. For the eight unsuccessful cases, the clip introduced excessive line noise, which saturated the amplifier. Among the successful subjects, the initial intracochlear response was a median 5.8 dB larger than the response at the RW. Throughout insertion, modiolar arrays showed median response drops after stylet removal while in lateral wall arrays the maximal median response magnitude was typically at the deepest insertion depth. Four main patterns of response magnitude were seen: increases > 5 dB (12/28), steady responses within 5 dB (4/28), drops > 5 dB (from the initial response) at shallow insertion depths ( 5 dB occurring at deeper depths (5/28). Hearing preservation, defined as 0.57, maximum of 0.80 for the maximal response). Conclusions Monitoring the cochlea with intracochlear ECochG during cochlear implantation is feasible, and patterns of response vary by device type. Changes in magnitude alone did not account for hearing preservation rates, but considerations of phase, latency, and neural contribution can help to interpret the changes seen and improve sensitivity and specificity. The correlation between the absolute magnitude obtained either before or during insertion of the ECochG and the hearing threshold changes suggest that cochlear health, which varies by subject, plays an important role.

  • response changes during insertion of a cochlear implant using extracochlear Electrocochleography
    Ear and Hearing, 2018
    Co-Authors: Christopher K Giardina, Kevin D. Brown, Oliver F. Adunka, Craig A Buchman, Stephen H Pulver, Harold C Pillsbury, Tatyana E Khan, Douglas C Fitzpatrick
    Abstract:

    OBJECTIVES 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. DESIGN 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. RESULTS Before CI insertion, responses to low-frequency tones at the RW were roughly 6 dB larger than when recording at either extracochlear site, but the two extracochlear sites did not differ from one another. During CI insertion, response losses from the promontory or adjacent to the stapes stayed within 5 dB in ≈61% (38/63) of cases, presumably indicating atraumatic insertions. Among responses which dropped more than 5 dB at any time during CI insertion, 12 subjects showed no response recovery, while in 13, the drop was followed by partial or complete response recovery by the end of CI insertion. In cases with recovery, the drop in response occurred relatively early (<15 mm insertion) compared to those where there was no recovery. Changes in response phase during the insertion occurred in some cases; these may indicate a change in the distributions of generators contributing to the response. CONCLUSIONS Monitoring the Electrocochleography during CI insertion from an extracochlear site reveals insertions that are potentially atraumatic, show interaction with cochlear structures followed by response recovery, or show interactions such that response losses persist to the end of recording.

  • clinical role of Electrocochleography in children with auditory neuropathy spectrum disorder
    International Journal of Pediatric Otorhinolaryngology, 2017
    Co-Authors: Tatyana E Fontenot, Kevin D. Brown, Oliver F. Adunka, Craig A Buchman, Christopher K Giardina, Holly F B Teagle, Lisa R Park, Douglas C Fitzpatrick
    Abstract:

    Abstract Objectives To assess Electrocochleography (ECochG) to tones as an instrument to account for CI speech perception outcomes in children with auditory neuropathy spectrum disorder (ANSD). Materials & methods Children ( Results On average, TR was larger in ANSD than in non-ANSD subjects. Most ANSD (73.3%) and non-ANSD (87.8%) subjects achieved open-set speech perception; TR accounted for 33% and 20% of variability in the outcomes, respectively. In the ANSD group, the PTA accounted for 69.3% of the variability, but there was no relationship with outcomes in the non-ANSD group. In both populations, nerve score was sensitive in identifying subjects at risk for not acquiring open-set speech perception, while the CAP and the ANN were more specific. Conclusion In both subject groups, the TRs correlated with outcomes but these measures were notably larger in the ANSD group. There was also strong correlation between PTA and speech perception outcome in ANSD group. In both subject populations, weaker evidence of neural activity was related to failure to achieve open-set speech perception.

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  • techniques for obtaining high quality recordings in Electrocochleography
    Frontiers in Systems Neuroscience, 2020
    Co-Authors: Michael J Simpson, Skyler G Jennings, Robert H. Margolis
    Abstract:

    There are several technical challenges to obtaining high-quality recordings of cochlear potentials in human Electrocochleography (ECochG). These challenges include electrical artifacts from devices such as acoustic transducers, biological artifacts from excessive myogenic and electroencephalographic potentials, and issues associated with the placement of a tympanic membrane (TM) electrode on the eardrum. This article presents approaches for dealing with these challenges for ECochG measurement using a TM electrode. Emphasis is placed on eliminating stimulus artifact, optimizing the placement of the electrode, and comparing a custom-made electrode with a commercially-available electrode. This comparison revealed that the custom-made electrode results in greater subject comfort, superior ease of placing the electrode on the eardrum, and larger compound action potential (CAP) amplitudes.

  • use of Electrocochleography in the diagnosis of meniere s disease
    Laryngoscope, 1998
    Co-Authors: Samuel C. Levine, Robert H. Margolis, Kathleen Daly
    Abstract:

    Objective: The diagnosis of Meniere's disease has always been a source of confusion. There is no single test that is definitive for the diagnosis. Recent advances have enabled clinicians to noninvasively test the function of the inner ear and its associated neural pathways. The electrocochleogram (ECOG) has been advocated as a reliable test that is diagnostic for Meniere's disease. This study was undertaken to assess the value of ECOG in establishing the diagnosis of Meniere's disease. Study Design: Patients who were suspected of having Meniere's disease were prospectively entered into a study of the diagnostic value of ECOG. Each patient had a complete evaluation including a detailed history, physical examination, laboratory studies, and audiometric tests. Setting: University otolaryngology clinic. Patients: A group of 199 patients who presented to a neurotology clinic and were suspected to have symptoms consistent with Meniere's disease. Intervention: ECOG testing. Main Outcome Measures: Audiometric thresholds, action potential magnitude (AP), summating potential amplitude (SP), AP latency, and clinical evaluations were assessed. Results: The ECOG was found to correlate with historical and audiometric criteria that are used to diagnose the disease. The percentage of abnormal ECOG did not correlate with stage of disease or duration of time that symptoms were present. Conclusions: The ECOG has limited value in the diagnosis of Meniere's disease. It appears to correlate with the length of time patients experience symptoms and their audiometric findings. It was not correlated with the number of symptoms that the patient experienced at the time that the study was conducted.

  • tympanic Electrocochleography for diagnosis of meniere s disease
    Archives of Otolaryngology-head & Neck Surgery, 1995
    Co-Authors: Robert H. Margolis, Eric M Fournier, Deborah Rieks, Samuel E Levine
    Abstract:

    Objective: Tympanic Electrocochleography (ECOG) is a noninvasive technique for recording cochlear potentials with an electrode placed on the tympanic membrane. Electrocochleography is used clinically in the evaluation of patients for endolymphatic hydrops. This study was undertaken to obtain normative data for ECOG responses to clicks and tone bursts and to determine clinical indicators that result in high test specificities. Design: Three cochlear potentials were measured; the eighth nerve compound action potential, the cochlear microphonic, and the summating potential. The subjects were 53 normal hearing adults with negative histories for symptoms of Meniere's disease. The ECOG responses were measured with a silver wire—rayon wick electrode that was placed on the tympanic membrane under direct microscopic visualization. Stimuli were condensation, rarefaction, and alternating polarity clicks and 1- and 2-kHz tone bursts. Results: Measures that appear to be useful in the evaluation of endolymphatic hydrops include the summating potential to action potential ratio, action potential latency difference to condensation and rarefaction clicks, and the tone-burst—evoked summating potential. Relationships among these measures were investigated, and abnormal criteria were determined that result in test specificities of 95%. Conclusions: Meniere's disease is viewed as a progressive disease in which ECOG characteristics vary with the disease state. Cases are presented to illustrate ECOG responses in various stages of the disease. The normative data presented in this article are useful for the detection of Meniere's disease in its early stages. (Arch Otolaryngol Head Neck Surg. 1995;121:44-55)

  • tympanic and transtympanic Electrocochleography in acoustic neuroma and vestibular nerve section surgery
    American Journal of Otology, 1993
    Co-Authors: S M Winzenburg, Robert H. Margolis, Samuel C. Levine, Stephen J Haines, Eric M Fournier
    Abstract:

    : Eighth nerve action potential (AP) amplitudes and latencies and cochlear microphonic (CM) amplitudes were compared using tympanic and transtympanic Electrocochleography (ECOG) in two patient groups. Tympanic ECOG was performed with a wick electrode placed on the tympanic membrane (TM). Transtympanic ECOG was performed with a needle electrode placed on the promontory of the anesthetized patient. Eighteen subjects were tested by tympanic ECOG as part of a preoperative assessment for either acoustic neuroma removal or transection of the vestibular portion of the eighth cranial nerve. Surgery occurred within 1 week of the preoperative evaluation. Intraoperative auditory monitoring was performed using transtympanic ECOG. Baseline recordings were compared to the preoperative tympanic ECOG data. Stimuli were condensation and rarefaction clicks and tone bursts, presented by an insert earphone. As expected, the two methods resulted in essentially identical response latencies and large amplitude differences, although the response amplitudes were extremely variable. The AP amplitude and the CM amplitude did not increase by the same factor with the transtympanic (TT) electrode compared to the tympanic electrode. On comparison of preoperative and intraoperative response amplitudes with regard to stimulus polarity, tympanic Electrocochleography appears to be a useful method of gathering preliminary information on the status of the patient's auditory system. In this study, tympanic ECOG was found to have some predictive value when trying to ascertain the best intraoperative monitoring situation.

  • tympanic Electrocochleography for evaluation of endolymphatic hydrops
    Laryngoscope, 1992
    Co-Authors: Samuel C. Levine, Robert H. Margolis, Eric M Fournier, S M Winzenburg
    Abstract:

    There has been increased interest in Electrocochleography for the diagnosis and intraoperative monitoring of patients with endolymphatic hydrops. Attention has been focused on the determination of the summating potential: action potential (SP:AP) ratio from alternating polarity clicks. Review of this technique at the University of Minnesota led to a reevaluation of the usual interpretation of these recordings. Separate examination of the rarefaction and condensation click recordings provides insight into abnormal response patterns. Cases are presented to illustrate a variety of normal and abnormal patterns including abnormal differences in the latency of condensation and rarefaction-click-generated action potentials, increased summating potential, uncanceled cochlear microphonic, and reduced action potential and summating potential amplitudes. These response categories may be useful in understanding the pathophysiology of Meniere's disease.