Cochlear implantation in an animal model documents cochlear damage at the tip of the implant

Andrade, José Santos Cruz de; Baumhoff, Peter; Cruz, Oswaldo Laércio Mendonça; Lenarz, Thomas; Kral, Andrej

doi:10.1016/j.bjorl.2020.07.017

Cited by 6 publications

(7 citation statements)

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“…The correlation between insertion depth and threshold shifts has been reported earlier, for a total of 24 insertions of which the 13 cases studied here were a subset (Andrade et al 2020). Noise exposure with band-restricted noise of either 8 kHz to 12 kHz or 14 kHz to 18 kHz (see Table 1 for details) extended the implantation-induced hearing loss with a significant elevation of thresholds up to 26.9 kHz in all 13 cases.…”

Section: Resultssupporting

confidence: 68%

“…Elevation of CAP thresholds between 5.7 kHz and 9.5 kHz with full insertion of CI shows that deep insertion of CI can affect the hearing. This has been shown in a separate study using the insertion data from cases further analyzed in the present study (Andrade et al 2020). It is interesting that this threshold elevation was not observed along the whole length of the electrode, but was rather limited to frequencies below 11.3 kHz.…”

Section: Physiological Interpretationsupporting

confidence: 75%

“…A separate analysis of four cases in which only five contacts were inserted revealed better hearing protection with near-normal thresholds, comparable to post-insertion IC thresholds reported in Sato et al (2016) using shorter CIs. This demonstrates that implantation up to the point of perceptible resistance, as often is in clinical practice, may lead to cochlear trauma (Andrade et al 2020). The present study additionally introduced hearing impairment by exposure to band-pass noise.…”

Section: Discussionmentioning

confidence: 87%

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Summating Potential as Marker of Intracochlear Position in Bipolar Electrocochleography

et al. 2022

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Objectives: Cochlear implantation criteria include subjects with residual low-frequency hearing. To minimize implantation trauma and to avoid unwanted interactions of electric- and acoustic stimuli, it is often recommended to stop cochlear implantation before the cochlear implant (CI) reaches the cochlear partition with residual hearing, as determined by an audiogram. For this purpose, the implant can be used to record acoustically evoked signals during implantation, including cochlear compound action potentials (CAP), cochlear microphonics (CMs), and summating potentials (SPs). The former two have previously been used to monitor residual hearing in clinical settings. Design: In the present study we investigated the use of intracochlear, bipolar SP recordings to determine the exact cochlear position of the contacts of implanted CIs in guinea pig cochleae (n = 13). Polarity reversals of SPs were used as a functional marker of intracochlear position. Micro computed tomography (µCT) imaging and a modified Greenwood function were used to determine the cochleotopic positions of the contacts in the cochlea. These anatomical reconstructions were used to validate the SP-based position estimates. Results: The precision of the SP-based position estimation was on average within ± 0.37 octaves and was not impaired by moderate hearing loss caused by noise exposure after implantation. It is important to note that acute hearing impairment did not reduce the precision of the method. The cochleotopic position of CI accounted for ~70% of the variability of SP polarity reversals. Outliers in the dataset were associated with lateral CI positions. Last, we propose a simplified method to avoid implantation in functioning parts of the cochlea by approaching a predefined frequency region using bipolar SP recordings through a CI. Conclusions: Bipolar SP recordings provide reliable information on electrode position in the cochlea. The position estimate remains reliable after moderate hearing loss. The technique presented here could be applied during CI surgery to monitor the CI approach to a predefined frequency region.

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Section: Resultssupporting

confidence: 68%

Section: Physiological Interpretationsupporting

confidence: 75%

Section: Discussionmentioning

confidence: 87%

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Summating Potential as Marker of Intracochlear Position in Bipolar Electrocochleography

et al. 2022

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“…In addition, even though small responses were in most cases associated with histological trauma, some cases showed no association with histological trauma, i.e., to osseous spiral lamina (OSL), basilar membrane, spiral ligament (Choudhury et al, 2011(Choudhury et al, , 2014DeMason et al, 2012;Honeder et al, 2016Honeder et al, , 2019. In addition, ECochG responses to low frequencies (associated to the apical cochlear turn) can be affected by basal trauma such as OSL and basilar membrane damage (Choudhury et al, 2011(Choudhury et al, , 2014Smeds et al, 2015), although electrode insertion was not affecting low frequencies in some studies (Robertson and Irvine, 1989;Chambers et al, 2019;Andrade et al, 2022). A recent study in CI recipients showed that insertion of a short electrode array can preserve the ECochG responses to the lower frequencies, indicating that basal trauma is not necessarily affecting apical areas (Dalbert et al, 2021).…”

Section: Introductionmentioning

confidence: 99%

Acute effects of cochleostomy and electrode-array insertion on compound action potentials in normal-hearing guinea pigs

Jwair

Ramekers²,

Thomeer³

et al. 2023

Front. Neurosci.

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IntroductionElectrocochleography (ECochG) is increasingly used in cochlear implant (CI) surgery, in order to monitor the effect of insertion of the electrode array aiming to preserve residual hearing. However, obtained results are often difficult to interpret. Here we aim to relate changes in ECochG responses to acute trauma induced by different stages of cochlear implantation by performing ECochG at multiple time points during the procedure in normal-hearing guinea pigs.Materials and methodsEleven normal-hearing guinea pigs received a gold-ball electrode that was fixed in the round-window niche. ECochG recordings were performed during the four steps of cochlear implantation using the gold-ball electrode: (1) Bullostomy to expose the round window, (2) hand-drilling of 0.5–0.6 mm cochleostomy in the basal turn near the round window, (3) insertion of a short flexible electrode array, and (4) withdrawal of electrode array. Acoustical stimuli were tones varying in frequency (0.25–16 kHz) and sound level. The ECochG signal was primarily analyzed in terms of threshold, amplitude, and latency of the compound action potential (CAP). Midmodiolar sections of the implanted cochleas were analyzed in terms of trauma to hair cells, modiolar wall, osseous spiral lamina (OSL) and lateral wall.ResultsAnimals were assigned to cochlear trauma categories: minimal (n = 3), moderate (n = 5), or severe (n = 3). After cochleostomy and array insertion, CAP threshold shifts increased with trauma severity. At each stage a threshold shift at high frequencies (4–16 kHz) was accompanied with a threshold shift at low frequencies (0.25–2 kHz) that was 10–20 dB smaller. Withdrawal of the array led to a further worsening of responses, which probably indicates that insertion and removal trauma affected the responses rather than the mere presence of the array. In two instances, CAP threshold shifts were considerably larger than threshold shifts of cochlear microphonics, which could be explained by neural damage due to OSL fracture. A change in amplitudes at high sound levels was strongly correlated with threshold shifts, which is relevant for clinical ECochG performed at one sound level.ConclusionBasal trauma caused by cochleostomy and/or array insertion should be minimized in order to preserve the low-frequency residual hearing of CI recipients.

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“…to osseous spiral lamina (OSL), basilar membrane, spiral ligament (Choudhury et al, 2011;DeMason et al, 2012;Choudhury et al 2014;Honeder et al, 2016;Honeder et al, 2019). In addition, ECochG responses to low frequencies (associated to the apical cochlear turn) can be affected by basal trauma such as OSL and basilar membrane damage (Choudhury et al, 2011;Choudhury et al, 2014;Smeds et al, 2015), although electrode insertion was not affecting low frequencies in some studies (Robertson & Irvine 1989;Chambers et al, 2019;Andrade et al, 2020). A recent study in CI recipients showed that insertion of a short electrode array can preserve the ECochG responses to the lower frequencies, indicating that basal trauma is not necessarily affecting apical areas (Dalbert et al, 2021).…”

Section: Introductionmentioning

confidence: 99%

Structure and hearing preservation in cochlear implant surgery

Jwair¹

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Preserving cochlear structures during cochlear implantation is considered one of the most important steps in improving the hearing performance of CI patients. Minimizing trauma to the cochlea, i.e. preserving the residual hearing, allows for better speech perception performance by the added benefits of acoustical stimulation to the electrical hearing with CI, and probably overall better electrical hearing due to deaccelerated degeneration of the auditory nerve. The differences between PM and LW arrays regarding structure preservation are substantial, and should be carefully considered before commencing cochlear implantation, especially in patients with (substantial) residual hearing. STL and TF of the array can cause severe intracochlear trauma by piercing the cochlear partition, and it impacts speech perception and the residual hearing of CI recipients. STL and TF were primarily associated with PM arrays. However, studies with CI recipients had a substantial risk of bias, mainly caused by lack of randomization, and lack of standardization of insertion approaches (i.e. RW and CO). Subsequent research with human cadaveric temporal bones showed that the interaction between array type and surgical approach is an important factor regarding insertion trauma. Research showed that scalar localization of LW arrays on CT scans is difficult to interpret, due to LW arrays translocating not only towards SV but also to SM. Therefore, LW array STL rates are probably underestimated in literature. Additionally, PM arrays have in general more efficient stimulation of the auditory nerve than LW arrays, potentially improving speech perception, and lowering battery consumptions. Currently it is not clear which aspect, the preserved cochlear structure or more efficient auditory nerve stimulation, is more important for CI recipients, and how this relates to the surgical approach. This notion should be tested in the clinical practice, particularly the consequences for preservation of residual hearing and hearing with CI in general including speech perception. Although the osseous spiral lamina and basilar membrane are not visible on CT scans, accurate assessment of scalar position is possible for both type of arrays if using an adaption of curved multiplanar reconstruction method (i.e. uncoiled cochlear duct). Lastly, ECochG during several stages of the cochlear implantation procedure showed that acute basal turn trauma in the form of cochleostomy and subsequent short array insertion can affect the apical region of the cochlea.

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Cochlear implantation in an animal model documents cochlear damage at the tip of the implant

Cited by 6 publications

References 43 publications

Summating Potential as Marker of Intracochlear Position in Bipolar Electrocochleography

Summating Potential as Marker of Intracochlear Position in Bipolar Electrocochleography

Acute effects of cochleostomy and electrode-array insertion on compound action potentials in normal-hearing guinea pigs

Structure and hearing preservation in cochlear implant surgery

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