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Site of cochlear stimulation and its effect on electrically evoked compound action potentials using the MED-EL standard electrode array.

Brill S, Müller J, Hagen R, Möltner A, Brockmeier SJ, Stark T, Helbig S, Maurer J, Zahnert T, Zierhofer C, Nopp P, Anderson I, Strahl S - Biomed Eng Online (2009)

Bottom Line: Specifically, significant higher ECAP amplitude, lower thresholds and steeper amplitude growth function slopes have been observed in the apical region.These differences could be explained by the location of the stimulating electrode with respect to the neural tissue in the cochlea, a higher density, or an increased neural survival rate of neural tissue in the apex.The Clinical Investigation has the Competent Authority registration number DE/CA126/AP4/3332/18/05.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Otorhinolaryngology, Plastic, Aesthetic and Reconstructive Head and Neck Surgery, University of Wuerzburg, Würzburg, Germany. brill_s@klinik.uni-wuerzburg.de

ABSTRACT

Background: The standard electrode array for the MED-EL MAESTRO cochlear implant system is 31 mm in length which allows an insertion angle of approximately 720 degrees . When fully inserted, this long electrode array is capable of stimulating the most apical region of the cochlea. No investigation has explored Electrically Evoked Compound Action Potential (ECAP) recordings in this region with a large number of subjects using a commercially available cochlear implant system. The aim of this study is to determine if certain properties of ECAP recordings vary, depending on the stimulation site in the cochlea.

Methods: Recordings of auditory nerve responses were conducted in 67 subjects to demonstrate the feasibility of ECAP recordings using the Auditory Nerve Response Telemetry (ART) feature of the MED-EL MAESTRO system software. These recordings were then analyzed based on the site of cochlear stimulation defined as basal, middle and apical to determine if the amplitude, threshold and slope of the amplitude growth function and the refractory time differs depending on the region of stimulation.

Results: Findings show significant differences in the ECAP recordings depending on the stimulation site. Comparing the apical with the basal region, on average higher amplitudes, lower thresholds and steeper slopes of the amplitude growth function have been observed. The refractory time shows an overall dependence on cochlear region; however post-hoc tests showed no significant effect between individual regions.

Conclusions: Obtaining ECAP recordings is also possible in the most apical region of the cochlea. However, differences can be observed depending on the region of the cochlea stimulated. Specifically, significant higher ECAP amplitude, lower thresholds and steeper amplitude growth function slopes have been observed in the apical region. These differences could be explained by the location of the stimulating electrode with respect to the neural tissue in the cochlea, a higher density, or an increased neural survival rate of neural tissue in the apex.

Trial registration: The Clinical Investigation has the Competent Authority registration number DE/CA126/AP4/3332/18/05.

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Related in: MedlinePlus

ECAP amplitudes for the different regions of the cochlea. ECAP amplitudes measured are shown for the different regions. There are significant differences between the basal and apical regions (p < 0.001) as well as the middle and apical regions (p = 0.003).
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Figure 3: ECAP amplitudes for the different regions of the cochlea. ECAP amplitudes measured are shown for the different regions. There are significant differences between the basal and apical regions (p < 0.001) as well as the middle and apical regions (p = 0.003).

Mentions: In Figure 3 ECAP amplitudes measured with an amplitude growth sequence are shown for the different cochlear stimulation sites. The mean ECAP amplitude was the lowest for the basal region (220.8 ± 114.4 μV); compared to 257.9 ± 129.7 μV for the middle and 341.3 ± 200.5 μV for the apical region. Mauchly's sphericity test, which was always performed with a Bonferroni corrected significance level of α = 0.05/3, showed that the assumption of sphericity is violated. Therefore, a Greenhouse-Geisser correction of ε = 0.748 was applied to the ANOVA resulting in p < 0.001 and F = 10.994. These results show that there is a significant effect of the stimulation region on the ECAP amplitude. Paired t-tests revealed that significant differences on ECAP amplitude exist between the basal and apical regions (p < 0.001) as well as the middle and apical regions (p = 0.004), though between the basal and middle regions no significant effect was found (p = 0.05).


Site of cochlear stimulation and its effect on electrically evoked compound action potentials using the MED-EL standard electrode array.

Brill S, Müller J, Hagen R, Möltner A, Brockmeier SJ, Stark T, Helbig S, Maurer J, Zahnert T, Zierhofer C, Nopp P, Anderson I, Strahl S - Biomed Eng Online (2009)

ECAP amplitudes for the different regions of the cochlea. ECAP amplitudes measured are shown for the different regions. There are significant differences between the basal and apical regions (p < 0.001) as well as the middle and apical regions (p = 0.003).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2803480&req=5

Figure 3: ECAP amplitudes for the different regions of the cochlea. ECAP amplitudes measured are shown for the different regions. There are significant differences between the basal and apical regions (p < 0.001) as well as the middle and apical regions (p = 0.003).
Mentions: In Figure 3 ECAP amplitudes measured with an amplitude growth sequence are shown for the different cochlear stimulation sites. The mean ECAP amplitude was the lowest for the basal region (220.8 ± 114.4 μV); compared to 257.9 ± 129.7 μV for the middle and 341.3 ± 200.5 μV for the apical region. Mauchly's sphericity test, which was always performed with a Bonferroni corrected significance level of α = 0.05/3, showed that the assumption of sphericity is violated. Therefore, a Greenhouse-Geisser correction of ε = 0.748 was applied to the ANOVA resulting in p < 0.001 and F = 10.994. These results show that there is a significant effect of the stimulation region on the ECAP amplitude. Paired t-tests revealed that significant differences on ECAP amplitude exist between the basal and apical regions (p < 0.001) as well as the middle and apical regions (p = 0.004), though between the basal and middle regions no significant effect was found (p = 0.05).

Bottom Line: Specifically, significant higher ECAP amplitude, lower thresholds and steeper amplitude growth function slopes have been observed in the apical region.These differences could be explained by the location of the stimulating electrode with respect to the neural tissue in the cochlea, a higher density, or an increased neural survival rate of neural tissue in the apex.The Clinical Investigation has the Competent Authority registration number DE/CA126/AP4/3332/18/05.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Otorhinolaryngology, Plastic, Aesthetic and Reconstructive Head and Neck Surgery, University of Wuerzburg, Würzburg, Germany. brill_s@klinik.uni-wuerzburg.de

ABSTRACT

Background: The standard electrode array for the MED-EL MAESTRO cochlear implant system is 31 mm in length which allows an insertion angle of approximately 720 degrees . When fully inserted, this long electrode array is capable of stimulating the most apical region of the cochlea. No investigation has explored Electrically Evoked Compound Action Potential (ECAP) recordings in this region with a large number of subjects using a commercially available cochlear implant system. The aim of this study is to determine if certain properties of ECAP recordings vary, depending on the stimulation site in the cochlea.

Methods: Recordings of auditory nerve responses were conducted in 67 subjects to demonstrate the feasibility of ECAP recordings using the Auditory Nerve Response Telemetry (ART) feature of the MED-EL MAESTRO system software. These recordings were then analyzed based on the site of cochlear stimulation defined as basal, middle and apical to determine if the amplitude, threshold and slope of the amplitude growth function and the refractory time differs depending on the region of stimulation.

Results: Findings show significant differences in the ECAP recordings depending on the stimulation site. Comparing the apical with the basal region, on average higher amplitudes, lower thresholds and steeper slopes of the amplitude growth function have been observed. The refractory time shows an overall dependence on cochlear region; however post-hoc tests showed no significant effect between individual regions.

Conclusions: Obtaining ECAP recordings is also possible in the most apical region of the cochlea. However, differences can be observed depending on the region of the cochlea stimulated. Specifically, significant higher ECAP amplitude, lower thresholds and steeper amplitude growth function slopes have been observed in the apical region. These differences could be explained by the location of the stimulating electrode with respect to the neural tissue in the cochlea, a higher density, or an increased neural survival rate of neural tissue in the apex.

Trial registration: The Clinical Investigation has the Competent Authority registration number DE/CA126/AP4/3332/18/05.

Show MeSH
Related in: MedlinePlus