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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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ECAP amplitude in relative refractory state for the different regions. The ECAP amplitude in relative refractory state shown for the different regions. There is a significant difference between the basal and apical region (p = 0.008).
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Figure 6: ECAP amplitude in relative refractory state for the different regions. The ECAP amplitude in relative refractory state shown for the different regions. There is a significant difference between the basal and apical region (p = 0.008).

Mentions: The results shown in Figure 6 represent the ECAP amplitude at the recovery inter-pulse interval (rIPI) as defined in Figure 1. The ECAP amplitudes presented here thus represent ECAP amplitudes in relative refractory state. They were derived using a recovery sequence for 16 experienced subjects where ECAP recovery sequences were available for all 3 regions. The mean ECAP amplitude in the basal region was 163.3 ± 87.7 μV, 192.8 ± 70.2 μV in the middle region and 223.4 ± 104.2 μV in the apical region. Mauchly's sphericity test showed that the assumption of sphericity is tenable. The ANOVA yielded p = 0.045 and F = 3.460, indicating a significant effect of stimulation region on ECAP amplitude in relative refractory state. Post-hoc tests revealed a significant effect between the basal and apical regions (p = 0.008). No significant effect was found between the middle and apical regions (p = 0.277) as well as the basal and middle regions (p = 0.178).


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 amplitude in relative refractory state for the different regions. The ECAP amplitude in relative refractory state shown for the different regions. There is a significant difference between the basal and apical region (p = 0.008).
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 6: ECAP amplitude in relative refractory state for the different regions. The ECAP amplitude in relative refractory state shown for the different regions. There is a significant difference between the basal and apical region (p = 0.008).
Mentions: The results shown in Figure 6 represent the ECAP amplitude at the recovery inter-pulse interval (rIPI) as defined in Figure 1. The ECAP amplitudes presented here thus represent ECAP amplitudes in relative refractory state. They were derived using a recovery sequence for 16 experienced subjects where ECAP recovery sequences were available for all 3 regions. The mean ECAP amplitude in the basal region was 163.3 ± 87.7 μV, 192.8 ± 70.2 μV in the middle region and 223.4 ± 104.2 μV in the apical region. Mauchly's sphericity test showed that the assumption of sphericity is tenable. The ANOVA yielded p = 0.045 and F = 3.460, indicating a significant effect of stimulation region on ECAP amplitude in relative refractory state. Post-hoc tests revealed a significant effect between the basal and apical regions (p = 0.008). No significant effect was found between the middle and apical regions (p = 0.277) as well as the basal and middle regions (p = 0.178).

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