Electrical Compound Action Potentials Recorded With Automated Neural Response Telemetry: Threshold Changes as a Function of Time and Electrode Position

Abstract

AutoNRT thresholds demonstrated significant change over time, limiting the ability to use intraoperatively recorded ECAP thresholds to predict postoperative measurements. In this study, electrodes 11 and 16 showed the least amount of change in ECAP threshold over time and therefore would be the best choices for estimating postoperative ECAP thresholds. Although not an ideal solution, mid-array ECAP thresholds obtained intraoperatively may prove to be helpful in creating a first MAP when no other behavioral or electrophysiological data are available.

Safety and Functional Results of Early Cochlear Implant Switch-On in Children

“…In fact, a spontaneous decrease of ECAP thresholds has been reported (18), and when electrode subgroups are considered, the stimulation effect looks similar in the 2 groups independently of switch-on timing. On the one hand, the stimulation effect (difference between mean pre-and post-switch-on autoNRT thresholds) appears more relevant in the early (10.53 T 9.93 CL) than in the control group (5.05 T 7.49 CL), and until 4 months postoperatively, the early connected CIs of our study on average do work with lower ECAP thresholds than the control ones.…”

Measures of the electrically evoked compound action potential threshold and slope in HiRes 90KTMusers

“…Cafarelli Dees et al (2005), however, found steepest slopes in the middle electrodes of the array, data taken from 141 adult users of the Nucleus CI24M CI system, and they also reported thresholds to be lower for the apical electrodes. Spivak et al (2011) reported a small but significant effeet of eleetrode position on eCAP thresholds in 71 users of the Nucleus Freedom device, with the most basal electrode tested showing the highest threshold and the most apieal the lowest. Brown et al (2010) measured thresholds in users of the Nucleus CI24M (straight electrode) and the CI24R (Contour eleetrode) and found slightly lower thresholds at the apieal end of both arrays.…”

“…Changes in eCAP threshold over time have also been reported in the literature, but reports have mainly been of ehanges between intra-operative and post-operative measures. Most studies have reported a reduction in thresholds (Gordon et al, 2004;Spivak et al, 2011), which is believed to be related to development of protein and fibrous tissue layers around the electrodes (Tykoeinski et al, 2005). In the present study we did not focus on this early time period, but found no evidence of any consistent changes over longer time periods.…”

Postimplantation Changes of Electrophysiological Parameters in Patients with Cochlear Implants

“…Yet the electrophysiological parameters of the electrode-nerve interface change substantially in the postoperative period, and this can significantly influence the setting of the T/C levels [Hughes et al, 2001;Pourjavid et al, 2011;Spivak et al, 2011]. This raises questions about the postoperative course of the electrophysiological parameters and whether the measurement of electrophysiological parameters should be repeated at every fitting.…”