Fig. 1

The left panel (a) depicts a representative ECAP waveform after biphasic stimulation. Note the negative peak N1 and the second positive peak P2, whose amplitude difference define the ECAP amplitude. The right panel (b) shows an ECAP amplitude growth function that normally exhibits a sigmoidal shape. The threshold of the ECAP amplitude growth function (ECAP-T) is normally defined as the crossing of the linear extrapolation in the inflection point of the sigmoid with the baseline. The estimation of the ECAP threshold can also be performed visually (ECAP-VT), being the stimulation level between the stimulation intensities before and when a first visible ECAP can be observed