A
neurostimulation device is disclosed, comprising: at least a lead comprising a plurality of electrodes for delivering stimulation pulses to nerves of a patient; a
driver circuit configured to generate stimulation pulses and apply them to the electrodes, wherein the nerves have a stimulation
threshold voltage which needs to be exceeded to stimulate the nerves; a sensing circuit connected to the electrodes and configured to sense a
signal that occurs responsive to a stimulation pulse, the sensed
signal having an
evoked compound action potential, ECAP, component, which is generated by the nerves responsive to a supra- threshold stimulation pulse, and an artifact component, which is caused by charging of the electrodes by a stimulation pulse regardless of whether the stimulation pulse is above or below threshold; a controller having a calibration mode in which the controller controls the
driver circuit to apply sub-threshold stimulation pulses such that no ECAP component is generated so the sensed
signal is dominated by the artifact component and a neurostimulating mode in which the controller controls the
driver circuit to apply supra-threshold stimulation pulses so that the sensed signal includes an ECAP component; and a
signal processing circuit operable to subtract, from the sensed signal collected in the neurostimulating mode, a scaled-up version of the sensed signal collected during the calibration mode, thereby to output a processed sensed signal with an enhanced ECAP component. The scaled-up version of the calibration mode sensed signal is at least in part obtained by amplifying the calibration mode sensed signal by a factor equal to the ratio of supra-threshold stimulation
pulse current applied in the neurostimulating mode divided by the sub-threshold stimulation
pulse current applied in the calibration mode.