A neurostimulation device has a stimulus, and a position of a measurement electrode relative to the stimulus, configured such that in artefact as arising relative to distance from the stimulus electrode a minima region of the artefact is substantially co-located with the measurement electrode. Or, a ratio of the inter-electrode spacing to the electrode length is between 2 and 3.66. Or, an impedance is connected to a passive electrode and is configured to reduce artefact arising on the measurement electrode.