Treating patients with therapeutically effective electroporation requires the use of voltage potentials which when applied to the patient can be painful due to the noxious overstimulation of the afferent pain-receptive nerve fibres. An electrode assembly which includes electrodes for applying effective electroporation voltages, also comprises at least one electrode configured to apply a non-noxious, non-painful electrical stimulation which may be referred to as a "nerve block adjacent to the electroporation site.