Apparatus, systems, and methods of controlling energy delivered to electrodes used in electrically and/or thermally induced neuromodulation are provided to improve neuromodulation. In particular, a catheter treatment device having a control algorithm that regulates current or current density delivered to an electrode is provided. The electrode may maintain a known and consistent electrode contact surface area with the vessel. The control algorithm controls energy delivery to provide consistent current or current density to the treatment site, even though the tissue impedance Z may vary from patient to patient and vessel to vessel, and despite changes in impedance of the treatment site during the course of the treatment. The controlled delivery of energy can be used to control and maintain placement of the zone of thermal treatment and reduce undesirable energy delivery to unwanted locations near the treatment site.