Apparatus and methods for treating an inter-vertebral disc by ablation, coagulation, shrinking, stiffening, or other treatment of disc tissue. A method of the invention includes positioning at least one active electrode within the inter-vertebral disc, and applying at least a first high frequency voltage between the active electrode(s) and one or more return electrode(s), wherein the volume of the nucleus pulposus is decreased, pressure exerted by the nucleus pulposus on the annulus fibrosus is reduced, and discogenic pain of a patient is alleviated. An apparatus of the invention includes an electrosurgical probe, an introducer needle adapted for passing the distal end of the probe therethrough, and a positioning unit for monitoring a position of the probe in relation to the introducer needle.