The Science of Conventional and Water-Cooled Monopolar Lumbar Radiofrequency Rhizotomy: An Electrical Engineering Point of View

Radiofrequency ablation (RFA) is a safe and effective pain therapy used to create sensorydysfunction in appropriate nerves via thermal damage. While commonly viewed as a simpleprocess, RF heating is actually quite complex from an electrical engineering standpoint,and it is difficult for the non-electrical engineer to achieve a thorough understanding ofthe events that occur. RFA is highly influenced by the configuration and properties of theperi-electrode tissues. To rationally discuss the science of RFA requires that examples beprocedure-specific, and lumbar RFA is the procedure selected for this review. Adequateheating of the lumbar medial branch has many potential failure points, and the underlyingscience is discussed with recommendations to reduce the frequency of failure in heatingtarget tissues. Important technical details of the procedure that are not generally appreciatedare discussed, and the status quo is challenged on several aspects of accepted technique. Therationale underlying electrode placement and the limitations of RF heating are, for the mostpart, commonly misunderstood, and there may even need to be significant changes in howlumbar radiofrequency rhizotomy (RFR) is performed. A new paradigm for heating targettissue may be of value. Foremost in developing best practices for this procedure is avoidingpitfalls. Good RF heating and medial branch lesioning are the rewards for understanding howthe process functions, attention to detail, and meticulous attention to electrode positioning.Key words: Electrical equipment and supplies, zygapophyseal joint, catheter ablation,lumbar vertebrae, low back pain, lumbar vertebrae/innervation, radiofrequency ablation,water-cooled radiofrequency ablation, conventional radiofrequency ablation, radiofrequencyelectrode behavior