RFA Using Multi-Tined Electrodes vs.Traditional Electrodes for Lumbar Spondylosis

Overview

Spondylosis is an anatomical defect of the small facet joints between the spinal vertebrae often due to load bearing and mechanical wear. It is a major contributor to lower back pain. The current standard of care in patients diagnosed with spondylosis in the lower back is to perform a radiofrequency ablation (RFA) of the lumbar medial branch nerves which carry the pain signals from that region to the brain. RFA accomplishes this by using radio waves transmitted through inserted electrodes. This leads to a temporary lesion or "burn"; stopping the pain signals from being transmitted as as well as changing the pain signals themselves. The electrodes themselves do not heat up but instead cause ions in the surrounding tissue to vibrate and heat up. When performing the procedure at the UAMS pain clinic, one can use the Stryker system with a single electrode end which protrudes out of the cannula or the Stratus Nimbus electrode with two prongs which expand in a "V"; formation along the sides of the cannula. While testing in chicken tissue shows that the latter electrode type produces a larger lesion size, anecdotal evidence suggests that it may lead to longer term pain relief. As such, the choice is currently left up to physician preference as both are FDA approved for use in this condition. This study is trying to assess if the larger lesion size results in a reduction in impairment of activities of daily living due to pain measured by the patient-reported PROMIS (Patient Reported Measurement Information System)-29 questionnaire. The PROMIS-29 is given to all patients who are seen in the UAMS Pain Clinic at initial and follow-up visits. In this study we would like to randomize what electrode and cannula set is used in RFA for patient's who are already going to be receiving the procedure for treatment for their spondylosis. The study team would then compare the PROMIS outcomes between cases that used the Stryker and Stratus Nimbus electrodes at 1,3,6,9 and 12 months. It is hypothesized that the Nimbus electrode will result in a greater reduction and improvement in PROMIS scores for a longer duration than the Stryker electrode.

This study is a single center double-blinded prospective randomized clinical trial. Patients will be recruited from the pool of patients seen by the Principal Investigators (PIs) and collaborating physicians in the UAMS pain management clinic through the Department of Anesthesiology. Candidacy for RFA is determined by the standard of care which includes diagnosis of axial low back pain without lower extremity radiation or other primary pain generators. These patients should not have had previous RFA's in the lumbar region before. These patients should receive greater than 80% pain relief following two diagnostic MBBs completed at separate times. In routine care, physicians discuss with patients the risks and benefits associated with the RFA procedure. In order to establish a baseline level of pain, disability, and impairment of daily living, patients are routinely asked to complete the PROMIS-29 questionnaire to the best of their ability. Once patients receive their second MBB they are to return 2 to 4 weeks later for RFA should they meet the necessary 80% pain relief. At the time of the procedure, a simple randomization performed by a staff member not involved in the patient's care, will be used to determine if the patient's procedure will involve the use of the Stratus Nimbus or the Stryker Venom electrode and cannula set. The provider performing the procedure will be made aware of which electrode is to be used. However, patients will be blinded to the group to which they were randomized. Patients will continue with conventional RFA as per standard of care. Patients will then be contacted at 1,3,6, 9, and 12 months for assessment of response to intervention including the PROMIS-29 questionnaire. Scores are then compared to those taken at baseline to determine efficacy of treatment and inform future care.