Radiofrequency Denervation for Low Back Pain is Safe and Effective in Select Patients
Surgeons commonly use radiofrequency (heat) energy to cut small sensory nerves around the facet (spinal) joints that are causing patients' low back pain. The procedure is called a radiofrequency denervation (RFD). The evidence for RFD as a safe and cost-effective treatment method is a bit sketchy. Some say it works well. Others show little or no benefit over sham (pretend) treatment.
In this Canadian study, carefully selected patients were treated with RFD at the pain generating spinal structure. What does carefully selected mean? And how do they know which joint is causing the pain? Both of these questions can be answered by the process used to choose patients for this treatment intervention.
First, everyone had chronic low back pain that had not responded to other conservative care methods. In fact, they all reported back pain lasting more than two years. The facet joints were identified as the primary cause of back pain by using fluoroscopic-guided nerve blocks. In this procedure, the surgeon uses special imaging (fluoroscopy) that allows him or her to see inside the body.
A local anesthetic (numbing agent) was injected around the nerve of the suspected facet joint. If more than 50 per cent of the patient's pain was relieved, the test was considered positive. A positive test meant that the facet joint tested was causing the low back pain. The diagnostic facet joint block was repeated a second time with the same results before patients were included in this study.
Once the bothersome facet joint was identified, then radiofrequency denervation was carried out. The irritated nerve causing chronic pain signals was burned for 90 seconds at a temperature of 80-degrees Celius (176-degrees Fahrenheit). A special probe was used to burn the nerve in three separate places. The result was to completely denervate (cut) the nerve and interrupt pain messages.
Other studies have been done measuring changes in pain and disability after radiofrequency denervation. This is the first one to look at other measures such as cost-effectiveness, patient satisfaction, employment status, disability, and analgesic intake (use of pain relievers).
Patients were surveyed before to obtain a baseline and then several times after the treatment to assess before and after changes for each of these factors. Commonly used tools such as the Oswestry Disability Questionnaire, visual analogue scale, patient satisfaction survey, and Beck Depression Index were administered.
The authors found that pain intensity was reduced significantly after treatment. The pain relief lasted a full six months but started to come back after that. The use of pain relievers was much less throughout the follow-up period (one full year).
Disability followed the same pattern as pain (decreased at first then slowly increased again). Along the same lines, patients were satisfied with the treatment and treatment results for the first six months. Patients reported being able to work more hours with fewer days absent during the year of the study.
Compared to other studies done in this area, the patients in this study had a much greater reduction in pain intensity. Similar to other studies, the results didn't last. There were no complications, so it seems the procedure is safe and effective for short-term pain relief. But it is not effective for long-term back pain stability.
The patients felt that even short-term pain relief was worth it. They saved money in how much they paid for pain relievers. They missed fewer days of work. The fact that the effects didn't last was disappointing and reflected in less overall satisfaction with the procedure.
The authors make several suggestions based on the results of this study. First, it may be possible to get more people back to work full-time (many returned part-time) if the treatment is followed by a formal occupational/vocational rehabilitation program. Second, patients might benefit from a supervised low back fitness program. Core stabilization, muscle flexibility, and aerobic fitness could be customized for each individual for best results.
And third, another study comparing the results with carefully selected patients should be compared with a control group. There was no control group in this study. The control group would include patients with nerve block diagnosis of facet joint-derived back pain who did not receive the radiofrequency denervation. Such a study might help sort out how much improvement occurs as a result of the natural course of time, how much is really from the nerve degeneration, and how much is a placebo effect (the patient expects to get better and does).
Robert S. Burnham, MSc, MD, FRCPC, et al. A Prospective Outcome Study on the Effects of Facet Joint Radiofrequency Denervation on Pain, Analgesic Intake, Disability, Satisfaction, Cost, and Employment. In Archives of Physical Medicine and Rehabilitation. February 2009. Vol. 90. No. 2. Pp. 201-205.
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