In Reply:—
We thank Dr. Cahana for his comments regarding our editorial on pulsed radiofrequency (PRF) treatment. Certainly, basic scientific experiments may help us to understand the analgesic effects of PRF. The caution is in the interpretation of the experiments; that is, PRF does affect sensory pathways in rats. Fos expression induced by PRF does not demonstrate how or whether this procedure may relieve persistent pain in patients. The study does not yet help us to understand its mechanism or justify its use in patients.
In a recent editorial, Rathmell and Carr discussed the difficulties of applying evidence-based medicine in the pain clinic:
The field of evidence-based medicine endeavors to educate practitioners about how to frame specific questions based on the clinical problems they are faced with every day. The idea is to get the best information available to the practicing clinician. It describes the best available evidence and if there is no good evidence it says so. In pain medicine, we are faced with an expanding array of treatment options that strike us as logical developments that should provide pain relief for our patients. However, there is a dearth of clinical evidence to guide rational choice and application of the majority of emerging treatments [such as pulsed radiofrequency]. The evidence-based medicine movement gives little guidance to practitioners whose tools are still under development. They simply remind us that no evidence regarding many of our techniques exists.
Despite Dr. Cahana's blanket condemnation that the knowledge provided through evidence-based medicine is fallible, we are entrenched in the scientific method and will not be fooled by lack of evidence.
The conceptual appeal of a minimally invasive, nondestructive technique such as PRF that can successfully treat any type of chronic pain is compelling. We hope that PRF will be shown to help patients with persistent pain problems through randomized controlled trials. However, there have been many procedures in medicine that were accepted as helping patients that we no longer perform because placebo-controlled, randomized, controlled trials demonstrated that there was no benefit. Certainly, ligating the internal mammary artery looked as though it relieved angina,3,,4 and arthroscopy for degenerative arthritis of the knee seemed to decrease knee pain. We no longer perform the procedures because placebo-controlled, randomized, controlled trials demonstrated no difference than a sham (incomplete) operation.6,,7, 8 Despite the wealth of anecdotal and uncontrolled evidence available that suggests that PRF is a useful treatment modality, it is up to our specialty and others using the treatment to assume that the procedure may not be truly effective (e.g. , perhaps a placebo effect) and to demonstrate using placebo-controlled, randomized, controlled trials that it is beneficial. If it works, its mechanisms should continue to be explored using basic science pain models. Our editorial was written in an effort to help readers understand the state of our knowledge regarding PRF, to suggest that the basic science findings to date in no way support or refute the link between PRF treatment and reduction in pain, and to urge clinical researchers to move on to much-needed controlled trials. Our editorial should not be taken as a blanket condemnation of this technique or the significant efforts of clinical investigators to date to describe their experience with PRF.
For the letters from Drs. Cosman and Sluijter, we are grateful. We thank them for clarifying the history of development of the technique of pulsed radiofrequency, and we apologize for omitting the details they have provided. One of us (J. P. R.) had extensive conversations with Mr. Rittman by telephone and via e-mail over a period of several months. I knew I was talking directly to one of the principals involved in developing PRF, and on this fact, all seem to agree. I assumed that all of the patent holders would tell a similar history, and it seems that they do. In closely reading the additional details provided by both Drs. Cosman and Sluijter, it seems I was lacking in detail, but I made no factual errors in my recounting of the history. It was my attempt at brevity that led to the statement “Mr. Rittman returned to the bench and quickly devised a means …”; this was not meant to imply that Mr. Rittman acted alone without many others involved nor that this process did not evolve over time, and Drs. Cosman and Sluijter have filled in these details and given credit to some of the others involved. As to the strong magnetic field versus the electrical field being responsible for the biologic effects of PRF, their comments clarify how the original concept was modified based on experimental observation. In the end, my brief account of correspondence with Mr. Rittman and the additional details provided by Drs. Sluijter and Cosman form a seldom-told story about how these innovators were involved in the origins of pulsed radiofrequency treatment that will be of interest to all who are familiar with the technique and historical value as this technique emerges.
*The University of Iowa, Iowa City, Iowa. tim-brennan@uiowa.edu
