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Title: Not Enough Evidence for Pulse Radiofrequency Therapy in Chronic Spine Pain: Presented at AAPM

"Not Enough Evidence for Pulse Radiofrequency Therapy in Chronic Spine Pain: Presented at AAPM"

By Crystal Phend SAN DIEGO, C.A. -- February 28, 2006 -- Although radiofrequency therapy is a very effective tool to control chronic spine pain when done correctly, non-destructive pulsed radiofrequency therapy does not have enough evidence to support its use, according to a presentation here at the American Academy of Pain Medicine's annual meeting (AAPM). "People have this misunderstanding of radiofrequency like it's magic, and it's not," said Way Yin, MD, Medical Director, Interventional Medical Associates, Bellingham, Washington, United States, in his lecture on February 24[^th.

Radiofrequency (RF) therapy uses an electrode to conduct current that destroys tissue with high temperatures or charged particles. In pain management, the goal of RF therapy is to selectively destroy nerve tissue to stop pain signals, Dr. Yin explained. For this to happen, the temperature must be at least 65 degrees Centigrade.

Several randomized placebo controlled trials have demonstrated near total relief of pain is possible with a meticulous approach to electrode placement since nerves cannot be seen using fluoroscopy and the electrodes only create small lesions.

"If we are not right on the nerve structure we want to lesion, we might as well stick it [the electrode] in the bed sheets for all the good it's going to do," Dr. Yin said.

In contrast, the concept of pulse RF is to block pain without creating a tissue lesion. It is a popular procedure because meticulous placement of electrodes is not critical, making it faster and easier than thermal RF therapy.

However, pulse RF is not true radiofrequency therapy because it does not create a lesion and therefore does not destroy or damage nerves, Dr. Yin said.

To destroy soft tissue with radiofrequency, primary or secondary heat must denature protein. Loss of nerve function occurs at 60 to 65 degrees Centigrade, but temperatures must be higher than 65 degrees Centigrade to block transmission of nerve signals entirely.

Pulse RF raises tissue temperatures to about 42 degrees Centigrade, which does not result in sufficient tissue injury, Dr. Yin said.

One study showed similar results with thermal RF and pulsed RF, but both were modest effects and may have been placebo responses, Dr. Yin said. No clinical outcomes have proven the efficacy of pulsed RF over sham, he added, and no long-term prospective studies or randomized, placebo controlled trial data support it.

Misrepresentation of pulsed RF as a nerve destroying procedure will discredit thermal RF and result in insurance companies refusing to pay any RF claims at all, he said.

"Think about RF as nothing more than a tool," Dr. Yin said. Clinicians must understand its limitations, theory, application, and the relevant anatomy involved to use it properly for the benefit of their patients.

Dr. Yin disclosed that he is on the advisory board of ArthroCare.

[Presentation title: Radiofrequency Techniques in Chronic Spine Pain: Efficacy and Controversies. Update session 306]

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