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TENS machine ineffective for chronic low back pain?

A new evidence-based review from the American Academy of Neurology concludes that transcutaneous electric nerve stimulation (TENS) is not recommended for use in treating chronic low-back pain but adds that TENS should be considered to treat diabetic neuropathy.

The report, from the academy's Therapeutics and Technology Assessment Subcommittee, was published online December 30, 2009 in the medical journal Neurology and reproduced on Medscape the next day. Authors on the new document are Richard M. Dubinsky, MD, MPH, from Kansas University Medical Center in Kansas City, and Janis Miyasaki, MD, MEd, from Toronto Western Hospital, Ontario, Canada.

In the highest-quality studies of chronic low back pain, there was no benefit of TENS compared to sham or placebo TENS, leading to the inevitable concTENS for back painlusion that it is of no benefit, and make a recommendation that it should not be used for chronic low back pain.

Diabetic neuropathy

However, in diabetic polyneuropathy, some studies showed slight benefit. The recommendation was that it should be considered in the treatment of diabetic polyneuropathy.

Systematic Review

TENS has been used to treat neurologic and other disorders for decades, the authors write. The biologic basis of its analgesic effect is not known, but it is used is based on the gate theory of pain, they note. In this assessment, the authors carried out a systematic literature search of Medline and Cochrane Library up to April 2009, looking for controlled clinical trials in which TENS was used to treat pain associated with neurological conditions.

Acute low back pain not normally seen in neurologic conditions was not considered in this review. All but 1 of the studies excluded patients with known causes of low-back pain, such as pinched nerves, severe scoliosis, severe spondylolisthesis, or obesity.

The studies included showed conflicting results in chronic low back pain. Two class 2 studies showed benefit, but 2 class 1 studies and another class 2 study showed no benefit. Because the Class I studies are stronger evidence, the conclusion was that TENS is in fact ineffective for the treatment of chronic low back pain.

Multiple sclerosis and TENS machine

Two class 2 studies suggested that TENS is probably effective in treating painful diabetic neuropathy.

The only specific neurologic cause of chronic low-back pain in which TENS was studied was multiple sclerosis, for which TENS was not shown to be of benefit.

The document makes 2 main recommendations:

Ø TENS is not recommended for the treatment of chronic low-back pain because of a lack of proven efficacy (level A, 2 class 1 studies).

Ø TENS should be considered for the treatment of painful diabetic neuropathy (level B, 2 class 2 studies).

Absence of Evidence

 Other experts urge some caution in interpreting these results. In an editorial accompanying the new document, Andreas Binder, MD, and Ralf Baron, MD, from the Division of Neurological Pain Research and Therapy in the Department of Neurology at Christian-Albrechts-Universität Kiel, Germany, write that the conclusions of Dr. Dubinsky and Dr. Miyasaki "may heat up the discussion on the usability of TENS and may be viewed as supporting the critics who questioned the value of TENS in pain therapy.

"However," they add, "absence of evidence is not evidence of absence. The clinical impact of meta-analyses is always limited by the quantity and quality of conducted trials."

TENS has had a long-standing role in pain management, is easy to handle, has a favorable benefit-to-risk ratio, and can be discontinued easily if it is not efficacious — all "desirable properties when treating pain," they write. The new document calls for further trials and even provides "clearcut recommendations for their conduction," they note.

"This updated evidence-based review is valuable in providing the limits of our evidence base," Dr. Binder and Dr. Baron conclude. "Nevertheless, it is not unreasonable to take a practical position that, in spite of the relatively weak scientific and clinical evidence, TENS still represents a valuable therapeutic alternative in neurologic pain disorders.

"Taking the favorable benefit-risk ratio when compared with other pain relieving methods into account, TENS remains a valuable part in the armamentarium of pain therapy."