Physics

Transcutaneous Electrical Nerve Stimulation

A slightly edited excerpt from Are Electromagnetic Fields Making Me Ill? by Brad Roth

A transcutaneous electrical nerve stimulation (TENS) device. The four electrodes
(white) are attached to the skin. (Yeza, CC BY-SA 4.0, https://creativecommons.org/licenses/by-sa/
4.0, via Wikimedia Commons)

Clyde Norman Shealy was only 23 when he graduated from the Duke School of Medicine. During the 1960s, he worked at Western Reserve University (now part of Case Western Reserve) developing methods to control pain. He describes a case study in a preliminary clinical report published in Anesthesia & Analgesia (Volume 46, Pages 489–491, 1967):

“A 70-year-old man was admitted to Lutheran Hospital in early March because of severe diffuse pain in the right lower part of the chest and the upper part of the abdomen…. On March 24, 1967, a thoracic laminectomy [removal of the covering around the spinal cord]… was performed and a Vitallium [an alloy of cobalt, chromium, and molybdenum] electrode measuring 3 by 4 mm. was approximated to the dorsal columns at D3 [one of the vertebrae in your spine]… At 6 p.m. on March 24, [electrical] stimulation was begun with 10 to 50 pulses per second (400-msec. [perhaps they meant μsec.?] pulses, 0.8 to 1.2 volts, and 0.36 to 0.52 ma.). The patient detected a ‘buzzing’ sensation in his back which extended around and throughout his chest but not into his legs. Both incisional and original pain were immediately abolished [my italics].”

Motivated by this success, Shealy continued his research into electrical stimulation. In order to avoid surgically implanting electrodes in the spine, he began to place them on the skin. This work led to what is now known as transcutaneous electrical nerve stimulation, or TENS for short. The Food and Drug Administration has approved TENS devices, and doctors often recommend them to control a variety of disorders, including back pain. You don’t need a prescription, as TENS units are now sold over-the-counter. Typically, users can adjust the stimulus pulse duration, intensity, and frequency to meet their needs.

In 2000, Sarah Milne and her coworkers performed a meta-analysis of randomized, controlled clinical trials for chronic lower back pain. Their study is included in the Cochrane Database of Systematic Reviews. The Cochrane Library is named after Archie Cochrane, a Scottish doctor who advocated for randomized, controlled clinical trials to improve medical care. It collects systematic reviews and meta-analyses about medical research and is an invaluable resource for evidence-based medicine. Milne and her colleagues examined five trials that included a total of 251 patients receiving TENS and 170 patients receiving a sham control. They found no statistically significant differences between the TENS group and the control group. They concluded that “the results of the meta-analysis present no evidence to support the use of TENS in the treatment of chronic low back pain.”

More recently, Lien-Chen Wu and his colleagues at the Taipei Medical University in Taiwan conducted a meta-analysis of a larger group of studies that used TENS to treat chronic back pain (Regional Anesthesia & Pain Medicine, Volume 43, Pages 425–433). They compared 12 randomized, controlled clinical trials that included a total of 700 patients. The controls varied between studies, and included sham treatment, placebos, or treatment with drugs. They concluded that, although TENS might allow the patients to better cope with daily physical activities, it “does not improve symptoms of lower back pain.”

Sometimes a major scientific professional organization will sponsor a review of a medical procedure. The American Academy of Neurology, a society representing over 36,000 neurologists and neuroscientists, conducted an evidence-based review and concluded that “transcutaneous electric nerve stimulation… is not recommended for the treatment of chronic low back pain.”

Several other meta-analyses have been performed, and the consensus is that the clinical studies to date are either inconclusive or mildly negative about the use of TENS. Harriet Hall, a former Air Force medical doctor who now writes about pseudoscience for the website sciencebasedmedicine.org, concluded that “there is some evidence for using TENS for some pain conditions, but that it doesn’t appear to be very effective for anything else” and that “it may be worth trying for patients who are desperate, but they should keep their expectations low.”

Clyde Norman Shealy, the inventor of transcutaneous electrical nerve stimulation, has become an advocate for alternative medicine. In 1978 he founded the American Holistic Medical Association. He is a proponent of “medical intuition,” a form of psychic healing or medical clairvoyance. He also promotes transcutaneous acupuncture, which works by electrical stimulation combined with application of “bliss oils” and makes use of the “five sacred energetic acupuncture rings: air, fire, earth, crystal, and water.” In 2019 Shealy received the Albert Einstein Award of Medicine from the International Association of Who’s Who, for his exemplary achievements within the field of Health Care. The Encyclopedia of American Loons describes him as a “remarkably versatile, prolific and respected crackpot, madman and woo-meister.”