Topical heat may effective for back pain
In our relentless pursuit of new technology and better and ever more effective drug therapies, we can sometimes overlook the fact that some basic truths of healing still apply. One of those truths may be the efficacy of continuous low-level heat therapy for back pain and other musculoskeletal discomfort, says Ron Stout, MD, MPH, medical director, global health care business, for Cincinnati-based Procter & Gamble. Part of the problem, he adds, is that we may have been operating under some erroneous assumptions about how low-level heat can best be used. "As clinicians, we have been trained for years to consider heat as part of our armamentarium for treating low back pain and other musculoskeletal pain, but we have also been trained to use it for no more than 20 minutes at a time," says Stout.
This protocol is not based in science as we know it today, but on the ways research was conducted in the 1950s, he explains. "At that time, the heat source was an infrared heat lamp. If you applied it for more than 20 minutes, you’d develop skin irritation — that is, you’d burn the skin. Today, I’m not aware of any clinicians who use those lamps."
Yet the most common nondrug therapies for back pain continued to be based on that research and with mixed results at best. "Doctors would tell their patients to go home to bed for a week," Stout notes. "During that time, you can lose 7% of your musculature, so this creates a vicious cycle; when you lose muscle, that increases the likelihood you will have back pain again."
Testing Grandma’s theories
Another misconception that grew out of earlier research was that superficial heat does not penetrate deeply, says Stout, but that was never really scientifically investigated until relatively recently. "We as doctors have said that if it feels good, put heat on the area for no more than 20 minutes, three times a day. But Grandma would tell us to go home, go to bed, go to sleep on the heating pad, and we would feel better in the morning — and we did," says Stout. "People would wake up with more relief than they would get from just using heat for 20 minutes at a time. Of course, another concern was that they’d have a higher propensity to get burned if they slept with the heating pad on a higher setting."
This aroused the curiosity of scientists, however. "As researchers, we had to ask, what’s going on? Does topical heat penetrate?" Stout poses. For the past eight years, Procter & Gamble, in partnership with Michigan State University, the University of Michigan, Brigham Young University, and others, conducted a series of studies into the subject. (See "Additional reading" at the end of this article.) "That research showed that low-level, long-term heat does penetrate tissues deeply," Stout observes.
The researchers understood that heat, time and temperature all interact to increase the likelihood of being burned. "We wanted to net out at a place that was efficacious and noninjurious," notes Stout. "We arrived at a product that works for a minimum of eight hours at 104° F." That product is the ThermaCare heat wrap.
"The real neat thing is not that it uses oxidation to create heat — we see that in hand warmers and boot warmers," notes Stout. "But we found a way to control that heat. We stole the micromesh technology from our colleagues in Bounty’ [paper towels] to control the rate at which oxygen gets to the chemical matrix."
In a recent study published in the journal Spine, Stout’s colleagues demonstrated that their heat wrap therapy provided more efficacy that ibuprofen and acetaminophen. Pain relief was greater for the heat wrap, not only on day one, but over a four-day period as well, and no serious adverse events were reported.
The success of long-term use of thermal heat wraps creates the opportunity for a true paradigm shift in the treatment of back and other musculoskeletal pain. "This shift will occur when physicians realize that they really don’t have to dump nonsteroidals [e.g., Motrin, Advil] down patients’ throats," says Stout. "When we give these pills, we recognize more and more that there’s a price to be paid."
There are significant side effects with nonsteroidals, notes Stout, from GI upset to ulcers. "Some people even have an idiosyncratic reaction such as anaphylactic shock," he says. "Nonsteroidals are not a benign therapy. They can also be associated with an increase in hypertension."
Stout is not suggesting that occ-med physicians throw away their pills. "But when we have a choice and efficacy is comparable, we have to get out of the habit of writing a quick scrip and look at exercise modalities and other therapies, instead of just counting on a pill." (For suggested protocols for treating back pain, see the charts below.)
Today, there are several heat wrap products on the market. On what basis should such products be selected? "No. 1, make sure the product has a consistent temperature profile," Stout advises. "We know that temperature, time, and pressure all interact to create the likelihood of getting blisters. One reason we picked 104° as a target is that for the vast majority of consumers it was efficacious and safe." The second piece, says Stout, is how long you can use the therapy. The third involves the area for which it is intended. "If you have sore muscles, can you efficiently and effectively get the heat to them?" asks Stout. The final consideration, he says, should be ease of use.
The ultimate lesson in all of this may be that Grandma knows best. "Grandma knew it, and science now supports it," Stout concludes.
[For more information, contact: Ron Stout, MD, MPH, medical director, global health care business, Procter & Gamble, Cincinnati. Telephone: (513) 622-2788.]
Additional reading
• Akin MD, Weingand KW, Hengehold DA, et al. Continuous low-level heat in the treatment of dysmenorrhea. Obstet Gynecol 2001; 97:343-349.
• Steiner DJ, Erasala GN, Hengehold DA, et al. Continuous low-level topical heat therapy for trapezius myalgia. Proceedings, 19th Annual Scientific Meeting of the American Pain Society, Atlanta; 2000.
• Nadler SF, Feinberg JH, Reisman S, et al. Effect of topical heat on electromyographic power density spectrum in subjects with myofascial pain and normal controls: A pilot study. Am J Phys Med Rehabil 2001; 80(11):809-815.
• Harris H, Stevenson S, Baldwin A, et al. Strength and soreness after eccentric exercise. Med Sci Sports Exercise 1998; 30(5):S102.
• Weingand K, Hengehold D, Knight E, et al. Topical heat provides pain relief of delayed-onset muscle soreness of the distal quadriceps muscle. Med Sci Sports Exercise 1999; 31(5):S75.
• Nadler SF, Steiner DJ, Erasala GN, et al. Continuous, low-level heat wrap therapy provides more efficacy than ibuprofen and acetaminophen for acute low back pain. Spine 2002; 27(10): 1,012-1,017.
In our relentless pursuit of new technology and better and ever more effective drug therapies, we can sometimes overlook the fact that some basic truths of healing still apply. One of those truths may be the efficacy of continuous low-level heat therapy for back pain and other musculoskeletal discomfort.
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