You may have considered many kinds of treatments for your chronic pain, including medication, physical therapy, and perhaps surgery. One other option that has gained popularity is transcutaneous electrical nerve stimulation, or TENS.
What is TENS?
A TENS machine is small — about the size of an iPad mini. It’s connected to a series of electrodes, which are put on your skin to deliver a low-voltage electrical charge. The electrical pulses stimulate nerve fibers in the area where you have pain and reduce the pain signals to your brain. The electrical charge may also cause your body to release natural hormones that decrease your pain levels.
You can get TENS treatments from a machine you use at home or from a device at your doctor’s or physical therapist’s office.
How Well Does It Work?
There’s not a lot of good research on TENS, and some of the results are conflicting. But there is evidence that it may work for some people. The amount of pain relief it provides, and for how long, varies from person to person.
Generally, TENS may provide pain relief at first for many people who try it. But after using it for a few months, it appears to become less effective. It’s best to think of TENS as something to try in addition to other methods of managing pain.
What Kind of Pain Can TENS Treat?
It’s not for all types of pain. But it might help with:
Pain after surgery. It’s most effective in treating mild to moderate pain after several types of operations, including heart surgery, chest surgery, hysterectomy and other gynecological surgeries, orthopedic surgery, and abdominal surgery.
Arthritis pain. TENS may ease arthritis pain. The results are mixed on how effective it is for rheumatoid arthritis.
Diabetes nerve damage (diabetic neuropathy). Studies show that TENS can help relieve pain from diabetic nerve damage, most commonly in the hands and feet.
Spinal cord injury pain. At least three studies on TENS and spinal cord injury pain have shown improvements in this kind of pain, which is hard to treat.
It has been a long day. You’re sprawled across the couch watching TV, you turn to get up and — yeow! — a shooting pain stabs through your lower back. What do you do? Fortunately for you, an infomercial comes on the tube marketing a new product that might just help.
You’ve seen him, Dr. Ho, surrounded by a bevy of bikini-clad babes shilling a tiny electrical device promising pain relief. In just 20 minutes, Dr. Ho’s Muscle Massage Therapy, a battery-operated hand-held device weighing in at 100 grams, promises to deliver electrical stimulation through two gel pads to ease those aching muscles.
Before you roll your eyes, guiltily remembering your impulse-purchased, Tony Robbins empowerment tapes stashed in your attic, consider that electrical devices have long been used in rehabilitation therapy.
Most people are familiar with ultrasound, which works by sending sound waves into the muscle to stimulate blood circulation and cellular activity. TENS devices (short for transcutaneous electrical nerve stimulation) are also used, primarily for pain relief: electrodes placed on the skin send low-frequency electrical impulses that interfere with the nerve pathways transmitting the sensation of pain. Other machines are sometimes used to promote muscle strength, emitting a stronger impulse than TENS units and causing the muscle to contract — essentially giving it an electrical workout.
Dr. Michael Ho, a chiropractor by training, is mum about how exactly his machine operates, saying only that it delivers electrical signals in a randomly generated pattern to promote muscle relaxation and pain relief, akin to a massage. Calling it a massage may be a bit of a misnomer because it doesn’t actually feel like one — more like a small jolt of electrical current, painless if the setting is low enough. A muscle will contract, or appear to jump involuntarily, when the device is used on it.
“It produces 12 different types of electrical stimulation, with different frequencies, wave frequencies, intensity, sequencing . . . ,” he says. “You use it to stimulate the nerve and simulate a massage, to reset the tone of the nerve that creates muscle tension. A TENS unit blocks pain, but this causes the muscle and nerve to relax and make the blood flow better.”
The intensity of the stimulation can be adjusted by the wearer and so can the type of massage. Three different programs run through distinct “massage” therapies, including sensations of kneading, rubbing and tapping. Along with your $135, you get the muscle massage therapy device as well as a video that not only tells users where to place the gel pads, but shows Dr. Ho demonstrating a regimen of exercises that pain sufferers should follow to help the healing process.
And while at first glance it seems that the energetic man on TV may be more salesman than credible researcher, it was his experience in the field of rehabilitation that led to his developing the device. Since graduating from Toronto’s Canadian Memorial Chiropractic College in 1987, he went on to found the Toronto Pain and Headache Clinic. It was there that he developed a prototype for use in the clinic.
And initial findings seem to support Dr. Ho’s claim that his product is a valuable new tool in rehabilitation therapy. An independent study performed by Prof. Stuart McGill, who teaches spin biomechanics at the University of Waterloo, confirms that using the device produces a definite physiological reaction in users.
Prof. McGill acknowledges his own skepticism about devices that claim to relieve pain because they often rely on soft scientific analysis. Self-reports about sensory perception cannot be objectively measured — while your migraine might feel like someone is trying to drill a hole through your head, you can’t actually prove it.
What can be measured, however, is the electrical profile of a muscle. Pain signals are sent through the nerves as electrical impulses, so that if a muscle spasm occurs, there is increased electrical activity in that muscle.
Prof. McGill used a technique called electromyography to measure the electrical profile of muscles both before and after use of the device for a 20-minute period. Testing 41 people with neck and shoulder pain, Prof. McGill discovered that use of the device reduced muscle spasms, “in most patients, on average.” And the effect was more pronounced when the spasms were initially stronger.
He also had patients rate their own perceived level of pain before and after the treatment and found that, on average, their pain decreased by 50 per cent.
In spite of his results, Prof. McGill is wary of endorsing the product: “Certainly it isn’t the most conclusive study, but it’s got the ball rolling.”
He’s currently conducting research into the way the device might improve oxygenation of the muscle. Preliminary studies show that Dr. Ho’s machine may reduce pain by increasing the level of oxygenation, possibly as a result of increased blood flow, which in turn could flush out pain-causing buildups of lactic acid.
Another difficulty in determining the device’s usefulness lies with Dr. Ho’s multitherapy approach. The device is supposed to be used in conjunction with his exercise program. So, it is difficult to determine if it’s the exercises or the massage device that is actually effective.
And without any long-term comparative studies, it’s hard to say if Dr. Ho’s device has any advantages over other therapies. A recent report suggested that traditional physical therapy can resolve 90 per cent of acute back-pain cases in one month. Dr. Ho suggests that his device, used with the exercise program, is effective in a similar period. So neither Dr. Ho’s therapy nor traditional therapy seems to have an advantage in reducing recovery periods. The one distinction is that Dr. Ho’s device doesn’t require the intervention of a medical practitioner.
While some people may prefer the home-care aspect of Dr. Ho’s approach, it is this self-diagnosis and self-monitoring that has other medical practitioners concerned.
“There’s no question that these types of devices work to stimulate the muscles,” says Prof. Ethne Nussbaum, an assistant professor in the department of physical therapy at the University of Toronto’s faculty of medicine who specializes in electrotherapy. “But it could be dangerous if there is an underlying condition that the patient is not aware of, or there may be better ways to treat the pain.”
Prof. Nussbaum maintains that electrical therapy is more effective once therapists have made an individualized assessment and started the treatment. She says that the use of electrical devices for pain relief is often relied on only after the physical condition has been resolved but the pain is still present.
However, Dr. Ho’s chief obstacle in gaining credibility in the medical community is that his “eye candy” infomercials are alienating practitioners.
“I’m more interested in evidence-based research on its use as an intervention,” says Prof. Judith Hunter, a physical therapist and researcher at U of T’s department of physical therapy in the faculty of medicine. She’s concerned that the public may be seduced by the television ads without bothering to learn more about the product.
“It’s just another muscle-stimulator. It’s not the only one out there, it just happens to be one that’s being marketed.”
And even Prof. McGill, who has conducted the only independent scientific tests, seems put off by the marketing strategy.
Prof. McGill acknowledges that his study only looked at neck and shoulder pain, with some back pain. However, Dr. Ho, in his advertising campaign, says that his device works on all kinds of pain, and brings immediate relief for all types of ailments, including arthritis, migraines and menstrual pain. The effectiveness of the device for these ailments has not been tested.
Dr. Ho says that he was forced to use TV advertising to demonstrate how the machine actually works because print cannot show the muscles contracting. Word of mouth is too slow to spread the message that his machine actually works, he says. And since pain relief is a serious business — an estimated 17 per cent of Canadians suffer from chronic pain, and lower-back pain affects 60 to 80 per cent of individuals at some point over their lives — Dr. Ho reasoned he had to take advantage of the medium to make his business viable.
Since going on the market four years ago, he has sold more than 250,000 units, with only two complaints lodged at the Better Business Bureau, one of which has been resolved.
While not familiar with Prof. McGill’s study, Prof. Hunter worries that one clinical trial does not constitute a large enough body of evidence to come to any conclusions about a therapy’s effectiveness. She’s not impressed with the stacks of patient testimonials — including those from athletes Gary Sheffield, an outfielder for the L.A. Dodgers, and Olympic hurdler Tony Dees — thanking Dr. Ho for his life-changing invention.
“I’m not surprised that it works for some people, you can always get testimonials for products like these,” says Prof. Hunter. Although skeptical, she does admit that “given that [the device]may have some positive effect, I suppose it’s not a bad thing.”
But Prof. Hunter also notes that a certain number of people getting a placebo, or dummy treatment, in a clinical trial will report that their condition has improved.
“It could be physiological,” she says. “No one is going to question the placebo effect in pain intervention, but until we understand why some placebo effects happen, I’m not convinced.”
