Tuesday, March 23, 2010

Do Biomagnetic Therapies Provide Pain Relief?

Editor’s NotebookBiomagnetic therapies date back centuries and have been applied in different forms to treat a variety of ailments. There are still questions about whether they heal or stop the progression of painful disorders, or merely provide temporary analgesic effects in some but not all cases.

Magnetic fields are fundamental components of our environment on Earth and interest in the potential therapeutic benefits of magnetism dates back centuries. For example, the famous 2nd Century A.D. physician, Galen of Pergamum, allegedly used natural magnets to help relieve pain in treating many illnesses. Modern medicine uses technologies to monitor magnetic fields, such as in electrocardiograms and magnetic resonance imaging. Increasing evidence is accumulating regarding biomagnetic therapies and increasing numbers of people are sleeping on magnetic pads at night and wearing small magnets during the day to achieve a various health benefits. Yet, this is not a widely accepted part of mainstream medicine in America.

Most research investigations into biomagnetic therapies have focused on two distinct areas: fixed or static magnets and, increasingly, pulsed bioelectric magnetic fields. As a complementary or alternative medicine (CAM) approach, biomagnetic therapies are noninvasive and mimic forces found in nature, so they also have been largely devoid of any adverse effects. This is currently an expansive and expanding field of exploration; somewhat controversial and oftentimes confusing. Much of the clinical research today is focusing on magnetic-pulse therapies, and two recent reports exemplify these initiatives.

PEMF Therapy for Painful Osteoarthritis
At the Orthopaedic Research Society's annual meeting in New Orleans, March 2010, researchers described a study demonstrating the benefits of pulsed electromagnetic fields (PEMF) for relieving arthritis pain. Investigators from the Osteoarthritis Center at Henry Ford Hospital, Detroit, presented a double-blind, randomized, placebo-controlled trial in which 34 patients used a portable battery-operated device emitting a low-intensity PEMF frequency [Nelson et al. 2010]. They reported that subjects receiving active PEMF therapy experienced more than 40% pain relief on their first day of treatment and this continued during the study (further data were unavailable at the time of this writing).

PEMF DeviceAll patients attached a small, lightweight, ring-shaped plastic device around their knees (directly over clothing, if preferred) for 15 minutes, twice daily for 6 weeks. The electromagnetic field depth extended across the knee and 5” on either side [see illustration]. All participants were given a device that appeared to work but some were randomly assigned active coils and others were given non-active coils (placebo group). The PEMF device was developed by Ivivi Health Sciences, which also funded the study.

Some research has demonstrated that targeted PEMF signals accelerate anti-inflammatory processes, and significant improvements in pain, edema, angiogenesis (blood vessel development), and tissue repair have been demonstrated in animal models. Human research has found significant reductions in pain, decreased use of pain medication, and the reduction of IL-1-beta (an objective marker of inflammation). Lead investigator Fred Nelson, MD, commented, "The exciting thing about this new approach is that it has been found to have no side effects, it is relatively low-cost in the long-run, and the onset of pain relief is immediate." His team plans to continue examining the consistency of the pain relief, how long it lasts, and if PEMF might benefit other painful joints.

sTMS Promising for Migraine Relief
In another recent study, which appeared in The Lancet Neurology, single pulse transcranial magnetic stimulation (sTMS) was found to help relieve pain in persons suffering migraine with aura [Lipton et al. 2010]. This was a well-designed randomized, double-blinded, parallel-group, sham-controlled trial conducted at 18 centers in the United States. The subjects, 201 adults aged 18 to 68 years having migraine with aura were randomly allocated to either sham (placebo) stimulation (n=99) or sTMS (n=102) and instructed to treat up to 3 attacks during a 3 month period while experiencing aura.

sTMS DeviceDuring the study, 164 patients treated at least one attack with sTMS (n=82) or sham stimulation (n=82). Pain-free response rates after 2 hours were significantly higher with sTMS (39%) than with sham stimulation (22%), for a therapeutic gain of 17% (95% CI 3-31%; p=0.018). Sustained pain-free response rates significantly favored sTMS at 24 hr. and 48 hr. post-treatment. No device-related serious adverse events were reported, and the incidence and severity of side effects were similar between sTMS and sham groups, including nausea, photophobia (light sensitivity), and phonophobia (sound sensitivity).

Some experts describe a migraine headache as an “electrical storm” in which the brain becomes hyperexcitable and has an abnormal response to normal stimuli or triggers. The investigational device used in this study — manufactured by Neuralieve, which also funded the research — is placed at the back of the head for less than a minute [see illustration], generating a focused, single magnetic pulse that induces a mild electric current in the brain. It is believed that this sort of targeted signal may depolarize — or short circuit — the hyperexcitability and interrupt progression of abnormal brainwaves associated with a migraine attack.

COMMENTS & CAVEATS: Interesting Possibilities
PEMF (pulsed electromagnetic field) therapy has been FDA-cleared to treat postoperative pain and edema, and both Medicare and Medicaid approve the use of these therapies for treating patients with chronic unhealing wounds, particularly to stimulate bone repair. Practitioners also have reported the use of this technology to treat sprains, neck pain, fibromyalgia, and other conditions. Few details were available regarding PEMF used for osteoarthritis in the small study by Nelson and colleagues [2010] and, while other studies have corroborated the benefits of PEMF for arthritis [refs. in EBSCO 2010], one systematic review of available evidence at the time concluded that there was little value of this approach in the management of knee osteoarthritis [McCarthy et al. 2006]. At least one very interesting and successful trial applied transcranial PEMF therapy (using a headset device) for the relief of chronic musculoskeletal pain, including fibromyalgia [Thomas et al. 2007].

In the various investigations of PEMF there appear to be wide variations in the applied electromagnetic field strengths, frequencies, waveforms, and durations of therapy, which strongly influence outcomes and make head-to-head comparisons of studies difficult. Unlike certain other “electrotherapies” — eg, spinal cord stimulation (SCS), deep brain stimulation (DBS), peripheral nerve stimulation (PNS), and others — there is no invasive implantation of electrodes. Consequently, various devices are marketed directly to consumers, ranging in cost from a couple hundred to many thousands of dollars. Some devices offer very high intensities for brief microseconds while others have weak intensities during continuous pulses, there are differences in waveforms utilized, and some use paddles, or mats, or conducting loop configurations. Therefore, this is a CAM modality that may be fraught with confusion and misgivings among patients who are misled by promotional advertising.

Transcranial magnetic stimulation (TMS) uses either single or repetitive applications of low frequency magnetic pulses to the brain. Two decades of clinical experience with TMS has demonstrated it to be safe and promising in the diagnosis, monitoring, and treatment of neurological and psychiatric disease (eg, depression) in adults. The technology used in the study by Lipton and colleagues [2010] was single pulse TMS, or sTMS, having a magnetic field approximately half the strength of a typical MRI device. Patients do not feel the mild electric current stimulated by the sTMS device, which passes through the skull and tissue to excite and depolarize neurons in the brain. This should not be confused with electroconvulsive therapy (ECT), in which stronger electrical currents are applied to the entire brain and sometimes cause short-term memory loss and other cognitive complications.

As with PEMF therapy, there can be many variations of TMS devices in terms of their construction and qualities of the magnetic field produced. The well-designed study by Lipton et al. [2010] demonstrated efficacy for treating migraine with aura; however, it also should be noted that the 17% absolute risk reduction would have an NNT of about 6; that is, only 1 of 6 patients would be expected to benefit from the procedure.

Finally, biomagnetic therapy using actual magnets appears to be a whole field unto itself and quite a burgeoning industry. Long popular in other countries, magnet therapy entered public awareness in the United States some years ago, stimulated by golfers and tennis players extolling the virtues of magnets in the treatment of their sports-related injuries. Magnetic knee, shoulder, neck, wrist, and ankle pads, as well as insoles and mattress pads, are widely available and touted as providing a myriad of healing benefits. Despite such enthusiasm, to date there is relatively little controlled clinical-trial evidence to support the use of magnets for any medical condition [EBSCO 2010]. We recently described a placebo-controlled trial that found no benefits of magnets in relieving arthritis pain, other than a possible placebo effect [blogpost here]. Other studies — usually small, underpowered, observational, and burdened by other limitations — have demonstrated some beneficial effects of magnets.

There is considerable disagreement, and some controversy, about the best shape, strength or intensity, polarity (eg, applying the North versus South poles), material composition, and other qualities of magnets necessary to achieve best therapeutic effects. Still, most critics concede that there is no physical harm in trying magnets for most people; although, there are questions about whether magnetic fields can disrupt pacemakers, insulin pumps, or other implanted devices, and their safety during pregnancy. Financial risk is a different matter; there may be little investment at the lower end of magnetic objects but it can cost hundreds of dollars for mattress pads and some other products. Caveat emptor.

There also have been concerns expressed about promotional claims for biomagnetic therapies, and a funding bias in some past research in which device manufacturers were involved in the support and design of trials (as may be the case in the trials noted above by Nelson et al. and Lipton et al.). Advertising messages sometimes appear to imply “FDA approval” of devices or products that, in fact, does not exist. Beyond this, within the realm of pain management and in the interest of pursuing more holistic approaches, it must be considered that certain therapies do help some persons with pain even if there is an incomplete understanding of the exact mechanisms or little incontrovertible evidence of efficacy. We are willing to contemplate interesting possibilities but it is always comforting to have a hefty dose of valid clinical evidence to support any conclusions and recommendations.

DISCLAIMER: We have no vested interests in, nor do we endorse, any biomagnetic therapies, products, or devices. This blog entry presents only a small sampling of readily available information on the subject of biomagnetic therapies, so interested readers are encouraged to consult the listed references, and other resources, in arriving at their own conclusions regarding this topic. — SBL

> EBSCO. Magnet Therapy. EBSCO Publishing [ebscohost.com online]. 2010 [
available here].
> Lipton RB, Dodick DW, Silberstein SD, et al. Single-pulse transcranial magnetic stimulation for acute treatment of migraine with aura: a randomised, double-blind, parallel-group, sham-controlled trial. The Lancet Neurology. 2010(Mar 4). Publication ahead of print [
abstract here].
> McCarthy CJ, Callaghan MJ, Oldham JA. Pulsed electromagnetic energy treatment offers no clinical benefit in reducing the pain of knee osteoarthritis: a systematic review. BMC Musculoskeletal Disorders. 2006;7(51) [
available here].
> Nelson F, Zvirbulis R, Pilla A. The use of a specific pulsed electromagnetic field (PEMF) in treating early osteoarthritis. Paper 1034. Presented at the 56th Annual Orthopaedic Research Society. March 6-9, 2010. New Orleans. From Henry Ford Hospital press release, March 8, 2010 [
access here]
> Thomas AW, Graham K, Prato FS, et al. A randomized, double-blind, placebo-controlled clinical trial using low-frequency magnetic field in the treatment of musculoskeletal pain. Pain Res Manage. 2007;12(4):249-258 [
available here].