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On
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- What are magnets?
- Is the use of magnets considered conventional medicine or complementary and alternative medicine?
- What is the history of the discovery and use of magnets to treat pain?
- How common is the use of magnets to treat pain?
- What are some examples of theories and beliefs about magnets and pain?
- How are static magnets used in attempts to treat pain?
- How are electromagnets used in attempts to treat pain?
- What is known from the scientific evidence about the effectiveness of magnets in treating pain?
- Are there scientific controversies associated with using magnets for pain?
- Have any side effects or complications occurred from using magnets for pain?
- What should consumers know if they are considering using magnets to treat pain?
- Is the National Center for Complementary and Alternative Medicine (NCCAM) funding research on magnets for pain and other diseases and conditions?
Introduction
Magnets are objects that produce a type of energy called
magnetic fields. Magnets are widely marketed to treat or ease the symptoms
of various diseases and conditions, including pain. This Research Report
provides an overview of the use of magnets for pain, summarizes current
scientific knowledge about their effectiveness for this purpose, and suggests
additional sources of information. Terms are defined in the “Definitions”
section.
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Key Points
- The vast majority
of magnets marketed to consumers to treat pain are of a type called
static (or permanent) magnets, because the resulting magnetic fields
are unchanging. The other magnets used for health purposes are called
electromagnets, because they generate magnetic fields only when electrical
current flows through them. Currently, electromagnets are used primarily
under the supervision of a health care provider or in clinical
trials.
- Scientific research
so far does not firmly support a conclusion that magnets of any type
can relieve pain. However, some people do experience some relief. Various
theories have been proposed as to why, but none has been scientifically
proven (see Question 5).
- Clinical trials
in this area have produced conflicting results (see Question
8). Many concerns exist regarding the quality and rigor of the studies
conducted to date, leading to a call for additional, higher quality,
and larger studies.
- The U.S. Food
and Drug Administration (FDA) has not approved the marketing of magnets
with claims of benefits to health (such as “relieves arthritis pain”).
The FDA and the Federal Trade Commission (FTC) have taken action against
many manufacturers, distributors, and Web sites that make claims not
supported scientifically about the health benefits of magnets.
- It is important
that people inform their health care providers about any therapy they
are currently using or considering, including magnets. This is to help
ensure a safe and coordinated course of care.
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1. What are magnets?
Magnets are objects that produce a type of energy called
magnetic fields. All magnets possess a property called polarity–that
is, a magnet’s power of attraction is strongest at its opposite ends,
usually called the north and south poles. The north and south poles attract
each other, but north repels north and south repels south. All magnets
attract iron.
Magnets come in different strengths, most often measured
in units called gauss (G). For comparison purposes, the Earth has a magnetic
field of about 0.5 G; refrigerator magnets range from 35 to 200 G; magnets
marketed for the treatment of pain are usually 300 to 5,000 G; and MRI
(magnetic resonance imaging) machines widely used to
diagnose medical conditions noninvasively produce up to 200,000 G.1
The vast majority of magnets marketed to consumers for
health purposes (see the box below) are of a type called
static (or permanent) magnets. They have magnetic fields that do not change.
Examples
of Products Using Magnets |
Shoe
insoles
Heel inserts
Mattress pads
Bandages
|
Belts
Pillows and
cushions
Bracelets and
other jewelry
Headwear
|
The other magnets
used for health purposes are called electromagnets, because they generate
magnetic fields only when electrical current flows through them. The magnetic
field is created by passing an electric current through a wire coil wrapped
around a magnetic core. Electromagnets can be pulsed–that is, the magnetic
field is turned on and off very rapidly.
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2. Is the use of magnets considered conventional medicine
or complementary and alternative medicine?
Conventional medicine and complementary and alternative
medicine (CAM) are defined in the box below.
About
CAM and Conventional Medicine |
Complementary
and alternative medicine (CAM) is a group of various medical
and health care systems, practices, and products that are not
presently considered to be part of conventional medicine. Conventional
medicine is medicine as practiced by holders of M.D. (medical
doctor) or D.O. (doctor of osteopathy) degrees and by allied
health professionals, such as physical therapists, psychologists,
and registered nurses. To find out more, see the NCCAM fact
sheet “What
Is Complementary and Alternative Medicine?” |
|
There are some uses
of electromagnets within conventional medicine. For example, scientists
have found that electromagnets can be used to speed the healing of bone
fractures that are not healing well.2,3
Even more commonly, electromagnets are used to map areas of the brain.
However, most uses of magnets by consumers in attempts to treat pain are
considered CAM, because they have not been scientifically proven and are
not part of the practice of conventional medicine.
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3. What is the history of the discovery and use of magnets
to treat pain?
Magnets have been used for many centuries in attempts
to treat pain.a By various accounts, this
use began when people first noticed the presence of naturally magnetized
stones, also called lodestones. Other accounts trace the beginning to
a shepherd noticing that the nails in his sandals were pulled out by some
stones. By the third century A.D., Greek physicians were using rings made
of magnetized metal to treat arthritis and pills made of magnetized amber
to stop bleeding. In the Middle Ages, doctors used magnets to treat gout,
arthritis, poisoning, and baldness; to probe and clean wounds; and to
retrieve arrowheads and other iron-containing objects from the body.
In the United States, magnetic devices (such as hairbrushes
and insoles), magnetic salves, and clothes with magnets applied came into
wide use after the Civil War, especially in some rural areas where few
doctors were available. Healers claimed that magnetic fields existed in
the blood, organs, or elsewhere in the body and that people became ill
when their magnetic fields were depleted. Thus, healers marketed magnets
as a means of “restoring” these magnetic fields. Magnets were promoted
as cures for paralysis, asthma, seizures, blindness, cancer, and other
conditions. The use of magnets to treat medical problems remained popular
well into the 20th century. More recently, magnets have been marketed
for a wide range of diseases and conditions, including pain, respiratory
problems, high blood pressure, circulatory problems, arthritis, rheumatism,
and stress.
a Sources for this historical discussion include
references 1, 4, and 5.
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4. How common is the use of magnets to treat pain?
A 1999 survey of patients who had rheumatoid arthritis, osteoarthritis,
or fibromyalgia and were seen by rheumatologists
reported that 18 percent had used magnets or copper bracelets, and that
this was the second-most-used CAM therapy by these patients, after chiropractic.6
One estimate places Americans’ spending on magnets to treat pain at $500
million per year; the worldwide estimate is $5 billion.7
Many people purchase magnets in stores or over the Internet to use on
their own without consulting a health care provider.
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5. What are some examples of theories and beliefs about magnets and
pain?
Some examples of theories and beliefs about using magnets to treat pain
are listed below. These range from theories proposed by scientific researchers
to claims made by magnet manufacturers. It is important to note that while
the results for some of the findings from the scientific studies have
been intriguing, none of the theories or claims below has been conclusively
proven. For the following, summaries of research from peer-reviewed
medical and scientific journals appear in Appendix
I:
- Static magnets
might change how cells function.
- Magnets might
alter or restore the equilibrium (balance) between cell death and growth.
- Because it contains
iron, blood might act as a conductor of magnetic energy. Static magnets
might increase the flow of blood and, therefore, increase the delivery
of oxygen and nutrients to tissues.
- Weak pulsed electromagnets
might affect how nerve cells respond to pain.
- Pulsed electromagnets
might change the brain’s perception of pain.
- Electromagnets
might affect the production of white blood cells involved in fighting
infection and inflammation.
Here are two other
theories and beliefs:
- Magnets might increase
the temperature of the area of the body being treated.
- “Magnetizing” or
“re-magnetizing” drinking water or other beverages might allow them
to hydrate the body better and flush out more “toxins” than ordinary
drinking water.
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6. How are static magnets used in attempts to treat pain?
Static magnets are usually made from iron, steel, rare-earth
elements, or alloys. Typically, the magnets are
placed directly on the skin or placed inside clothing or other materials
that come into close contact with the body. Static magnets can be unipolar
(one pole of the magnet faces or touches the skin) or bipolar (both poles
face or touch the skin, sometimes in repeating patterns).8
Some magnet manufacturers make claims about the poles of magnets–for
example, that a unipolar design is better than a bipolar design, or that
the north pole gives a different effect from the south pole. These claims
have not been scientifically proven.1,9
A small number of rigorous scientific studies have examined the efficacy
of static magnets in treating pain. This evidence is discussed in Question
8 and Appendices II and III.
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7. How are electromagnets used in attempts to treat pain?
Electromagnets were approved by the FDA in 1979 to treat bone fractures
that have not healed well.2,3
Researchers have been studying electromagnets for painful conditions,
such as knee pain from osteoarthritis, chronic pelvic pain, problems in
bones and muscles, and migraine headaches.3,9-12
However, these uses of electromagnets are still considered experimental
by the FDA and have not been approved. Currently, electromagnets to treat
pain are being used mainly under the supervision of a health care provider
and/or in clinical trials.
An electromagnetic therapy called TMS (transcranial
magnetic stimulation) is also being studied by researchers. In TMS, an
insulated coil is placed against the head, near the area of the brain
to be examined or treated, and an electrical current generates a magnetic
field into the brain. Currently, TMS is most often used as a diagnostic
tool, but research is also under way to see whether it is effective in
relieving pain.13,14 A
type of TMS called rTMS (repetitive TMS) is believed
by some to produce longer lasting effects and is being explored for its
usefulness in treating chronic pain, facial pain, headache, and fibromyalgia
pain.15,16 A related form
of electromagnetic therapy is rMS (repetitive magnetic
stimulation). It is similar to rTMS except that the magnetic coil is placed
on or near a painful area of the body other than the head. This therapy
is being studied as a treatment for musculoskeletal pain.17,18
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8. What is known from the scientific evidence about the effectiveness
of magnets in treating pain?
Overall, the research findings so far do not firmly support claims that
magnets are effective for treatment of pain.
Findings from Reviews of Scientific Studies
Reviews take a broad look at the findings from a group of individual research
studies. Such reviews are usually either a general review,
a systematic review, or a meta-analysis.
There are not many reviews available on CAM uses of magnets to treat pain.
Appendix II provides examples of six reviews
published from August 1999 through August 2003 in English in the National
Library of Medicine’s MEDLINE database.
- Often, these reviews
compared what is known from the clinical trials of magnets for painful
conditions to what is known from conventional treatments or from other
CAM treatments for the same condition(s).
- One review found
that static magnetic therapy may work for certain conditions but that
there is not adequate scientific support to justify its use.1
- Three reviews found
that electromagnetic therapy showed promise for the treatment of some,
but not all, painful conditions, and that more research is needed.9,19,20
One of these reviews also looked at two randomized clinical
trials (RCTs) of static magnets.9
One reported significant pain relief in subjects using magnets, but
the other did not.
- Another review
concluded that TMS has an effect on the central nervous system that
might relieve chronic pain and, therefore, should be studied further.14
- The remaining review
found no studies on magnets for neck pain and stated that rigorous studies
are much needed.21
- It is important
to note that the reviews pointed out problems with the rigor of most
research on magnets for pain.9,14,19,20
For example, many of the clinical trials involved a very small number
of participants, were conducted for very short durations (e.g., one
study applied a magnet a total of one time for 45 minutes), and/or lacked
a placebo or sham group for
comparison to the magnet group.19,20
Thus, the results of many trials may not be truly meaningful. Most reviews
stated that more and better quality research is needed before magnets’
effectiveness can be adequately judged.
Findings from
Clinical Trials
The studies in Appendix III give an overview
of scientific research from 15 RCTs published in English from January
1997 through March 2004 and cataloged in the National Library of Medicine’s
MEDLINE database. These trials studied CAM uses of static magnets or electromagnets
for various kinds of pain.
- The results of
trials of static magnets have been conflicting. Four of the nine static
magnet trials analyzed found no significant difference in pain relief
from using a magnet compared with sham treatment or usual medical care.7,8,22,23
Four trials did find a significant difference, with greater benefit
seen from magnets.24-27 The remaining trial
compared only a weaker strength magnet to a stronger magnet, and found
benefit from both (there was no difference between groups in how much
benefit).28
- Trials of electromagnets
yielded more consistent results. Five out of six trials found that these
magnets significantly reduced pain.10,11,17,18,29
The sixth found a significant benefit to physical function from using
electromagnets, but not to pain or stiffness.30
- Some study authors
suggested that a placebo effect could have been responsible for the
pain relief that occurred from magnets.22,30
- While criticizing
many of these studies, it is fair to say that testing magnets in clinical
trials has presented challenges. For example, it can be difficult to
design a sham magnet that appears exactly like an active magnet. Also,
there has been concern about how many participants have tried to determine
whether they have been assigned an active magnet (for example, by seeing
whether a paperclip would be attracted to it); this knowledge could
affect how meaningful a trial’s results are.
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9. Are there scientific controversies associated with
using magnets for pain?
Yes, there are many controversies. Examples include:
- The mechanism(s)
by which magnets might relieve pain have not been conclusively identified
or proven.
- Pain relief while
using a magnet may be due to reasons other than the magnet. For example,
there could be a placebo effect or the relief could come from whatever
holds the magnet in place, such as a warm bandage or a cushioned insole.22,24
- Opinions differ
among manufacturers, health care providers who use magnetic therapy,
and others about which types of magnets (strength, polarity, length
of use, and other factors) should be used and how they should be used
in studies to give the most definitive answers.
- Actual magnet strengths
can vary (sometimes widely) from the strengths claimed by manufacturers.
This can affect scientists’ ability to reproduce the findings of other
scientists and consumers’ ability to know what strength magnet they
are actually using.26,31,32
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10. Have any side effects or complications occurred from
using magnets for pain?
The kinds of magnets marketed to consumers are generally
considered to be safe when applied to the skin.7
Reports of side effects or complications have been rare. One study reported
that a small percentage of participants had bruising or redness on their
skin where a magnet was worn.33
Manufacturers often recommend that static magnets not
be used by the following people1:
- Pregnant women,
because the possible effects of magnets on the fetus are not known.
- People who use
a medical device such as a pacemaker, defibrillator, or insulin pump,
because magnets may affect the magnetically controlled features of such
devices.
- People who use
a patch that delivers medication through the skin, in case magnets cause
dilation of blood vessels, which could affect the delivery of the medicine.
This caution also applies to people with an acute sprain, inflammation,
infection, or wound.
There have been rare
cases of problems reported from the use of electromagnets. Because at
present these are being used mainly under the supervision of a health
care provider and/or in clinical trials, readers are advised to consult
their provider about any questions.
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11. What should consumers know if they are considering
using magnets to treat pain?
- It is important
that people inform all their health care providers about any therapy
they are using or considering, including magnetic therapy. This is to
help ensure a safe and coordinated plan of care.
- In the studies
that did find benefits from magnetic therapy, many have shown those
benefits very quickly. This suggests that if a magnet does work, it
should not take very long for the user to start noticing the effect.
Therefore, people may wish to purchase magnets with a 30-day return
policy and return the product if they do not get satisfactory results
within 1 to 2 weeks.
- If people decide
to use magnets and they experience side effects that concern them, they
should stop using the magnets and contact their health care providers.
- Consumers who are
considering magnets, whether for pain or other conditions, can consult
the free publications prepared by Federal Government agencies. See “For
More Information.”
|
If
You Buy a Magnet…
- Check on
the company’s reputation with consumer protection agencies.
- Watch for
high return fees. If you see them before purchase, ask that they
be dropped and obtain written confirmation that they will be.
- Pay by credit
card if possible. This offers you more protection if there is
a problem.
- If you buy
from sources (such as Web sites) that are not based in the United
States, U.S. law can do little to protect you if you have a problem
related to the purchase.
Sources:
The FDA and the Pennsylvania Medical Society
|
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12. Is the National Center for Complementary and Alternative
Medicine (NCCAM) funding research on magnets for pain and other diseases
and conditions?
Yes. For example, recent projects supported by NCCAM include:
- Static magnets,
for fibromyalgia pain and quality of life
- Pulsed electromagnets,
for migraine headache pain
- Static magnets,
for their effects on networks of blood vessels involved in healing
- TMS, for Parkinson’s
disease
- Electromagnets,
for their effects on injured nerve and muscle cells
In addition, the papers
by Alfano et al.,26 Swenson,21
and Wolsko et al.27 report on research funded
by NCCAM.
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For More Information
-
NCCAM Clearinghouse
Toll-free in the U.S.: 1-888-644-6226
International: 301-519-3153
TTY (for deaf or hard-of-hearing callers): 1-866-464-3615
E-mail: info@nccam.nih.gov
Web site: nccam.nih.gov
Address: NCCAM Clearinghouse, P.O. Box 7923, Gaithersburg, MD 20898-7923
Fax: 1-866-464-3616
Fax-on-Demand service: 1-888-644-6226
-
CAM on PubMed
Web site: www.nlm.nih.gov/nccam/camonpubmed.html
CAM on PubMed, a database developed jointly by NCCAM and the National
Library of Medicine, offers citations to (and in most cases, brief
summaries of) articles on CAM in scientifically based, peer-reviewed
journals. CAM on PubMed also links to many publisher Web sites, which
may offer the full text of articles.
- U.S. Food and
Drug Administration (FDA)
Web site: www.fda.gov
Toll-free in the U.S.: 1-888-INFO-FDA (1-888-463-6332)
The FDA is a Federal agency responsible for protecting
the public health by assuring the safety, efficacy, and security of
medicines, biological products, medical devices, foods, cosmetics,
and consumer products that produce radiation.
Center for
Devices and Radiological Health (CDRH)
Web site: www.fda.gov/cdrh
Toll-free: 1-888-463-6332
The CDRH has consumer information on magnets and magnetic devices
and on buying medical devices online.
-
Federal Trade
Commission (FTC)
Web site: www.ftc.gov
Toll-free in the U.S.: 1-888-382-4357
The FTC is a Federal agency that works to maintain a competitive marketplace
for both consumers and businesses. It regulates all advertising, except
prescription drugs and medical devices, ensuring that advertisements
are truthful and not misleading for consumers. Brochures include ”
‘Miracle’ Health Claims: Add a Dose of Skepticism.”
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Definitions
Alloy: A metallic substance consisting of either a mixture of
two or more metals, or a metal that has been mixed with a nonmetal.
Anecdotal evidence: Evidence made up of one or more anecdotes.
In science, an anecdote is a story about a person’s experience, told by
that person.
Chiropractic: An alternative medical system that focuses on the
relationship between bodily structure (primarily that of the spine) and
function, and how that relationship affects the preservation and restoration
of health. Chiropractors use a type of hands-on therapy called manipulation
(or adjustment) as an integral treatment tool.
Clinical trial: A research study in which a treatment or therapy
is tested in people to see whether it is safe and effective. Clinical
trials are a key part of the process in finding out which treatments work,
which do not, and why. Clinical trial results also contribute new knowledge
about diseases and medical conditions.
Diabetic peripheral neuropathy: A nerve disorder caused by diabetes.
This disorder leads to a partial or complete loss of feeling in the feet
and, in some cases, the hands, and pain and weakness in the feet.
Efficacy: In scientific research, a treatment’s efficacy is its
power to obtain a desired effect, such as reducing pain.
ET: Electromagnetic therapy.
Fibromyalgia: A chronic disorder involving musculoskeletal pain,
multiple tender points on the body, and fatigue.
General review: An analysis in which information from various
studies is summarized and evaluated. Conclusions are then made based on
this evidence.
Magnetic resonance imaging (MRI): A test that uses powerful magnets
and radio waves to create detailed pictures of structures and organs inside
the body.
Meta-analysis: A type of research review that uses statistical
techniques to analyze results from a collection of individual studies.
Myofascial pain syndrome: A chronic musculoskeletal pain disorder.
Pain may occur when “trigger points,” or especially tender areas on the
body, are touched, or in other points in the body.
Peer reviewed: Reviewed before publication by a group of experts
in the same field.
Placebo: A placebo is designed to resemble as much as possible
the treatment being studied in a clinical trial, except that the placebo
is inactive. An example of a placebo is a pill containing sugar instead
of the drug or other substance being studied. By giving one group of participants
a placebo and the other group the active treatment, the researchers can
compare how the two groups respond and get a truer picture of the active
treatment’s effects. In recent years, the definition of placebo has been
expanded to include other things that could have an effect on the results
of health care, such as how a patient and a health care provider interact
and what the patient expects to happen from the care.
Plastic change: The ability of the brain’s connections to change,
which affects many functions such as learning and recovery from damage.
Prospective study: A type of research study in which participants
are followed over time for the effect(s) of a health care treatment.
Pulsed ET: Pulsed electromagnetic therapy, in which the magnetic
field created by an electric current is turned on and off very rapidly.
Randomized clinical trial (RCT): In a randomized clinical trial,
each participant is assigned by chance (through a computer or a table
of random numbers) to one of two groups. The investigational group receives
the therapy, also called the active treatment. The control group receives
either the standard treatment, if there is one, for their disease or condition,
or a placebo.
Rare-earth element: One of a group of relatively scarce, metallic
elements or minerals. Examples include lanthanum, neodymium, and ytterbium.
Rheumatologist: A physician (M.D. or D.O.) who specializes in
inflammatory disorders of the joints, muscles, and fibrous tissues.
rMS: Repetitive magnetic stimulation. In rMS, an insulated coil
is placed against a part of the body other than the head, and an electrical
current generates a magnetic field into that area.
rTMS: Repetitive transcranial magnetic stimulation. This type
of transcranial magnetic stimulation, or TMS (see definition below), is
believed by some to produce longer lasting effects.
Sham: A sham device or procedure is one type of placebo (defined
above). When the treatment under study is a procedure or device (not a
drug or other substance), a sham procedure or device may be designed that
resembles the active treatment but does not have any active treatment
qualities.
Systematic review: A type of research review in which data from
a set of studies on a particular question or topic are collected, analyzed,
and critically reviewed.
TMS: Transcranial magnetic stimulation. In this type of electromagnetic
therapy, an insulated coil is placed against the head, and an electrical
current generates a magnetic field into the brain.
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- Segal NA, Toda Y, Huston J, et al. Two configurations of static magnetic
fields for treating rheumatoid arthritis of the knee: a double-blind
clinical trial. Archives of Physical Medicine and Rehabilitation.
2001;82(10):1453-1460.
- Thuile C, Walzl M. Evaluation of electromagnetic fields in the treatment
of pain in patients with lumbar radiculopathy or the whiplash syndrome.
NeuroRehabilitation. 2002;17(1):63-67.
- Nicolakis P, Kollmitzer J, Crevenna R, et al. Pulsed magnetic field
therapy for osteoarthritis of the knee: a double-blind sham-controlled
trial. Wiener Klinische Wochenschrift. 2002;114(15-16):678-684.
- Blechman AM, Oz MC, Nair V, et al. Discrepancy between claimed field
flux density of some commercially available magnets and actual gaussmeter
measurements. Alternative Therapies in Health and Medicine. 2001;7(5):92-95.
- McLean MJ, Engström S, Holcomb R. Static magnetic fields for the treatment
of pain. Epilepsy & Behavior. 2001;2:S74-S80.
- Brown CS, Ling FW, Wan JY, et al. Efficacy of static magnetic field
therapy in chronic pelvic pain: a double-blind pilot study. American
Journal of Obstetrics and Gynecology. 2002;187(6):1581-1587.
- McLean MJ, Holcomb RR, Wamil AW, et al. Blockade of sensory neuron
action potentials by a static magnetic field in the 10 mT range. Bioelectromagnetics.
1995;16(1):20-32.
- Fanelli C, Coppola S, Barone R, et al. Magnetic fields increase cell
survival by inhibiting apoptosis via modulation of Ca2+ influx. The
FASEB Journal. 1999;13(1):95-102.
- Martel GF, Andrews SC, Roseboom CG. Comparison of static and placebo
magnets on resting forearm blood flow in young, healthy men. Journal
of Orthopaedic and Sports Physical Therapy. 2002;32(10):518-524.
- Ryczko MC, Persinger MA. Increased analgesia to thermal stimuli in
rats after brief exposures to complex pulsed 1 microTesla magnetic fields.
Perceptual and Motor Skills. 2002;95(2):592-598.
- Johnson MT, McCullough J, Nindl G, et al. Autoradiographic evaluation
of electromagnetic field effects on serotonin (5HT1A) receptors in rat
brain. Biomedical Sciences Instrumentation. 2003;39:466-470.
- Johnson MT, Vanscoy-Cornett A, Vesper DN, et al. Electromagnetic fields
used clinically to improve bone healing also impact lymphocyte proliferation
in vitro. Biomedical Sciences Instrumentation. 2001;37:215-220.
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Appendix I
Research on Theories
and Beliefs On How Magnets Might Relieve Pain
Theory: Static
magnets might change how cells function.
Description of Studies: (1) Mouse nerve cells were exposed to static
magnetic fields of three different strengths, and the cells were stimulated
with pulses of electricity. (2) Mouse nerve cells were exposed to a static
magnetic field and capsaicin (a pain-producing substance).
Findings: (1) Exposure of nerve cells in culture to a static 110-G
magnetic field reduced their ability to transmit electrical impulses.
(2) Magnets prevented mouse nerve cells from responding to capsaicin.
Citations: (1) McLean et al., 199534
and (2) McLean et al., 200132
Theory: Magnets
might alter/restore the balance between cell death and growth.
Description of Study: Cultures of the U937 human lymphoma (a tumor
of lymph node tissue) cell line were exposed to a static magnetic field
at the same time that they were treated with agents that cause cell death.
Findings: Static magnet fields protected some cells from agents
that cause cell death and allowed them to survive and grow.
Citation: Fanelli et al., 199935
Theory: Static
magnets might increase blood flow.
Description of Study: Randomized clinical trial (RCT) of 20 healthy
young men who wore static magnets or placebo devices on their forearms
for 30 minutes.
Findings: Blood flow was not significantly different when comparing
the results of the magnet session with the placebo session.
Citation: Martel et al., 200236
Theory: Weak
pulsed electromagnets might affect how nerve cells respond to pain.
Description of Study: The pain threshold to a hot surface was measured
for rats before and 30 and 60 minutes after exposure to weak pulsed electromagnets
for 30 minutes.
Findings: An increase in pain threshold (analgesic effect) was
found 30 and 60 minutes after exposure to pulsed electromagnets.
Citation: Ryczko and Persinger, 200237
Theory: Pulsed
electromagnets might change the brain’s perception of pain.
Description of Study: Rats were exposed to pulsed electromagnets
(treatment group) or static magnetics (control group) 4 hours/day, for
up to 28 days. The brains were removed and changes in the number of serotonin
(a brain chemical that affects stress and pain) receptors were examined.
Findings: Significant increases in the number of receptors that
bind serotonin were observed in the brains of the rats exposed to a pulsed
electromagnet.
Citation: Johnson et al., 200338
Theory: Electromagnets
might affect the production of white blood cells involved in fighting
infection and inflammation.
Description of Study: Human and rat white blood cells were exposed
to electromagnets or pulsed electromagnets.
Findings: Both the human and rat cells exposed to either type of
electromagnetic therapy (ET) showed a modest increased capacity to multiply.
Citation: Johnson et al., 200139
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Appendix II
General and Systematic Reviews on CAM Magnetic Therapy
for Pain Published From August 1999 to August 2003
Static Magnetic Therapy
Authors: Ratterman et al., 20021
Type: General review
Description: Summarized 9 clinical trials on static magnetic therapy
for treating postpolio pain, diabetic peripheral neuropathy,
neck pain, low-back pain, fibromyalgia, postsurgical pain, and headache.
Findings: The authors stated that static magnets may work for certain
conditions, but there is not adequate scientific support to justify their
use.
Electromagnetic Therapy
Authors: Hulme et al., 200319
Type: Systematic review
Description: Looked at 3 RCTs that compared pulsed electromagnets
(2 RCTs) or direct electric stimulation (1 RCT) with placebo in treating
osteoarthritis. Both trials of pulsed electromagnets studied osteoarthritis
of the knee; one of these studied osteoarthritis of the neck as well.
The primary measure of effectiveness was pain relief.
Findings: The review found the RCTs to show that pulsed electromagnets
had a small-to-moderate effect on knee pain, and a much smaller effect
on neck pain. They concluded that “the current limited evidence does not
show a clinically important benefit” of pulsed electromagnets for treating
osteoarthritis of the knee or neck. They also identified a need for larger
trials to see whether clinically important benefits exist.
Authors: Huntley and Ernst, 200020
Type: Systematic review
Description: Reviewed 12 RCTs for 7 CAM modalities for pain and
other symptoms of multiple sclerosis. Included one RCT of rMS
(38 patients) and one RCT of pulsed electromagnets (30 patients).
Other modalities examined were nutritional therapy, massage, Feldenkrais
bodywork, reflexology, neural therapy, and psychological counseling.
Findings: Both magnet studies reviewed found short-term benefits
in relieving painful muscle spasms and other symptoms, and in improving
activity levels. Authors called for “rigorous research” on CAM for multiple
sclerosis patients.
Authors: Pridmore and Oberoi, 200014
Type: General review
Description: Discussed an array of basic and clinical research
on TMS, focusing on its effect on the central nervous system
(CNS) and on its potential effectiveness in relieving chronic pain.
Findings: Authors concluded, “Evidence indicates that TMS can produce
plastic changes in the CNS, which are observable at
both the cellular and psychological levels.” Citing a lack of comprehensive
studies, they proposed that “studies are justified to determine whether
TMS can provide short-term or long-term relief in chronic pain.”
Electromagnetic and Static Magnetic
Therapies
Author: Swenson, 200321
Type: General review
Description: Searched for studies on various treatments for nonspecific
neck pain.
Findings: Found no studies on magnets for neck pain, despite the
popular interest in magnetic therapy, and “several very limited reports”
from use for other pain. The author stated that rigorous studies are “desperately
needed,” especially those that could effectively double-blind patients
and practitioners to treatment.
Authors: Vallbona and Richards, 19999
Type: General review
Description: Pulsed Electromagnets–Commented on 32 RCTs
of pulsed electromagnets for conditions such as neck/shoulder pain,
bone and joint diseases, neurologic disorders, sleep disorders, wounds
and ulcers, postoperative bowel obstruction, and perineal trauma from
childbirth. Pain is a key symptom of many of the conditions examined,
and pain intensity was a clinical outcome measure in many of the studies.
Static Magnets–Discussed two RCTs: one for neck and shoulder pain
and one for postpolio pain.
Findings: Pulsed Electromagnets–Authors found that 26 of
32 RCTs of pulsed ET showed it to be an effective
treatment for the conditions studied. Pain was decreased in disorders
including neck pain, osteoarthritis, and leg ulcers. Static Magnets–An
RCT of static magnets for neck and shoulder pain did not find any significant
pain relief in subjects using magnets. An RCT of static magnets for postpolio
pain yielded data that “suggest significant pain relief realized by patients
who were exposed to active magnets.” Vallbona and Richards noted that
many studies of static magnets rely on anecdotal evidence
or small study sizes, are sponsored by magnet manufacturers, and/or are
not published in peer-reviewed journals.
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Appendix III
Reports on Randomized Clinical Trials of Magnetic Therapy for Pain From
January 1997 to March 2004
Static Magnetic Therapy
Authors: Wolsko et al., 200427
Description: Participants (26) with osteoarthritis of the knee
received either a sleeve containing magnets, to be worn over the knee
area, or a placebo sleeve that appeared identical. They wore their sleeves
for the first 4 hours and then at least 6 hours a day for 6 weeks. Knee
pain was measured at 4 hours, 1 week, and 6 weeks.
Findings: There was a statistically significant improvement in
pain in the treatment group at 4 hours, but not at 1 week or 6 weeks.
Authors: Winemiller et al., 20037
Description: Participants (95) who had had plantar heel pain
for at least 30 days received either shoe insoles containing a magnet
or insoles that were identical except for having no magnet. They wore
the insoles at least 4 hours a day 4 days/week for 8 weeks. Outcomes were
measured by a daily pain diary.
Findings: There were no significant differences in pain outcomes
between the two groups. Both experienced significant improvement in morning
foot pain and in enjoyment of their jobs (because of reduced foot pain).
Authors: Weintraub et al., 200324
Description: Patients (259) with diabetic peripheral neuropathy
wore static magnetic shoe insoles or an unmagnetized sham device continuously
for 4 months. Primary outcome measures were burning, numbness and tingling,
exercise-induced foot pain, and sleep interruption due to pain.
Findings: Authors found that statistically significant reductions
in burning, numbness and tingling, and exercise-induced foot pain occurred
in the treatment group, but only during months 3 and 4. Some patients
in the treatment group with more severe baseline pain had significant
reductions in numbness and tingling and in foot pain throughout the study
period.
Authors: Hinman et al., 200225
Description: Participants (43) with chronic knee pain wore
pads containing static magnets or placebos over their painful joints for
2 weeks. Outcomes were measured using self-administered ratings of pain
and physical function, and a timed 50-foot walk.
Findings: At the end of 2 weeks, those wearing magnets reported
significantly less pain, and better daily physical function and walking
speed, than those wearing placebos. Most of those wearing magnets experienced
pain relief within 30 minutes of the initial application of the magnets.
Authors: Carter et al., 200222
Description: Participants (30) with carpal tunnel syndrome
wore a magnetic or placebo device on the wrist over the carpal tunnel
area for 45 minutes. Participants rated their pain at 15-minute intervals
while wearing the device, after removing the device, and after 2 weeks.
Findings: The magnet was no more effective than the placebo in
relieving pain. Significant pain reduction was reported for both treatment
and placebo groups during a 45-minute application. The reduction in pain
was still detectable 2 weeks later; authors suggested that this could
be from a placebo effect.
Authors: Segal et al., 200128
Description: Patients (64) with rheumatoid arthritis of the
knee received one of two magnetic devices: one containing four strong
magnets or one containing only one weaker magnet. There was no nonmagnetic
or sham treatment. Devices were worn continuously for 1 week. Outcome
measures were the participants’ pain diaries in which they assessed their
level of pain twice a day.
Findings: Both devices produced significant pain reduction after
1 week of use. A significant difference was not seen between the two groups.
The authors indicated that a nonmagnetic placebo treatment should be used
in future studies.
Authors: Alfano et al., 200126
Description: Patients with fibromyalgia (94 subjects) received
either (1) usual care, (2) a pad containing static magnets placed between
the mattress and box springs, (3) an eggcrate-like foam mattress pad containing
static magnets of varying strength, or (4) a mattress pad containing magnets
that had been demagnetized. Outcome measures were functional status, pain,
and the number and intensity of tender points after 6 months.
Findings: Compared with the usual-care group and the sham group,
people who used the pads containing active magnets reported improvements
in function, pain intensity level, number of tender points, and intensity
of tender points after 6 months. However, except for pain intensity, measurements
were not significantly different from scores reported for the sham treatment
group or the usual-care group.
Authors: Collacott et al., 20008
Description: Participants (20) who had had chronic low-back
pain for at least 6 months wore a magnetic device for 1 week (6 hours/day,
3 days/week). After 1 week of no treatment, the participants wore a sham
device for 1 week (6 hours/day, 3 days/week). The primary outcome was
pain intensity, which was measured by a visual analog scale.
Findings: No significant differences in outcomes were found between
the magnetic and sham therapies.
Authors: Caselli et al., 199723
Description: Participants (34) with heel pain wore a molded
insole with or without a static magnetic foil insert for 4 weeks. The
outcomes were measured in terms of the foot function index (pain, disability,
and activity restriction).
Findings: Use of the magnetic insole was no more effective than
the sham as measured by the foot function index. About 60% of patients
from both groups noted improvement in heel pain after 4 weeks, which suggests
that the molded insole itself was effective in treating heel pain.
Electromagnetic Therapy
Authors: Smania et al., 200318
Description: Participants (18) who had painful trigger points from
myofascial pain syndrome received, over a period
of 2 weeks, either 10 sessions of rMS or a sham treatment. During each
20-minute treatment, two different coils from the rMS device delivered
pulsed ET when placed on each patient’s trigger point. Patients were evaluated
for 1 month after the treatments, using pain scales and clinical exams.
Findings: The participants who received the magnetic therapy had
significant improvement in all pain measurements and in some range-of-motion
measurements that persisted throughout the evaluation period. The placebo
group did not show any significant improvement.
Authors: Nicolakis et al., 200230
Description: Participants (32) with osteoarthritis of the knee
lay on a pulsed electromagnetic mat or a sham mat for 30 minutes twice
a day for 6 weeks. The primary outcome measures were pain, stiffness,
and physical function.
Findings: At the end of 6 weeks, physical function scores were
significantly improved for the treatment group compared with the sham
group. Pain and stiffness decreased for both groups, with what the study
authors called a “marked” placebo effect for participants using the sham
treatment. There was no significant difference between the groups for
pain and stiffness.
Authors: Thuile and Walzl, 200229
Description: Two prospective studies of
ET for low-back pain (100 participants) and whiplash
(92 participants). Half of the participants in each study received ET
twice a day for 2 weeks plus standard medications. The other half received
only standard medications. ET consisted of applying a low-energy, low-frequency
magnetic field cushion for 16 minutes and using a whole-body mat for 8
minutes. Evaluation of the low-back pain participants consisted of counting
the interval to reported pain relief and/or painless walking, and measuring
hip flexion to the point of pain. Participants in the whiplash study reported
their pain on a 10-point scale and had their range of motion measured.
Findings: In the low-back pain study, the ET group reported the
following compared with the control group: statistically significant pain
relief and/or pain-free walking 3.5 days sooner and increased ability
to bend at the hip. In the whiplash study, the ET group, compared with
the control group, had significantly decreased pain in the head, neck,
and shoulder/arm areas after treatment, and significantly greater range
of motion.
Authors: Pipitone and Scott, 200111
Description: Patients (69) with osteoarthritis of the knee
used a pulsed electromagnet or a sham device for 6 weeks. Devices were
placed on or between the knees for 10 minutes three times a day. The primary
outcome measure was a reduction in pain.
Findings: Pulsed ET significantly reduced pain, measured by several
scales, over a 6-week period in the treatment group, and did not produce
any adverse effects. No improvements were noted with the placebo-treated
group. The authors suggested further studies of pulsed ET for osteoarthritis
and other conditions.
Authors: Jacobson et al., 200110
Description: Participants (176) with osteoarthritis of the knee
were treated with ET for a total of 48 minutes per treatment session for
eight sessions during a 2-week period or sat near the electromagnet with
the magnet off (placebo). Participants used a subjective 10-point scale
to rate their pain level before and after each treatment and 2 weeks after
the final treatment. Patients also kept a diary of pain intensity before,
during, and 2 weeks after the trials, in which they recorded entries daily
upon waking and before going to sleep. They did not take any medicines
or use topical analgesics.
Findings: ET significantly reduced pain after a treatment session
in the magnet-on (treatment) group (46% reduction) compared to the magnet-off
(placebo) group (8%).
Authors: Pujol et al., 199817
Description: Patients (30) with localized injury to the
musculoskeletal system received 40 minutes of either rMS treatment
or sham treatment. Stimulation intensity was adjusted in each patient
to avoid excessive discomfort. Outcome measure was a 101-point pain rating
scale.
Findings: After one treatment, the pain score decreased significantly
in rMS-treated patients compared with sham-treated patients (59% versus
14% reduction). The effect persisted for several days.
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NCCAM Publication No.
D208
May 2004
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