A wealth of articles on Pulsing Electromagnetic
Field therapy (PEMF) technology is available. Following is a selection
of abstracts, articles and references on PEMF. This information has been
collected to indicate the benefits on the use of pulsing electromagnetic
field therapy and many are double blind, placebo controlled studies.
The Effect of Pulsed Electromagnetic Fields in the
Treatment of Osteoarthritis of the Knee and Cervical Spine. Report of
Randomized, Double-Blind, Placebo Controlled Trials.
Low-amplitude, extremely low frequency magnetic fields for
the treatment of osteoarthritic knees. A double-blind clinical study.
Pulsed Electromagnetic Field Therapy, PEMT. How does it
work?
Magnetic pulse treatment for knee osteoarthritis: a
randomised, double-blind, placebo-controlled study.
Electrochemical therapy of pelvic pain: effects of pulsed
electromagnetic fields (PEMF) on tissue trauma.
Evaluation of electromagnetic fields in the treatment of
pain in patients with lumbar radiculopathy or whiplash syndrome.
We assessed the efficacy and tolerability of low-frequency
pulsed electromagnetic fields (PEMF) therapy in patients with clinically
symptomatic knee osteoarthritis (OA) in a randomised,
placebo-controlled, double-blind study of six weeks' duration.
Pulsed magnetic field therapy and the physiotherapist
Treatment of migraine with pulsing electromagnetic fields:
a double-blind, placebo-controlled study.
The Effect of Pulsed Electromagnetic Fields in the
Treatment of Osteoarthritis of the Knee and Cervical Spine. Report of
Randomized, Double-Blind, Placebo Controlled Trials
OBJECTIVE. We conducted a randomized, double blind clinical trial to
determine the effectiveness of pulsed electromagnetic fields (PEMF) in
the treatment of osteoarthritis (OA) of the knee and cervical spine.
METHODS. A controlled trial of 18 half-hour active or placebo treatments
was conducted in 86 patients with OA of the knee and 81 patients with OA
of the cervical spine, in which pain was evaluated using a 10 cm visual
analog scale, activities of daily living using a series of questions
(answered by the patient as never, sometimes, most of the time, or
always), pain on passive motion (recorded as none, slight, moderate, or
severe), and joint tenderness (recorded using a modified Ritchie scale).
Global evaluations of improvement were made by the patient and examining
physician. Evaluations were made at baseline, midway, end of treatment,
and one month after completion of treatment.
RESULTS. Matched pair t tests showed extremely significant changes from
baseline for the treated patients in both knee and cervical spine
studies at the end of treatment and the one month follow-up
observations, whereas the changes in the placebo patients showed lesser
degrees of significance at the end of treatment, and had lost
significance for most variables at the one month follow-up. Means of the
treated group of patients with OA of the knee showed greater improvement
from baseline values than the placebo group by the end of treatment and
at the one month follow-up observation. Using the 2-tailed t test, at
the end of treatment the differences in the means of the 2 groups
reached statistical significance for pain, pain on motion, and both the
patient overall assessment and the physician global assessment. The
means of the treated patients with OA of the cervical spine showed
greater improvement from baseline than the placebo group for most
variables at the end of treatment and one month follow-up observations;
these differences reached statistical significance at one or more
observation points for pain, pain on motion, and tenderness.
CONCLUSION. PEMF has therapeutic benefit in painful OA of the knee or
cervical spine.
Trock D. et.al. Department of Medicine, Danbury
Hospital, CT. J. of Rheumatology
Low-amplitude, extremely low frequency magnetic
fields for the treatment of osteoarthritic knees: a double-blind
clinical study.
CONTEXT: Non-invasive magneto-therapeutic approaches to bone healing
have been successful in past clinical studies. OBJECTIVE: To determine
the effectiveness of low-amplitude, extremely low frequency magnetic
fields on patients with knee pain due to osteoarthritis. DESIGN:
Placebo-controlled, randomized, double-blind clinical study. SETTING: 4
outpatient clinics. PARTICIPANTS: 176 patients were randomly assigned to
1 of 2 groups, the placebo group (magnet off) or the active group
(magnet on). INTERVENTION: 6-minute exposure to each magnetic field
signal using 8 exposure sessions for each treatment session, the number
of treatment sessions totalling 8 during a 2-week period, yielded
patients being exposed to uniform magnetic fields for 48 minutes per
treatment session 8 times in 2 weeks. The magnetic fields used in this
study were generated by a resonator, which consists of two 18-inch
diameter (46-cm diameter) coils connected in series, in turn connected
to a function generator via an attenuator to obtain the specific
amplitude and frequency. The range of magnetic field amplitudes used was
from 2.74 x 10(-7) to 3.4 x 10(-8) G, with corresponding frequencies of
7.7 to 0.976 Hz. OUTCOME MEASURES: Each subject rated his or her pain
level from 1 (minimal) to 10 (maximal) before and after each treatment
and 2 weeks after treatment. Subjects also recorded their pain intensity
in a diary while outside the treatment environment for 2 weeks after the
last treatment session (session 8) twice daily: upon awakening (within
15 minutes) and upon retiring (just before going to bed at night).
RESULTS: Reduction in pain after a treatment session was significantly
(P < .001) greater in the magnet-on group (46%) compared to the
magnet-off group (8%). CONCLUSION: Low-amplitude, extremely low
frequency magnetic fields are safe and effective for treating patients
with chronic knee pain due to osteoarthritis.
Jacobson J. et.al. Inst. for Biophysical Research,
Jupiter, FL, USA
Pulsed Electromagnetic Field Therapy, PEMT. How does
it work?
All living cells within the body possess potentials between the inner
and outer membrane of the cell, which, under normal healthy
circumstances, are fixed. Different cells, e.g. Muscle cells and Nerve
cells, have different potentials of about -70 mV respectively. When
cells are damaged, these potentials change such that the balance across
the membrane changes, causing the attraction of positive sodium ions
into the cell and negative trace elements and proteins out of the cell.
The net result is that liquid is attracted into the interstitial area
and swelling or oedema ensues. The application of pulsed magnetic fields
has, through research findings, been shown to help the body to restore
normal potentials at an accelerated rate, thus aiding the healing of
most wounds and reducing swelling faster. The most effective frequencies
found by researchers so far, are very low frequency pulses of a 50Hz
base. These, if gradually increased to 25 pulses per second for time
periods of 600 seconds (10 minutes), condition the damaged tissue to aid
the natural healing process.
Pain reduction is another area in which pulsed electromagnetic therapy
has been shown to be very effective. Pain signals are transmitted along
nerve cells to pre-synaptic terminals. At these terminals, channels in
the cell alter due to a movement of ions. The membrane potential
changes, causing the release of a chemical transmitter from a synaptic
vesicle contained within the membrane. The pain signal is chemically
transferred across the synaptic gap to chemical receptors on the
post-synaptic nerve cell. This all happens in about 1/2000th of a
second, as the synaptic gap is only 20 to 50 nm wide. As the pain
signal, in chemical form, approaches the post-synaptic cell, the
membrane changes and the signal is transferred. If we look at the
voltages across the synaptic membrane then, under no pain conditions,
the level is about -70 mV. When the pain signal approaches, the membrane
potential increases to approximately +30 mV, allowing a sodium flow.
This in turn triggers the synaptic vesicle to release the chemical
transmitter and so transfer the pain signal across the synaptic gap or
cleft. After the transmission, the voltage reduces back to its normal
quiescent level until the next pain signal arrives.
The application of pulsed magnetism to painful sites causes the membrane
to be lowered to a hyper-polarization level of about -90 mV. When a pain
signal is detected, the voltage must now be raised to a relatively
higher level in order to fire the synaptic vesicles. Since the average
change of potential required to reach the trigger voltage of nearly +30
mV is +100 mV, the required change is too great and only +10 mV is
attained. This voltage is generally too low to cause the synaptic
vesicle to release the chemical transmitter and hence the pain signal is
blocked. The most effective frequencies that have been observed from
research in order to cause the above changes to membrane potentials, are
a base frequency of around 100Hz and pulse rate settings of between 5
and 25Hz.
Lecture abstract Dr. D. Laycock, Ph.D. Med. Eng.
MBES, MIPEM, B.Ed.
Magnetic pulse treatment for knee osteoarthritis: a
randomised, double-blind, placebo-controlled study.
We assessed the efficacy and tolerability of low-frequency pulsed
electromagnetic fields (PEMF) therapy in patients with clinically
symptomatic knee osteoarthritis (OA) in a randomised,
placebo-controlled, double-blind study of six weeks' duration. While the
treated group demonstrated improvement over different indices to the
contrary, the control group demonstrated none. There were no clinically
relevant adverse effects attributable to active treatment. These results
suggest that the unipolar magnetic devices are beneficial in reducing
pain and disability in patients with knee OA resistant to conventional
treatment in the absence of significant side effects.
Pipitone N. et.al. Rheumatology Department, King's
College Hospital (Dulwich), London, UK.
Electrochemical therapy of pelvic pain: effects of
pulsed electromagnetic fields (PEMF) on tissue trauma.
Unusually effective and long-lasting relief of pelvic pain of
gynaecological origin has been obtained consistently by short exposures
of affected areas to the application of a magnetic induction device.
Treatments are short, fasting-acting, economical and in many instances
have obviated surgery. This report describes typical cases such as
dysmenorrhoea, endometriosis, ruptured ovarian cyst, acute lower urinary
tract infection, post-operative haematoma, and persistent dyspareunia in
which pulsed magnetic field treatment has not, in most cases, been
supplemented by analgesic medication. Of 17 female patients presenting
with a total of 20 episodes of pelvic pain, 16 patients representing 18
episodes (90%) experienced marked, even dramatic relief, while two
patients representing two episodes reported less than complete pain.
Jorgensen W. et.al. International Pain Research
Institute, Los Angeles, California.
Evaluation of electromagnetic fields in the
treatment of pain in patients with lumbar radiculopathy or whiplash
syndrome.
Back pain and whiplash syndrome are very common diseases involving
tremendous costs and extensive medical effort. A quick and effective
reduction of symptoms, especially pain, is required. In two prospective
randomized studies, patients with either lumbar radiculopathy in the
segments L5/S1 or whiplash syndrome were investigated. Electromagnetic
devices are pulsed field (PEMF) and constant wave (CW) types. These
studies indicate both are effective, PEMF usually more quickly than CW.
Pulsed magnetic fields appear to have a considerable and statistically
significant potential for reducing pain in cases of lumbar radiculopathy
and whiplash syndrome.
Thuile Ch. et.al. International Society of Energy
Medicine, Vienna, Austria.
We assessed the efficacy and tolerability of
low-frequency pulsed electromagnetic fields (PEMF) therapy in patients
with clinically symptomatic knee osteoarthritis (OA) in a randomised,
placebo-controlled, double-blind study of six weeks' duration.
Patients with radiographic evidence and symptoms of OA (incompletely
relieved by conventional treatments), according to the criteria of the
American College of Rheumatology, were recruited from a single tertiary
referral centre. 75 Patients fulfilling the above criteria were
randomised to receive active PEMF treatment by unipolar magnetic devices
or placebo. Six patients failed to attend after the screening and were
excluded from analysis. The primary outcome measure was reduction in
overall pain assessed on a four-point Likert scale ranging from nil to
severe. Secondary outcome measures included the WOMAC Osteoarthritis
Index (Likert scale) and the EuroQol (Euro-Quality of Life, EQ-5D).
Baseline assessments showed that the treatment groups were equally
matched. Although there were no significant differences between active
and sham treatment groups in respect of any outcome measure after
treatment, paired analysis of the follow-up observations on each patient
showed significant improvements in the actively treated group in the
WOMAC global score (p = 0.018), WOMAC pain score (p =
0.065), WOMAC disability score (p = 0.019) and EuroQol score (p
= 0.001) at study end compared to baseline. In contrast, there were no
improvements in any variable in the placebo-treated group. There were no
clinically relevant adverse effects attributable to active treatment.
These results suggest that PEMF magnetic devices are beneficial in
reducing pain and disability in patients with knee OA resistant to
conventional treatment in the absence of significant side-effects.
Further studies using different types of magnetic devices, treatment
protocols and patient populations are warranted to confirm the general
efficacy of PEMF therapy in OA and other conditions.
Nicoḷ Pipitone, David L. Scott
Pulsed magnetic field therapy and the
physiotherapist
The therapeutic effect of the application of pulsed magnetic field
therapy (PMFT) has at last received world-wide recognition, although for
a long time many practitioners saw it only as an aid to fracture union.
Research has now shown that it has the potential to improve a wide range
of conditions, although few understood just how it achieved its
effectiveness. Extensive research has since been carried out to
determine the mechanism by which this occurs. For the physiotherapist,
presented with a wide range of clinical problems, PMFT is an invaluable
aid to the clinic.
Resolution of soft tissue injuries:
Over the past few years, research has shown that its effectiveness is
not through heat production - as is the case with some modern treatments
- but is at the cellular level. One significant outcome of this is the
effect it has on soft tissue injuries. As early as 1940 it was suggested
that magnetic fields might influence membrane permeability. It has since
been established that magnetic fields can influence ATP (Adenosine
Tri-phosphate) production; increase the supply of oxygen and nutrients
via the vascular system; improve the removal of waste via the lymphatic
system; and help to re-balance the distribution of ions across the cell
membrane. Healthy cells in tissue have a membrane potential difference
between the inner and outer membrane. This causes a steady flow of ions
through its pores. In a damaged cell the potential is raised and an
increased and an increased sodium inflow occurs. As a result,
interstitial fluid is attracted to the area, resulting in swelling and
oedema.
The application of PMFT to damaged cells accelerates the
re-establishment of normal potentials (Sansaverino) increasing the rate
of healing and reducing swelling. This can help to disperse bruising
also. A magnetic field pulsed at 5Hz with a base frequency of 50Hz can
have the same effect as an ice pack in that in that it causes
vasoconstriction.
Effects on fracture repair:
Acceptance of magnetic fields in medicine came about foremost in the
field of orthopedics. Low frequency and low intensity fields have been
used extensively for the treatment of non-union fractures. By 1979 this
method was approved in the USA as a safe and effective treatment for
non-union fractures; for failed arthroses; and for congenital pseudo-arthroses.
According to Bassett this method has been used by more than 6,000
surgeons. The success rate was over 80% for tibial lesions. No patient
suffered complications and biological side-effects included improved
healing and increased neural function. In-depth research carried out to
investigate this, shows that magnetic fields influence the process of
bone formation in the intercellular medium. Madronero showed that bone
healing was promoted by means of the influence of the magnetic field on
the crystal formation of calcium salts.
Pain reduction:
Pulsed magnetic field therapy has been shown to bring about a reduction
of pain, which again is due to action at the cellular level. Pain is
transmitted as an electric signal, which encounters gaps at intervals
along its path. The signal is transferred in the form of a chemical
signal across the synaptic gap and this is detected by receptors on the
post-synaptic membrane. A charge of about -70mV exists across the inner
and outer membranes, but when a pain signal arrives it raises this to
+30mV. This action causes channels to open in the membrane, triggering
the release of a chemical transmitter and allowing ions to flow into the
synaptic gap. The cell then re-polarizes to its previous resting level.
Research by Warnke suggests that PMFT affects the quiescent potential of
the membrane, lowering it to a hyper-polarized level of -90mV.
Transmission is effectively blocked since the pain signal is unable to
raise the potential to the level required to trigger the release of the
chemical transmitter. Again, the frequency of the applied magnetic field
is important, as the most effective frequency to produce this effect was
found to be a base frequency of 100Hz pulsed at between 5 and 25 pulses
per second.
Clinical applications:
The value of pulsed magnetic field therapy has been shown to cover a
wide range of conditions, with well documented trials carried out by
hospitals, rheumatologists and physiotherapists. For example, the
department of rheumatology at Addenbrookes Hospital carried out
investigations into the use of PMFT for the treatment of persistent
rotator cuff tendinitis. The treatment was applied to patients who had
symptoms refractory to steroid injection and other conventional
treatments. At the end of the trial, 65% of these were symptom free,
with 18% of the remainder being greatly improved.
Lau (School of Medicine, Loma University, USA) reported on the
application of PMFT to the problems of diabetic retinopathy. Patients
were treated over a 6-week period, 76% of the patients had a reduction
in the level of numbness and tingling. All patients had a reduction of
pain, with 66% reporting that they were totally pain-free. Many research
studies, including Lau, reported on the application of PMFT for
conditions such as sports injuries and for patients with joint and
spinal problems. Although these are too numerous to mention
individually, in almost every instance there was a reduction, if not
complete resolution of symptoms. Soft tissue injuries and joint pains
tended to be resolved within 5 days of treatment. Patients with cervical
problems and low back pain were also successfully treated, whereas
previous treatment with ice, traction and other therapies had been
unsuccessful. In yet another trial, the effect of applying PMFT to
sufferers of Multiple Sclerosis was investigated (Geseo) 70% of
sufferers had a reduction of weakness, pain and spasticity, with 50%
reporting improvement of their bladder incontinence. Through the
evaluation of hundreds of research papers, a number of points have been
established regarding PMFT: The field must be pulsed, with low frequency
to achieve the best effect.
Different conditions require different frequencies. For example, 5Hz
causes vasoconstriction whilst 10Hz and above causes vasodilatation.
Biological effectiveness is achieved in just 10 minutes for most
injuries, so that long treatment sessions are not required. When used at
the correct level there are no recorded side effects. Although PMFT is
not yet recommended for use during pregnancy or in the presence of
tumors, there are papers to suggest that magnetic fields can inhibit the
growth of tumors.
Dr. D. C. Laycock, Ph.D. Med. Eng. Westville
Consultants
Treatment of migraine with pulsing electromagnetic
fields: a double-blind, placebo-controlled study.
The effect of exposure to pulsing electromagnetic fields on migraine
activity was evaluated by having 42 subjects (34 women and 8 men), who
met the International Headache Society's criteria for migraine,
participate in a double-blind, placebo-controlled study. During the
first month of follow-up, 73% of those receiving actual exposure,
reported decreased headaches (45% substantial decrease, 14% excellent
decrease) compared to half of those receiving the placebo (15% worse,
20% good, 0% excellent). Ten of the 22 subjects who had actual exposure
received 2 additional weeks of actual exposure, after their initial
1-month follow-up. All showed decreased headache activity (50%
substantial, 38% excellent). Eight of the subjects in the placebo group
elected to receive 2 weeks of actual exposure after the initial 1-month
follow-up with 75% showing decreased headache activity (38% substantial,
38% excellent). In conclusion, exposure to pulsing electromagnetic
fields for at least 3 weeks is an effective, short-term intervention for
migraine.
Sherman R. et.al. Orthopedic Surgery Service,
Madigan Army Medical Center, Tacoma, WA, USA.
|
