1.8.2 MET
This again is different because microcurrent works at the microampere
level. In almost all cases, maximum intensity (600 – 1000 µS) should
be set. Most patients won’t even feel this. Sometimes a sharp spikey
sensation is reported but that does not influence the effect. If the
patient reports these sharp feelings as uncomfortable the intensity
should be decreased until it disappears. For back problems, this will
probably never happen.
2. Treatment Effects
How do we know when the effect is good or fair? What does the patient
report? It is important to have an answer to these questions because
correcting one single parameter can influence results.2.1
Gate-Control
Patients report first signs of pain decrease after 10 to 15 minutes of
stimulation. Most patients say they have less pain than before
treatment but the pain isn’t gone. Effects usually do not last longer
than a few minutes. Those who reported unbearable pain before
treatment usually have no effect at all after it. There is no evidence
for this in the literature but it is often observed, probably because
every system has its limits. Conclusion: intense pain shouldn’t be
treated with TENS on gate-control basis and the effect is limited in
time.
2.2 Endorphin Release
This effect usually lasts longer than controlling the gates. However,
the same problem occurs because even with pain decrease lasting 60
minutes after at least 20 minutes of stimulation, the effect is still
limited. To get some comfort the patient will have to switch the TENS
on again. The endorphin effect lasts longer than the enkephalin or
dynorphin effect. Most authors describe the endorphin release as a
powerful tool to reduce pain, more powerful than the gate-control.
2.3 Other Effects
Sometimes “counter-irritation” and “Wedensky-inhibition” are mentioned
as pain reducing effects. Probably only poor effects come from it and
regular TENS frequencies are too low to cause this Wedensky-effect.
Certainly, the patient won’t be pain free on this basis for hours. So
let’s deny them for the purpose of this comparison. The observations
made by Cheng indicate that currents above 5 mA will cause the ATP
production and aminoisobutyric acid uptake to drop under control
levels at electrode site. If the electrode site is the place of
injury, this indicates that the current may cause a slowdown in the
healing process. Due to electrode position in back pain, this may be
no problem in this kind of treatment. |
2.4 Cellular Level
MET causes no gate to close, neither is there an endorphin effect with
trunk electrode positions. It has an effect at the cellular level,
very close to the cause of the problem. Na2+ and Ca2+ seem to
penetrate better through the cell membrane. Scientific reports tell
there’s an increase in ATP production by 500 percent, plus 30-40
percent aminoisobutyric acid, and 255 percent hydroxi proline. The
mechanisms aren’t fully understood but usually the patient is
pain-free or has at least a very good effect after the first
treatment. Effects can last a few minutes up to several hours or in
rare cases, days. Nevertheless, if the pain comes back there is more
good news because the effects are cumulative; if the effect doesn’t
last long enough after the first treatment, it usually does after the
second or third one. The intensity of pain decrease is an important
parameter also because microcurrent usually manages to treat quite
intense pain. There are limits, of course, but an overall impression
is that the pain decreasing effects are much better than those of
endorphin release.3. Indications and Contra-indications
Usually TENS works well when used with facet joint problems. Other
causes sometimes (even when indicated) give less of a result.
MET responds well to almost every kind of back pain: facet joint,
disc, degenerative joint disease, sacroiliaca joint, sub-clinical
involvement of an organ, no matter what the cause.
Contraindications of TENS are known and will not further be discussed.
Interestingly, there are almost no contraindications for MET. Of
course the use of an old demand-type pacemaker is on the list as is
pregnancy but other than that, MET can be used almost without
restrictions.
4. Conclusion
To achieve its effects, TENS works either on gate-control or on
gate-control and endorphin release, thus having a symptomatic pain
relieving effect. Other effects on the pain will probably only be
complementary. MET has a completely different mechanism, which at this
time is not fully understood, but works on a cellular level and
probably has its effects much closer to the cause of the injury. It
looks as if TENS is going to lose this competition.
TENS should only be used in vertebral electrode positions, whether the
problem is a backache or not. MET on the other hand must be used in
electrode positions with the injury (or the disease) between the
electrodes. MET will, in most cases, be much more satisfying than TENS
because of the longer lasting and more intense effects. However, a
trial and observation approach is recommended. Some prefer the TENS
sensation over the subthreshold MET treatment.
Last but not least, one shouldn’t forget that literature indicates
that there could be a negative effect of milliampere current on
pathological tissue. Due to the necessary electrode positions in the
treatment of back pain, this may be less important here. Although this
paper is about electrotherapy and back pain, never forget that other
therapy techniques (manual therapy, osteopathy, nutrition and exercise
programs, even surgery etc.) may also be necessary to solve the
patient’s problem. |
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|
European perspective: a comparison between TENS and MET.
“Scientific
reports tell there’s an increase in ATP production by 500 percent,
plus 30-40 percent aminoisobutyric acid, and 255 percent hydroxi
proline.”