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Samenvatting SV physical applications
- Cours
- Physical Applications
- Établissement
- Universiteit Antwerpen (UA)
SV van de theorielessen
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Chapter 1 – Pain decreasing currentsSV RK UIT CURSUS/ PPT
Electrophysical agents = general medical treatment that uses some kind of electrically rated energy in order to obtain
a physiological effect in the body
Pijn reduceren wilt zeggen dat er minder pijn zal zijn maar EPA realiseert geen cure, alleen een symptomatisch effect
en wordt in een behandelplan toegepast icm met meerdere technieken.
Spierstimulatie wil zeggen dat de elektrische current spieren kan doen contraheren voor zowel diagnose als
behandeling. De diagnose gebeurt adhv een S/D curve, behandeling houdt in dat men de kracht en contractiliteit van
de spieren behoudt of verbetert of de spieren doet relaxeren.
De te bekomen cellulaire effecten houden chemische reacties in op cel niveau zoals bvb tissue repair of lokale
hyperaemie. Deze kunnen helend werken en aldus de pijn doen verdwijnen (causaal effect).
Lokaal/ Slowing down nerve conduction velocity TENS
perifeer -> vertraagde doorgave van (pijn)signalen doorheen de afferente zenuwen
-> symptomatisch
Hyperaemie MET
-> Toename van de bloedcirculatie lokaal tgv vasodilatatie -> meer nutrienten en afvoer
afvalstoffen
-> monophasic mA (MET) voor sterk effect
Reductie van substance-P TENS
-> Neurotransmitter die pijn signaliseert aan de hersenen MET (?)
Weefselherstel MET
-> toename van energie (ATP) voor herstel
-> regulatie van voltage gated ion channels helpen -> reguleert Ca2+ en Na+ influx
Spinaal Gate control theory of pain TENS
-> dikkere afferente vezels stimuleren om meer info rii de hersenen te krijgen -> deze MET (?)
overrulen de pijninfo die van de dunnere vezels komen
Centraal Ascending/ Descending pathways TENS
-> current neemt ruimte in in beide pathways
Endogene opiate release TENS
-> opiaten (oa endorfine) -> 4HZ gaat de … stimuleren dus opiate release
Site ABB Effect (1) Effect (2) Current
Local NCV Slowing down nerve conduction Symptomatic TENS
velocity
LH Local hyperaemia Symptomatic or causal(?) MET (minimal effect)
SP Reduction of substance-P symptomatic or causal(?) TENS – MET(?)
TR Tissue repair Causal MET
Spinal GC Gate control theory of pain Symptomatic TENS – MET (min. effect)
Central AD Ascending and descending pathways Symptomatic (TENS)
E Endogenous opiate release Symptomatic (TENS)
,SUMMARY
From a variety of pain decreasing currents only TENS and MET have been selected. Using TENS or MET currents for
pain control is strictly related to the place where the physiological effects can take place in the body. The options are:
at stimulation site, in the dorsal column (spinal) and in the brain (central).
At stimulation site slowing down nerve conduction speed and reducing substance-P are significant but symptomatic
for TENS current and the conduction speed effect is rather short-lived. Local hyperaemia is a pure monophasic (direct)
current effect. It can cure but needs many treatment sessions. TENS current does not cause it and MET only to a
minimum. Tissue repair is a pure MET effect, it treats the cause of the tissue damage if it is still curable.
At the dorsal column TENS current can very well cause the symptomatic gate control effect. In the brain TENS current
activates descending inhibitory pathways and the production of opiates (endorphins) with symptomatic but strong
pain reducing effects.
Sensory stimuli evoked by TENS currents travel over complex pathways from afferent nerves over the spinal cord to
the brain and cause different kinds of descending effects including motor responses and sympathetic nerve activity.
The anatomical structures where the currents can have their physiological effects relate to type I to IV afferent fibres
and lamina in the dorsal horn. Substance-P plays an important role in the onset of soft tissue inflammations and pain.
In this way inflammation is a part of a natural recovery system and some electric currents can either amplify or inhibit
this reaction.
Additionally, research has shown that TENS currents with short pulse width selectively stimulates large afferent fibres
which supports the gate control pain decreasing mechanism. By increasing the pulse width the TENS current will
address small afferent fibres as well. Finally a frequency of 100 Hz plays an important role in obtaining
electroanalgesia.
,PARAMETERS
The previous paragraph explained what currents to use and what the pain decreasing effects are. At the same time
one needs to understand the physiological changes in the body (= why). So, having had the “what” and the “why”
question, the only issue remaining is, how to do this? The answer lies in using the correct parameter settings. The
parameters have been selected in a random order, there is no hierarchy.
FROM PULSE SHAPE TO INTENSITY (the PPT slides will lead you step by step through every parameter)
PARAMETERS SUMMARY
1. Pulse shape: in terms of perception there is little difference between the different pulse shapes of the same electric
current type, the sensation is limited to a bit softer or harder. For TENS & Co, probably only the mono/biphasic is
important, but with MET there can be an important difference, according to Kirsch (2002).
2. Frequency: a higher frequency means more stimuli which equals more current and consequently more sensation,
but a higher frequency feels softer and a lower one is a bit more aggressive, up to ±25 Hz also more beating. The choice
is linked to the pain decreasing mechanism.
3. Pulse width: a wider pulse means longer lasting stimuli which corresponds to more current and therefore more
sensation, sometimes 10 µs more or less is sufficient for a noticeable difference, the difference is much bigger than
with the frequency. The choice is important in the (a)selective stimulation of thick or thick and thin afferents. This
corresponds to the choice of the pain decreasing mechanism GC or E.
4. Pulse interval: meant to avoid adaptation, both TENS and MET use this possibility.
5. Modulation: means that the frequency and/or the pulse width and/or intensity will vary within set or adjustable
limits. Also meant to avoid adaptation. Little frequency variation (90-100 Hz) is hardly noticed. The 50-100 Hz variation,
which suits very well in gate control, is clearly felt.
6. Electrodes: for TENS vertebral and/or local; with MET always right through the pathology! With MET, the treatment
time also plays a role: 20 minutes with probe/plate electrodes and ≥30 minutes with adhesive electrodes.
7. Treatment time: linked to the PDM: for GC 20 to 30 minutes; for Enk 30 minutes; for βE 40 minutes, for TR 30 to 60
minutes. Too short treatments usually miss their goal and too long treatments often cause habituation, so that after
a while no pain relief occurs. Repeat treatment several times per day for TENS and usually once every 2 days for MET.
8: Intensity: related to the PDM: for GC above the motor threshold; for Enk above the sensory threshold; for βE just
below the nocisensory threshold; for TR ±600 µA!
Parameter 9, CC vs CV is common to pain relief and muscle stimulation. This parameter cannot be used incorrectly in
pain relief and only becomes important with muscle stimulation. Hence, CC and CV are only discussed at the end of
this chapter.
TWO CURRENTS
As pointed out before this EPA course discusses only two electric currents, TENS and MET. The other known and
sometimes also popular current types will add nothing new because they have just the same physiological effects as
TENS and MET and are therefore only mentioned briefly in Appendix 1. They are available in both tabletop
electrotherapy devices as well as in portable units. The latter makes an important reference to parameter 7, the
treatment time.
PARAMETER CONCLUSIONS
✓ Some parameters do not influence the final result very much, nevertheless the parameter setting can be very
specific!
✓ A few parameters leave only little room for variation. Deviating from a specific setting will almost certainly reduce
or even eliminate the physiological effect. This is the reason why this EPA course is a call to apply the techniques
accurately.
✓ In order to adequately work with the treatment time parameter, portable devices are essential in the event of
chronic pain syndromes (repeat several times on daily basis) or in pathologies with a lot of tissue damage (long
treatment times).
, ✓ Since too low intensities do not cause any physiological effects, and too high intensities may either cause tissue
damage or work on an unintended pain relief mechanism (endorphins instead of gate control), the intensity is
reasonably difficult to adjust in TENS currents. In the event no physical effects occur, an ethical problem has been
caused and in the second possibility, the treatment misses its goal. Consequently, if the patient (e.g. due to problems
with understanding or fear for electric current) has difficulties in setting the correct intensity, the use of TENS is not
really appropriate. This problem does not arise with MET current!
PHYSIOLOGICAL EFFECT DISCUSSION
SLOWING DOWN NERVE CONDUCTION VELOCITY (NCV)
✓ Wherever the electrodes are, peripheral or vertebral, the effect always works but it is short-lived. About five
minutes after treatment the effect is gone again.
✓ This is a symptomatic effect and therefore does not cause healing! If total recovery occurs, it is not the result of
NCV. In chronic pathologies, the symptomatic effect is not a counter argument.
✓ The authors did their research with a TENS current, but the effect is likely to occur with the other milliamp currents
too. Due to its minor after-effects, it is practically impossible to use! Fortunately, empirical data shows that the effect
overlaps with the effects of gate control and endorphin release.
LOCAL HYPERAEMIA (LH)
✓ Local hyperaemia can only be caused by direct (monophasic) currents. This means only by a MET current where the
effect is very low due to the microamp level of the intensity. It is not caused by a TENS current.
REDUCTION OF SUBSTANCE-P (SP)
✓ It is reported as a high frequency TENS current effect but to date it remains unclear whether it can be caused by a
MET current.
✓ Though it remains uncertain the effect is estimated to be symptomatic and therefore does not cause healing! If
total recovery occurs, it is not the result of SP. In chronic pathologies, the symptomatic effect is not a counter
argument.
TISSUE REPAIR (TR)
✓ This is a cellular effect at stimulation site and can only be caused by a MET current, a TENS current does not
contribute to this.
✓ The MET current is very much alike the electric activity at cell level and causes different kinds of chemical changes
to the cells. In turn these chemical changes contribute to a faster healing of pathologies that can still recover
completely. As such it treats the cause.
✓ The effect only occurs if the current flows through the tissue in the correct way; causing, in the use of MET, the
electrode parameter to be the most complex one.
✓ A treatment time of 20 to 60 minutes is recommended. Longer treatment is permitted in the treatment of acute or
persistent injuries. After the treatment, in order to give the tissue time to recover, a break of at least 2 days is
recommended. The effect usually does not appear right after the treatment, it may even take a few treatments before
the tissue recovery starts and the pain decreases. Moreover, it is cumulative in the following treatments (= 2nd
treatment already has a longer lasting and better effect than the 1st, 3rd better than 2nd, etc). Sometimes the
problem also appears to be definitely gone after a single treatment!
GATE CONTROL (GC)
✓ The effect is very strong in TENS currents, with MET however, it remains unclear whether this mechanism works.
Based on empirical data, the effect seems to be minimal.
✓ This is a symptomatic effect and therefore does not cause healing! If total recovery occurs, it is not the result of GC.
In chronic pathologies, the symptomatic effect is not a counter argument, on the contrary in many cases the effect is
very complementary to medication.
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