ELECTRICAL STIMULATION FOR PAIN RELIEF Flashcards by Rai Christiana

Electrical stimulators capable of delivering pulsed currents, for __ nerve fibers through the skin using __

depolarizing peripheral (sensory), surface electrodes

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Application of pulsed electrical current for inducing electroanalgesia

TRANSCUTANEOUS ELECTRICAL NERVE STIMULATION (TENS)

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Primarily used to address pain/relieve pain

TRANSCUTANEOUS ELECTRICAL NERVE STIMULATION (TENS)

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GATE CONTROL THEORY (GCT) by

Melzack and Wall

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GATE CONTROL THEORY (GCT)

Substantia gelatinosa in lamina 2 @ spinal cord (allows the passageway of pain if the gates are open) –> Once the pain reaches the thalamus and the higher centers of the brain, it will be perceived as painful

Pain signals are transmitted by A-delta fibers and C fibers

Electrical stimulation will stimulate the heavy
myelinated and larger A-beta fibers, allowing faster conduction of nerve velocity going to the higher centers and will reach first the SG

o Inhibitory nature of SG is activated thus
closing the gate
o Pain signals cannot pass through the gate
o Majority of the pain sig

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DESCENDING PATHWAY INHIBITORY TRACT (DPIT) aka

Endogenous Opiate System/Endorphin Release

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Opiopeptines; also referred as

endorphins
and encephalins

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controls the pain by binding to specific
opioid receptors in the nervous system

Opiopeptines

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will allow the release of these
opiopeptines

Electrical simulation

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Influences certain areas of the brain
(___ found in
the brain stem)

periaqueductal and ruffae nucleus

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Strongly inhibits transmission of pain signals
from the spinal cord to the higher centers of
the brain

DESCENDING PATHWAY INHIBITORY TRACT (DPIT)

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DESCENDING PATHWAY INHIBITORY TRACT (DPIT) leads to

Leads to analgesia
Chemical in nature
Stays in the blood system of the body
therefore has a more lasting effect as
compared to GCT

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Convential TENS aka

high-rate TENS

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Most commonly used mode of TENS in the clinics

CONVENTIONAL TENS

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Uses short-duration high-frequency pulses to
produce comfortable sensation without muscle contractions to modulate acute pain (GCT)

o Can relieve pain d/t gate control theory
o Effect is not that long-lasting

CONVENTIONAL TENS

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process by which there is
an adaptation that happens

Accommodation

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Stimulus is modulated to

prevent accommodation

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Conventional TENS Accomodation

Decrease in frequency of action
potentials and decrease in
subjective sensation of the
stimulation when ES is applied
without variation

o Constantly applying a certain parameter
causes the nerve to just adapt
▪ No longer respond effectively to the
application of ES
▪ Gate control principle can no longer
be activated

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Convential TENS Parameter

Adequate amount of intensity should be
applied for the patient to comfortably feel
the electricity

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Conventional TENS Parameters

Waveform, Pulse freq, Pulse Duration, Intensity, Treatment Time

Cameron

-
100-150 pps
50-80 usec
comfortable, tingling sensation
20-30 min

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Conventional TENS Parameters

Waveform, Pulse freq, Pulse Duration, Intensity, Treatment Time

Michlovitz

Mono-/Biphasic PC
High: ~ 100 pps
Short: 50-100 usec
comfortable, tingling sensation
20-30 min

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Conventional TENS Parameters

Waveform, Pulse freq, Pulse Duration, Intensity, Treatment Time

Clinical

Biphasic PC
High: 80-110 pps
Short: 50-150 usec
comfortable, tingling sensation
20-30 min

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Acupuncture-like TENS

low-rate TENS

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Repetitive stimulation of motor nerves to produce
brief repetitive muscle contractions/twitches;

ACUPUNCTURE-LIKE TENS

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ACUPUNCTURE-LIKE TENS Stimulation of __ nerves to produce __ (activation of DPIT) Pain relief is more long-term

Aδ, brief sharp pain

ACUPUNCTURE-LIKE TENS Parameter Setting

Reaching the brief sharp pain even without visible muscle twitches is already sufficient enough to activate the DPIT

Acupuncture TENS Parameters Waveform, Pulse freq, Pulse Duration, Intensity, Treatment Time Cameron

- 2-10 pps 200-300 usec Visible muscle twitches (motor); brief sharp pain (sensory) 20-45 min

Acupuncture TENS Parameters Waveform, Pulse freq, Pulse Duration, Intensity, Treatment Time Michlovitz

mono/biphasic Low: <10 pps Long: >150 usec Visible muscle twitches (motor); brief sharp pain (sensory) 20-45 min

Acupuncture TENS Parameters Waveform, Pulse freq, Pulse Duration, Intensity, Treatment Time Clinical

Biphasic PC <10 pps >150 usec Visible muscle twitches (motor); brief sharp pain (sensory) 20-45 min

Combining sensory TENS (high frequency, short pulse duration) and motor TENS (low frequency, long pulse duration) Intensity up to patient’s maximal tolerance (DPIT)

BRIEF-INTENSE STIMULATION

Brief-Intense Stimulation Waveform, Pulse freq, Pulse Duration, Intensity, Treatment Time Michlovitz

Mono/Biphasic ~100 pps >150 usec Visible strong muscle twitches (motor) <15 min

Brief-Intense Stimulation Waveform, Pulse freq, Pulse Duration, Intensity, Treatment Time Clinical

Mono/Biphasic ~80-100 pps >150 usec Visible strong muscle twitches (motor) <15 min

*Aka point stimulation/electroacupuncture * Applied using a probe electrode over acupuncture points o Results to higher current density on the area * Pain relief via DPIT

HYPERSTIMULATION

Hyperstimulation Waveform, Pulse freq, Pulse Duration, Intensity, Treatment Time Michlovitz

Monophasic Low: 1-5 pps High: 100 pps Long:>250 usec Highest tolerated painful stimulus (noxious) 30-60 sec to each point

Hyperstimulation Waveform, Pulse freq, Pulse Duration, Intensity, Treatment Time Clinical

Monophasic 80-100 pps >150 usec Highest tolerated painful stimulus (noxious) 30-60 sec to each point

: pt will not feel anything even with ES

Subsensory

: intensity is increased therefore electricity can be felt in the body

Sensory

muscle contractions start to happen

Motor level

as intensity further increases, pain can be felt (tolerated painful stimulus)

Noxious level

* Burst: defined as series of pulses delivered in groups or packets * Stimulation is delivered in bursts * Pain relief via DPIT

BURST MODE TENS

Burst Mode Tens Waveform, Pulse freq, Pulse Duration, Intensity, Treatment Time Cameron

10 bursts 100-300 usec Visible muscle contraction (motor) 20-30 min

Burst Mode Tens Waveform, Pulse freq, Pulse Duration, Intensity, Treatment Time Michlovitz

<10 pps >150 usec Visible muscle contraction (motor) 20-30 min

Burst Mode Tens Waveform, Pulse freq, Pulse Duration, Intensity, Treatment Time Michlovitz

<10 pps >150 usec Visible muscle contraction (motor) 20-30 min

* Minimum frequency required for evoking tetanic muscle contraction * Causes high skin resistance

Low-Frequency Current (1-1,000 Hz)

* Causes lower skin resistance

Medium-Frequency Current (1,000-10,000 Hz)

Thermal effects

High-Frequency Current (>10,000 Hz)

effects ranges between the low-frequency and medium-frequency currents

Electrical

High skin resistance = pt has a tendency to feel discomfort when__-frequency currents are applied

low

__-frequency current by itself has no effect on the body

Medium

is originally used and by the time it enters the body, it will be combined to produce a low-frequency current which is responsible to produce a physiologic effect o Allows for more comfort

Medium-frequency current

2 waveforms both fall on the positive side and will add-up o If both fall below the isoelectric line, adding them up will produce a much lower peak

Constructive interference

If the two waveforms that are applied simultaneously and the first one produces a lower effect and the other one has a positive effect, it will only negate each other

Destructive interference

wavelengths are slightly different from each other ▪ There is a point where they will add up and there is a point where they can cancel out

Out-of-phase

If the waves are ___, both interferences will occur

out-of-phase

process where we produce a lower frequency from the 2 medium frequency currents o Series of constructive and destructive interferences

* Heterodyne

Amplitude modulated frequencies that are summated is now called the

beat ▪ Responsible for producing the physiologic effects

Sensory application

: 4 kHz

Motor application:

2 kHz

difference between the 2 original AC’s; typically between 1-200 Hz

Beat frequency

constant differences between the 2 circuits

Constant beat frequency/selective beat frequency

frequency between the 2 circuits varies within preselected ranges (modulated type to address accommodation)

Variable beat frequency/automatic or sweep beat frequency

Pain relief =

80-200 Hz

Motor application =

50 Hz or lower

Scanning of amplitudemodulated beats at an arc of ~45deg that allows current to conduct through a greater volume of tissue * Diffused pain

Quadripolar scanning

Maximum amplitude modulation effect occurs at 45deg to perpendicular lines extending between the 2 circuits * Localized pain

Quadripolar static

o Application of two-medium frequency currents via four electrodes so that they intersect in the tissues (quadripolar)

Quadripolar scanning mode/two-circuit scanning interference field

Modulation already happened in the machine before it is brought to the pt ▪ Beat frequency is delivered by 2 electrodes o Application of two-medium frequency currents by mixing the two currents in the stimulator prior to application via two electrodes (one-circuit); (bipolar)

Premodulated mode/Exogenous/Bipolar method

Created when three-circuit IFC is applied with three pairs of electrodes contained within two Y-shaped applicators that allows the three currents to intersect within the tissues o Depicts the 3D nature of our tissues

Hexapolar mode/Three-circuit IFC

Sensory effect

Cutaneous stimulation of sensory nerve fibers o Analgesic effect via GCT ▪ Wedensky Inhibition of type C nociceptive fibers: makes the stimulation more comfortable and addresses non-acute type of pains

Motor Effect

Synchronous excitation of the large diamater, lower-threshold and more excitable motor nerve fibers ▪ Versus physiologic muscle contraction → asynchronous excitation of motor nerve fibers ▪ Disadvantage: results to early fatigue o Gildemeister effect: IFC may also mimic pattern of normal physiologic muscle contraction (asynch) o Wedensky inhibition of motor nerve fibers ▪ If applied for prolonged period of time, IFC can inhibit muscle response d/t adaptation or loss of excitation of the nerves (refractory state) ▪ Variable beat frequency is important to prevent this phenomenon

Tens & IFC indication

Pain control

IFC Indication

* Relief of muscle spasm * Promote tissue healing * Edema reduction * Muscle re-education

Contraindications

* Over anterior cervical area *may activate the carotid nerves/vagus nerve = effect on heart and lung function * Rate-responsive or demand-type cardiac pacemakers or implanted cardioverter-defibrillators (ICD) * Deep venous thrombosis * Over abdominal, pelvic or lumbar areas of pregnant women in 1st trimester * Epileptic episodes * Over hemorrhagic area * Over cancerous area * Within 3m from SWD device

Precautions

* Over thoracic cage area * Over cranial area * Over metal implants * Confused or unreliable patients * Over damaged skin