ELECTRICAL STIMULATION FOR PAIN RELIEF Flashcards
Electrical stimulators capable of delivering pulsed currents, for __ nerve fibers through the skin using __
depolarizing peripheral (sensory), surface electrodes
Application of pulsed electrical current for inducing electroanalgesia
TRANSCUTANEOUS ELECTRICAL NERVE STIMULATION (TENS)
Primarily used to address pain/relieve pain
TRANSCUTANEOUS ELECTRICAL NERVE STIMULATION (TENS)
GATE CONTROL THEORY (GCT) by
Melzack and Wall
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
DESCENDING PATHWAY INHIBITORY TRACT (DPIT) aka
Endogenous Opiate System/Endorphin Release
Opiopeptines; also referred as
endorphins
and encephalins
controls the pain by binding to specific
opioid receptors in the nervous system
Opiopeptines
will allow the release of these
opiopeptines
Electrical simulation
Influences certain areas of the brain
(___ found in
the brain stem)
periaqueductal and ruffae nucleus
Strongly inhibits transmission of pain signals
from the spinal cord to the higher centers of
the brain
DESCENDING PATHWAY INHIBITORY TRACT (DPIT)
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
Convential TENS aka
high-rate TENS
Most commonly used mode of TENS in the clinics
CONVENTIONAL TENS
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
process by which there is
an adaptation that happens
Accommodation
Stimulus is modulated to
prevent accommodation
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
Convential TENS Parameter
Adequate amount of intensity should be
applied for the patient to comfortably feel
the electricity
Conventional TENS Parameters
Waveform, Pulse freq, Pulse Duration, Intensity, Treatment Time
Cameron
-
100-150 pps
50-80 usec
comfortable, tingling sensation
20-30 min
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
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
Acupuncture-like TENS
low-rate TENS
Repetitive stimulation of motor nerves to produce
brief repetitive muscle contractions/twitches;
ACUPUNCTURE-LIKE TENS
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
