Electrotherapy’s Role in Pain
Management
Philadelphia 2004
Joseph A. Gallo, ATC, PT
Associate Professor
Hesser College
Applied Medical Sciences
Clinician Performance Rehab
Workshop Agenda
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Electrotherapy for
pain: why use it?
General
electrophysiology a
practical review
Waveform principles
Clinical Selection of
waveforms and
parameter settings
Introduction
z Why
the interest in electrotherapy???
z Why the confusion???
z Importance of terminology
z “The Parameters”
z Why treat the pain impairment???
Fundamentals
“we can only build as high as our foundation is deep” - unknown
The pain Impairment
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What is pain?
What Physiologic and psychological effect does it
have on our patients?
Inhibition of muscle
Lack of confidence, tentativeness, depression
Poorly managed acute pain can lead to chronic
pain, chronic inhibition of mm, disuse atrophy and
contracture
Concepts Related to Pain
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Subjective response
Central Biasing
Psychosocial component of pain appears to be
accentuated when other life stressors are
predominate
Role of positive belief systems and attitude
Ethnicity1
1. Zborowski M: People in Pain. Sanfrancisco, Jossey-Bass, 1969
Treating Pain: The Controversy
Argument #1
¾ “Using passive modalities to treat pain is of
no use; the cause of the pain must be
identified and resolved”
Argument #2
“ Pain interferes with treatment of the
underlying pathology and if left untreated
can lead to further dysfunction”
Assessing Pain
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Pain assessment is critical to assessing the
effectiveness of electroanalgesia treatments
Numeric pain scale (NPS) 0-10
High test retest reliability (ICC = .96)1
Strong correlation to VAS (r=.85)2
Visual analogue Scale (VAS)
1.
Ferraz et al. J Rheumatol. 1991;18:1269.
2.
Paice et al. Cancer Nurs. 1997;20:88-93
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Assessing Pain Continued
z Body
Pain Diagram
z Mcgill pain questionnaire
z Interview/history/symptom behavior
Pain/Inflammatory Cycle
Neurobiology of Pain
Electrotherapy and Pain
Control
z Theories
of pain
control using
electrotherapy
– Gate Control
Theory
– Opiate-mediated
Control
Gate Theory of Pain Control
z Melzak
and Wall 1965
z Substantia Gelatinosa and T-cell (dorsal
horn of SC) controls nerve impulses to
the brain. Only allows one impulse
through at a time; like a gate.
– A-delta afferents “fast pain” 4-30 m/s
– C- fibers “slow pain” 0.5 -2 m/s
– A-beta afferents “pleasant/fast” 36-72 m/s
T-cell
Pain
Sensory
Motor
Brain
Opiate-Mediated pain Control
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Descending endogenous opiate system
Supraspinal pain modulation that produces a descending
inhibition of pain chemically at the dorsal horn of the spinal
cord
The spinal gate is closed from influence from above
The periaductal gray matter secretes endogenous opiates
in the blood plasma and cerebral spinal fluid
Endogenous opiate peptides - enkephalins, beta-endorphin
– Endorphin means “Morphine Within” – longer lasting
pain suppression
– Enkephalin means “Within the Head” – shorter acting
pain suppression
Opiate-Mediated pain Control
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Chronic pain patients have been found to have
below normal levels of endorphins in their
cerebral spinal fluid
Endorphins have been shown to increase in the
cerebral spinal fluid with twitch level electrical
stimulation.
Goal of electrotherapy is to boost the levels of
Endorphins in a patient
What is Electrotherapy?
z It
is the application of electrical stimulation
transmitted through the body via electrodes
for therapeutic purposes.
z The current flows through the body from
one electrode to the other and causes
different physiological reactions depending
on the type of current selected, the
parameters of the selected current.
Review of Electrotherapy
Currents: Yes! It Is This Simple
Electrotherapy Currents
Pulsed Current
Alternating Current
Direct Current
Pulsed Current
Alternating Current
Direct Current
Selecting Electrotherapy
Parameters: Terminology
z “Electrotherapy
is about building pulses
(PC) or cycles (AC)”
z “The ht (amplitude), Width (phase or cycle
duration), and frequency are maniplulated
to create a desired physiologic response”
Pulse (PC) and Cycle (AC)
Characteristics
z Amplitude:
(intensity) mA = “how tall”
z Width: microseconds
¾ Phase duration (Pulsed current)
¾ Cycle duration (alternating current)
™ Carrier frequency of 2500 Hz = 400
microseconds
™ Carrier frequency of 5000 Hz = 200
microseconds
Strength Duration Curve: the basis
for selection amplitude and “width”
Frequency
z Refers
to how many times per second the
pulse or cycle is delivered
z Termed beat frequency when AC is used
z Difference between carrier frequency and
beat frequency
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Carrier frequency indirectly describes cycle
duration
General Electrophysiology
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Clinical Stimulators
– Patients tissue
Generic Stimulator
completes an electrical
circuit
– The lead wires carry the
current from the
stimulator through the
electrodes to and
Anode positive pole
Cathode negative pole
through the patient
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– Skin is a resistor
impeding current flow
Generic Patient
– Subcutaneous tissue is a
conductor
General Electrophysiology
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Target Tissue
Generic Stimulator
– Sensory, motor, or pain nerve
fibers
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The current flows through
the target tissue to the other
electrode and up the other
lead wire to the stimulator
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-
Generic Patient
The patient completes the circuit
Electrode Issues
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Electrodes should be
placed so the flow of
current can reach the
target tissue
The farther apart the
deeper the penetration
Placed too close the
potential exists for
greater concentration
Superficially this can
result in discomfort
Choosing appropriate electrode
size
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Small electrode
(ex: 2 x 2 inches)
Increases current
density
Recruits fewer motor
units
More uncomfortable
Large electrode
(ex: 4 x 5 inches)
¾ Decreases current
density
¾ Recruits more motor
units
¾ More comfortable
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Electrode Skin Interface
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The skin is a resistor to
the flow of current
– Good skin preparation is
important
– To lower impedance clean
the skin (alcohol or soap)
– Proper electrodes and
conductive medium are
essential
– Pearls and pitfalls
Electrode Placement
Strategies For Pain
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Bracket structure
a. Proximal / Distal
b. Medial / Lateral
c. Anterior / Posterior
Directly over the site of
pain
Interferential is a quad
polar (4) electrode
application. The area
should be bracketed “X”.
Bi-polar placement
Electrode Placement
Strategies Cont..
Structure and
Innervation
a. Major nerve root
b. Dermatome
c. Superficial
peripheral nerve
d. Acupuncture and
trigger points
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b
Quad-polar placement
Literature review of applications: USA
Application
Pain Management
Acute
Chronic
Spasms
Post-Operative
Muscle Weakness
Min to moderate
Moderate to Sever
Disuse Atrophy
Re-education
Increase ROM
Prevent Venous
Thrombosis
IFC
Premod
VMS
HVP
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yes
Inflammation / Edema
Increase local
circulation
Tissue healing
Spasticity
management
Contracture
management
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MicroCurrent
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Russian
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Three Categories of
Electrotheraputic Currents
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Direct Current:
Historically refereed to
as “Galvanic Current”
involves the
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continuous or
0
uninterrupted flow of
charged particles.
Clinical apllications
– Iontophoresis
– Stimulating denervated
muscle
Direct Current
Alternating Current
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Historically referred
to as “Faradic
Current” involves the
continuous or
uninterrupted bidirectional flow of
charged particles.
– Interferential
Stimulation
– Premodualted
– Russian
Beat Frequency: 100 Hz
Pulsed Current
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Pulsed or interrupted
current is an isolated
unit of uni- or bidirectional movement
of charged particles
that periodically ceases
for a finite period of
time.
– Twin Peak High Volt
Pulsed Current
– Monophasic, biphasic
VMS™, Microcurrent,
Common TENS, Low
Volt
Waveforms: various
configurations of the 3
electrotherapy currents
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High Volt Pulsed current
Biphasic
VMS™
Premodulated
Interferential
Russian
Microcurrent
High Voltage Pulsed Current
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Volt current is a rapid succession
of two brief high voltage impulses. The
current flows in only one direction,
which is determined by the selection of
either a “positive” or “negative” polarity
setting.
VMS™
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VMS™ a
trademarked name
of the Chattanooga
Group
Variable Muscle
Stimulation
– Symmetrical
Biphasic Square
Waveforms with a
100 mSec interphase
interval
Premodulated
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The two medium
frequency sine
waves are mixed in
the system and
delivered to the
patient with two
electrodes.
Premodulated Current
Beat Frequency: 100 Hz
Premodulated Current – is simply taking two alternating
medium frequency currents mixed within the electronics of the unit
and delivered through two electrodes.
Clinical Benefits
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Comfortable
Simple two pad
setup
Easily applied to
small joints of the
upper extremity
Acute or chronic
pain
Interferential
Quad-Polar
z Alternating
Current
z Continuous medium-frequency sine wave
z Uses two channels of differing carrier
frequencies to create a “beat” frequency
within the tissues.
– Scan - amplitude modulation
– Sweep - frequency modulation
– Intensity - output amplitude
Interferential
Channel 1
5,000 Hz
Channel 2
5,100 Hz
Interferential Characteristics
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Amplitude modulated, medium frequency, sine wave
Interferential Current – is simply taking two channels of
alternating medium frequency current and arranging the electrodes in
a crossing pattern.
Ch. 2
Ch. 1
Ch. 1
Ch. 2
Clinical Benefits
z Comfort
z Targeting
hard to
reach tissues (e.g.subscapularis)
z Pain modulation
– Acute
– Chronic
Acute or chronic pain
Russian
z Characteristics
– Sinusoidal alternating current with a 2,500
Hz carrier frequency.
– Current modulated at 50 Hz
2500 Hz
Burst
Microcurrent
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Subsensory level
Microcurrent wave
forms vary btwn
manufacturers
Pulsed current
Alternating current
Low intensity direct
current
Clinical Decision Process: choosing a
waveform to meet your objective
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Concept: “the waveform
is not the treatment”
We use waveforms to
deliver a specific
electrotherapy
intervention (e.g. sensory
level electroanalgesia)
Always choose treatment
first than choose suitable
waveform
International overlay
Options
There are 5 waveforms
approved for pain
management by the
FDA.
z Interferential Quad-Polar
z Premodulated Bi-polar
z Microcurrent
z TENS – Symmetrical
and Asymmetrical
Biphasic
Electrotherapy Treatments for
Pain Modulation
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Sensory level electroanalgesia (AKA: high frequency
TENS, Conventional Tens)
Waveforms - IFC, Premod, HVPC, Biphasic
Motor level electroanalgesia (AKA: low frequency
TENS, acupuncture like TENS)
Waveforms - IFC, Premod, Biphasic
Brief Intense TENS (need a unit with on/off time)
Waveforms - Biphasic, “Russian” (AC)
* High Intensity Noxious Electrical Stimulation for pain
modulation
Sensory Level Electroanalgesia
AKA: High frequency TENS or Conventional TENS
Acute pain management
Phase Duration: 2-50 microseconds
Frequency: >80 pps
On/off time: none
Amplitude: Perceptible tingling, no motor
response should be elicited
Duration of Rx: 15-30 min
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-Amplitude, frequency or duration modulations can be used to minimize accommodation-
Mech of action: segmental non-opiate, gate control theory
Sensory Level Electroanalgesia
Using the IFC or Premod
waveform
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Acute Pain Management
Gate Control
4 pad application (IFC), 2 pads (premod)
– Carrier frequency: 5000 HZ (usually preprogramed)
– Beat Frequency: 80-150 Hz, fast sweep
– Intensity Level: Sufficient to produce a moderate
strong, sensory tingling effect, with no motor
response
– Duration: 20-30 minutes
Interferential Stimulation: De Domenico Ph.D
Sensory Level Electroanalgesia
Clinical Application Notes
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Believed to relieve pain through the gate control theory of
pain modulation via hyperstimulation of A-beta nerves
Treatment of choice for acute conditions
Amplitude: increase to twitch and back off slightly
Literature reports little pain relief post Rx; pain relief
beyond Rx time may occur if pain-spasm cycle is
interrupted
Waveforms: Pulsed Current, *HVPC, IFC(AC), Premod
(AC)
Robinson AJ, Snyder-Mackler L. Clinical Electrophysiology. 2nd ed. Williams &
Wilkins.
Introduction to Motor Level
Electroanalgesia: “Twitch Level
Stimulation”
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Endorphins are released at a pulses rate
range of 1 to 15 pps (approx.) Twitch level
stimulation
Enkephalins are released at the higher pulse
rates of 80 pps and up. Twitch level
stimulation
Endorphin induced pain suppression lasts
longer than pain suppression induced by
enkephalins
Motor Level Electroanalgesia
AKA: Low frequency TENS, Acupuncture like Tens, opiate
induced electroanalgesia, twitch level stimulation
Phase Duration: ≥ 150 microseconds
Frequency: 2-4 pps (≤ 10 pps is acceptable)
On/off time: None
Amplitude: Strong visible muscle contraction
Duration of treatment: Literature suggests 3045 minutes
Robinson AJ, Snyder Mackler L. Clinical Electrophysiology
Motor Level Electroanalgesia
Using Premod or IFC waveform
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Mode: 2 pad application(premod)
4 pad application (IFC)
Carrier frequency: 2500 – 5000 Hz (usually
pre-programed in machine (e.g. Chatt vectra =
5000Hz)
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Beat Frequency:1 to 10 Hz or 2 Hz constant
On/off time: none
Intensity Level: Strong visible muscle
contraction
Duration: 30-45 minutes
Interferential Stimulation: De Domenico Ph.D
Motor Level Electroanalgesia
Clinical Application Notes
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Believed to reduce pain through the activation of
endogenous opiates
The literature reports greater carry over of pain
relief; up to several hours
Research suggests that stronger contractions
produce greater analgesia
Not a good choice for acute injuries
Waveforms: pulsed currents, IFC (AC), and
Premod (AC)
High Intensity Noxious
Electrical Stimulation for Pain
Modulation
Type of Stimulator: Alternating Current unit
Carrier Frequency: 2500 Hz
Frequency: 50 bursts / second
On / Off Time: 12 sec on / 8 seconds rest
Electrode Placement: Small electrodes (1x2cm)
directly over the site of pain
Amplitude: maximum tolerable
Treatment time: 10 minutes
High Intensity Noxious Cont..
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Excellent preliminary results in pilot studies and
in one published case report
Theoretical Construct of Case report
- Decreased force output (strength) can be
caused by mm inhibition secondary to
pain. –not always a strength issue- speedy return of strength after just 2
ES treatments to painful patella tendon
No high quality research studies to date
Muller et al J Orthop Sports Phys Ther. 2000;30:138-142.
Brief Intense TENS
AKA: Hyperstimulation analgesia
Phase Duration: > 300 microseconds
Frequency: 100-150 pps
Amplitude: Noxious with visible and
palpable muscle contraction
On time: 10 -15 seconds
Off time: 4-7 seconds
Duration of Rx: 15-30 minutes
Brief Intense TENS:
Clinical Application Notes
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The high frequency (pps) and limited rest between
contractions is believed to induce electrical fatigue
of muscles in spasm
Since this is an aggressive treatment method, not
all patients are candidates
Not indicated for acute injuries
Good clinical results for reduction of muscle
spasm associated with LBP (opinion)
Duration of pain relief: < 30 min
Microcurrent
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Monophasic rectangular
wave with selectable or
alternating polarity
Stimulation at a subsensory
level (< 1mA)
Do you believe in something
you can not feel?
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What are your experiences?
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More studies are necessary
Clinical Applications
z Common
treatment guidelines:
– Healing phase
z Ultra-low frequencies under 1 Hz (.3 Hz)
z Ultra-low amplitude 10-80 uA
– Pain Settings
z High frequency 3 - 30 Hz
z Amplitude 150 - 600 uA
– Patients not responding at 3-30 Hz range should proceed
to 300-990 Hz range
* Linda Manley M.Ed, ATC, PT - Microcurrent Universal Treatment
Techniques and Applications
Common Treatment guidelines
cont..
Treatment time:
z Probes
– 5-30 seconds per site
– GSR mode helps locate areas of low impedance
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Electrodes
– General soft tissue injuries 20-30 minutes
– Nerve root and low back injuries 30-60 minutes
Polarity guidelines: positive for acute conditions
negative for chronic conditions
HVPC to Retard the formation of
Edema
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Fish, Mendel and associates published
extensively from 1990 through 1997 on
electrical stimulation and edema
– HVPC waveform to a sensory level cathode at the
site of injury retards the formation of edema.
– Stimulation when applied to acute inflammation does
not reduce it but retards the formation of edema.
– Excellent addition to standard acute care of athletic
injuries; must begin prior to the formation of edema
HVPC: Prevention of Edema
z Mechanism
– Reduce the leakage of
large protein
molecules and fluid
from the blood,
through the walls of
the small blood
vessels into the
interstitium.
Parameter Settings
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Waveform: Twin Peak High Volt Pulsed Current
Frequency: 120 pps
Polarity: Negative
Ramp: None
Amplitude: 10% below motor threshold
Time: 30 minutes 4 times per day
Electrode placement
– Cathode (negative electrode) placed over the site of
injury. Should be smaller in size than the anode
(positive electrode)
– Anode (positive) placed in a convenient site. Does not
need to be proximal as the effects are local effects.
Water Bath Technique
z Electrode
placement
– Carbon rubber cathode (-) immersed in
room temperature water with
accompanying edematous limb
– Anode (+) electrode placed proximally on
same limb or trunk
Summary of Key Points
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Treating the pain impairment can interrupt the
pain spasm cycle and allow rehab to progress
faster
Chose electrotherapy treatments based on stage of
tissue healing and desired physiologic response
Remember that the waveform is not the treatment
– choose the treatment first than select a waveform
that has the necessary characteristics to deliver the
treatment. Often several correct options!
Summary of Key Points
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Utilize the continuum of electrotherapy treatments based
on stage of healing
Progress from sensory level to motor level analgesia
(opiates) when tissue is ready
Assess pain pre and post treatment to determine
effectiveness of electrotherapy the intervention
HVPC role in standard acute care of athletic injuries
Questions
Thank You
z Email
josephjag4@aol.com
z Office Number (603) 668-6660
x2119