Electrotherapy’s Role in Pain Electrotherapy’s Role in Pain ManagementManagement

Philadelphia 2004Philadelphia 2004

Joseph A. Gallo, ATC, PT Associate Professor

Hesser College Applied Medical Sciences

Clinician Performance Rehab

Workshop AgendaWorkshop Agenda

Electrotherapy for pain: why use it?General electrophysiology a practical reviewWaveform principlesClinical Selection of waveforms and parameter settings

IntroductionIntroduction

Why the interest in electrotherapy???Why the confusion???Importance of terminology“The Parameters”Why treat the pain impairment???

Fundamentals“we can only build as high as our foundation is deep” - unknown

The pain ImpairmentThe pain Impairment

What is pain?What Physiologic and psychological effect does it have on our patients?Inhibition of muscleLack of confidence, tentativeness, depressionPoorly managed acute pain can lead to chronic pain, chronic inhibition of mm, disuse atrophy and contracture

Concepts Related to PainConcepts Related to Pain

Subjective responseCentral BiasingPsychosocial component of pain appears to be accentuated when other life stressors are predominateRole of positive belief systems and attitudeEthnicity1

1. Zborowski M: People in Pain. Sanfrancisco, Jossey-Bass, 1969

Treating Pain: The Controversy Treating Pain: The Controversy

Argument #1“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 Assessing Pain

Pain assessment is critical to assessing the effectiveness of electroanalgesia treatmentsNumeric 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

Assessing Pain ContinuedAssessing Pain Continued

Body Pain DiagramMcgill pain questionnaireInterview/history/symptom behavior

Pain/Inflammatory CyclePain/Inflammatory Cycle

Neurobiology of PainNeurobiology of Pain

Electrotherapy and Pain Electrotherapy and Pain ControlControl

Theories of pain control using electrotherapy– Gate Control

Theory– Opiate-mediated

Control

Gate Theory of Pain ControlGate Theory of Pain Control

Melzak and Wall 1965Substantia 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

BrainT-cell

PainMotorSensory

OpiateOpiate--Mediated pain ControlMediated pain Control

Descending endogenous opiate systemSupraspinal pain modulation that produces a descending inhibition of pain chemically at the dorsal horn of the spinal cordThe spinal gate is closed from influence from aboveThe 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

OpiateOpiate--Mediated pain ControlMediated pain Control– 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?What is Electrotherapy?

It is the application of electrical stimulation transmitted through the body via electrodes for therapeutic purposes. The current flows through the body from one electrode to the other and causes different physiological reactions dependingon the type of current selected, the parameters of the selected current.

Review of Electrotherapy Review of Electrotherapy Currents: Yes! It Is This Simple Currents: Yes! It Is This Simple

Pulsed Current Alternating Current Direct Current

Electrotherapy Currents

Pulsed CurrentPulsed Current

Alternating CurrentAlternating Current

Direct CurrentDirect Current

Selecting Electrotherapy Selecting Electrotherapy Parameters: Terminology Parameters: Terminology

“Electrotherapy is about building pulses (PC) or cycles (AC)”“The ht (amplitude), Width (phase or cycle duration), and frequency are maniplulatedto create a desired physiologic response”

Pulse (PC) and Cycle (AC) Pulse (PC) and Cycle (AC) CharacteristicsCharacteristics

Amplitude: (intensity) mA = “how tall”Width: microsecondsPhase duration (Pulsed current)Cycle duration (alternating current)Carrier frequency of 2500 Hz = 400 microsecondsCarrier frequency of 5000 Hz = 200 microseconds

Strength Duration Curve: the basis Strength Duration Curve: the basis for selection amplitude and “width”for selection amplitude and “width”

FrequencyFrequency

Refers to how many times per second the pulse or cycle is deliveredTermed beat frequency when AC is usedDifference between carrier frequency and beat frequencyCarrier frequency indirectly describes cycle duration

General ElectrophysiologyGeneral ElectrophysiologyClinical Stimulators– Patients tissue

completes an electrical circuit

– The lead wires carry the current from the stimulator through the electrodes to and through the patient

– Skin is a resistor impeding current flow

– Subcutaneous tissue is a conductor

+ -

Generic Patient

Cathode negative poleAnode positive pole

Generic Stimulator

General ElectrophysiologyGeneral Electrophysiology

Generic StimulatorTarget Tissue– Sensory, motor, or pain nerve

fibers

The current flows through the target tissue to the other electrode and up the other lead wire to the stimulator

+ -

Generic PatientThe patient completes the circuit

Electrode IssuesElectrode IssuesElectrodes should be placed so the flow of current can reach the target tissueThe farther apart the deeper the penetrationPlaced too close the potential exists for greater concentrationSuperficially this can result in discomfort

Choosing appropriate electrode Choosing appropriate electrode sizesize

Small electrode (ex: 2 x 2 inches)

Increases current densityRecruits fewer motor unitsMore uncomfortable

Large electrode (ex: 4 x 5 inches)Decreases current densityRecruits more motor unitsMore comfortable

Electrode Skin InterfaceElectrode Skin InterfaceThe 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 Electrode Placement Strategies For PainStrategies For Pain

Bracket structurea. Proximal / Distalb. Medial / Lateralc. 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 Electrode Placement Strategies Cont..Strategies Cont..

a

b

Structure and Innervation

a. Major nerve rootb. Dermatome c. Superficial

peripheral nerved. Acupuncture and

trigger points Quad-polar placement

Literature review of applications: USALiterature review of applications: USAApplication IFC Premod VMS HVP Micro-

CurrentRussian

Pain ManagementAcuteChronicSpasmsPost-Operative

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Muscle WeaknessMin to moderateModerate to SeverDisuse AtrophyRe-educationIncrease ROM

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Prevent VenousThrombosis √ √ √

Inflammation / Edema √ √√ √

Increase localcirculation

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Tissue healing√ √

Spasticitymanagement

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Contracturemanagement

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yes

Three Categories of Three Categories of Electrotheraputic CurrentsElectrotheraputic Currents

Direct Current: Historically refereed to as “Galvanic Current” involves the continuous or uninterrupted flow of charged particles.Clinical apllications– Iontophoresis – Stimulating denervated

muscle

+0-

Direct Current

Alternating CurrentAlternating Current

Historically referred to as “Faradic Current” involves the continuous or uninterrupted bi-directional flow of charged particles.– Interferential

Stimulation– Premodualted – Russian

Beat Frequency: 100 Hz

Pulsed CurrentPulsed CurrentPulsed or interrupted current is an isolated unit of uni- or bi-directional 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 Waveforms: various configurations of the 3 configurations of the 3 electrotherapy currents electrotherapy currents

High Volt Pulsed currentBiphasicVMS™PremodulatedInterferentialRussianMicrocurrent

High Voltage Pulsed CurrentHigh Voltage Pulsed CurrentHigh 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™VMS™

VMS™ a trademarked name of the Chattanooga GroupVariable Muscle Stimulation– Symmetrical

Biphasic Square Waveforms with a 100 mSec interphase interval

PremodulatedPremodulated

The two medium frequency sine waves are mixed in the system and delivered to the patient with two electrodes.

Premodulated Current

Beat Frequency: 100 HzBeat 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 BenefitsClinical Benefits

ComfortableSimple two pad setupEasily applied to small joints of the upper extremityAcute or chronic pain

InterferentialInterferentialQuadQuad--Polar Polar

Alternating CurrentContinuous medium-frequency sine waveUses 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 CharacteristicsInterferential CharacteristicsAmplitude modulated, medium frequency, sine waveInterferential 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 BenefitsClinical Benefits

ComfortTargeting hard to reach tissues (e.g.-subscapularis)Pain modulation– Acute– Chronic Acute or chronic pain

RussianRussian

Characteristics– Sinusoidal alternating current with a 2,500

Hz carrier frequency.– Current modulated at 50 Hz2500 Hz

Burst

MicrocurrentMicrocurrent

Subsensory levelMicrocurrent wave forms vary btwnmanufacturersPulsed currentAlternating currentLow intensity direct current

Clinical Decision Process: choosing a Clinical Decision Process: choosing a waveform to meet your objective waveform to meet your objective

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

OptionsOptionsThere are 5 waveforms approved for pain management by the FDA.Interferential Quad-Polar Premodulated Bi-polar MicrocurrentTENS – Symmetrical and Asymmetrical Biphasic

Electrotherapy Treatments for Electrotherapy Treatments for Pain ModulationPain Modulation

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 Sensory Level ElectroanalgesiaElectroanalgesiaAKA: High frequency TENS or Conventional TENS AKA: High frequency TENS or Conventional TENS

• Acute pain managementPhase Duration: 2-50 microsecondsFrequency: >80 ppsOn/off time: noneAmplitude: Perceptible tingling, no motor

response should be elicitedDuration of Rx: 15-30 min-Amplitude, frequency or duration modulations can be used to minimize accommodation-

Mech of action: segmental non-opiate, gate control theory

Sensory Level Sensory Level ElectroanalgesiaElectroanalgesiaUsing the IFC or Using the IFC or PremodPremod

waveformwaveformAcute Pain ManagementGate 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 Sensory Level ElectroanalgesiaElectroanalgesiaClinical Application Notes Clinical Application Notes

Believed to relieve pain through the gate control theory of pain modulation via hyperstimulation of A-beta nervesTreatment of choice for acute conditionsAmplitude: increase to twitch and back off slightlyLiterature reports little pain relief post Rx; pain relief beyond Rx time may occur if pain-spasm cycle is interruptedWaveforms: Pulsed Current, *HVPC, IFC(AC), Premod(AC)Robinson AJ, Snyder-Mackler L. Clinical Electrophysiology. 2nd ed. Williams & Wilkins.

Introduction to Motor Level Introduction to Motor Level ElectroanalgesiaElectroanalgesia: “Twitch Level : “Twitch Level

Stimulation”Stimulation”Endorphins are released at a pulses rate range of 1 to 15 pps (approx.) Twitch level stimulationEnkephalins 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 Motor Level ElectroanalgesiaElectroanalgesiaAKA: Low frequency TENS, Acupuncture like Tens, opiate AKA: Low frequency TENS, Acupuncture like Tens, opiate induced induced electroanalgesiaelectroanalgesia, twitch level stimulation, twitch level stimulation

Phase Duration: ≥ 150 microsecondsFrequency: 2-4 pps (≤ 10 pps is acceptable)On/off time: NoneAmplitude: Strong visible muscle contractionDuration of treatment: Literature suggests 30-

45 minutesRobinson AJ, Snyder Mackler L. Clinical Electrophysiology

Motor Level Motor Level ElectroanalgesiaElectroanalgesiaUsing Using PremodPremod or IFC waveformor IFC waveform

Mode: 2 pad application(premod) 4 pad application (IFC)

Carrier frequency: 2500 – 5000 Hz (usually pre-programed in machine (e.g. Chatt vectra = 5000Hz)Beat Frequency:1 to 10 Hz or 2 Hz constantOn/off time: noneIntensity Level: Strong visible muscle contractionDuration: 30-45 minutes

Interferential Stimulation: De Domenico Ph.D

Motor Level Motor Level ElectroanalgesiaElectroanalgesiaClinical Application NotesClinical Application Notes

Believed to reduce pain through the activation of endogenous opiatesThe literature reports greater carry over of pain relief; up to several hoursResearch suggests that stronger contractions produce greater analgesiaNot a good choice for acute injuriesWaveforms: pulsed currents, IFC (AC), and Premod (AC)

High Intensity Noxious High Intensity Noxious Electrical Stimulation for Pain Electrical Stimulation for Pain

Modulation Modulation Type of Stimulator: Alternating Current unitCarrier Frequency: 2500 HzFrequency: 50 bursts / secondOn / Off Time: 12 sec on / 8 seconds restElectrode Placement: Small electrodes (1x2cm)

directly over the site of painAmplitude: maximum tolerableTreatment time: 10 minutes

High Intensity Noxious Cont..High Intensity Noxious Cont..

Excellent preliminary results in pilot studies and in one published case reportTheoretical Construct of Case report

- Decreased force output (strength) can be caused by mm inhibition secondary topain. –not always a strength issue-

- speedy return of strength after just 2ES 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 TENSBrief Intense TENSAKA: AKA: HyperstimulationHyperstimulation analgesiaanalgesia

Phase Duration: > 300 microsecondsFrequency: 100-150 ppsAmplitude: Noxious with visible and

palpable muscle contractionOn time: 10 -15 secondsOff time: 4-7 secondsDuration of Rx: 15-30 minutes

Brief Intense TENS:Brief Intense TENS:Clinical Application NotesClinical Application Notes

The high frequency (pps) and limited rest between contractions is believed to induce electrical fatigue of muscles in spasmSince this is an aggressive treatment method, not all patients are candidatesNot indicated for acute injuriesGood clinical results for reduction of muscle spasm associated with LBP (opinion)Duration of pain relief: < 30 min

MicrocurrentMicrocurrentMonophasic rectangular wave with selectable or alternating polarityStimulation at a subsensory level (< 1mA)Do you believe in something you can not feel? What are your experiences?More studies are necessary

Clinical ApplicationsClinical ApplicationsCommon treatment guidelines:– Healing phase

Ultra-low frequencies under 1 Hz (.3 Hz)Ultra-low amplitude 10-80 uA

– Pain SettingsHigh frequency 3 - 30 HzAmplitude 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 Common Treatment guidelines cont..cont..

Treatment time:Probes– 5-30 seconds per site– GSR mode helps locate areas of low impedance

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 HVPC to Retard the formation of Edema Edema

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 HVPC: Prevention of Edema

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 SettingsParameter SettingsWaveform: Twin Peak High Volt Pulsed CurrentFrequency: 120 ppsPolarity: NegativeRamp: NoneAmplitude: 10% below motor thresholdTime: 30 minutes 4 times per dayElectrode 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 TechniqueWater Bath Technique

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 PointsSummary of Key Points

Treating the pain impairment can interrupt the pain spasm cycle and allow rehab to progress fasterChose electrotherapy treatments based on stage of tissue healing and desired physiologic responseRemember 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 PointsSummary of Key PointsUtilize the continuum of electrotherapy treatments based on stage of healing Progress from sensory level to motor level analgesia (opiates) when tissue is readyAssess pain pre and post treatment to determine effectiveness of electrotherapy the intervention HVPC role in standard acute care of athletic injuries

QuestionsQuestions

Thank YouThank You

Email josephjag4@aol.com Office Number (603) 668-6660 x2119