Electrical Stimulation and Pain Control

Electrotherapy’sElectrotherapy’s RoleRole inin PainPain ManagementManagement PhiladelphiaPhiladelphia 20042004

Joseph A. Gallo, ATC, PT Associate Professor Hesser College Applied Medical Sciences Clinician Performance Rehab WorkshopWorkshop AgendaAgenda z Electrotherapy for pain: why use it? z General electrophysiology a practical review z Waveform principles z Clinical Selection of waveforms and parameter settings IntroductionIntroduction 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 TheThe painpain ImpairmentImpairment z What is pain? z What Physiologic and psychological effect does it have on our patients? ¾ Inhibition of muscle ¾ Lack of confidence, tentativeness, depression ¾ Poorly managed acute pain can lead to chronic pain, chronic inhibition of mm, disuse atrophy and contracture ConceptsConcepts RelatedRelated toto PainPain z Subjective response z Central Biasing z Psychosocial component of pain appears to be accentuated when other life stressors are predominate z Role of positive belief systems and attitude z Ethnicity1

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

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” AssessingAssessing PainPain z Pain assessment is critical to assessing the effectiveness of electroanalgesia treatments z Numeric pain scale (NPS) 0-10 ¾ High test retest reliability (ICC = .96)1 ¾ 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 AssessingAssessing PainPain ContinuedContinued z Body Pain Diagram z Mcgill pain questionnaire z Interview/history/symptom behavior Pain/InflammatoryPain/Inflammatory CycleCycle NeurobiologyNeurobiology ofof PainPain ElectrotherapyElectrotherapy andand PainPain ControlControl

z Theories of pain control using electrotherapy – Gate Control Theory – Opiate-mediated Control GateGate TheoryTheory ofof PainPain ControlControl 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 Brain T-cell

Pain Motor Sensory OpiateOpiate--MediatedMediated painpain ControlControl

™ 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 OpiateOpiate--MediatedMediated painpain ControlControl

– 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 WhatWhat isis Electrotherapy?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. ReviewReview ofof ElectrotherapyElectrotherapy Currents:Currents: Yes!Yes! ItIt IsIs ThisThis SimpleSimple

Electrotherapy Currents

Pulsed Current Alternating Current Direct Current PulsedPulsed CurrentCurrent AlternatingAlternating CurrentCurrent DirectDirect CurrentCurrent SelectingSelecting ElectrotherapyElectrotherapy Parameters:Parameters: TerminologyTerminology 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” PulsePulse (PC)(PC) andand CycleCycle (AC)(AC) CharacteristicsCharacteristics 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 StrengthStrength DurationDuration Curve:Curve: thethe basisbasis forfor selectionselection amplitudeamplitude andand “width”“width” FrequencyFrequency 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 ¾ Carrier frequency indirectly describes cycle duration GeneralGeneral ElectrophysiologyElectrophysiology z Clinical Stimulators Generic Stimulator – Patients tissue completes an electrical circuit – The lead wires carry the current from the stimulator through the electrodes to and through the patient Anode positive pole Cathode negative pole + - – Skin is a resistor impeding current flow – Subcutaneous tissue is a Generic Patient conductor GeneralGeneral ElectrophysiologyElectrophysiology

Generic Stimulator z Target Tissue – Sensory, motor, or pain nerve fibers

z The current flows through the target tissue to the other electrode and up the other + - lead wire to the stimulator Generic Patient

The patient completes the circuit ElectrodeElectrode IssuesIssues z Electrodes should be placed so the flow of current can reach the target tissue z The farther apart the deeper the penetration z Placed too close the potential exists for greater concentration z Superficially this can result in discomfort ChoosingChoosing appropriateappropriate electrodeelectrode sizesize z Small electrode z Large electrode (ex: 2 x 2 inches) (ex: 4 x 5 inches) ¾ Increases current ¾ Decreases current density density ¾ Recruits fewer motor ¾ Recruits more motor units units ¾ More uncomfortable ¾ More comfortable ElectrodeElectrode SkinSkin InterfaceInterface z 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 ElectrodeElectrode PlacementPlacement StrategiesStrategies ForFor PainPain z Bracket structure a. Proximal / Distal b. Medial / Lateral c. Anterior / Posterior • Directly over the site of pain • Interferential is a quad polar (4) electrode Bi-polar placement application. The area should be bracketed “X”. ElectrodeElectrode PlacementPlacement StrategiesStrategies Cont..Cont.. z Structure and Innervation a. Major nerve root a b. Dermatome b c. Superficial peripheral nerve d. Acupuncture and trigger points Quad-polar placement LiteratureLiterature reviewreview ofof applications:applications: USAUSA Application IFC Premod VMS HVP Micro- Russian Current Pain Management Acute √ √ √ √ Chronic √ √ √ √ √ √ √ Spasms √ √ √ √ Post-Operative Muscle Weakness Min to moderate √ √ √ Moderate to Sever √ √ √ √ √ √ Disuse Atrophy √ √ √ Re-education √ √ √ Increase ROM Prevent Venous Thrombosis √√ √

Inflammation / Edema √√yes √√ Increase local √√ circulation √√ Tissue healing √√ Spasticity √ management Contracture √ management √ ThreeThree CategoriesCategories ofof ElectrotheraputicElectrotheraputic CurrentsCurrents z Direct Current: Historically refereed to as “Galvanic Current” involves the + continuous or uninterrupted flow of 0 - charged particles. Direct Current z Clinical apllications – Iontophoresis – Stimulating denervated muscle AlternatingAlternating CurrentCurrent z Historically referred to as “Faradic Current” involves the continuous or uninterrupted bi- directional flow of charged particles. – Interferential Beat Frequency: 100 Hz Stimulation – Premodualted – Russian PulsedPulsed CurrentCurrent z Pulsed 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:Waveforms: variousvarious configurationsconfigurations ofof thethe 33 electrotherapyelectrotherapy currentscurrents z High Volt Pulsed current z Biphasic z VMS™ z Premodulated z Interferential z Russian z Microcurrent HighHigh VoltageVoltage PulsedPulsed CurrentCurrent z High 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™ z VMS™ a trademarked name of the Chattanooga Group z Variable Muscle Stimulation – Symmetrical Biphasic Square Waveforms with a 100 mSec interphase interval PremodulatedPremodulated

z 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. ClinicalClinical BenefitsBenefits

z Comfortable z Simple two pad setup z Easily applied to small joints of the upper extremity z Acute or chronic pain InterferentialInterferential QuadQuad--PolarPolar 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 InterferentialInterferential CharacteristicsCharacteristics z Amplitude modulated, medium frequency, sine wave z 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 ClinicalClinical BenefitsBenefits z Comfort z Targeting hard to reach tissues (e.g.- subscapularis) z Pain modulation – Acute – Chronic Acute or chronic pain RussianRussian z Characteristics – Sinusoidal alternating current with a 2,500 Hz carrier frequency. – Current modulated at 50 Hz

2500 Hz

Burst MicrocurrentMicrocurrent z Subsensory level z Microcurrent wave forms vary btwn manufacturers ¾ Pulsed current ¾ Alternating current ¾ Low intensity direct current ClinicalClinical DecisionDecision Process:Process: choosingchoosing aa waveformwaveform toto meetmeet youryour objectiveobjective

Concept: “the waveform is not the treatment” z We use waveforms to deliver a specific electrotherapy intervention (e.g. sensory level electroanalgesia) z Always choose treatment first than choose suitable waveform International overlay OptionsOptions 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 ElectrotherapyElectrotherapy TreatmentsTreatments forfor PainPain ModulationModulation z Sensory level electroanalgesia (AKA: high frequency TENS, Conventional Tens) Waveforms - IFC, Premod, HVPC, Biphasic z Motor level electroanalgesia (AKA: low frequency TENS, acupuncture like TENS) Waveforms - IFC, Premod, Biphasic z Brief Intense TENS (need a unit with on/off time) Waveforms - Biphasic, “Russian” (AC) z * High Intensity Noxious Electrical Stimulation for pain modulation SensorySensory LevelLevel ElectroanalgesiaElectroanalgesia 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 -Amplitude, frequency or duration modulations can be used to minimize accommodation- Mech of action: segmental non-opiate, gate control theory SensorySensory LeveLevell EElectroanalgesialectroanalgesia UsingUsing thethe IFCIFC oror PremodPremod waveformwaveform z Acute Pain Management z Gate Control z 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 SensorySensory LevelLevel ElectroanalgesiaElectroanalgesia ClinicalClinical ApplicationApplication NotesNotes z Believed to relieve pain through the gate control theory of pain modulation via hyperstimulation of A-beta nerves z Treatment of choice for acute conditions z Amplitude: increase to twitch and back off slightly z Literature reports little pain relief post Rx; pain relief beyond Rx time may occur if pain-spasm cycle is interrupted z Waveforms: Pulsed Current, *HVPC, IFC(AC), Premod (AC) Robinson AJ, Snyder-Mackler L. Clinical Electrophysiology. 2nd ed. Williams & Wilkins. IntroductionIntroduction toto MotorMotor LevelLevel ElectroanalgesiaElectroanalgesia:: “Twitch“Twitch LevelLevel Stimulation”Stimulation” z Endorphins are released at a pulses rate range of 1 to 15 pps (approx.) Twitch level stimulation z Enkephalins are released at the higher pulse rates of 80 pps and up. Twitch level stimulation z Endorphin induced pain suppression lasts longer than pain suppression induced by enkephalins MotorMotor LevelLevel ElectroanalgesiaElectroanalgesia 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 30- 45 minutes

Robinson AJ, Snyder Mackler L. Clinical Electrophysiology MotorMotor LevelLevel ElectroanalgesiaElectroanalgesia UsingUsing PremodPremod oror IFCIFC waveformwaveform

¾ Mode: 2 pad application(premod) 4 pad application (IFC) ¾ Carrier frequency: 2500 – 5000 Hz (usually pre-programed in machine (e.g. Chatt vectra = 5000Hz) ¾ Beat Frequency:1 to 10 Hz or 2 Hz constant ¾ On/off time: none ¾ Intensity Level: Strong visible muscle contraction ¾ Duration: 30-45 minutes Interferential Stimulation: De Domenico Ph.D MotorMotor LevelLevel ElectroanalgesiaElectroanalgesia ClinicalClinical ApplicationApplication NotesNotes z Believed to reduce pain through the activation of endogenous opiates z The literature reports greater carry over of pain relief; up to several hours z Research suggests that stronger contractions produce greater analgesia z Not a good choice for acute injuries z Waveforms: pulsed currents, IFC (AC), and Premod (AC) HighHigh IntensityIntensity NoxiousNoxious ElectricalElectrical StimulationStimulation forfor PainPain ModulationModulation 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 HighHigh IntensityIntensity NoxiousNoxious Cont..Cont.. z Excellent preliminary results in pilot studies and in one published case report z 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 z No high quality research studies to date

Muller et al J Orthop Sports Phys Ther. 2000;30:138-142. BriefBrief IntenseIntense TENSTENS 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 BriefBrief IntenseIntense TENS:TENS: ClinicalClinical ApplicationApplication NotesNotes z The high frequency (pps) and limited rest between contractions is believed to induce electrical fatigue of muscles in spasm z Since this is an aggressive treatment method, not all patients are candidates z Not indicated for acute injuries z Good clinical results for reduction of muscle spasm associated with LBP (opinion) z Duration of pain relief: < 30 min MicrocurrentMicrocurrent z Monophasic rectangular wave with selectable or alternating polarity z Stimulation at a subsensory level (< 1mA) z Do you believe in something you can not feel? z What are your experiences? z More studies are necessary ClinicalClinical ApplicationsApplications 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 CommonCommon TreatmentTreatment guidelinesguidelines cont..cont.. Treatment time: z Probes – 5-30 seconds per site – GSR mode helps locate areas of low impedance z 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 HVPCHVPC toto RetardRetard thethe formationformation ofof EdemaEdema z 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:HVPC: PreventionPrevention ofof EdemaEdema 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. ParameterParameter SettingsSettings z Waveform: Twin Peak High Volt Pulsed Current z Frequency: 120 pps z Polarity: Negative z Ramp: None z Amplitude: 10% below motor threshold z Time: 30 minutes 4 times per day z 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. WaterWater BathBath TechniqueTechnique z Electrode placement – Carbon rubber cathode (-) immersed in room temperature water with accompanying edematous limb – Anode (+) electrode placed proximally on same limb or trunk SummarySummary ofof KeyKey PointsPoints z Treating the pain impairment can interrupt the pain spasm cycle and allow rehab to progress faster z Chose electrotherapy treatments based on stage of tissue healing and desired physiologic response z 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! SummarySummary ofof KeyKey PointsPoints z Utilize the continuum of electrotherapy treatments based on stage of healing ¾ Progress from sensory level to motor level analgesia (opiates) when tissue is ready ¾ Assess pain pre and post treatment to determine effectiveness of electrotherapy the intervention ¾ HVPC role in standard acute care of athletic injuries QuestionsQuestions ThankThank YouYou zEmail [email protected] zOffice Number (603) 668-6660 x2119