Practical issues of Practical issues of EPAs restricted to low EPAs restricted to low

frequency currentsfrequency currents

Thangamani RamalingamThangamani Ramalingam

Section 1- Section 1- BASICSBASICS

Section 2- Section 2- CLINICAL DECISION MAKING CLINICAL DECISION MAKING

Section 3- Section 3- THE PRACTICAL ISSUESTHE PRACTICAL ISSUES

ElectricalElectrical Stimulation Stimulation

The In’s & Out’s of Getting The In’s & Out’s of Getting ZappedZapped

Electrical CurrentsElectrical Currents• Continuous Currents:Continuous Currents:

– Direct CurrentDirect Current (DC) – polarity remains constant (DC) – polarity remains constant• IontophoresisIontophoresis

• Car batteryCar battery

– Alternating CurrentAlternating Current (AC) – polarity at each end (AC) – polarity at each end is constantly reversedis constantly reversed• Household currentHousehold current

• Pulsatile Currents:Pulsatile Currents:– MonophasicMonophasic – similar to DC (either +/-) but is – similar to DC (either +/-) but is

not constantnot constant– BiphasicBiphasic – similar to AC (+/- phases) but due to – similar to AC (+/- phases) but due to

interpulse intervals it can’t be ACinterpulse intervals it can’t be AC– PolyphasicPolyphasic

Direct Direct CurrentCurrent• DCDC

• Uninterrupted unidirectional Uninterrupted unidirectional flow of electronsflow of electrons

• Pattern – square wave Pattern – square wave recognized by continuous recognized by continuous current flow only on one side ofcurrent flow only on one side ofthe baselinesthe baselines

• Electrons travel from the Electrons travel from the cathode to the anodecathode to the anode

• ““Galvanic” can be used to describe DCGalvanic” can be used to describe DC• Example: FlashlightExample: Flashlight

– Positive pole lacks electrons, Negative pole has excess Positive pole lacks electrons, Negative pole has excess electronselectrons

– Electrons leave the (-) pole, go through the wire, then the bulb Electrons leave the (-) pole, go through the wire, then the bulb & back to the (+) pole. (When electrons = at (-) & (+) poles & back to the (+) pole. (When electrons = at (-) & (+) poles the battery is dead!)the battery is dead!)

Alternating Alternating CurrentCurrent

• ACAC• Bidirectional flow of Bidirectional flow of electrons – direction & electrons – direction & magnitude of flow reverses magnitude of flow reverses although magnitude may not although magnitude may not be = on both sides of the baseline.be = on both sides of the baseline.• AC possesses no true positive or negative AC possesses no true positive or negative

pole.pole.• Electrons shuffle back & forth between the 2 Electrons shuffle back & forth between the 2

electrodes as they take turn being (+) & (-).electrodes as they take turn being (+) & (-).• Household electricity uses AC.Household electricity uses AC.

Pulsed CurrentsPulsed Currents

Pulse AttributesPulse Attributes

• A = AmplitudeA = Amplitude• B = Phase DurationB = Phase Duration• C = Pulse DurationC = Pulse Duration• D = Interpulse D = Interpulse

IntervalInterval

A

B

C

D

E

F• E = Intrapulse E = Intrapulse IntervalInterval

• F = Pulse PeriodF = Pulse Period

B

F

Pulse AttributesPulse Attributes• Pulse charge:Pulse charge: # of electrons contained within a # of electrons contained within a

pulsepulse– Expressed in Expressed in micro coulombsmicro coulombs

• Pulse frequency:Pulse frequency: # of events per second # of events per second– Measured pulses per second (pps) or the cycle Measured pulses per second (pps) or the cycle

frequency of AC is cycles per second (cps) or Hzfrequency of AC is cycles per second (cps) or Hz– Low-frequency currents:Low-frequency currents: less than 1,000 cycles less than 1,000 cycles

or pulses per second (electrical stimulation units or pulses per second (electrical stimulation units used for biological effects)used for biological effects)

– Medium-frequency currents:Medium-frequency currents: 1,000-100,000 1,000-100,000 pps/cpspps/cps

– High-frequency currents:High-frequency currents: greater than 100,000 greater than 100,000 pps/cps (used for heating effects- diathermy)pps/cps (used for heating effects- diathermy)

Pulse AttributesPulse Attributes• Pulse Rise Time:Pulse Rise Time: amount of time needed for amount of time needed for

the pulse to reach its peak value (the pulse to reach its peak value (nanosecondsnanoseconds))– Rapidly rising pulses cause nerve depolarizationRapidly rising pulses cause nerve depolarization

• Pulse Decay Time:Pulse Decay Time: amount of time required amount of time required for the pulse to go from its peak back to zero for the pulse to go from its peak back to zero

• Pulse Train:Pulse Train: individual patterns of waveforms, individual patterns of waveforms, durations &/or frequencies that are linked durations &/or frequencies that are linked together (repeat @ regular intervals)together (repeat @ regular intervals)– Amplitude Ramp:Amplitude Ramp: gradual rise &/or fall in amplitude of gradual rise &/or fall in amplitude of

a pulse train (causes a gradual a pulse train (causes a gradual in the force of m. in the force of m. contractions by progressive recruitment of motor contractions by progressive recruitment of motor units)units)

Measures of Electrical Current Measures of Electrical Current FlowFlow• Resistance:Resistance: ( (RR) – opposition to electron flow in a ) – opposition to electron flow in a

conducting materialconducting material– Type, length, & cross-sectional area of the Type, length, & cross-sectional area of the

material & temperature of the circuit determine material & temperature of the circuit determine the amount of resistance offered to the flow of the amount of resistance offered to the flow of electronselectrons

– Conductors:Conductors: materials allowing current to pass materials allowing current to pass with relative easewith relative ease

– Resistors/Insulators:Resistors/Insulators: materials that tend to oppose materials that tend to oppose current flowcurrent flow

• Impedance:Impedance: ( (ZZ) ) Alternating CurrentAlternating Current– Inductance:Inductance: degree that a varying current can degree that a varying current can

induce voltage (H – henry) (negligible in biological induce voltage (H – henry) (negligible in biological systems)systems)

– Capacitance:Capacitance: frequency-dependent ability to store frequency-dependent ability to store a charge (C); many cell membranes are capacitorsa charge (C); many cell membranes are capacitors

Circuit TypesCircuit Types

So What?So What?

What happens in the Body?What happens in the Body?• Current enters the body through a Current enters the body through a SERIESSERIES circuit. circuit.

• Once the current enters the tissues, it takes Once the current enters the tissues, it takes many different many different PARALLELPARALLEL paths. paths.

• Electrical stim is applied Electrical stim is applied trans- cutaneouslytrans- cutaneously except for some bone growth stimulators that except for some bone growth stimulators that may be implanted into the muscle or bone.may be implanted into the muscle or bone.

• Resting potentialResting potential – potential difference between – potential difference between the inside & outside of the membranethe inside & outside of the membrane

• CathodeCathode – depolarization of the nerve occurs – depolarization of the nerve occurs

• AnodeAnode – hyperpolarization of the nerve occurs – hyperpolarization of the nerve occurs

What happens in the Body?What happens in the Body?• CathodeCathode – pH becomes basic (greater than 7) – pH becomes basic (greater than 7)• AnodeAnode – pH becomes acidic (less than 7) – pH becomes acidic (less than 7)• NaNa++ move towards cathode, picks up an move towards cathode, picks up an

electron, & through reaction with Helectron, & through reaction with H22O, liquefies O, liquefies proteins, causing a general softening of the proteins, causing a general softening of the tissues in the area & a decrease in nerve tissues in the area & a decrease in nerve irritabilityirritability

• Tissues under anode harden because chemical Tissues under anode harden because chemical mediators for a coagulation of proteinmediators for a coagulation of protein

• Effects not as pronounced when monophasic, Effects not as pronounced when monophasic, biphasic or AC are usedbiphasic or AC are used

• Na+ moves from inside the cell to the outside Na+ moves from inside the cell to the outside the cell allowing K+ to move into the cell the cell allowing K+ to move into the cell (Sodium-potassium pump)(Sodium-potassium pump)

Physiological effects of Physiological effects of electrical stimulationelectrical stimulation

• Cellular level Cellular level

• Tissue levelTissue level

• Segmental levelSegmental level

• Systemic levelSystemic level

Therapeutic Uses for Electrical Therapeutic Uses for Electrical StimulationStimulation• Control acute & chronic painControl acute & chronic pain• Reduce edemaReduce edema• Reduce & or inhibit muscle spasmReduce & or inhibit muscle spasm• Reduce joint contracturesReduce joint contractures• Minimize atrophyMinimize atrophy• Facilitate tissue healingFacilitate tissue healing• Facilitate muscle reeducationFacilitate muscle reeducation• Facilitate fracture healingFacilitate fracture healing• Strengthen muscleStrengthen muscle

Clinical application of Clinical application of Electricity: minimizing the Electricity: minimizing the resistanceresistance• Reduce the skin-electrode resistanceReduce the skin-electrode resistance

– Minimize air-electrode interfaceMinimize air-electrode interface– Keep electrode clean of oils, etc.Keep electrode clean of oils, etc.– Clean the skill on oils, etc.Clean the skill on oils, etc.

• Use the shortest pathway for energy flowUse the shortest pathway for energy flow

• Use the largest electrode that will Use the largest electrode that will selectively stimulate the target tissuesselectively stimulate the target tissues

• If resistance increases, more voltage will be If resistance increases, more voltage will be needed to get the same current flowneeded to get the same current flow

Clinical Application of Clinical Application of Electricity: Material of Electricity: Material of CircuitCircuit• Not all of the Not all of the

body’s tissues body’s tissues conduct electrical conduct electrical current the samecurrent the same

• Excitable TissuesExcitable Tissues– NervesNerves– Muscle fibersMuscle fibers– blood cellsblood cells– cell membranescell membranes

• Non-excitable Non-excitable tissuestissues– BoneBone– CartilageCartilage– TendonsTendons– LigamentsLigaments

• Current prefers to Current prefers to travel along travel along excitable tissuesexcitable tissues

Stimulation ParameterStimulation Parameter::

• Amplitude: the intensity of the Amplitude: the intensity of the current, the magnitude of the current, the magnitude of the charge. The amplitude is associated charge. The amplitude is associated with the depth of penetration.with the depth of penetration.– The deeper the penetration the more The deeper the penetration the more

muscle fiber recruitment possible muscle fiber recruitment possible – remember the all or none response and remember the all or none response and

the Arndt-Schultz Principlethe Arndt-Schultz Principle

Simulation ParameterSimulation Parameter• Pulse duration: the length of time the Pulse duration: the length of time the

electrical flow is “on” also known as electrical flow is “on” also known as the pulse width. It is the time of 1 the pulse width. It is the time of 1 cycle to take place (will be both cycle to take place (will be both phases in a biphasic current)phases in a biphasic current)– phase duration important factor in phase duration important factor in

determining which tissue stimulated: if determining which tissue stimulated: if too short there will be no action potentialtoo short there will be no action potential

Stimulation Parameter:Stimulation Parameter:

• Pulse rise time: the time to peak Pulse rise time: the time to peak intensity of the pulse (ramp)intensity of the pulse (ramp)– rapid rising pulses cause nerve rapid rising pulses cause nerve

depolarizationdepolarization– Slow rise: the nerve accommodates to Slow rise: the nerve accommodates to

stimulus and a action potential is not stimulus and a action potential is not elicitedelicited•Good for muscle re-education with assisted Good for muscle re-education with assisted

contraction - ramping (shock of current is contraction - ramping (shock of current is reduced)reduced)

Stimulation ParametersStimulation Parameters

• Pulse Frequency: (PPS=Hertz) How many Pulse Frequency: (PPS=Hertz) How many pulses occur in a unit of timepulses occur in a unit of time– Do not assume the lower the frequency the Do not assume the lower the frequency the

longer the pulse durationlonger the pulse duration– Low Frequency: 1K Hz and below (MENS .1-1K Low Frequency: 1K Hz and below (MENS .1-1K

Hz), muscle stim units)Hz), muscle stim units)– Medium frequency: 1K to 100K Hz Medium frequency: 1K to 100K Hz

(Interferential, Russian stim ,LVGS)(Interferential, Russian stim ,LVGS)– High Frequency: above 100K Hz (diathermies)High Frequency: above 100K Hz (diathermies)

Stimulation ParameterStimulation Parameter::• Current types: alternating or Direct Current types: alternating or Direct

Current (AC or DC)Current (AC or DC)– AC indicates that the energy travels in a AC indicates that the energy travels in a

positive and negative direction. The wave positive and negative direction. The wave form which occurs will be replicated on form which occurs will be replicated on both sides of the iso -electric lineboth sides of the iso -electric line

– DC indicated that the energy travels only DC indicated that the energy travels only in the positive or on in the negative in the positive or on in the negative directiondirection

DC AC

Stimulation Parameter:Stimulation Parameter:

• Waveforms; the path of the Waveforms; the path of the energy. May be smooth (sine) energy. May be smooth (sine) spiked, square,, continuous etc.spiked, square,, continuous etc.

• Method to direct currentMethod to direct current– Peaked - sharperPeaked - sharper– Sign - smootherSign - smoother

Stimulation Parameter:Stimulation Parameter:

• Duty cycles: on-off time. May also be Duty cycles: on-off time. May also be called inter-pulse interval which is the called inter-pulse interval which is the time between pulses. The more rest of time between pulses. The more rest of “off” time, the less muscle fatigue will “off” time, the less muscle fatigue will occuroccur– 1:1 Raito fatigues muscle rapidly1:1 Raito fatigues muscle rapidly– 1:5 ratio less fatigue1:5 ratio less fatigue– 1:7 no fatigue (passive muscle exercise)1:7 no fatigue (passive muscle exercise)

Stimulation Parameter:Stimulation Parameter:

– Average current (also called Root Average current (also called Root Mean Square)Mean Square)•the “average” intensitythe “average” intensity

•Factors effective the average current:Factors effective the average current:– pulse amplitudepulse amplitude– pulse durationpulse duration– waveform (DC has more net charge over time waveform (DC has more net charge over time

thus causing a thermal effect. AC has a zero thus causing a thermal effect. AC has a zero net charge (ZNC). The DC may have long term net charge (ZNC). The DC may have long term adverse physiological effects)adverse physiological effects)

Stimulation Parameter:Stimulation Parameter:

• Current DensityCurrent Density– The amount of charge per unit area. The amount of charge per unit area.

This is usually relative to the size of the This is usually relative to the size of the electrode. Density will be greater with a electrode. Density will be greater with a small electrode, but also the small small electrode, but also the small electrode offers more resistance.electrode offers more resistance.

Capacitance:Capacitance:

• The ability of tissue (or other material) The ability of tissue (or other material) to store electricity. For a given to store electricity. For a given current intensity and pulse durationcurrent intensity and pulse duration– The higher the capacitance the longer The higher the capacitance the longer

before a response. Body tissues have before a response. Body tissues have different capacitance. From least to most:different capacitance. From least to most:•Nerve (will fire first, if healthy)Nerve (will fire first, if healthy)

•Muscle fiberMuscle fiber

•Muscle tissueMuscle tissue

Capacitance:Capacitance:

• Increase intensity (with decrease Increase intensity (with decrease pulse duration) is needed to pulse duration) is needed to stimulate tissues with a higher stimulate tissues with a higher capacitance.capacitance.

• Muscle membrane has 10x the Muscle membrane has 10x the capacitance of nervecapacitance of nerve

Factors effecting the Factors effecting the clinical application of clinical application of electricityelectricity

– Factors effecting the clinical application of Factors effecting the clinical application of electricity Rise Time: the time to peak electricity Rise Time: the time to peak intensityintensity

•The onset of stimulation must be rapid The onset of stimulation must be rapid enough that tissue accommodation is enough that tissue accommodation is preventedprevented

•The lower the capacitance the less the The lower the capacitance the less the charge can be storedcharge can be stored

•If a stimulus is applied too slowly, it is If a stimulus is applied too slowly, it is disperseddispersed

SECTION-2SECTION-2

HISTORY OF ESHISTORY OF ES

• 420B.C-hippocrates-in torpaedo fish420B.C-hippocrates-in torpaedo fish• 46A.D-scribonius largus-gout/headache46A.D-scribonius largus-gout/headache• 1700-luigi galvani & alessantro volta1700-luigi galvani & alessantro volta• 1745-leyden jar for ES1745-leyden jar for ES• 1831-michael faraday1831-michael faraday• 1850s-duchene-motor points(father of ES)1850s-duchene-motor points(father of ES)• 1909-rheo/chron-louis1909-rheo/chron-louis• 1916-SD curve-Adrian1916-SD curve-Adrian• FES-1961-libersonFES-1961-liberson• 1962-HVPC-robert becker1962-HVPC-robert becker

Recent perceptions in Recent perceptions in practicepractice

Clinical decision makingClinical decision making

Research basedResearch basedClient centered (patient preferences)Client centered (patient preferences)Context relevant (professional Context relevant (professional

knowledge)knowledge)

No recipes No recipes

only only insightinsight

Basic Model of Basic Model of ElectrotherapyElectrotherapy

Electrotherapeutic Electrotherapeutic WindowsWindows •  Amplitude window

• Frequency window

• Acute window

• chronic window

• Energy based window

• Time based window

• Interval based

window

The The Arndt-SchulzArndt-Schulz rule or  rule or lawlaw

FAMFAMFrequency Analysis MethodFrequency Analysis Method

• The external currents with different frequencies are considered to cause different effects in tissues. Thus we assume that tissue reactions on different frequencies in different states of the body will also differ from each other.

• Measuring the sensory, motor and pain thresholds by stimulating the tissue with the interference current may offer a diagnostic tool in physiotherapy and rehabilitation

S-D CurveS-D Curve

EvidenceEvidence based based practicepractice

Lack of Evidence Lack of Evidence

VsVs

Evidence of lackEvidence of lack

•   Van Tulder Van Tulder et alet al. [. [11] specify that "strong ] specify that "strong evidence" is provided by multiple high quality evidence" is provided by multiple high quality randomised trials with consistent findings, randomised trials with consistent findings,

• "moderate evidence" is provided by consistent "moderate evidence" is provided by consistent findings in multiple low quality trials, andfindings in multiple low quality trials, and

• "limited or conflicting evidence" is provided by "limited or conflicting evidence" is provided by only one randomised trial or by inconsistent only one randomised trial or by inconsistent findingsfindings

• ““No evidence”one low quality RCT/CCT No evidence”one low quality RCT/CCT

RecommendationsRecommendations

Effects of therapyEffects of therapy

ExperiencesExperiences

PrognosisPrognosis

Diagnostic testsDiagnostic tests

PEDroPEDro

Cochrane libraryCochrane library

CINAHLCINAHL

PubmedPubmed

PubmedPubmed

pubmed pubmed

Critically appraised paper Critically appraised paper (peer reviewed) is more (peer reviewed) is more

reliablereliable

Clinical guidelines Clinical guidelines always superior than always superior than systematic reviewssystematic reviews

Clinical guidelines as Clinical guidelines as a resource for EBPa resource for EBP

• www.show.scot.nhs.uk/sign/www.show.scot.nhs.uk/sign/

• www.nice.org.ukwww.nice.org.uk

• www.nhmrc.gov.au/publicationswww.nhmrc.gov.au/publications

• www.nzgg.org.nzwww.nzgg.org.nz

• www.guideline.gov.usawww.guideline.gov.usa

• www.g-i-n.net/index.cfm(guidelineswww.g-i-n.net/index.cfm(guidelines international network)international network)

SECTION-3SECTION-3

The practical issuesThe practical issues

• Electricity is an Electricity is an element of PT element of PT modalities most modalities most frightening and frightening and least understood.least understood.

• Understanding the Understanding the basis principles will basis principles will later aid you in later aid you in establishing establishing treatment treatment protocols.protocols.

TENSTENS

• Cathode is placed proximally in TENS except in Cathode is placed proximally in TENS except in AL-TENSAL-TENS

• Transcutaneous Electrical Nerve Stimulation Transcutaneous Electrical Nerve Stimulation ((TENSTENS) uses similar-sized electrodes ) uses similar-sized electrodes

• Over superficial vascular structures because Over superficial vascular structures because transmission of currents may go through transmission of currents may go through neural tissue as well as ionic fluidsneural tissue as well as ionic fluids

• Can cause muscle contractions, but that is not Can cause muscle contractions, but that is not why it is usedwhy it is used

• Moderate caffeine levels (200 mg, approx 2-3 c. Moderate caffeine levels (200 mg, approx 2-3 c. coffee) may decrease effectiveness of TENScoffee) may decrease effectiveness of TENS

IFTIFT

• 4KHZ-pain relief4KHZ-pain relief

• 2KHZ-muscle stimulation2KHZ-muscle stimulation

• Pre modulated/4ELPre modulated/4EL

• Able to penetrate tissues with little Able to penetrate tissues with little resistanceresistance

• No accomadation/gildemeister effectNo accomadation/gildemeister effect

Wound Healing: E- stim for Wound Healing: E- stim for Tissue Repair (ESTR)Tissue Repair (ESTR)

• Robert Becker – 1962Robert Becker – 1962• Theory - “Current of Injury”Theory - “Current of Injury”

– normal bioelectric system, nonexcitable normal bioelectric system, nonexcitable tissues have a chargetissues have a charge•skin -----skin -----•deeper tissues +++++deeper tissues +++++•neuraxis ++++++neuraxis ++++++•periphery -------periphery -------

– Wounds - system is disturbed & creates a Wounds - system is disturbed & creates a “current of injury” that initiates tissue “current of injury” that initiates tissue healing . . . inflammatory process, migration of healing . . . inflammatory process, migration of cells, etc..cells, etc..

– Use of E-stim magnifies the “current of injury” Use of E-stim magnifies the “current of injury” to initiate, maintain, or speed the process.to initiate, maintain, or speed the process.

““Current of Injury” Current of Injury” cont...cont...• Further research establishedFurther research established

– Wound tissue is (+) & skin around is (-); this Wound tissue is (+) & skin around is (-); this difference is the “skin battery” or “current of difference is the “skin battery” or “current of injury” and must exist for proper healing; injury” and must exist for proper healing; if it fails or is disrupted, then slow/no healing if it fails or is disrupted, then slow/no healing can occur. E -stim can help restore the “skin can occur. E -stim can help restore the “skin battery”.battery”.

• Further supported by evidence that many chronic Further supported by evidence that many chronic

wounds lost (+) polarity; e-stim w/ the anode (+) wounds lost (+) polarity; e-stim w/ the anode (+) over the wound enhanced healing. (using DC)over the wound enhanced healing. (using DC)

• If healing plateaued, switching polarity = good If healing plateaued, switching polarity = good outcomeoutcome– Kloth & Feedar, Kloth & Feedar, Phys TherPhys Ther, April 88, April 88

Contemporary Theory: Contemporary Theory: GalvanotaxisGalvanotaxis

Process can be corrected and/or enhanced Process can be corrected and/or enhanced by attraction of cells to the wound thru by attraction of cells to the wound thru

use of anode (+) or cathode (-)use of anode (+) or cathode (-)Leukocytes, fibroblasts, endothelial & Leukocytes, fibroblasts, endothelial &

epithelial cells, etc.. all have polarity epithelial cells, etc.. all have polarity and can be electrically attracted.and can be electrically attracted.

Treatment polarity depends on stage Treatment polarity depends on stage of the woundof the wound

READ THE ARTICLE: Kloth & READ THE ARTICLE: Kloth & McCulloch (1996)McCulloch (1996)

Electrode PlacementElectrode Placement• OptionsOptions

– Directly over the woundDirectly over the wound– Directly in the wound *Directly in the wound *– Straddle the woundStraddle the wound

• More information FYI:More information FYI:http://http://

medicaledu.com/estim.htmmedicaledu.com/estim.htm

ELECTROTHERAPY ELECTROTHERAPY TREATMENT OF SWELLING TREATMENT OF SWELLING I I EDEMAEDEMA STAGESTAGE RxRx CURRENCURREN

TTPolarityPolarity FREQFREQ RESPONSRESPONS

EETIMETIME

ACUTEACUTE Control Control of of

FormatioFormationn

HVPCHVPC (--)(--) 120 PPS120 PPS SUBMOTOSUBMOTORR

30 Min/30 Min/4 HRS 4 HRS during during acute acute stagestage

SUBACUTSUBACUTE E I I

CHRONICCHRONIC

ReductioReductionn

HVPCHVPCBIPHASIBIPHASI

CCRUSSIANRUSSIAN

N/AN/A Varies: Varies: need need ms. ms.

pumppump

MOTORMOTOR 20 min 20 min dailydaily

Voluntary contraction Vs Voluntary contraction Vs Electrical stimulationElectrical stimulation

• Recruitment orderRecruitment order

small->large small->large

• Fibre type Fibre type

slow->fast twitchslow->fast twitch

• Central fatigue Central fatigue

• Fatigue resistant motor Fatigue resistant motor units firstunits first

• More force-more fatigue More force-more fatigue

• OppOpp

• OppOpp

• Peripheral fatiguePeripheral fatigue

• OppOpp

• high/low-no differencehigh/low-no difference

Faradic Vs galvanicFaradic Vs galvanic

• AC/DCAC/DC

• Short duration Short duration pulsepulse

• <1sec or micro sec<1sec or micro sec

• DCDC

• Long duration pulseLong duration pulse

• >1sec>1sec

• elicits a muscle elicits a muscle contraction from de -contraction from de -nervated muscle, but nervated muscle, but the phase duration is the phase duration is so long that C fibers so long that C fibers are also stimulatedare also stimulated

DenervatedDenervated muscle muscle stimulationstimulation

• ES may disrupt regenerating NMJES may disrupt regenerating NMJ• Trauma of the muscleTrauma of the muscle• Time consumingTime consuming• Three stimulation sessions/dayThree stimulation sessions/day three to five sets of 5-20 isometric three to five sets of 5-20 isometric

contractionscontractions• 5s –rest period/contraction5s –rest period/contraction• 1m-rest period /set1m-rest period /set• pW >than chronoxiepW >than chronoxie

Muscle ContractionsMuscle Contractions

1 pps = twitch 1 pps = twitch 10 pps = summation10 pps = summation

25-30 pps = tetanus (most fibers will 25-30 pps = tetanus (most fibers will reach tetany by 50 pps)reach tetany by 50 pps)

50-100 micro sec –sensory stimulation50-100 micro sec –sensory stimulation

200-300 micro sec –motor stimulation200-300 micro sec –motor stimulation

Frequency selection:Frequency selection:

• 100Hz - pain relief100Hz - pain relief

• 50-60 Hz = muscle contraction50-60 Hz = muscle contraction

• 1-50 Hz = increased circulation1-50 Hz = increased circulation

• The higher the frequency (Hz) the The higher the frequency (Hz) the more quickly the muscle will fatiguemore quickly the muscle will fatigue

• 1-4 Hz-beta endorphin1-4 Hz-beta endorphin

• 40-100Hz-enkepalin,serotonin40-100Hz-enkepalin,serotonin

Electrocution and dangersElectrocution and dangers

• Electric and earth shockElectric and earth shock

• ELCB ELCB

• BF/CF areasBF/CF areas

• Guidelines by Robertson et al(2001)Guidelines by Robertson et al(2001)

• AC is more dangerous than DC(P=V*I)AC is more dangerous than DC(P=V*I)– The strongest stimulation is where the The strongest stimulation is where the

current exits the bodycurrent exits the body

Unexpected effects of ESUnexpected effects of ES

Over and above the Over and above the normal normal physiological and physiological and psychological limitspsychological limits

• SkinSkin

• EyesEyes

• General symptomsGeneral symptoms

• Cardio-respCardio-resp

• NeurologicalNeurological

• AttitudeAttitude

• musculoskeletalmusculoskeletal

Risk ManagementRisk Management

• Risk grading-0,(1,2),3Risk grading-0,(1,2),3

• Safety& maintenance( quality Safety& maintenance( quality assurance)assurance)

• InfectionInfection

• AversionAversion

• Children (guidelines) Children (guidelines)

ES for neurological ES for neurological conditionsconditions

• UMN lesion- FESUMN lesion- FES

• LMN lesion- enhance re innervationsLMN lesion- enhance re innervations

maintain muscle propertymaintain muscle property

• UMN&LMN- no use (Eg: ALS) UMN&LMN- no use (Eg: ALS)

The history of FES The history of FES before 19th centurybefore 19th century

Liberson, et al 1961

First registered FES workFirst registered FES work

Parastep (Sigmedics Inc.)Parastep (Sigmedics Inc.)

Parastep System Parastep System ComponentsComponents

• Restoration of hand function in C5-6 tetraplegia Restoration of hand function in C5-6 tetraplegia and CVAand CVA– Wrist movement must be preservedWrist movement must be preserved– 3 channels self-adhesive electrodes over motor points3 channels self-adhesive electrodes over motor points– Conductive panels in the glove make contact electrodesConductive panels in the glove make contact electrodes– Control: wrist movements (tenodesis) sensed by a Control: wrist movements (tenodesis) sensed by a

transducertransducer•Wrist flexed > extensors tension > hand opensWrist flexed > extensors tension > hand opens

•Wrist extended > flexors tension > hand closesWrist extended > flexors tension > hand closes

– Independent Don-DoffIndependent Don-Doff

Bionic GloveBionic Glove

Lower Limb: Odstock foot Lower Limb: Odstock foot drop stimulatordrop stimulator

• One channel stimulatorOne channel stimulator• Stimulation: Stimulation:

– common peroneal nerve at head common peroneal nerve at head of fibula (TA) orof fibula (TA) or

– popliteal fossa (withdrawal reflex)popliteal fossa (withdrawal reflex)

• Heel switch trigger: Heel switch trigger: – Heel off > stimulation ONHeel off > stimulation ON– Heel on > stimulation OFFHeel on > stimulation OFF

• Rise and fall stimulation envelope Rise and fall stimulation envelope can be adjustedcan be adjusted

• Odstock 2 Channel Stimulator Odstock 2 Channel Stimulator (O2CHS) for bilateral dropped foot(O2CHS) for bilateral dropped foot

Handmaster (NESS, Handmaster (NESS, Israel)Israel)

ReferencesReferences

• Electrotherapy in rehab-meryl roth Electrotherapy in rehab-meryl roth gershgersh

• Orthopaedic PT secrets-placzek & Orthopaedic PT secrets-placzek & boyceboyce

• Electrotherapy explained-low and reedElectrotherapy explained-low and reed

• Practical EBP- herbertPractical EBP- herbert

• electrotherapyEBP-Tim watsonelectrotherapyEBP-Tim watson

QUERIESQUERIES