Electrical Stimulation Currents Therapeutic Modalities Chapter 5

Electrical Stimulation Currents

Therapeutic Modalities

Chapter 5

Electricity is an element of PT. May be most frightening and least understood.

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

Electromagnetic RadiationsElectromagnetic Radiations

Other Forms Of Radiation Other Than Other Forms Of Radiation Other Than Visible Light May Be Produced When An Visible Light May Be Produced When An Electrical Force Is AppliedElectrical Force Is Applied

Other Forms Of Radiation Other Than Other Forms Of Radiation Other Than Visible Light May Be Produced When An Visible Light May Be Produced When An Electrical Force Is AppliedElectrical Force Is Applied

RedRedRedRed

OrangeOrangeOrangeOrange

YellowYellowYellowYellow

GreenGreenGreenGreen

BlueBlueBlueBlue

VioletVioletVioletViolet

InfraredInfraredInfraredInfrared

UltravioletUltravioletUltravioletUltraviolet

Electromagnetic RadiationsElectromagnetic Radiations

In Addition, Other Forms Of Radiation In Addition, Other Forms Of Radiation Beyond Infrared And Ultraviolet Regions Beyond Infrared And Ultraviolet Regions May Be Produced When An Electrical May Be Produced When An Electrical Force Is AppliedForce Is Applied

These Radiations Have Different These Radiations Have Different Wavelengths And Frequencies Than Wavelengths And Frequencies Than Those In The Visible Light SpectrumThose In The Visible Light Spectrum

In Addition, Other Forms Of Radiation In Addition, Other Forms Of Radiation Beyond Infrared And Ultraviolet Regions Beyond Infrared And Ultraviolet Regions May Be Produced When An Electrical May Be Produced When An Electrical Force Is AppliedForce Is Applied

These Radiations Have Different These Radiations Have Different Wavelengths And Frequencies Than Wavelengths And Frequencies Than Those In The Visible Light SpectrumThose In The Visible Light Spectrum

Collectively The Various Collectively The Various Types Of Radiation Form The Types Of Radiation Form The

Electromagnetic SpectrumElectromagnetic Spectrum

Collectively The Various Collectively The Various Types Of Radiation Form The Types Of Radiation Form The

Electromagnetic SpectrumElectromagnetic Spectrum

Electrical Stimulating CurrentsElectrical Stimulating CurrentsElectrical Stimulating CurrentsElectrical Stimulating Currents

Commercial Radio and TelevisionCommercial Radio and TelevisionCommercial Radio and TelevisionCommercial Radio and Television

Shortwave DiathermyShortwave DiathermyShortwave DiathermyShortwave Diathermy

Microwave DiathermyMicrowave DiathermyMicrowave DiathermyMicrowave Diathermy

InfraredInfraredInfraredInfraredLASERLASERLASERLASER

Visible LightVisible LightVisible LightVisible Light

UltravioletUltravioletUltravioletUltraviolet

Ionizing RadiationIonizing RadiationIonizing RadiationIonizing Radiation

{{{{

LongestLongestWavelengthWavelength

LongestLongestWavelengthWavelength

ShortestShortestWavelengthWavelength

ShortestShortestWavelengthWavelength

LowestLowestFrequencyFrequency

LowestLowestFrequencyFrequency

HighestHighestFrequencyFrequency

HighestHighestFrequencyFrequency

Wavelength And FrequencyWavelength And FrequencyWavelength And FrequencyWavelength And Frequency

Wavelength-Distance Between Peak Of One Wave and Peak of the Next Wave

Frequency-Number Of Wave Oscillations Or Vibrations Per Second (Hz, CPS, PPS)

Velocity=Wavelngth X Frequency

Wavelength-Distance Between Peak Of One Wave and Peak of the Next Wave

Frequency-Number Of Wave Oscillations Or Vibrations Per Second (Hz, CPS, PPS)

Velocity=Wavelngth X Frequency

Electromagnetic Radiations Share Electromagnetic Radiations Share Similar Physical CharacteristicsSimilar Physical CharacteristicsElectromagnetic Radiations Share Electromagnetic Radiations Share Similar Physical CharacteristicsSimilar Physical Characteristics

Produced When Sufficient Electrical Or Chemical Forces Are Applied To Any Material

Travel Readily Through Space At An Equal Velocity (300,000,000 meters/sec)

Direction Of Travel Is Always In A Straight Line

Produced When Sufficient Electrical Or Chemical Forces Are Applied To Any Material

Travel Readily Through Space At An Equal Velocity (300,000,000 meters/sec)

Direction Of Travel Is Always In A Straight Line

Electromagnetic Radiations Share Similar Physical CharacteristicsElectromagnetic Radiations Share Similar Physical Characteristics

When Contacting Biological Tissues May Be…

When Contacting Biological Tissues May Be…


When Contacting Biological Tissues May Be…Reflected

When Contacting Biological Tissues May Be…Reflected


When Contacting Biological Tissues May Be…ReflectedTransmitted

When Contacting Biological Tissues May Be…ReflectedTransmitted


When Contacting Biological Tissues May Be…ReflectedTransmittedRefracted

When Contacting Biological Tissues May Be…ReflectedTransmittedRefracted


When Contacting Biological Tissues May Be…ReflectedTransmittedRefractedAbsorbed

When Contacting Biological Tissues May Be…ReflectedTransmittedRefractedAbsorbed

Laws Governing The Effects of Laws Governing The Effects of Electromagnetic RadiationsElectromagnetic RadiationsLaws Governing The Effects of Laws Governing The Effects of Electromagnetic RadiationsElectromagnetic Radiations

Arndt-Schultz PrincipleArndt-Schultz PrincipleNo Changes Or Reactions Can Occur In The No Changes Or Reactions Can Occur In The

Tissues Unless The Amount Of Energy Tissues Unless The Amount Of Energy Absorbed Is Sufficient To Stimulate The Absorbed Is Sufficient To Stimulate The Absorbing Tissues Absorbing Tissues

Arndt-Schultz PrincipleArndt-Schultz PrincipleNo Changes Or Reactions Can Occur In The No Changes Or Reactions Can Occur In The

Tissues Unless The Amount Of Energy Tissues Unless The Amount Of Energy Absorbed Is Sufficient To Stimulate The Absorbed Is Sufficient To Stimulate The Absorbing Tissues Absorbing Tissues


Law Of Grotthus-DraperLaw Of Grotthus-DraperIf The Energy Is Not Absorbed It Must Be If The Energy Is Not Absorbed It Must Be

Transmitted To The Deeper TissuesTransmitted To The Deeper TissuesThe Greater The Amount Absorbed The Less The Greater The Amount Absorbed The Less

Transmitted and Thus The Less PenetrationTransmitted and Thus The Less Penetration

Law Of Grotthus-DraperLaw Of Grotthus-DraperIf The Energy Is Not Absorbed It Must Be If The Energy Is Not Absorbed It Must Be

Transmitted To The Deeper TissuesTransmitted To The Deeper TissuesThe Greater The Amount Absorbed The Less The Greater The Amount Absorbed The Less

Transmitted and Thus The Less PenetrationTransmitted and Thus The Less Penetration


Cosine LawCosine LawThe Smaller The Angle Between The The Smaller The Angle Between The

Propagating Radiation And The Right Angle, Propagating Radiation And The Right Angle, The Less Radiation Reflected And The Greater The Less Radiation Reflected And The Greater The AbsorptionThe Absorption

Cosine LawCosine LawThe Smaller The Angle Between The The Smaller The Angle Between The

Propagating Radiation And The Right Angle, Propagating Radiation And The Right Angle, The Less Radiation Reflected And The Greater The Less Radiation Reflected And The Greater The AbsorptionThe Absorption

SourceSourceSourceSource


Inverse Square Inverse Square LawLawThe Intensity Of The Intensity Of

The Radiation The Radiation Striking A Surface Striking A Surface Varies Inversely Varies Inversely With The Square With The Square Of The Distance Of The Distance From The SourceFrom The Source

Inverse Square Inverse Square LawLawThe Intensity Of The Intensity Of

The Radiation The Radiation Striking A Surface Striking A Surface Varies Inversely Varies Inversely With The Square With The Square Of The Distance Of The Distance From The SourceFrom The Source

Source

1 Inch

2 Inch

Electromagnetic ModalitiesElectromagnetic Modalities

The Majority of Therapeutic Modalities Used By Athletic Trainers Emit A Type Of Energy With Wavelengths And Frequencies That Can Be Classified As Electromagnetic Radiations

The Majority of Therapeutic Modalities Used By Athletic Trainers Emit A Type Of Energy With Wavelengths And Frequencies That Can Be Classified As Electromagnetic Radiations

Electromagnetic Modalities Include...Electromagnetic Modalities Include...Electromagnetic Modalities Include...Electromagnetic Modalities Include...

Electrical Stimulating CurrentsShortwave And Microwave DiathermyInfrared Modalities

Thermotherapy Cryotherapy

Ultraviolet Radiation TherapyLow-Power LasersMagnet Therapy

Electrical Stimulating CurrentsShortwave And Microwave DiathermyInfrared Modalities

Thermotherapy Cryotherapy

Ultraviolet Radiation TherapyLow-Power LasersMagnet Therapy

General Therapeutic Uses of ElectricityControlling acute and chronic pain Edema reductionMuscle spasm reductionReducing joint contracturesMinimizing disuse/ atrophyFacilitating tissue healingStrengthening muscleFacilitating fracture healing

Contraindications of Electrotherapy

Cardiac disabilityPacemakersPregnancyMenstruation (over abdomen, lumbar or

pelvic region)Cancerous lesionsSite of infectionExposed metal implantsNerve Sensitivity

Terms of electricity

Electrical current: the flow of energy between two pointsNeeds

A driving force (voltage)some material which will conduct the electricity

Amper: unit of measurement, the amount of current (amp)

Conductors: Materials and tissues which allow free flow of energy

Fundamentals of Electricity

Electricity is the force created by an imbalance in the number of electrons at two pointsNegative pole: an area of high electron

concentration (Cathode)Positive pole: an area of low electron

concentration (Anode)

Charge

An imbalance in energy. The charge of a solution has significance when attempting to “drive” medicinal drugs topically via iontophoresis and in attempting to artificially fire a denervated muscle

Charge: Factors to understand

Coulomb’s Law: Like charges repel, unlike charges attractLike charges repel

allow the drug to be “driven”Reduce edema/blood

Charge: Factors

Membranes rest at a “resting potential” which is an electrical balance of charges. This balance must be disrupted to achieve muscle firingMuscle depolarization is difficult to achieve with

physical therapy modalitiesNerve depolarization occurs very easily with PT

modalities


Insulators: materials and tissues which deter the passage of energy

Semiconductors: both insulators and conductors. These materials will conduct better in one direction than the other

Rate: How fast the energy travels. This depends on two factors: the voltage (the driving force) and the resistance.


Voltage: electromotive force or potential difference between the two poles

Voltage: an electromotive force, a driving force. Two modality classification are:Hi Volt: greater than 100-150 VLo Volt: less than 100-150 V


Resistance: the opposition to flow of current. Factors affecting resistance:Material compositionLength (greater length yields greater

resistance)Temperature (increased temperature, increase

resistance)

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

Minimize air-electrode interfaceKeep electrode clean of oils, etc.Clean the skin of oils, etc.

Use the shortest pathway for energy flowUse the largest electrode that will selectively

stimulate the target tissuesIf resistance increases, more voltage will be

needed to get the same current flow

Clinical application of Electricity: TemperatureRelationship

An increase in temperature increases resistance to current flow

ApplicabilityPreheating the tx area may increase the

comfort of the tx but also increases resistance and need for higher output intensities

Clinical Application of Electricity: Length of CircuitRelationship:

Greater the cross-sectional area of a path the less resistance to current flow

Application:Nerves having a larger diameter are

depolarized before nerves having smaller diameters

Clinical Application of Electricity: Material of CircuitNot all of the body’s

tissues conduct electrical current the same

Excitable TissuesNervesMuscle fibersblood cellscell membranes

Non-excitable tissuesBoneCartilageTendonsLigaments

Current prefers to travel along excitable tissues

Stimulation Parameter:Amplitude: the intensity of the current,

the magnitude of the charge. The amplitude is associated with the depth of penetration.The deeper the penetration the more muscle

fiber recruitment possible remember the all or none response and the

Arndt-Schultz Principle

Simulation ParameterPulse duration: the length of time the

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

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

Stimulation Parameter:

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

depolarizationSlow rise: the nerve accommodates to

stimulus and a action potential is not elicitedGood for muscle reeducation with assisted

contraction - ramping (shock of current is reduced)

Stimulation Parameters

Pulse Frequency: (PPS=Hertz) How many pulses occur in a unit of timeDo not assume the lower the frequency the longer the

pulse durationLow Frequency: 1K Hz and below (MENS .1-1K Hz),

muscle stim units)Medium frequency: 1K ot 100K Hz (Interferential,

Russian stim LVGS)High Frequency: above 100K Hz (TENS, HVGS,

diathermies)


Current types: alternating or Direct Current (AC or DC)AC indicates that the energy travels in a

positive and negative direction. The wave form which occurs will be replicated on both sides of the isoelectric line

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

DC AC


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

Method to direct currentPeaked - sharperSign - smoother


Duty cycles: on-off time. May also be called inter-pulse interval which is the time between pulses. The more rest of “off” time, the less muscle fatigue will occur1:1 Raito fatigues muscle rapidly1:5 ratio less fatigue1:7 no fatigue (passive muscle exercise)


Average current (also called Root Mean Square)the “average” intensityFactors effecting the average current:

• pulse amplitude• pulse duration• waveform (DC has more net charge over time thus

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


Current DensityThe amount of charge per unit area. This is

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

Capacitance:

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

response. Body tissues have different capacitance. From least to most:Nerve (will fire first, if healthy)Muscle fiberMuscle tissue

Capacitance:

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

Muscle membrane has 10x the capacitance of nerve

Factors effecting the clinical application of electricity

Factors effecting the clinical application of electricity Rise Time: the time to peak intensityThe onset of stimulation must be rapid

enough that tissue accommodation is prevented

The lower the capacitance the less the charge can be stored

If a stimulus is applied too slowly, it is dispersed

Factors effecting the clinical application of electricity

An increase in the diameter of a nerve decreased it’s capacitance and it will respond more quickly. Thus, large nerves will respond more quickly than small nerves.

Denervated muscles will require a long rise time to allow accommodation of sensory nerves. Best source for denervated muscle stimulation is continuous current DC

Factors effecting the clinical application of electricity:Ramp: A group of waveforms may be

ramped (surge function) which is an increase of intensity over time.The rise time is of the specific waveform and is

intrinsic to the machine.

Law of DuBois Reymond:

The amplitude of the individual stimulus must be high enough so that depolarization of the membrane will occur.

The rate of change of voltage must be sufficiently rapid so that accommodation does not occur

The duration of the individual stimulus must be long enough so that the time course of the latent period (capacitance), action potential, and recovery can take place

Muscle Contractions & Frequency

Are described according to the pulse width1 pps = twitch10 pps = summation25-30 pps = tetanus (most fibers will reach tetany by 50

pps)Frequency selection:

100Hz - pain relief50-60 Hz = muscle contraction1-50 Hz = increased circulationThe higher the frequency (Hz) the more quickly the

muscle will fatigue

Frequency selection:

100Hz - pain relief50-60 Hz = muscle contraction1-50 Hz = increased circulationThe higher the frequency (Hz) the more

quickly the muscle will fatigue

Electrodes used in clinical application of current:

Electrodes used in clinical application of current: At least two electrodes are required to complete the circuit

The body becomes the conductorMonophasic application requires one negative electrode

and one positive electrodeThe strongest stimulation is where the current exists the

bodyElectrodes placed close together will give a superficial

stimulation and be of high density

Electrodes used in clinical application of current:

Electrodes spaced far apart will penetrate more deeply with less current density

Generally the larger the electrode the less density. If a large “dispersive” pad is creating muscle contractions there may be areas of high current concentration and other areas relatively inactive, thus functionally reducing the total size of the electrode

A multitude of placement techniques may be used to create the clinical and physiological effects you desire

General E-Stim Parameters

Other:E lectrode Spacing

Burst Option, Voltage/Acc.Accupoint (1-5pps)

Tim e: 20-60 m in

PPS: 70-100Polarity: purpose & com fort

Hz: 100+Tens, HVGS, IFC

Pain

Other:E lectrode Spacing

Voltage/Acc.W ith m uscle cxn or pain reduction

Tim e: 20 m in

PPS: 120Polarity: negative

Hz: 100-150HVGS, IFC

Edem a

Other:E lectrode Spacing, surge

Burst Option, Voltage/Acc.Accupoint (1-5pps)

Tim e: Fatigue (1-15 m in)

PPS: 1-20Polarity: purpose & com fort

Hz: 50-60Type: depends on purpose

Muscle Re-ed.

O ther:E lectrode Spacing

Voltage/Acc.Accupoint

Tim e: 20 m in

PPS: vary but typically tens likePolarity: purpose & com fort

Hz: 100+ or 1(? inc. circ)IFC , Ionto, Mens (?)

Tissue Healing

E-Stim for Pain Control: typical Settings

Electrode P lacem entB iopolar: D ista l & P roxim al to m uscle

Monopolar: O ver m otor points

Alternating R ate: Alternating

Polarity: + or -

Pulse R ate: <1535-50 for tonic contraction

Intensity: S tong & com fortable

N eurom uscular S tim ulationH igh Volt Pulsed S tim

E lectrode P lacem entD irectly over m otor points

Mode: continuous

Phase D uration < 100 usec

Pulse R ate: 60-100 pps

Intensity: Sensory

G ate C ontro l TheoryH igh-Volt Pulsed S tim

E lectrode P lacem entD irectly over m otor points

Mode: C ontinuous

Phase D uration: 150-250 usec

Pulse R ate 2-4 pps

Intensity: Motor level

O piate R eleaseH igh-Volt Pulsed S tim

E lectrode P lacem entG rid Tech: d ista l & proxim al to site

Mode: 15-60 sec at each site

Phase D uration: 300-1000 usec

Pulse R ate: 120pps

Intensity: N oxiousType title here

Brief-Intense (P robe)H igh-Volt Pulsed S tim

High Volt Pulsed Stimulation

CURRENT CONCEPTSEVIDENCE BASED ES increased 20% verses control (no

activity) demonstrating that ES “can alter the blood flow in muscle being stimulated” Currier et all 1996

Currier et al 1988: Similar study but 15%Bettany et al 1990: Edema formation in

frogs decreased with HVPC 10 minutes after the trauma

Walker et al 1988: HVS at a pulse rate of 30 Hz and intensities to evoke 10% - 20% MVC did not increase blood flow to the popliteal artery. The exercise group demonstrated 30% increase

Von Schroeder et al 1991: Femoral venous flow shown to increase greatest with passive SLR elevation, then CPM, active ankle dorsiflexion, manual calf compression and passive dorsiflexion

CURRENT CONCEPTSEVIDENCE BASED

HVPS

The application of monophasic current with a known polarity typically a twin-peaked waveformduration of 5 - 260 msec

Wide variety of uses:muscle reeducation (requires 150V)nerve stimulation (requires 150V)edema reductionpain control

Clinical Application:

Physiological response can be excitatory and non-excitatory

ExcitatoryPeripheral nerve

stimulation for pain modulation (sensory, motor and pain fibers)

Promote circulation: inhibits sympathetic nervous system activity, muscle pumping and endogenous vasodilatation

Non-Excitatory (cellular level)

Protein synthesisMobilization of blood

proteinsBacteriocyte affects

(by increased CT micro-circulation there is a reabsorption of the interstitial fluids)

Setting the ES with no twitch has purpose

General Background

Early in history HVS was called EGS (electrical galvanic stimulation), then HVGS, then HVPS

Current qualifications to be considered HVSMust have twin peak monophasic currentMust have 100 or 150 volts (up to 500 V)

HVPS

PrecautionsStimulation may cause

unwanted tension on muscle fibers

Muscle fatigue if insufficient duty cycle

Improper electrodes can burn or irritate

Intense stim may result in muscle spasm or soreness

Contraindications Cardiac disability Pacemakers Pregnancy Menstruation Cancerous lesion Infection Metal implants Nerve sensitivity

Indications past slide

Treatment Duration

General - 15-30 minutes repeated as often as needed

Pain reduction - sensory 30 minutes with 30 minute rest between tx

Current Parameters

greater than 100-150 Vusually provides up to 500 Vhigh peak, low average currentstrength duration curve = short pulse

duration required higher intensity for a response

high peak intensities (watts) allow a deeper penetration with less superficial stimulation

Current Parameters

Pulse Rate: ranges from 1-120 pps varies according to the

desire clinical application Current

Pulse Charge related to an excess or

deficiency of negatively charged particles

associated with the beneficial or harmful responses (thermal, chemical, physical)

Modulations intrapulse spacing duty cycle: reciprocal mode

usually 1:1 ratio ramped or surged cycles

Clinical Considerations: always reset intensity after

use (safety) electrode arrangements may

be mono or bipolar units usually have a hand

held probe for local (point) stimulation

most units have an intensity balance control

Application TechniquesMonopolar: 2 unequal sized electrodes. Smaller is

generally over the treatment site and the large serves as a dispersive pad, usually located proximal to the treatment area

Bipolar: two electrodes of equal size, both are over or near the treatment site

Water immersion - used for irregularly shaped areasProbes: one hand-held active lead

advantages: can locate and treat small triggersdisadvantages: one on one treatment requires full

attention of the trainer

Electrodes

Materialcarbon impregnated silicone electrodes are

recommended but will develop hot spots with repeated use

you want conductive durable and flexible material

tin with overlying sponge has a decreased conformity and reduced conductivity

Electrodes

Sizebased on size of target areacurrent density is important. The smaller the

electrode size the greater the density

Neuromuscular StimulationRoles:

re-educate a muscle how to contract after immobilization (does not produce strength augmentation but retards atrophy)

Parameter Setting

Intensity Strong, comfortable

Pulsefrequency

Muscle cxn <15ppsTonic cxn 35-50 pps

Polarity + or -

Alternation Yes

Pain Control

Roles:Control acute or chronic pain both sensory (gate control - 100-150 pps)) and motor level (opiate release - through voltage)

Parameter Setting for Gate ControlMethod

Intensity Sensory

Pulsefrequency

60-100 pps

PhaseDuration

< 100sec

Mode Continuous

Placement Directly over pain site

Parameter Setting OpiateRelease

Intensity Motor Level 150V

PhaseDuration

150-250 msec

Pulsefrequency

2-4pps

Mode Continuous

Placement Directly over pain site

Pain Control - Opiate Release Setting

Evidence Based

Clinical Studies on HVPC and pain modulation is misleading – pain associated with muscle spasm is decreased secondary to muscle fatigue/exhaustion (Belanger, 2003)

Studies on muscle strengthening have indicated no effect (Alon 1985, Mohr et al, 1985; Wong 1986)

Control and Reduction of Edema

Roles:Sensory level used to limit acute edemaMotor-level stimulation used to reduce subacute or chronic inflammation

Parameter Setting Sensory Level Control

Intensity Sensory

Pulsefrequency

120 pps

Polarity -

PulseDuration

Maximum allowed by generator

Mode Continuous

Motor-Level Edema Reduction

Cell Metabolism: increased and may increase blood flowWound Healing: May increase collagnase levels and inhibit bacteria in infected wounds (for this effect 20 min - polarity followed by 40 min + polarity recommended)

Parameter Setting

Intensity Strong, comfortable

Pulsefrequency

Low 2-4 pps

Polarity + or -

Alternation Yes

Russian Current

Continuous sine-wave modulation of 2,5000 pps and burst-modulated for fixed periods of 10 msec resulting in a frequency of 50 bursts per second.

Thought to depolarize both sensory and motor concomitantly (knots 1977). Thus simulating muscle training.No North American has been able to duplicate

Knots’ claims

T.E.N.S.

General Concepts:

An Approach to pain controlTrancutaneous Electrical Nerve Stimulation:Any stimulation in which a current is applied across

the skin to stimulate nerves1965 Gate Control Theory created a great popularity

of TENSTENS has 50-80% efficacy rateTENS stimulates afferent sensory fibers to elicit

production of neurohumneral substances such as endorphins, enkephalins and serotonin (i.e. gate theory)

TENS

IndicationsControl Chronic PainManagement post-

surgical painReduction of post-

traumatic & acute pain

Precautions Can mask underlying pain Burns or skin irritation prolonged use may result

in muscle spasm/soreness

caffeine intake may reduce effectiveness

Narcotics decrease effectiveness

Research is variable regarding the benefits of TENS Therapy (see Table 2-2; Belanger, 2001)

TENS may be:

high voltageinterferentialacuscopelow voltage AC stimulatorclassical portable TENS unit

Biophysical Effects

Primary use is to control pain through Gate Control Theory(between 0-100% can be placebo effect (Thorsteinsson et al.,

1978, Wall,1994)

Opiate pain relief through stimulation of naloxone (antagonist to endogenous opiates)

May produce muscle contractionsVarious methods

High TENS (Activate A-delta fibers)Low TENS (release of -endorphins from pituitary)Brief-Intense TENS (noxious stimulation to active C fibers)

Techniques of TENS application:

Conventional or High Frequency Short Duration , high frequency and low to comfortable current

amplitude Only modulation that uses the Gate Control Theory (opiate all others)

Acupuncture or Low Frequency Long pulse duration, Low frequency and low to comfortable current

amplitude Brief Intense

Long pulse duration, high frequency, comfortable to tolerable amplitude Burst Mode

Burst not individual pulses, modulated current amplitude Modulated

Random electronic modulation of pulse duration, frequency and current amplitude

Protocol for Various Methods of TENS

Parameter High TENS Low TENS Brief-IntenseTENS

Intensity Sensory Motor Noxious

Pulse Fq 60-100 pps 2-4 pps Variable

PulseDuration

60-100 sec 150-250 sec 300-1000sec

Mode Modulated ModulatedBurst

Modluated

Tx Duration As needed 30 min 15-30 min

Onset ofRelief

< 10 min 20-40 min <15 min

Conventional Tens/High Frequency TENSParesthesia is created without motor

responseA Beta filers are stimulated to SG

enkephlin interneuron (pure gate theory)Creates the fastest relief of all techniquesApplied 30 minutes to 24 hoursrelief is short lives (45 sec 1/2 life)May stop the pain-spasms cycle

Application of High TENS

Pulse rate: high 75-100 Hz (generally 80), constant

Pulse width: narrow, less than 300 mSec generally 60 microSec

Intensity: comfortable to tolerance

Set up:

2 to 4 electrodes, often will be placed on post-op. Readjust parameters after response has been established. Turn on the intensity to a strong stimulation. Increase the pulse width and ask if the stimulation is getting wider (if deeper=good, if stronger...use shorter width)

Low Frequency/Acupuncture-like TENS:Level III pain relief, A delta fibers get Beta

endorphinsLonger lasting pain relief but slower to

startApplication

pulse rate low 1-5ppx (below 10)Pulse width: 200-300 microSecIntensity: strong you want rhythmical

contractions within the patient’s tolerance

Burst Mode TENS

Carrier frequency is at a certain rate with a built in duty cycle

Similar to low frequency TENSCarrier frequency of 70-100 Hz packaged in bursts

of about 7 bursts per secondPulses within burst can varyBurst frequency is 1-5 bursts per secondStrong contraction at lower frequenciesCombines efficacy of low rate TENS with the comfort

of conventional TENS

Burst Mode TENS - Application

Pulse width: high 100-200 microSecPulse rate: 70-100 pps modulated to 1-5

burst/secIntensity: strong but comfortabletreatment length: 20-60 minutes

Brief, Intense TENS: hyper-stimulation analgesia

Stimulates C fibers for level II pain control (PAG etc.)Similar to high frequency TENSHighest rate (100 Hz), 200 mSec pulse width intensity to

a very strong but tolerable levelTreatment time is only 15 minutes, if no relief then treat

again after 2-3 minutesMono or biphasic current give a “bee sting” sensationUtilize motor, trigger or acupuncture points.

Brief Intense TENS - Application

Pulse width: as high as possiblePulse rate: depends on the type of

stimulatorIntensity: as high as toleratedDuration: 15 minutes with conventional

TENS unit. Locus stimulator is advocated for this treatment type, treatment time is 30 seconds per point.

Locus point stimulator

Locus (point) stimulators treatment occurs once per day generally 8 points per sessionAuricular points are often utilized

Treat distal to proximalAllow three treatment trails before efficacy

is determinedUse first then try other modalities

Modulated Stimulation:

Keeps tissues reactive so no accommodation occurs

Simultaneous modulation of amplitude and pulse width

As amplitude is decreased, pulse width is automatically increased to deliver more consistent energy per pulse

Rate can also be modulated

Electrode Placement:

May be over the painful sites, dermatomes, myotomes, trigger points, acupuncture points or spinal nerve roots.

May be crossed or uncrossed (horizontal or vertical

Contraindications:

Demand pacemakersover carotid sinusesPregnancyCerebral vascular disorders (stroke

patients)Over the chest if patient has any cardiac

condition

Interferential Current - IFC

Interferential Current

History: In 1950 Nemec used interference of electrical currents to achieve therapeutic benefits. Further research and refinements have led to the current IFC available today Two AC are generated on separate channels (one channel

produces a constant high frequency sine wave (4000-5000Hz) and the other a variable sine wave

The channels combine/interface to produce a frequency of 1-100 Hz (medium frequency)

Evidence Based: Although IFC has been used for 40 years, only a few clinical studies have been published regarding use (DeDomenico, 1981,1987; Savage, 1984; Nikolova, 1987).

Effects of IFC treatment:

Primary Physiological Effect: Capacity of IFC to depolarize Sensory and motor nerve fibers

Main Therapeutic EffectsSensory nerve fibers - Pain reduction - receive a

lower amplitude stimulation than the area of tissue affected by the vector, thus IFC is said to be more comfortable than equal amplitudes delivered by conventional means

Blood flow/edema managementMuscle fatigue - muscle spasm - is reduced when

using IFC versus HVS due to the asynchronous firing of the motor units being stimulated

Positive effects of IFC include:

reduction of pain and muscle discomfort following joint or muscle trauma

these effects can be obtained with the of IFC and without associated muscle fatigue which may predispose the athlete to further injury.

Evidence Based Research

Low frequency This has been claimed as the key to IFC (Savage, 1984,

Nikolova, 1987)Palmer, 1999: IFC unlikely to produce physiological and

therapeutic effects different from those achieved by TENS Alon, 1999 states that IFC simply provides a more expensive,

different, least effective and somewhat redundant approach to achieving the same effects as other electrical stimulation parameters/waveforms

Pain sensation: Although the physiological changes are not different with IFC, Pain perception is decreased with IFC (Palmer, 1999)

Evidence Based Literature:

IFC does not lower skin impedance (Alon, 1999; Gerleman et al, 1999) Any pulsed biphasic current, regardless of waveform, having a medium

frequency are capable of a deeper stimulating effect (Alon, 1999; Hayes, 2000; Kloth, 1991;) Snyder-Mackler, et al 1989)

Increased Circulation is an anecdotal claim and has not been recreated in studies (Bersglien et al, 1988; Indergand et al.k 1995; Johnson, 1999; Nusswbaum et al., 1990: Olson et al., 1999)

Analgesic Effect: Similar not superior to other stimulations (TENS) (DeDomenico, 1982, 1987; Nikolova, 1987; Savage, 1984) Stephenson et al., 1995: Superior to a control group with ice/pain Cramp et al., 2000: Failed to demonstrate any effective pain relief with

IFC

Principles of wave interference - Combined EffectsConstructive, Destructive, & ContinuousConstructive interference: when two

sinusoidal waves that are exactly in phase or one, two, three or more wavelengths our of phase, the waves supplement each other in constructive interference

+ =

Principles of wave interference - Combined EffectsDestructive interference: when the two

waves are different by 1/2 a wavelength (of any multiple) the result is cancellation of both waves

+ =

Principles of wave interference - Combined EffectsContinuous Interference

Two waves slightly out of phase collide and form a single wave with progressively increasing and decreasing amplitude

=+

Amplitude-Modulated Beats:

Rate at which the resultant waveform (from continuous interference) changes

When sine waves from two similar sources have different frequencies are out of phase and blend (heterodyne) to produce the interference beating effect

IFC

Duration of tx 15-20 minutesBurst mode typically

applied 3x a week in 30 minute bouts

Precautionssame as all electrical

currents

ContraindicationsPain of central originPain of unknown origin

IndicationsAcute painChronic painMuscle spasm

IFC Techniques of treatment:

Almost exclusively IFC is delivered using the four-pad or quad-polar technique.

Various electrode positioning techniques are employed:Electrodes (Nemectrody: vacuum electrodes):

four independent pads allow specific placement of pads to achieve desired effect an understanding of the current interference is essential

four electrodes in one applicator allows IFC treatment to very small surface areas. The field vector is pre-determined by the equipment

Quad-polar Technique

Pads placed at 45º angles from center of tx area

Can reduce inaccuracy of appropriate tissues by selecting rotation or scan

Channel A

Channel B

Channel A

Channel B

SCAN

Bipolar Electrode Placement

The mix of two channels occurs in generator instead of tissues

Biopolar does not penetrate tissues as deeply, but is more accurate

When effects are targeted for one muscle or muscle group only one channel is used

Two-circuit IFC:

At other points along the time axes the wave amplitude will be zero because the positive phase from one circuit cancels the negative phase from the second circuit (destructive interference)

The rhythmical rise and fall of the amplitude results in a beat frequency and is equal to the number of times each second that the current amplitude increases to its maximum value and then decreases to its minimum value

Special Modulations of IFC:

Constant beat frequencies (model): the difference between the frequencies of the two circuits is constant and the result is a constant beat frequency. That is, if the difference in frequency between the two circuits is 40 pps, the beat frequency will be constant at 40 bps.

Special Modulations of IFC:

Variable beat mode: the frequency between the two circuits varies within preselected ranges. The time taken to vary the beat frequency through any programmed range is usually fixed by the device at about 15 sec. IFC machines often allow the clinician to choose from a variety of beat frequency programs.

Pain ControlSimilar to TENS - beat frequency 100Hz

• Low beat frequencies when combined with motor level intensities (2-10Hz) initiate the release of opiates

• 30 Hz frequencies affects the widest range of receptorsParameter Range

Intensity Sensory

Electrode Config Quadpolar

Beat Fq High – Gate ControlLow – Opiate release

Sweep Fq Long Duration

Neuromuscular Stimulation

Beat frequency of approximately 15 HZ is used to reduce edema

General ParametersParameter Range

Intensity 1-100mA

Carrier Fq 2500-5000Hz

Beat Fq 0-299 Hz

Sweep Fq 10-500sec

IFC Technique of treatment:

Electrode placement:The resultant vector should be visualized in placing

the electrodes for a treatment . The target tissue should be identified and the vector positioned to hit that area. Typically at 45º angles is most effective.

Segregation of the pin tips is essential in the proper electrode positioning for IFC. The electrodes may be of the same size or two different sizes (causing a shift in the intersecting vector). Treatment through a joint has also been advocated without adequate research to establish efficacy of the treatment technique.

Bone Stimulating Current:

Bone Stimulating Current:Bone Stimulating Current:IFC has been used (Laabs et al) studied the healing of a surgically induced fracture in the forelegs of sheep. Their study indicated an acceleration of healing in the sheep treated with IFC as compared to the control group


This study validated an earlier study by Gittler and Kleditzsch which showed similar results in callus formation in rabbits. Several other studies have shown an increase in the healing rate of fractures but the exact mechanism by which the healing occurs is not understood.


Some speculation is that an increased blood flow to the injured area is produced which allowed natural healing processes to occur more rapidly.

In one study (mandible fractures ) the IFC caused very mild muscle contraction of the jaw and this muscle activity was thought to have been a potential accelerator of the healing.

MENS or LIDC (low-intensity direct current)

MENS

No universally accepted definition or protocol & has yet to be substantiated

This form of modality is at the sub-sensory or very low sensory levelcurrent less than 1000A (approx 1/1000 amp

of TENS)Theorized that this is the current of injury

(Becker et al 1967, Becker & Seldon, 1987)

Biophysical Effects

Theory:Currents below 500A increases the level of ATP

(high Amp decreases ATP levels)Increase in ATP encourages amino acid

transport and increased protein synthesisMENS reestablishes the body’s natural electrical

balance allowing metabolic energy for healing without shocking the system (other types of e-stim)

Studies conducted indicate no difference from control group for wound healing

MENS

Duration 30 min to 2 hours up to 4x a

day Research suggests high degree

of variability on tx protocols Precautions

Dehydrated patients on Scar tissue (too much

impedance) Contraindications

Pain of unknown origin Osteomyelitis

Inconclusive Data: DOMS as an indication

(Allen et al 1999, Weber et al 1994)

Indications Acute & Chronic Pain Acute & Chronic

Inflammation Edema reduction sprains & Strains Contusion TMJ dysfunction Neuropathies Superficial wound healing Carpal Tunnel Syndrome

Electrode Placement

Electrodes should be placed in a like that transects the target tissuesRemember that electrical current travels in path of least

resistance, thus it is not always a straight line.

Either the + or – electrode can be placed on the injured tissue (Research is inconclusive: Lampe 1998, Sussmen et al 1999)Suggest alternating + and - electrode

TARGET

Application Techniques

Standard electrical stimulation padsgenerator may have bells & Whistles since

MENS is sub-sensory

Probe


MENSHas been advocated in the healing of bone, using implanted

electrodes and delivering a DC current with the negative pole at the fracture site. Further use of MENS has allowed increased rate of fracture healing using surface electrodes in a non-invasive technique. Theories on the physiology behind the healing focus on the electrical charge present in the normal tissue as compared to the electrical charge found with the injured tissue. MENS is said to allow an induction of an electrical charge to return to he tissues to a better “healing” environment

Research on bone stimulating current is inconclusive.

Microcurrent Electrical Stimulation

Tissue & Bone Healing

Electrical Stimulation

Physiological effect of electrical currents on nonexcitable tissue for tissue repair in its various forms:

(a) improvement of vascular status,

(b) edema control,

(c) wound healing,

(d) osteogenesis

Current of Injury (Theory)

Wounds are initially positive with respect to surrounding tissue

This positive polarity triggers the onset of repair processes

Maintaining this positive polarity would potentiate healing

“Anode over the wound” was suggested by most of the previous studies

Anode (+) Cathode (-)

Electrical Stimulation for Tissue RepairWound healing is also impeded by

infectionElectrical stimulation using the negative

lead of a DC generator has been shown in culture and in vivo either to be bacteriostatic or to retard the growth of common gram+ and gram- microorganisms

Electrical Stimulation for Tissue RepairThere is no evidence for the effectiveness

of sub-sensory-level stimulation for the healing of open wound

Electrical Stimulation for Bone HealingThe “current of injury” theory for bone: a

relative negativity of the injured tissue with respect to the uninjured.

Electrical Stimulation for Bone Healing The three best-studied and most

commonly used techniques are

(a) Cathodal placement in the fracture site and anodal placement on the skin at some distance.

(b) Implantation of the entire system

(c) The use of pulsed electromagnetic fields (PEMFs)

Electrical Stimulation for Bone HealingPEMFs is the use of inductive coils to the

skin or cast to deliver an asymmetrical, biphasic pulse at a frequency of about 15 pps.

Semiinvasive DC, totally invasive DC, and PEMF were the only FDA-approved (and physician administered) osteogenic means.

Electrical Stimulation for Bone Healing60 Hz sinusoidal AC, pulsed current, and

interference modulations of higher-frequency alternating currents are also being used.

Electrical Stimulation

Treatment Strategies

HVPS: Neuromuscular Stimulation Output Intensity

Strong, intense, comfortable contractions. Pulse frequency

If duty cycle cannot be adjusted: Low for individual muscle contractions (<15 pps).Adjustable duty cycle: Moderate for tonic contractions (>50 pps).

Duty CycleInitial treatments should begin with a low (e.g, 20%) duty cycle and be increased as the muscle responds.

Electrode placementBipolar: Proximal and distal to the muscle (or muscle group) to be stimulated. This method offers the most direct method of stimulating specific areas.Monopolar: Over motor points or muscle belly. Place the cathode over motor points

Bipolar electrode arrangement

HVPS: Sensory-level Pain Control

Output Intensity Sensory levelPulse frequency 60 to 100 ppsPhase duration <100 µsec*Mode ContinuousElectrode arrangement Monopolar or bipolarPolarity Acute: Positive

Chronic: NegativeElectrode placement Directly over or

surrounding the painful

site* Not adjustable on most HVPS units.

HVPS: Motor-level Pain Control

Output Intensity Motor levelPulse rate 2–4 ppsPhase duration 150–250 µsecMode ContinuousElectrode arrangement Monopolar or bipolarPolarity Acute: positive

Chronic: NegativeElectrode placement Directly over the painful

site, distal to the spinalnerve root origin, triggerpoints, or acupuncture

points

HVPS: Brief-Intense Pain Control ProtocolOutput Intensity NoxiousPulse rate >120 ppsPhase duration 300 to 1000 µsecMode Probe

15 to 60 sec at each siteElectrode arrangement Monopolar (probe)Polarity Acute: Positive

Chronic: NegativeProbe placement Gridding technique,

stimulating hypersensitiveareas working from distal

to proximal

HVPS: Sensory-level Edema Control Intensity: Sensory level Pulse duration: Maximum possible duration Pulse frequency: 120 pps. Polarity: Negative electrodes over injured

tissues Mode: Continuous Electrode placement: The immersion

method should be used when possible, or the active electrodes should be grouped over and around the target tissues.

Treatment duration Four 30-minute treatments, followed by 60-

minute rest periods or

Four 30-minute treatments, each followed by 30-minute rest periods.

Comments Start treatment as soon as possible after the

trauma. The body part should be wrapped and

elevated between sessions. This treatment regimen should not performed

if gross swelling is present. Cathode (-)

Anode (+)

HVPS: Edema Reduction

Intensity: Strong, yet comfortable muscle contraction Avoid contraindicated joint motio

Pulse frequency: Low Polarity: Positive or negative. Mode: Alternating. Electrode placement

Bipolar: Proximal and distal ends of the muscle group proximal to the edematous area.

Monopolar: Active electrodes follow the course of the venous return system.

Comment: Ice may be applied to the injured area, but this could impede venous return by increasing the viscosity of fluids in the area

IFS: Sensory-level Pain Control

Carrier Frequency: Based on patient comfort

Burst Frequency: 80 to 150 Hz Sweep: Fast Electrode Arrangement:

Quadripolar Electrode Placement: Around

the periphery of the target area Output Intensity: Strong

sensory level Treatment Duration: 20 to 30

minutes

Premodulated Neuromuscular Stimulation

Carrier Frequency: 2500 Hz Burst Frequency: 30 to 60 bps Burst Duty Cycle: 10 percent Cycle Duration: 400 µsec On/off Duty Cycle: 10:50 sec Ramp: 2 sec Electrode Placement: Bipolar:

Proximal and distal ends of the muscle

Output Intensity: Strong muscle contraction. Discomfort may be experienced

Treatment Duration: 10 cycles or until fatigue occurs

Documents

Electrical Stimulation Currents Therapeutic Modalities Chapter 5