(Transcutaneous Electrical Nerve (Transcutaneous Electrical Nerve

Stim) Stim) TENS for Pain TENS for Pain ControlControl

Bodychart Pain DrawingBodychart Pain Drawing

VASVAS

Spadoni G et al. The Evaluation of Change in Pain Intensity: A Comparison of the P4 and Single-Item Numeric Pain Rating Scales. J Orthop Sports Phys Ther 2004;34:187-193.

Chung Faces Pain Rating Chung Faces Pain Rating ScaleScale

THEORIES & THEORIES & MODELS OF MODELS OF

PAIN CONTROL PAIN CONTROL MECHANISMSMECHANISMS

ASSUMPTIONSASSUMPTIONS

These concepts involve OVERLAPPING These concepts involve OVERLAPPING PROCESSES that occur normallyPROCESSES that occur normally

Use these to better understand pain Use these to better understand pain perception and as a perception and as a rationalerationale for your for your direct interventions for pain controldirect interventions for pain control

STIMULATION OF STIMULATION OF MECHANORECEPTORSMECHANORECEPTORS

Accomplished everyday by:Accomplished everyday by:– Rubbing a painful areaRubbing a painful area– ““Walking off” the painWalking off” the pain

Stimulation of mechanoreceptors Stimulation of mechanoreceptors should be at the same neurological should be at the same neurological level as the pain.level as the pain.

Stimulation of A-beta fibers does Stimulation of A-beta fibers does control the pain to some degree,control the pain to some degree, BUT BUT HOW ????????HOW ????????

Endogenous Opiates Endogenous Opiates TheoriesTheories

Key neurotransmitters areKey neurotransmitters are– EnkephalinEnkephalin– EndorphinEndorphin– SerotoninSerotonin– Substance PSubstance P

Binding of endogenous opiates to receptor Binding of endogenous opiates to receptor sites inhibits transmission of “pain signals” sites inhibits transmission of “pain signals” to the brain.to the brain.

Presynaptic Inhibition @ Presynaptic Inhibition @ the Dorsal Horn (Gate Control)the Dorsal Horn (Gate Control)

Gate Control / Presynaptic Gate Control / Presynaptic Inhibition: Clinical ApplicationInhibition: Clinical Application

Massage, heat, ice, pressure, exercise, Massage, heat, ice, pressure, exercise, stretching, manual therapystretching, manual therapy

TENS : rapid stimulation of large TENS : rapid stimulation of large afferents by usingafferents by using

- High Frequency- High Frequency- Short Pulse Duration (width)- Short Pulse Duration (width)- Sensory amplitude- Sensory amplitude

Called Called Conventional / High Freq TENSConventional / High Freq TENS Ideal for acute pain Ideal for acute pain

Descending Inhibition of Descending Inhibition of pain via PAG & RNpain via PAG & RN

Inhibition of pain by Inhibition of pain by Endorphin Endorphin

(also decending)(also decending)

Descending Inhibition & Descending Inhibition & Endorphin: Clinical ApplicationEndorphin: Clinical Application

massage, ice, pressure (massage), massage, ice, pressure (massage), exercise, manual therapyexercise, manual therapy

TENS - activate small afferents; A delta & TENS - activate small afferents; A delta & C fibersC fibers

- Low Frequency- Low Frequency

- Long (high) pulse duration- Long (high) pulse duration

- High Amplitude; uncomfortable- High Amplitude; uncomfortable

Called Called Low Freq / Acupuncture-likeTENSLow Freq / Acupuncture-likeTENS Targets chronic pain Targets chronic pain

A word about A word about COUNTER-IRRITANT COUNTER-IRRITANT

CREAMSCREAMS Old concept - “brain gives preference to Old concept - “brain gives preference to

most prominent sensations”most prominent sensations” Many creams & rubs such as Ben-Gay, Many creams & rubs such as Ben-Gay,

Icy-Hot, Mineral Ice, Atomic Balm, Icy-Hot, Mineral Ice, Atomic Balm, Cramergesic, and many “liniments” are Cramergesic, and many “liniments” are classified as “counterirritant creams”; but classified as “counterirritant creams”; but think about how the application and the think about how the application and the active ingredients CAN TRIGGER pain active ingredients CAN TRIGGER pain control mechanisms.control mechanisms.

Word of Word of caution

TENS Devices: Parameters TENS Devices: Parameters you must master for HF & you must master for HF &

LF TENSLF TENSAmplitudeAmplitudeFrequencyFrequencyDuration / WidthDuration / WidthModulations - to delay the onset of Modulations - to delay the onset of

accommodationaccommodationElectrode PlacementElectrode PlacementPatient Instruction in home usePatient Instruction in home use

Examples of Current Modulations used by TENS units to delay

accommodation

Name them

On & over the area of painOn & over the area of pain Surround the area of pain Surround the area of pain (pass e-stim thru the area of pain)(pass e-stim thru the area of pain)

Away from the site of pain but still depolarize the nerve(s) Away from the site of pain but still depolarize the nerve(s) that supply the area of pain:that supply the area of pain:– Stim the peripheral nerve carrying the pain Stim the peripheral nerve carrying the pain

(IF the nerve is superficial & proximal to the pain)(IF the nerve is superficial & proximal to the pain)– Stim within the Stim within the samesame dermatome or myotome as dermatome or myotome as

the area of pain.the area of pain.– Stim the nerve plexus carrying pain stimulus Stim the nerve plexus carrying pain stimulus

(rare & only possible at brachial plexus)(rare & only possible at brachial plexus) Acupuncture PointsAcupuncture Points      

Electrode Placement Electrode Placement RationalesRationales

TENS for Pain: Knowledge TENS for Pain: Knowledge you must conveyyou must convey

Sensory fibers activatedSensory fibers activatedPain control theories utilizedPain control theories utilizedTimeframe for pain controlTimeframe for pain controlTreatment timeTreatment timeApplicable to what type of pain?Applicable to what type of pain?

Sampling of Evidence on TENS Sampling of Evidence on TENS

EfficacyEfficacy: Mixed results in research have : Mixed results in research have occurred due to several factors, such as occurred due to several factors, such as waveform type, frequency, pulse rate, waveform type, frequency, pulse rate, intensity, electrode placement, treatment intensity, electrode placement, treatment time, outcome measures (pain), time, outcome measures (pain), systematic vs individualized Rx.systematic vs individualized Rx.

Variation and Variation and InconclusivenessInconclusiveness