Transcutenous Electrical Nerve Stimulation

(TENS)

Prof.Dr . Mohammed Taher Ahmed OmarRehabilitation Science Department

CAMS-KSU momarar@ksu.edu.sa

TENS: Transcutaneous Electrical Nerve Stimulation

TENS is a low frequency electrical current used to stimulate peripheral nerves using skin surface electrodes aiming to relief pain (acute or chronic ).

TENS is non-invasive anon pharmacological physical therapy modalities used to relief pain through stimulation of peripheral nerve using surface electrodes.

Modern TENS devices have 4 specifications Parameters :

1. Waveforms

2. Frequency or Rate3. Pulse width or Duration4. Amplitude or Intensity

Specification of TENS: Waveforms

Rectangular waveforms are consider for hypersensitive and chronic pain, e.g. nerve injury.

Spike-like pulse are recommended for intense or hyperirritating acute pain.

Specification of TENS: Frequency or Rate

Low Frequency (1-20):Stimulate small unmyelinated nerve fibers Increase endorphin production(supra-spinal)Delayed relief of painUsed for Chronic pain

Frequency 1-500Hz

High Frequency (80-120):Stimulate Large myelinated nerve fibers Gait control theory (spinal)Immediate relief of pain Used for Acute pain

The burst frequency of TENS units is low, ranging 1-10Hz, with in each burst the number of pulses per second ranging between 5-10 pulses.

Specification of TENS: Pulse width or Duration

50μS 100-150μs 200μs >200μs

Large myelinated nerve fibers

respond more effectively (sensory touch))

Normal neuromuscular system

Small myelinated nerve fibers

respond more effectively

Neurological

disorders

Pulse duration 50-500 microseconds

Specification of TENS: Amplitude or Intensity

TENS units intensity ranges form 1 mA to 120 mA “Ideal intensity” = patient perceived comfortable sensation

Patients need to increase the intensity when the body accommodates to the stimulus (when they don’t feel the stimulation anymore)

Dying batteries can cause fading intensities

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Modes of TENS Application

Therapist can achieve variations of TENS by adjusting the current parameters such as: Discuss.Frequenc

y

Duration Amplitude

Pattern

Parameters

TENS (pattern ) Modes Conventional-High-frequency

Sensory TENS Acupuncture-Low-frequency

Motor TENS

Frequency (Hz) 80-120Hz 1-20Hz

Pulse duration (µS) ≤150µS ≥200µS

Intensity (mA)Sensory(Tangling)

Sub-motor Sensory(Tangling)

Rhythmic muscles contraction

Pain modulation Spinal Gait Theory Supra-Spinal (Beta-endorphin / Enkephalin)

Nerve fibers stimulated Large mylinated (Aβ) fibers Large mylinated (Aδ) and C fibers

Treatment time 15-30minutes for1 or 2 times daily

Onset of analgesia Rapid (≤30min) Slow (30-120min)

Duration of pain relief Short (30minutes to 2h) Long (6-7h)

Uses Acute/postoperative pain Chronic pain

Parameters

TENS (pattern ) Modes

Brief -intense TENS Burst –TENS

Frequency (Hz) 80-120Hz 50-100Hz burst (1- 5pps)

Pulse duration (µS) ≥ 150µs 100-200µS

Intensity (mA)Sensory(Tangling)

Non-Rhythmic muscles contr.Sensory

Strong-Rhythmic muscles contr.

Pain modulation Supra-Spinal (Beta-endorphin / Enkephalin)

Nerve fibers stimulated Sensory/motor/nociceptive fibers

A beta/ A delta/C fibers Sensory/motor

Treatment time 15minutes 20-30minutes

Onset of analgesia Rapid (≤30min) Slow onset (within hours)

Duration of pain relief Long Long

Uses Painful procedure Chronic neuromuscular pain

TENS (pattern ) Modes Conventiona

l High-

frequency

Acupuncture

Low-frequency

Brief Intense

Burst

This mode is characterized by the random modulation of

Pulse duration, Pulse frequency, and Current amplitude.

Modes: Modulated TENS

Pain modulation Using ES:TENS application

The main therapeutic effect of TENS therapy is to relief pain via triggering and modulation of complex neurohormonal, neurophysiological , and cognitive systems involving the peripheral as well as the central nervous system,

Discuss.

How does TENS reduce pain perception?

Physiological Effects of ;TENS applicationThere are 4 theories about the physiological effects of TENS: 1. Gate control theory 2. Opiate-mediated control theory 3. Central basing theory 4. Local vasodilatation of blood vessels in ischemic tissues

The Pain is Reduced

Pain ”C”

The A fiber signals reach and close the gate.

Many of the pain fiber transmissions stop at the substantia gelatinosa and do not reach the brain.

TENS “A”

Physiological Effects of; Opiate-mediated TheoryStimulation of A-delta & C fibers causes release of

B-endorphins from the PAG & NRM

ACTH/B-lipotropin is released from the anterior pituitary gland in response to pain – broken down into B-endorphins and corticosteroids

Mechanism of action–similar to enkephalins to block ascending nerve impulses

Physiological Effects of; Central Biasing Theory Descending neurons are activated by: stimulation

of A-delta & C neurons, cognitive processes, anxiety, depression, previous experiences, expectations

Cause release of enkephalins form PAG and serotonin NRM.

Enkephalin interneuron in area of the SG blocks A-delta & C neurons

Indication of TENS Applications

Evidence base research is inconclusive regarding weather TENS can reduce pain with a verity of stimulation parameters

The main indication for TENS therapy have been , so far , the management of:

Postoperative pain,

Low back pain,

Chronic pain.

Indications: Postoperative pain

Abdominal surgery Post-laporatomy, Post-inguinal hernia, Post choleccytectomyThoracic surgery ThoractomyUrological surgery Prostatectomy, Hemorrhoidectomy

Orthopedic surgeryTotal knee replacement, Total hip replacement, Amputation, phantom limbShoulder arthography, Spinal surgeryObstetrical & gynecological surgeryHysterectomy Cesarean Dental surgery.Molar distraction

Indications: Neuromuscular Pain

Post traumatic pain. Post-multiple rib fracture. Low back & neck pain . Osteoarthritis Rheumatoid arthritis. Craniofacial pain& acute orofacial pain. Ankylosing spondylitis. Temporomandibular pain. Myofascial pain. Peripheral nerve injuries with radiculopathies Reflex sympathetic dystrophy. Neuropathic pain

Contraindication: TENS Applications

Cardiac a pacemaker Undiagnosed pain.Epilepsy Over Venous or arterial thrombosis or thrombophlebitisNear operating diathermy deviceOver the antrio-lateral aspect of neck/ eyes/ mucosal

surfacesUsing electrodes on infected (inflamed) skin Electrodes across the chest of a patient with cardiac disease

Dangerous and Precaution Associated with TENS

Areas of skin irritation, damage or lesions Areas with impaired sensation Over abdominal, lumbosacral or pelvic regions during

pregnancy other than for labor/delivery Tissues vulnerable to hemorrhage or hematoma Extreme caution is needed with patients taking narcotic

medication or who are known to have hyposensitive areas.

Incompetent patients may not be able to manage the device and it must be kept out of reach of children.

For patients with diagnosed malignancies that have been diagnosed as terminal, TENS can be used for pain control with informed consent of the patient. Otherwise, TENS should not be used when malignancies are present..

Electrodes Placement

1. On and /or Around the painful area.

2. Over specific dermatome of painful area.

3. Over specific myotomes of painful area .

4. Spinal cord segment.

5. Course of peripheral nerve

6. Over trigger point./Acupuncture point.

7. Par incisional

Evidence base research : There is considerable variations on site of stimulation and electrodes

placement was reported across different studies.

Negative Electrodes should be placed distal to the positive electrodes The negative electrodes may be located at

Electrodes Placement

          Electrode placement for shoulder pain. 

Electrode placement for tennis elbow.

          Electrode placement for Knee pain. 

Electrodes Placement

Electrode placement for lower back painElectrode placement

for upper back pain

Electrode placement for neck pain

Electrode placement for

back pain with sciatica.

HPI: 28 y.o female c/o acute neck pain yesterday when she woke up. Does not recall doing any particular exacerbating activity. Reports pain is 10/10 and is unable to keep her head straight b/c it hurts too much. Denies numbness or tingling to BUE’s. PMHx: hypothyroidism, allergies to cortisone, diabetes under control. O/E: Posture: rounded shoulders, shrugged up with neck flexed by 10% and rotated to the R. and SB to the L. ROM: Flexion 50%, Extension unable to bring head to neutral, R. Rotation 100%, L. Rotation unable to bring to neutral, R. SB unable to bring to neutral, L. SB 100%. Neurological: Dermatomes and myotomes intact.

1. Is TENS appropriate for this patient? 2. How would you set the Parameters and electrode positions? 3. What would you tell the patient to put her at ease with this kind

of treatment? 4-How would you determine pre-treatment pain level? 5. How would you go about removing the TENS unit, how would

you put your patient at ease during the procedure? How would you assess if treatment was effective?

6. What if pain increased after treatment? 7. What if pain did not change?