Transcutaneous electrical nerve stimulation (TENS) is a non-invasive technique that uses low voltage electrical currents to stimulate nerves for pain relief. TENS works by activating A-beta fibers through the skin which closes the pain gate in the spinal cord and reduces pain signal transmission. There are different TENS modalities for acute or chronic pain including conventional TENS, acupuncture TENS, and brief intense TENS. TENS is used to treat various pain conditions like postoperative pain, arthritis, and labor pain by placing electrodes on the skin over painful areas.

1. TENS
Dr. Anvita Telang (PT)
Assistant Professor (Musculoskeletal sciences)

3. ◦ Transcutaneous nerve stimulation- simple, non invasive analgesic technique used in healthcare
by physiotherapists
◦ Transcutaneous electrical nerve stimulation (tens) is the application of low frequency current in
the form of pulsed rectangular currents through surface electrodes on the patient’s skin to
reduce pain.
◦ Pulse shape: rectangular
◦ Pulse width: microseconds (100 microsec to 200 microsec)
◦ Frequency: 2 Hz – 600 Hz
◦ Intensity: 0-60 miliamps (mA)

4. Uses of TENS
Analgesic effects: (acute pain) Chronic pain
Postoperative pain Low back pain
Labour pain Arthritis
Dysmenorrhoea Phantom limb pain
Musculoskeletal pain Trigeminal neuralgia
Bone fracture Peripheral nerve injuries
Metastatic bone pain

5. Non analgesic effects of TENS
Antiemetic effects Improving blood flow
Nausea, morning sickness, travel sickness Diabetic neuropathy
Nausea associated with chemotherapy Healing of wounds and ulcers

6. FOUR CHANNEL
TENS
TWO CHANNEL TENS

7. TENS FOR WOUND HEALING
TENS FOR LABOUR PAIN

8. History of TENS
◦ Egyptians used to treat arthritis pain by using some electrogenic fish. This increased the
popularity of using electricity in medicine (2500 BC).
◦ Melzac and wall (1965) provided a physiological rationale for electroanalgesia effects and
proposed the pain gate mechanism theory.
◦

9. What is pain
◦ Pain is an unpleasant disturbed sensation, which accompanies the activation of nociceptors. Pain
is a subjective phenomenon with multiple dimension.
◦ Nociceptors are the sensory receptors, which carries pain stimulus. Any physical, chemical,
thermal or mechanical stimulus like heat, cold or pressure activates these nociceptors. These are
free nerve endings found in all body tissues. They carry pain stimulus to the higher centers.
◦ A Delta fibers: Fast conducting large diameter myelinated fibers, which conducts with a velocity
of 5–30 m/s. C-fibers: Slow conducting small diameter nonmyelinated fibers, which conducts
with a velocity of 2–5 m/s.

10. ◦ Fast pain is transmitted over the larger, faster-conducting A-delta afferent neurons and
originates from receptors located in the skin.
◦ Slow pain is transmitted by the C afferent neurons and originates from both superficial (skin)
and deeper (ligaments and muscle) tissue.

11. ◦ Painful stimuli activates nociceptors (A delta and C) transmitted to spinal cord in the
substansia gelatinosa (via dorsal route) transmitted to higher parts of the spinal cord and to
the thalamus (located in the cortex) via the spinothalamic tract.
◦ Pain afferents send branches to the periaqueductal grey region in the mid brain and activates
the descending pathway from there the impulses travel to the dorsal horn of spinal cord,
impulses are blocked or inhibited.

13. Pain gate mechanism
◦ Pain gate control: The pain gate theory was first postulated by Ron Melzack
and Pat Wall in 1965.
◦ The Gate Control Theory of Pain is a mechanism, in the spinal cord (substansia
gelatinosa), in which pain signals can be sent up to the brain to be processed to
accentuate the possible perceived pain, or attenuate it at the spinal cord itself.

14. ◦ The 'gate' is the mechanism where pain signals can be let through or restricted. One of two things can
happen, the gate can be 'open' or the gate can be 'closed':
• If the gate is open, pain signals can pass through and will be sent to the brain to perceive the pain.
• If the gate is closed, pain signals will be restricted from travelling up to the brain, and the sensation of
pain won't be perceived.

16. Types of TENS
◦ Conventional TENS or High TENS
◦ Acupuncture TENS or Low TENS
◦ Brief Intense TENS
◦ Burst TENS
◦ Modulated TENS

19. Physical principles
◦ Large diameter fibres such as A beta and A alpha have low threshold of activation to electrical
stimuli when compared with small diameter fibre (A delta and C)
◦ TENS works on the principle of pain gate mechanism. Where A beta fibres are selectively
stimulated without activating small diameter nociceptive fibres (A delta and C)
◦ This type of TENS is the conventional type of TENS (low intensity and high frequency)
◦ Skin offers high resistance at this pulse frequency therefore, such a current will stimulate
superficial cutaneous nerve fibres rather than deep seated visceral and muscle fibres.
◦ TENS is applied to the patient using surface electrodes on the skin (cathode is black, anode is
red)

20. Conventional TENS
◦ Aim of conventional TENS is to activate selectively A beta fibres without activating small
diameter A Delta and C fibres
◦ Conventional TENS segmental analgesia which is localised to the dermatome
◦ Produces strong comfortable and non painful paraesthesia (tingling sensations)
◦ Pattern is usually continuous

21. Acupuncture like TENS (AL-TENS)
◦ This type of TENS should be defined as the induction of forceful but non-painful phasic muscle
contraction at myotomes related to the origin of the pain
◦ The purpose of this type of TENS is to selectively activate small diameter fibres (A delta) by
induction of phasic muscle twitches
◦ TENS is delivered over the motor points
◦ Patients report slight discomfort when these low frequency pulses are used to generate muscle
twitches
◦ Extra segmental analgesia in the same manner as acupuncture
◦ Elevates plasma beta endorphins levels and causes analgesia

22. Brief intense TENS
◦ The aim of this type of TENS is to activate
small diameter A delta fibres by delivering
TENS over the peripheral nerves arising at the
site of the pain at an intensity tolerable to the
patient.
◦ TENS is delivered over the site of pain using
high frequency and high intensity currents
which are tolerable to the patient.
◦ It is used as a counter irritant and can be
delivered only for a short duration of time
◦ Mechanism of action – peripheral blockade of
nociceptive afferent activity, segmental and
extra segmental analgesia

23. Conventional TENS
◦ High TENS or conventional TENS
◦ High frequency low intensity
◦ Tingling pins and needles sensation
◦ Presynaptic inhibition of transmission of nociceptive A delta and C fibres in substansia
gelatinosa
◦ Used in acute pain and superficial pain
◦ Frequency : 100-150 Hz
◦ Pulse width : 100-500 microseconds
◦ Intensity : 12-30 mA

24. Acupuncture TENS
◦ High intensity and low frequency
◦ Stimulation of A delta and C fibers
◦ Release of endogenous opiods ( enkephalins and beta endorphins)
◦ Used in chronic and deep pain
◦ Frequency : 1-5 Hz
◦ Pulse width : 100-150 microseconds
◦ Intensity : 300 mA

25. Burst tens
◦ Called as wave train
◦ Series of pulses repeated 1-5 times per second
◦ Each burst consists of individual pulses like high or conventional TENS
◦ Used for pain relief
◦ Frequency: 50-150 Hz

26. Brief TENS
◦ Long duration 0.2 ms
◦ Used for local pain relief
◦ Should be used for not more than 15 mins
◦ Frequency : 100 Hz
◦ Intensity : 20-50 mA

27. Modulated TENS
◦ Modulation in pulse length frequency and amplitude
◦ To improve patient tolerance
◦ To prevent accommodation

28. Indications
◦ Chronic pain syndrome
◦ Phantom limb pain
◦ Reflex sympathetic dystrophy
◦ Postoperative pain
◦ Obstetric pain.

29. Contraindications
1. Continuous application of high TENS may result in some electrolytic reaction below the skin
surface
2. TENS is contraindicated in patients having cardiac pacemakers may be because of possible
interference with the frequency of pacemaker
3. TENS should be avoided in first three months of pregnancy.
4. TENS should be avoided in hemorrhagic conditions.
5.TENS should be avoided over open wounds, carotid sinus, over the mouth, near eyes, etc

30. Methods of Treatment Electrode
placement
◦ TENS electrode can be placed over:
1. Area of greater intensity of pain
2. Appropriate peripheral nerve
3. To the appropriate dermatome or spinal nerve
4. To the acupuncture, motor or trigger points