The document discusses Transcutaneous Electrical Nerve Stimulation (TENS) and its use for pain management. It provides details on: - How TENS works according to the Gate Control Theory of pain, using electrical pulses to stimulate nerve fibers and inhibit pain signals. - The different TENS settings and modes used for different types of pain relief, such as high vs low frequency TENS. - Contraindications and safe application of TENS, including electrode placement and skin conditions. - Guidelines for self-administration and maintenance of TENS units.

1. Prof. (Dr.) Nidhi Sharma
Professor, MMIPR, MM (DU),
Mullana-Ambala, Haryana

2. To provide students with knowledge and
understanding of
A. Mechanism of Pain
B. Pain relief
C. TENS feature
D. Application of TENS

3.  TENS is a device used by physiotherapists to
aid in the management of pain.
 TENS delivers a low voltage electrical current
to nerves via conductive pads called
electrodes which are placed over specific
areas of skin.

4.  TENS does not treat the cause of pain but
acts on the perception or sensation of pain.
 TENS acts in 2 main ways:
 Electrical impulses block pain signals before
they travel to the brain.
 Triggers the release of the body’s own pain
relieving chemicals such as endorphins.

5.  Pain is felt as a result of the brain's response
to electrical (neural) and chemical (hormonal)
changes in the body as a result of damage.
 Signals from damage or injury are picked up
by sensory receptors in nerve endings. The
nerves then transmit the signal via the nerves
to spinal cord and brain.

7.  In 1965, Ronald Melzack from McGill
University in Montreal Canada and Patrick
Wall from University College London UK,
published their seminal paper which
proposed a gating mechanism in the central
nervous system to regulate the flow of nerve
signals from peripheral nerves en-route to
the brain.

8.  According to this Gate-Control Theory of
Pain.
 Activity in large diameter low threshold
mechanoreceptive (touch-related) nerve
fibers could inhibit the transmission of action
potentials from small diameter higher
threshold nociceptive (pain-related) fibers
through pre and post synaptic inhibition in
the dorsal horn of spinal cord.
 https://www.youtube.com/watch?v=oQLFfvG
M7nI

9.  Nociceptive fibers (A-delta and C-fibers) have a
higher threshold of activation than
mechanoreceptive fibers (A-beta fibers).
 Ron Melzack and Patrick Wall in 1965 proposed
that it would be possible to selectively stimulate
mechanoreceptive fibers by titrating the
amplitude of electrical currents delivered across
the surface of the skin (ie TENS).
 This would prevent signals from nociceptive
fibers from reaching higher centres of the brain,
thus reducing pain
 In essence, TENS electrically rubs pain away.

10.  Evidence gathered from studies suggested
that low frequency TENS effects may be due
to release of endogenous opioids.
 This explains why analgesia may persist for
hours after electrical stimulation has stopped
because endorphins have long lasting effects
in the central nervous system.
 The released opioids may generate their
analgesic action at peripheral, spinal and
supraspinal sites.Other neurochemicals
released are GABA , adenosine, acetylcholine
etc.

11.  An Approach to pain control
◦ Trancutaneous Electrical Nerve Stimulation:
◦ Any stimulation in which a current is applied
across the skin to stimulate nerves
◦ 1965 Gate Control Theory created a great
popularity of TENS
◦ TENS has 50-80% efficacy rate
◦ TENS stimulates afferent sensory fibers to elicit
production of neurohumneral substances such
as endorphins, enkephalins and serotonin (i.e.
gate theory)

12.  Pain can be managed in the short term using
analgesics, but long-term use can be
detrimental to the patient's health.
 Side effects of the long use of analgesics may
affect on liver, kidney or stomach.
 In many cases where pain is constant, a
medical practitioner or physiotherapist may
recommend the use of a TENS unit.
 Why TENS?
Because it is safe, effective and virtually with
no side effects.

13.  Primary use is to control pain through Gate
Control Theory
 May produce muscle contractions
 Various methods
◦ High TENS (Activate A-delta fibers)
◦ Low TENS (release of -endorphins from pituitary)
◦ Brief-Intense TENS (noxious stimulation to active C
fibers)

14.  A TENS unit provides electrical stimulation to the
painful area using electrodes attached to the skin.
 Some scientists say:
electrical signal
v
nerve sensation stops
v
natural pain relieving substances (endorphins)
v
no pain messages to brain
v
no pain.

15.  Conventional TENS (low intensity, high
frequency)
 Acupuncture like TENS or Low TENS (high
intensity, low frequency)
 Brief Intense TENS (high intensity, high
frequency)
 Burst Mode
 Modulated
Conventional TENS is most commonly used
technique

16.  Acupuncture points
 Trigger points, motor points
 Dermatomes, spinal segments
 Areas with greatest pain intensity
 Peripheral nerves
 May be horizontal or vertical
 Crossed or uncrossed

17. Electrodes must be positioned on healthy sensate
skin which should be checked prior to application.
Electrodes are positioned on relevant dermatomes
so that paraesthesia can be directed into the painful
area.
Exceptions include :
 Hyperaesthesia and mechanical allodynia because
TENS may aggravate pain.
 Hypoaesthesia because TENS is not effective in
non sensate skin and may cause skin irritation
due to accidental use of excessively high
intensities.
 Damaged or fragile skin eg- wounds, eczema.

18. Parameter High TENS Low TENS Brief-Intense
TENS
Intensity Sensory Motor Noxious
Pulse Fq 60-100 pps 2-4 pps Variable
Pulse
Duration
60-100 sec 150-250 sec 300-1000sec
Mode Modulated Modulated
Burst
Modulated
Tx Duration As needed 30 min 15-30 min
Onset of
Relief
< 10 min 20-40 min <15 min

19. HIGH TENS
(COMMON PARAMETER)
LOW TENS
(LESS COMMOMN PARAMETER
FREQUENCY : 100-150Hz FREQUENCY : 1-5Hz
PULSE WIDTH : 100-
500micro sec.
PULSE WIDTH : 100-
150micro sec.
INTENSITY : 12-30 mA INTENSITY : 30mA

20. 1- Two different modes:
a- Continuous (continuous stream)
b- Intermittent (short bursts)
 Usually the continuous mode is used but for long
term treatment intermittent mode is used
2- Adjustable.
 We can control three variables:
a- Output voltage.
b- Width of the pulses.
c- Pulse rate.

21. Continuous Mode:
 Output Voltage: Adjustable from 12V to 80V.
 Pulse Rate: Adjustable from 4.6Hz to 410Hz.
 Pulse Width: Adjustable between 70 and 320
µs.
Intermittent Mode :
 Duty cycle: 24% at 1.2Hz

22.  Paresthesia is created without motor
response
 A Beta filers are stimulated to SG enkephalin
interneuron (pure gate theory)
 Creates the fastest relief of all techniques
 Applied 30 minutes
 relief is short lived (45 sec 1/2 life)
 May stop the pain-spasms cycle

23.  Pulse rate: high 75-100 Hz (generally 80),
constant
 Pulse width: narrow, less than 300 mSec
generally 60 microSec
 Intensity: comfortable to tolerance

24.  2 to 4 electrodes, often will be placed on
post-opp. 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

25.  Level III pain relief, A delta fibers get Beta
endorphins
 Longer lasting pain relief but slower to start
 Application
◦ pulse rate low 1-5ppx (below 10)
◦ Pulse width: 200-300 microSec
◦ Intensity: strong you want rhythmical contractions
within the patient’s tolerance

26. ◦ Carrier frequency is at a certain rate with a built
in duty cycle
◦ Similar to low frequency TENS
◦ Carrier frequency of 70-100 Hz packaged in
bursts of about 7 bursts per second
◦ Pulses within burst can vary
◦ Burst frequency is 1-5 bursts per second
◦ Strong contraction at lower frequencies
◦ Combines efficacy of low rate TENS with the
comfort of conventional TENS

27.  Pulse width: high 100-200 microSec
 Pulse rate: 70-100 pps modulated to 1-5
burst/sec
 Intensity: strong but comfortable
 treatment length: 20-60 minutes

28. ◦ Stimulates C fibers for level II pain control (PAG
etc.)
◦ Similar to high frequency TENS
◦ Highest rate (100 Hz), 200 mSec pulse width
intensity to a very strong but tolerable level
◦ Treatment time is only 15 minutes, if no relief then
treat again after 2-3 minutes
◦ Mono or biphasic current give a “bee sting”
sensation
◦ Utilize motor, trigger or acupuncture points.

29.  Pulse width: as high as possible
 Pulse rate: depends on the type of stimulator
 Intensity: as high as tolerated
 Duration: 15 minutes with conventional TENS
unit. Locus stimulator is advocated for this
treatment type, treatment time is 30 seconds
per point.

30.  Locus (point) stimulators treatment occurs
once per day generally 8 points per session
◦ Auricular points are often utilized
 Treat distal to proximal
 Allow three treatment trials before efficacy is
determined
 Use first then try other modalities

31.  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

32.  May be over the painful sites, dermatomes,
myotomes, trigger points, acupuncture points
or spinal nerve roots.
 May be crossed or uncrossed (horizontal or
vertical

35.  Musculoskeletal pain :
 Acute postoperative pain and acute post
traumatic pain.
 Chronic pain eg. OA, RA
 Chronic low back pain
 Painful diabetic

36.  Someone with a pacemaker
 Someone with undiagnosed pain
 Someone with a heart condition
 On head or neck of someone with epilepsy
 On the eyes
 Over mucosal surface
 Using electrode on infected skin
 Electrode should not be placed near carotid
artery in anterolateral region of neck.

37.  Areas of skin irritation, damage or lesion
 Areas with impaired sensation
 Over abdominal, lumbosacral or pelvis
regions during pregnancy other than for
labor/ delivery.
 Tissues vulnerable to hemorrhage or
hematoma.

38.  Safe
 Portable
 Inexpensive
 Can use it your self
 Non painful

39.  Ensure machine is switched off before
applying and removing electrodes Use only
the gel designed for TENS as this improves
the current passing through the skin.
 Self adhesive electrodes can also be used
 Slowly turn up intensity until definite but
comfortable sensation is felt .
 You will feel a tingling or prickling sensation
under the areas of the electrodes .

40. >You may need to further increase the intensity
in the one session as the body “accommodates”
or gets used to the sensation
 Avoid increasing the intensity to the point where
definite muscle movement happens
 It is useful to keep a diary about the different
settings you used and electrode positioning and
what effect there was on pain .

41.  Over skin that has decreased sensation
 Over the heart or at the front of neck
 If you have a cardiac pacemaker
 Over broken skin or red areas
 Over scars or wounds
 Over metal implants
 Over abdomen if pregnant

42.  Wash and dry skin before use.
 Check skin under electrodes after use of TENS
for irritation and redness. If this happens
STOP using TENS and consult your
physiotherapist.
 Gel must be reapplied to electrodes if using
TENS for greater than 1 hours continuously.

43.  Wash electrodes with soap and water after use
 Keep electrodes clean and dry .
 Self-adhesive electrodes should be cleaned and
placed on backing sheet between use .
 Remove electrode leads from TENS unit and
wipe clean on a regular basis .
 Battery will need replacing on a regular basis in
battery based TENS mechins.

44. THANK YOU