This power point presentation will be useful for physiotherapy student to understand TENS Briefly which is important for electrotherapy subject

1. Trans cutaneous Electrical Nerve stimulation
Prepared by –Dr Pankaj R jayswal
[M.P.T ORTHO]

2. T.E.N.S
 It is the electrotherapeutic modality used for the Nerve
stimulation
 Trans cutaneous =“Through Skin ”
 Nerve stimulation = current have sufficient intensity to
depolarize sensory ,motor ,pain nerves

3. “Application of Pulse Rectangular
Wave Current”

4. Types Of Wave current
Symmetrical Biphasic
Asymmetrical Biphasic
Monophasic Waveform

5. Stimulation Parameters of TENS
• Three types of current
• Accurate description in term of TENS is
difficult
• They are
i. Modified direct current
ii. Pulsed current

6. Direct current [D.C]- unidirectional current flows
continuously in one direction
Alternate current [A.C] – Bidirectional current
flows continuously
Pulsed Current - it is one in which the
unidirectional or bidirectional flow of current
periodically ceases over time

7. Its more accurate to describe TENS
as a pulsed current & not A.C or D.C

8. Waveform
• Wave form of current simply refers to its
shape as seen on a graph of Amplitude v/s
time

9. Monophasic wave form
Current flows in only in one direction
One electrode as a anode [+] ,other electrode
as a Cathode [-]

10. Biphasic wave form
Current flows in both direction
Each Electrode as a cathode at some part of
waveform

11. Symmetrical waveform
 First phase of waveform is mirror image of second
waveform
 But opposite direction
 Each electrode act as a active electrode [Cathode ]
during alternate phase
 It prevents electrochemical effect due to excessive
polarity

12. Asymmetrical waveform
 Two phases which are not equal in size[different in
magnitude as well as duration ]
 Difference in equality [slight bias in positive side ]
 That’s why one phase is able to depolarize ,act as a
mono phasic waveform

13.  “T.E.N.S Wave form have zero net DC means equal
amount of charges under the positive as well as
negative portion of waveform”
 Prevents chemical skin irritation
 A DC current can potentially cause skin irritation due to
build up of charges under the electrodes

14. Wave form Selection
Rectangular
Triangular
Sine wave
Spike waves

15. Spike waves
More irritating to skin ,require frequent
movement of electrode
Shorter treatment times to avoid skin irritation
Acute pain or resistant tissue ,immediate
temporary relief
For intense or hyper irritating stimulation

16. Square ,Rectangular or sine wave
Longer duration waveform
For some nerve damage associated with pain
pathology
Less skin irritation ,long lasting effect
For chronic pain patient

17. Frequency
• Means number of pulses delivered per second
• Time depended characteristic
Frequency =1/period

18. Period is the time elapsed between a specific
point on the waveform of the pulse to the
identical point on the next pulse
For AC current ,time to complete one cycle

19. For pulse current
For alternate current
For acute cases –high frequency
For chronic cases –low frequency

20. Pulse width or duration
Time dependent characteristic ,in microsecond
Confusion is there regarding to the pulse duration
Some text either positive or negative
Some text refer both
Most text refer to duration of only positive
component of wave form

21. It is length of time the current actually act on the
patient during each pulse
In normal Neuro-muscular system ,100-150μs
In neurologic damage ,wider widths i.e 200 -300
μs

22. Amplitude or Intensity
 Means a magnitude of current or voltage applied by
the unit
 Measured in mA or volt
 Current is due to electron movement ,Volt is driving
force ,require for current to pass in body
 So its level of current require to depolarize the nerve
membrane

23. Ohm’s law V=IR
A. Low amplitude
B. Brief intense amplitude

24. • For T.E.N.S ,1 -100 mA
• Based on sensation rather than readings
• Constant current
• Constant voltage

25. Modulation
i. Frequency modulation
ii. Pulse width modulation
iii. Amplitude modulation- “cause discomfort ”
Prevents the accommodation tendency which make
Rx ineffective

26. Type of T.E.N.S Or Modes
 High frequency /Low intensity TENS[Conventional ]
 Low frequency/High Intensity TENS[Acupuncture
T.E.N.S ]
 Brief Intense T.E.N.S
 Burst T.E.N.S
 Modulated T.E.N.S

27. High frequency /Low intensity
TENS[Conventional ]
High frequency 40-150Hz
Short pulse Duration 50-80 μs,50 μs common
Gradually increase the intensity
Neither painful nor elicit muscle contraction

28. Mechanism of action
Stimulate large low thresold Aβ fibers ,cause pain
relief via pain gate mechanism at substansia
gelatinosa
Decrease the neural activity by affecting dorsal
horn neuron activity

29. Doses
• Method for self treatment
• Duration varies 30 -60 min once / twice a day
to continue for a minimum 8 hrs/day to even
full 24 hrs

30. Indication or Therapeutic uses
Acute soft tissue injury
Pain associated with musculoskeletal
disorder, post operative pain ,inflammatory
condition ,myofascial pain

31. Low frequency/High Intensity
TENS[Acupuncture T.E.N.S ]
Low f[1 -5Hz ]
Long pulse duration [2000 μs]
High intensity up to 30 mA or up to patient can
tolerate to produce visible muscle contraction

32. Mechanism of action
 Stimulate high thresold Aδ & C fibers, release of
endogenous opiates ,reduce pain at spinal level
 Stimulate pituitary gland ,helps to release β-
endorphin ,blocks the receptor site of Aδ & C fibers
,block the transmission of pain ]
 Additional muscle contraction gives sensory
information through muscle spindle

33. Electrode placement
• For muscle contraction
• Over acupuncture point ,motor point of
muscle ,myotome related painful area
• Patient will experience par aesthesia,twitching
type muscle contraction

34. Dose
Once per day up to 20- 30 min or at times up
to 45 min
Acute relief of pain may not be experienced
,but relief may be last long

35. Therapeutic uses
Long standing deep aching pain
Myo fascial pain
Muscle spasm

36. Brief Intense T.E.N.S
High “F”100-150 Hz
Long pulse duration 150-250 us
Highest tolerable Intensities
No longer than 15 min at a time

37. Mechanism of Action
Pain relief is due to activation of activity in
brainstem that dampen or amplify pain impulse
Amplification protocol is refereed to “Noxious
level T.E.N.S”
During the passage through the brain ,short
circuit occurs ,stimulate the release of
endogenous opiates in raphe nuclei

38. Descending pain suppression system activated,
loops efferent impulses down the spinal cord
Opiates inhibit the release of substance P , a
neurotransmitter of noxious impulses
High level analgesia is achieved though this ,but
transitary

39. Therapeutic T.E.N.S
Local painful condition
Painful procedure as skin debridement ,suture
removal

40. Burst T.E.N.S
Provides packaging of several stimuli in groups
Presented in “bursts ”of energy sensed by the
patient as a single stimulus
High “F ” 40-150 Hz
High intensity
Short pulse

41. • High frequency train of pulses delivered at low
frequency
• Combination of conventional and acupuncture
TENS ,Mechanism of pain relief by both
method

42. Modulated T.E.N.S
Pulse length ,frequency & amplitude can be
constantly & automatically changed
Provide 3 of parameter changed in cyclic fashion
Prevent adaptation ,appropriate of conventional
T.E.N.S used for longer period
Modulated output is more comfortable to the
patient

43. Wave train
Some manufactures have designed a series of
modulations ,bursts & standard modes in a
pre-programmed flow in a form of wave train

44. Advantage of T.E.N.S
Non invasive device
Portable
User friendly ,can be used by patient at home
Non addictive

45. Disadvantage of T.E.N.S
Intolerant to sensation of ES
Skin irritation due to allergic reaction with
conductive medium
Thermal burn due to chemical reaction or high
current density

46. • Intense or prolonged stimulation cause
muscle spasm or muscle soreness
• Narcotics decrease the effect of TENS

47. Physiological effects
Pain control
Blood circulation

48. Pain control
Decrease transmission of noxious impulses to
CNS by affecting conductivity of small fibers
Affecting the large motor fibers ,interfering
normal guarding pattern of muscle [muscle
spasm ]

49. Blood circulation
Cutaneous vasodilatation due to sensory
nerve stimulation ,axon reflex subsequent
release of histamine
Monophasic pulses alter cellular growth &
activity. improve healing

50. Indication
Chronic pain
Acute/chronic pain of oesteogenic ,myogenic ,
neurogenic origin
Post surgical pain
Reduction of post traumatic acute pain

51. Application of TENS
Large mains operated
Small battery operated or pocket model

52. Electrodes
Design depends on anatomical location ,duration
of Rx, clinic or home Rx ,sensitivity of pt , skin
irritation
Different size & shape
Small electrode for motor point ,more density

53. Large electrode for large muscle stimulation
Edge of rectangular or square electrode cause
electric field concentration ,current density
hot spot
Long rectangular electrode for post
operatively incision pain

54. • Disposable electrode ,cut down according to
anatomical position

55. Electrode placement
Site of pain over great tenderness
Dermatomes and myotomes ,along with long axis
Trigger point ,acupuncture point ,motor point
Peripheral nerve –along the nerve where it is
superficial

56. Method of electrode placement
 Direct placement
 Contiguous placement
 Placement of stimulation point
 Dermatome placement
 Spinal root placement
 Contra lateral placement

58. Direct placement
• The electrodes over the skin on or around
painful site
• Each channel runs parallel to each other

59. Contiguous placement
• When direct placement is contraindicated i.e.
Post operative incision ,lacerations
• Electrode near to vicinity of pain
• Current will run parallel to each other or cross
each other

60. Stimulation point placement
• Motor point ,acupuncture point ,trigger point
• Sensitive to stimulation ,in many condition
,they are located closely
• Single TENS electrode stimulates all point

61. Trigger point
• Sensitive area in muscle or connective tissue[Fascia ] that
become painful when compressed .hyperirritable spot
associated within a taut bands of skeletal muscle
• Compression on trigger point can cause radiating pain
• And also it is a point from which pain radiates Through
out the muscle & fascia cause myofascial pain syndrome

62. Dermatome placement
• Situation in which pain is distributed according to
dermatome wise
• Electrode placement is on affected &
contralateral side
• Other technique involves putting one electrode at
the corresponding spinal and nerve root & other
distal end of dermatome

63. Spinal root placement
• Placement of electrode parallel to spinal
column between the transverse process
• Stimulate the spinal root associated with pain

64. Contra lateral placement
• Placement of electrode on the opposite side of
body approximately the location from which the
pain is arising from injured site
• Theory of bilateral transfer
• “sensory impulses of one side of body got
confused with noxious impulses of opposite side
because of crossing of nerve tract in spinal cord ”

65. Preparation of Patient
• Skin below the stimulation should have intact
sensory mechanism
• Work on skin resistance ,cleaned with alcohol
,soap ,water to remove surface lipid
• Moisten the skin before application

66. • Comfortable position ,not to move or
electrode movement
• Explanation to sensation
• After sometime increase the intensity

67. Preparation of apparatus
• Adjust output parameter –pulse duration &
pulse frequency
• Select the electrode – depend on type of TENS
• Select the output mode –depends on method
and duration of TENS
• Before starting ,intensity should be “zero”
• Increase the output intensity gradually
channel wise

68. • Balance the channel
• Increase the intensity after sometime

69. Contraindication
• Electrode should not put over carotid sinus
,anterior aspect of neck ,cause vasovagal reflex &
hypotensive response,decrease BP
• Skin sensation loss, require a great intensity for
stimulation ,cause skin irritation & burn

70. • Child or adult
• Should not used on the head or neck region of
epileptic pt
• Neck of pt of cva or tia
• Allergic to gel or chemical reaction

71. Precaution with pacemaker
• can give in asynchronous type pacemaker
• Not in synchronous type of pacemaker leads
ventricular arrhythmia

72. • Electrode should placed as close as possible
• Should put away from heart area
• Lowest intensity of current given
• In cases of light headedness or dizziness ,turn off
TENS

73. Neurophysiology of pain
 the experience of pain results from a physiological
response to noxious stimuli
 Different factors that influences the perception of pain in
different individuals
 Cultural differences ,state of emotion & past experience

74. Definition
• “A sensory & emotional experience associated
with actual or potential tissue damage or
described in terms of such damage ”

75. • Pain should not be viewed exclusively as
either a sensation or an emotion ,either
assumption preclude particular characteristic
necessary for painful experience

76. • It should be understood that
“ no rigid pathway for perception of pain
But a multidimensional anatomical &
physiological system involved which take
subjective factor into consideration”

77. • The term Nociception is used to describe the
specific response to noxious stimuli

78. Acute Pain
• Its body’s response to
noxious stimulus
• Body’s protective
mechanism get activated
• Symptoms reflect to
underlying pathology
• Sign and symptoms of
inflammation are very
strong
• Intense pain
Chronic pain
• Original pathology is healed
• No straight relationship
between symptoms –
pathology
• Less inflammation
• Subject feel mild pain in
certain activity

79. Pain pathways
• Peripheral nervous system
• Spinal cord
• Brainstem & thalamus
• Cerebral cortex

80. Peripheral nervous system
• sensory receptors are specialized structures that
responds to specific stimuli & fulfill the role of
Transducers
• Nociceptors –the receptors that responds to
noxious stimuli

81. • Types
 mechanical
Thermal
Polymodal [responds to many kind of stimuli
mechanical,thermal ,chemical]

82. • Their structure is bare or free nerve endings
,termination of Aδ & c fibers
• Aδ fibers responds to strong mechanical
stimulation & damaging heat above 45degree
• Present as a discrete sensitive spots in the skin all
over the body surface [small in number in muscle
& joints ]

83. • Their impulses are carried by small myelinated
fiber at speed 15 m/sec
• Provokes immediate flexor withdrawal reflex
• ,evokes rapid well localized conscious awareness

84. • C fibers receptors are sensitive to many stimuli
• Probably sensitive to the chemicals released from
the tissue damage
• Inflammatory changes leading to release of
hydrogen ions, histamine ,serotonin
,acetylcholine ,bradykinin ,prostagladin E &
F,ATP,ADP & lactic acid

85.  All of that stimulate or sensitize C nociceptors ,gives dull
aching pain
 Slow pain is transmitted by unmyelinated c fibers at a
speed of 1m /s
 Their free nerve endings are found in all innervated body
tissue except the CNS

86. Afferent Fibers
• For most types of sensation except that of
smell ,there are three type of neurons
between the periphery & cerebral cortex
• The first order neurons [from peripheral
receptors to dorsal horn]
• Second order neuron [from dorsal horn to
terminates in the thalamas ]
• third order neuron [from thalamas to sensory
cortex]

87. Dorsal horn
Cell bodies of Aδ & c fibers lie in dorsal root
ganglia of spinal cord
In dorsal horn of spinal cord ,10 lamina e are
there
That laminae consist cell bodies of 2nd order
neurons
Incoming Aδ & c fibers synapses mainly in
laminae 1,2,3 & 5

88. • Once synapsed ,they crossed opposite side
and ascend in one of two central pathway

89. Spinal Tracts
• Lateral spinothalamic tract
• Multisynaptic Ascending system

90. Brainstem Structure
• Reticular formation
• Periaqueductal grey matter & nucleus raphe
magnus

91. Thalamas
• Relay station for most type sensation
• Ventrobasal complex –primary sensory cortex
• Medial & interlaminar complex-cerebral
cortex ,basal ganglia ,limbic system

92. Cerebral cortex
• Somatosensory cortex ,located in post cenral
gyrus at parital lobe of cerebral cortex
• Perception & interpretation of sensation
occurs
• Association cortex relates the sensation to
past experience & memory