1. Therapeutic Electrical Modalities

2. Learning Objectives
Be familiar with the characteristics of electric modalities that are applied for therapeutic purposes
Identify physiological and therapeutic effects of electric modalities
Be familiar with contraindications and precautions in using electric modalities
Identify adverse effects for each modality

3. Learning Objectives Cont’d . . .
Be familiar with the multiple uses of electrical stimulation (ES)
When given a clinical scenario, be able to:
Define goals of treatment with ES
Choose the appropriate device
Select the appropriate parameters
Apply the treatment safely and competently
Modify treatment if needed

4. Therapeutic Electrical Currents
The application of electrical current to the body for therapeutic purposes, such as:
Pain relief
Neuromuscular Electrical stimulation
Tissue/wound healing
Direct stimulation of denervated muscle

5. Terminology Charge Current Resistance Conductance Impedance Current:AC DC
Pulsatile/pulsed
Amplitude or intensity

6. Pulsed currents Monophasic or biphasic Pulse duration Pulse frequency
- interval between pulses
can be manipulated independently
Modulations
Frequency
Amplitude
Burst

7. Therapeutic Electrical Stimulation Applications
Pain Relief
Neuromuscular Electrical Stimulation (NMES)
Tissue/wound healing
Iontophoresis
Deinervated muscle

8. Transcutaneous Nerve Stimulation (TENS)

9. TENS Stimulates nerve fibers for the symptomatic relief of pain
Device applies an electrical signal through lead wires and electrodes attached to the patient's skin
Electrode placement varies:
Typically placed in a peripheral nerve distribution
Locations can be distal or proximal to pain site

10. How It Works Gate Control Theory:
Pain signals can be blocked at the level of the spinal cord before they are transmitted to the thalamus
TENS stimulates large Ia myelinated afferent nerve fibers that stimulate the substantia gelatinosa in the spinal cord, closing the gate on pain transmission to the thalamus

11. Gate Control Theory

12. Physiological Effects of TENS
Selective stimulation of large diameter, myelinated fibres
Gate Control Theory
Stimulates release of endorphins
Endorphin/opiate theory
Stimulates release of other transmitters
NA, 5-HT
?mild heating  enhanced healing?
Placebo

13. Therapeutic uses of TENS
PAIN RELIEF:
Acute, Subacute, Chronic & Referred
Musculoskeletal
Neurologic
Obstetric
Oncologic*
Cardiac- angina

14. Modes of TENS Conventional Acupuncture Burst mode
Brief-intense/noxious level

15. Conventional TENS High-frequency, low-intensity stimulation
most effective type of stimulation
Amplitude is adjusted to produce minimal sensory discomfort
Pain relief begins after 10–15 minutes and stops shortly after removing stimulation
Useful for neuropathic pain
Duration of treatment is 30 minutes to hours

16. Acupuncture Low frequency, high intensity stimulation
Amplitude high enough to produce muscle contraction
Onset of pain relief can be delayed several hours
Pain relief persists hours after removing stimulation
Useful for acute musculoskeletal conditions
Treatment sessions last 30–60 minutes

17. Burst Mode
High frequency stimulation bursts at low frequency intervals
Delayed onset of pain relief
Treatment can range 30–60 minutes

18. Brief-intense/Noxious Level
Hyper-stimulation
High frequency, high intensity stimulation
It is considered that this mode stimulates C-fibers causing counter-irritation
Rarely tolerated more than 15–30 minutes

19. TENS Unit
intensity
timer
frequency
Pulse width
mode

20. TENS Dosage Burst mode Brief Intense 80-125 pps 2 bursts per sec
Conventional
Burst mode
Brief Intense
pps
2 bursts per sec
125 pps
microsec
250
Comfortable tingling
Muscle twitch
Strong sensation
Acute pain, fast relief
Deep, chronic achy pain
Rapid relief for intense pain

21. Modulation Modes SD: strength-duration MW: modulated width
Amplitude and width modulate alternately – subtle change in sensation
Allows higher total amount of charge to be used
MW: modulated width
Stronger Weaker
MR: modulated rate
Faster  Slower
CM: combination modulation
Rate and width
‘Diffuse’ sensation

22. Electrode placement Single channel: Dual channel: 2 electrodes

23. Single channel Surround the pain Over the pain
Within dermatome/myotome
On trigger points or acupuncture points within dermatome
Spinal segment: one near spine, other over pain or trigger point within the dermatome/myotome

24. Dual channel Bracket Cross – fire Bilateral placement- both limbs
Contralateral:
Phantom pain, skin irritation or wound
General placement: flood the limb
Overlap channels

25. Precautions Decreased sensation Pregnancy Malignancy
Decreased mentation
Be careful with repeated applications and prolonged use, adhesives/tape and gel can all cause dermatitis
Make sure the entire electrode has good coverage for gel and don’t use too high a current - can cause electrical burns on the skin!

26. Contraindications UNDIAGNOSED PAIN ANY electronic implant
Some Pacemakers (fixed rate ok but rate responsive are affected)
Cardioverter-defribrillators
Some Bladder stimulators
Metal implants???

27. Interferential Current (IFC)

28. Interferential Current
Another form of TENS:
Differs from TENS as it allows deeper penetration with more comfort (compliance) and increased circulation
AMC (amplitude modified current)
Frequencies interfere with the transmission of pain messages at the spinal cord level

29. How does it work? 2 “medium frequency” currents
Low frequency (e.g. TENS) = <1000Hz
Medium frequency ,000 Hz
2 currents with different frequencies
Currents ‘interfere’ with one another
“Beat frequency” is the difference between the 2 currents

30. Example
C1 = 5000 Hz
C2= 5100 Hz
fixed Beat frequency = 100 bps

31. Indications for IFC Urinary incontinence Pain relief
Blood flow/edema management
May be effective due to the combination of pain relief (allowing more movement), muscle stimulation and enhanced blood flow

32. TENS vs. IFC Physiological effects: Why not TENS?
Depolarize sensory and motor nerves
Why not TENS?
“Medium frequency”  less skin impedance
Less impedance  more patient comfort
More patient comfort  tolerate higher amplitude current  deeper penetration

33. Contraindications Same as TENS Plus: With suction cup electrodes:
Bruising
Cross-infection from sponges

34. IFC Application Stimulator type Electrode placement Electrode fixation
As precisely as possible so that patient feels the stimulation over the targeted area
Electrode fixation
Self-adhesive pads
Non-adhesive taped in place
Coupling medium
Gel for electrode pads

35. Sweep Beat frequency is modulated Thought to prevent adaptation E.g.
C1 fixed at 5000
C2 varies
Gives a VARIABLE BEAT FREQUENCY

36. Uses of sweep Sweep ranges: Pain relief 80-150 bps
Muscle rehab bps
Edema 1-10 bps (intermittent muscle contractions)
Selection of a wide frequency i.e 1-100Hz is less efficent + ? Counter-productive

37. Set-Up of IFC
Bi-polar
Quadripolar
Quadripolar with scan

38. Bi-polar method “Pre-mod” 2 electrodes Single channel
Current is ‘modulated’ within the machine
Similar to TENS

39. Quadripolar method 4 electrodes 2 channels
Interference occurs where the fields cross one another WITHIN the tissues
Cloverleaf pattern

40. Quadripolar field

41. Quadripolar With Scan “Automatic vector scan”
AMPLITUDE is varied by the machine
E.g.
C1 fixed amplitude/intensity
C2 variable amplitude
Pattern of interference is different

42. Quad With Scan

43. IFC Scan Uses of scan: Large area of treatment Diffuse pain
Location of pain difficult to pinpoint

44. Neuromuscular Electric Stimulation (NMES)

45. NMES
Consists of transcutaneous electrical stimulation for muscles with or without intact PNS, or central control
More powerful than TENS unit
Multiple muscles can be activated in a coordinated fashion to attain certain functional goals (ambulation, transfers)

46. Types of Muscle Contraction
Voluntary:
Recruits Type I first, then Type 2
Spatial summation
Recruitment of additional motor units
Temporal summation
Increased firing rate
Gradual increase in force generated

47. Types of Muscle Contraction
Electrically stimulated contraction:
Reverse pattern of recruitment
Type II Type I
All motor units fire at once
Easy to produce fatigue
Use “Ramp up” for comfort

48. Features of NMES Currents
Pulse duration
Pulse rate/frequency: pps

49. Therapeutic Uses of NMES
Strengthens muscles
Motor Re-education
Increases ROM
Enhances endurance
Reduces muscle spasm/spacity

50. Strength Training Recruits maximum numbers of motor units
Used if volitional control affected by
pain
reflex inhibition
motivation
Works by overload fatigue

51. Strength Training Can improve strength but not as well as:
voluntary contraction
ES + voluntary contraction
“high load/low reps”
Longer rest periods

52. Motor Re-Education Use NMES for:
Contraction is not readily under voluntary control (e.g. pelvic floor)
Teaching a new action (e.g. tendon transfer)
Injured peripheral nerve is regenerating

53. Motor re-education
Demonstration to convince patient that contraction IS possible (e.g. hysterical paralysis)
Enhanced recruitment or timing during a functional movement:
Functional Electrical Stimulation
Related to a particular task e.g. sit-to-stand, hand to mouth

54. Increase ROM Stretch contractures * Contract-relax
Facilitate tendon glide
Break adhesions *
*Patient may not be able to generate sufficient force

55. Enhance Endurance Use sub-maximal force over longer period of time
Similar to low load/high reps at the gym
Equal work and rest periods

56. Promote circulation Muscle pump Prolonged immobilization
Prevents complications from immobility such as deep vein thrombosis (DVT), and osteoporosis
Low load, high reps

57. Decrease spasm/spasticity
Stimulate antagonist
reciprocal inhibition
Stimulate agonist
fatigue
Stimulate both alternately

58. Contraindications and Precautions
The Big Five
Carotid sinus
Venous or arterial thrombosis/ thrombophlebitis
Areas of skin irritation
Open wounds

59. Features of NMES Currents
On time
Off time
Rise time/ramp up
Fall time/ ramp down

60. IFC Set-Up Size matters!
Small electrodes  concentrates the charge  greater effect
Larger electrodes  dissipates the charge  can tolerate greater amplitude
Match electrode size to the size of the muscle

61. Set-Up Continued Conductivity matters! Skin prep Coupling medium:
Sensation testing
Coupling medium:
Lots of gel
Cover ENTIRE electrode
No gel on skin between electrodes

62. Set-Up Continued Location matters! Parallel to muscle fibers
Over motor points
Farther apart  deeper penetration of current?
No closer than ½ the diameter of each electrode
Precision vs. overflow

63. Adverse Affects Electrical burn due to fold or poor gel technique
Skin irritation

64. Iontophoresis

65. What is it?
Introduction of ions into the body using direct electrical current
Transports ions across a membrane or into a tissue
Painless, sterile, noninvasive technique
Demonstrated to have a positive effect on the healing process

66. Continued . . .
Low-level electrical current carries drug ions through the skin and into underlying tissue
Type of medication used will be based on the desired effect to the treated area
Most common medication is Dexamethasone

67. How it Works
Electrical unit uses a direct current that is either a positively or negatively charged active electrode
An oppositely charged dispersive electrode is attached
The medication is placed on the active electrode so that the active electrode has the same charge as the medication

68. Continued . . .
When the electrodes are placed on the skin and activated, the charge from the electrode will drive the medication away from the electrode and into the area being treated
The electrical charge will push the medication through the skin and into the tissue to be treated

69. Indications Inflammation Edema Bone spurs/calcium deposits
Fungal infections
Scars
Wounds
Muscle spasms

70. Physiological and Therapeutic Effects
Decreased edema and inflammation
Pain control
Tissue adhesion
Decreases muscle spasm
Wound healing
Therapeutic:
Delivers medication at a constant rate so the effective plasma concentration remains within the therapeutic window for an extended period of time

71. Therapeutic window
The range between the minimum plasma concentration of a drug necessary for a therapeutic effect and the maximum effective plasma concentration (above which adverse effects may occur)

72. Preparing the Patient for ES
Sensory testing:
Which sensation?
Why?
Skin prep
Remove oil
Moisten
Hair
Clip, don’t shave

73. Iontophoresis Generator
Intensity: 3-5 mA
Unit adjusts to normal variations in tissue impedance
Reduces the likelihood of burns
Automatic shutdown

74. Iontophoresis Generator
Adjustable Timer
Up to 25 min

75. Iontophoresis Generator
Lead wires
Active electrode
Inactive electrode

76. Current Intensity
Low amperage currents are more effective than high currents
Higher currents tend to reduce effective penetration
Recommended current: 3-5 mA
Maximum current may be determined by the size (surface area) of the active electrode
Current may be set so that the current density under the active electrode falls between mA/cm2

77. Current Intensity
Increase current slowly until patient reports tingling or prickly sensation
If pain or a burning sensation occurs, current is too great and should be decreased
When terminating treatment, current should be slowly decreased to zero before electrodes are disconnected

78. Treatment Time Ranges between 10-20 min
Check skin every 3-5 minutes for signs of irritation
Decrease current during treatment to accommodate for decrease in skin impedance to avoid pain or burning

79. Dosage of Medication
Dosage is expressed in milliampere-minutes (mA-min)
Total drug dose delivered (mA-min) = current X treatment time
Typical iontophoresis drug dose is 40 mA-min

80. Traditional Electrodes
Older electrodes made of tin, copper, lead, aluminum, or platinum backed by rubber
Completely covered by sponge, towel, or gauze which contacts skin
Absorbent material is soaked with ionized solution (medication)

81. Commercial Electrodes
Electrodes have a small chamber covered by a semi-permeable membrane into which ionized solution may be injected
The electrode self adheres to the skin

82. Electrode Preparation
Shave and clean skin prior to attaching the electrodes to ensure maximum contact
Do not excessively abrade the skin during cleaning
Damaged skin has lower resistance to current
Increased risk of burns

83. Electrode Preparation
Attach self-adhering active electrode to skin

84. Electrode Preparation
Inject ionized solution into the chamber

85. Electrode Preparation
Attach self-adhering inactive electrode to the skin and attach lead wires from the generator

86. Electrode Placement
Size of electrodes can cause variation in current density
Smaller = higher density
Larger = lower density
Electrodes should be separated by at least the diameter of active electrode
Wider separation minimizes superficial current density
Decreased risk for burns

87. Electrode Placement

88. Selecting the Appropriate Ion
Negative ions (medication) driven into tissues by the negative lead
Accumulation of negative ions in the tissues
Produces an acidic reaction through the formation of hydrochloric acid
Results in hardening of the tissues by increasing protein density

89. Continued . . .
Positive ions (medication) driven into tissues by the positive lead
Accumulation of positive ions in the tissues
Produces an alkaline reaction through the formation of sodium hydroxide
Results in softening of the tissues by decreasing protein density
Useful in treating scars or adhesions
Some positive ions may also produce an analgesic effect

90. Selecting the Appropriate Ion
Inflammation
Dexamethasone (-)
Hydrocortisone (-)
Salicylate (-)
Spasm
Calcium (+)
Magnesium (+)
Analgesia
Lidocaine (+)
Edema
Hyaluronidase(+)
Salicylate (-)
Mecholyl (+)
Open Skin Lesions
Zinc (+)
Scar Tissue
Chlorine (-)
Iodine (-)

91. Adverse Effects
Chemical burns
Thermal burns
Skin irritations

92. Patient Preparation
For All Types of ES

93. Preparing the Patient Explain what, why, how What: Why: How:
full name plus ‘translation’ of what it is
Why:
Pain relief, muscle strengthening, etc
How:
Gate control?
Opiate release?

94. Preparing the Patient Sensation testing
Test/demonstrate on yourself first
Check for
broken leads
dead batteries
Sensitive dials
Gain confidence of patient

95. Preparing the Patient Prepare electrodes
Plug the leads in first
Use correct gel
No gel BETWEEN electrodes!
Moisten self-adhesive electrodes or IFC pads WELL
Tape or strap electrodes securely

96. Questions??

97. Comprehension Check
What are the 4 main purposes of applying therapeutic electric currents?
What pain mechanism is affected by the use of TENS?
What are the 4 modes of TENS? Which would be used for chronic pain?
What are the contraindications for TENS?
When and why is IFC used over TENS?

98. Comprehension Check
How should the electrodes be set up to achieve a quadipoloar field for IFC?
What are the therapeutic uses for NMES?
What are the indications for iontophoresis?
How is the maximum current of iontophoresis determined?
What is the typical dosage of a drug for iontophoresis?

99. Answers
The 4 main purposes of applying therapeutic electric currents are:
Pain relief
Neuromuscular Electrical stimulation
Tissue/wound healing
Direct stimulation of denervated muscle
The pain mechanism affected by the use of TENS is the gate control theory

100. Answers The 4 modes of TENS are: Conventional Acupuncture
Burst mode (used for chronic pain)
Brief-intense/noxious level

101. Answers The contraindications for TENS are: Some Bladder stimulators
UNDIAGNOSED PAIN
ANY electronic implant
Some Pacemakers (fixed rate ok but rate responsive are affected)
Cardioverter-defribrillators
Some Bladder stimulators
Metal implants???
When and why is IFC used over TENS?

102. Answers IFC is used over TENS because:
“Medium frequency”  less skin impedance
Less impedance  more patient comfort
More patient comfort  tolerate higher amplitude current  deeper penetration
To achieve a quadipolar field for IFC the electrodes from the same circuit diagonal to each other forming a box around the target site

103. Answers The therapeutic uses for NMES are: Strengthens muscles
Motor Re-education
Increases ROM
Enhances endurance
Reduces muscle spasm/spacity

104. Answers The indications for iontophoresis are: Inflammation Edema
Bone spurs/calcium deposits
Fungal infections
Scars
Wounds
Muscle spasms

105. Answers
The maximum current of iontophoresis is determined by the size (surface area) of the active electrode
The typical dosage of a drug for iontophoresis is 40 mA-min