In physical therapy the knowldge about waves is very necessary

3. Course Outline
INTRODUCTION & GENERAL CONSIDERATION
• Types of Current Used: Low Frequency Current & High Frequency Current
LOW FREQUENCY CURRENT
• Faradic Current, Sinusoidal Current, Galvanic Current, Superimposed Current, Modified Direct Current, Dia
Dynamic, Interferential Current, Bio-Feed Back, Tens, Electrodiagnosis.
HIGH FREQUENCY CURRENT
• Short Wave Diathermy, Long Wave Diathermy, Microwave, Ultrasound.
FARADIC & SINUSOIDAL CURRENT
• Introduction & Definition, Physiological Effects, Therapeutic Effects Uses, Methods & Technique of
Application, Care of Equipments, Electrodes & Rubber, Straps, Dangers & Precautions.
• Earth Shocks in Apparatus Working on Mains (b) Antiseptic Technique & Precautions.
GALVANIC
• Introduction & Definition, Physical Effect, ‘Physiological Effect & Uses’, Techniques & Methods of
Application.
• (a) Bath Treatments (b) Size & Position of Electrodes (c) Ionization:
• Theory of Medical Ionization, Proof of Medical Ionization, Effect of Various Ions: Iodine, Salicylate,
Chlorine, Albucid, Zinc, Copper, Histamine, Carbachol, Amichol, Renotin, Novacain, Lithium.
TECHNIQUE OF MEDICAL IONIZATION
• (General Technique)
• Wounds, Sinuses, The Nose, The Eye, the Ear
• Surgical Ionization: The Modified Direct Current
• Modification of Current: Interrupted Direct Current, Surged Direct Current, Physiological Effects,
Therapeutic Uses, Techniques & Methods of Application.
• Neoplasms of Articular Tissues, Torticollis, Garylion, Bursitis etc., Nervous System-Poliomyelitis,

4. SUPER IMPOSED CURRENT
• Introduction & Definition, Effects & Uses of Super Imposes Current.
• Techniques & Method of Application, Dangers & Precaution.
ELECTRICAL REACTION
• Normal & Abnormal Reactions of Muscle & Nerve to Faradism & Interrupted Galvanism,
Changes in Electrical Reaction in: Upper Motor Neuron Lesions, Lower Motor Lesion,
Muscular Diseases.
DIADYNAMIC CURRENT
• Introduction & Definition, Physiological Effects, Therapeutic Uses, Dangers & Precautions,
Techniques of Application,
INTERFERENTIAL CURRENT
• Theory of Interferential Therapy, Physiological Effects of Interference Current, Indications,
Contra Indications & Dangers, Techniques of Treatment.
BIO-FEEDBACK & IT’S DEFINITION
• Definition of Bio-Feedback, Physiological Effects Therapeutic Uses, Indications Contra
Indications & Dangers, Techniques of Application.
TRANSCUTANEOUS/ELECTRICAL NERVE STIMULATION
• Definition, Pain Modulation Theory, Technique of Application, Indication, Contra Indications &
Dangers.

5. ELECTRODIAGNOSIS
• Normal & Abnormal Reactions of Muscle & Nerve to Faradism &
Interrupted Galvanism.
CHANGES IN ELECTRICAL REACTION IN
• A Lesion of the Upper Motor Neuron, A Lesion of the Lower Motor
Neuron, Damage to the Muscle Itself, A Fault At the Neuromuscular
junction, A Functional Disorders.
• Definition of Rheobase, Chronaxie & Accommodation.
TYPES OF ELECTRICAL REACTIONS
• Normal, Complete Denervation, Partial Denervation, Myasthenic.
• Intensity Duration Curves, Theory of Intensity Duration Curve, Technique &
Plotting
• Graphs of Intensity Duration Curve, Advantages. Nerve Conduction Test,
Rheobase, Chronxie & Accomoodity Test: Faradic Interrupted Galvanic Test
(Qualitative & Quantitative).
• Nerve Conduction Velocity Test, Neurography, Repitition, Stimulation,
EMG Spontaneous & Recruitment Patterns, Indication of Nerve
Conduction Velocity & Electromyography.

6. Why use electrical modalities?
• To create muscle contraction through nerve or
muscle stimulation
• To simulate sensory nerves to help in treating
pain
• To create an electrical field in biologic tissues
to stimulate or alter the healing process.
• To create an electrical field on the skin surface
to drive ions beneficial to the healing process
into or through the skin.
6

7. Electrical stimulation frequency
categories:
• Low frequency: 1-1,000 pps or Hz.
• Medium frequency: 1,000-10,000 pps or Hz.
• High frequency: >10,000 pps or Hz.

8. • low frequency currents
– 1-1,000 pps.
– affects sensory and motor nerves
• high frequency currents
– >10,000 pps.
– no effect on sensory and motor nerves
• Medium frequency currents
– 1,000-10,000 pps.
– stimulates sensory and motor nerves
– little skin resistance

9. Current Types
• Direct Current
• Alternating Current
• Pulsed Current
9

10. Direct Current
Description:
• One-directional flow of
electrons
• Constant positive and
negative poles
10

11. Alternating Current
Description:
• Bidirectional flow of
electrons
• No true positive and negative
poles
11

12. Pulsed Currents
MONOPHASIC CURRENT
Description:
• One-directional flow marked by
periods of non-current flow
• Electrons stay on one side of the
baseline or the other
BIPHASIC CURRENT
Description:
• Bidirectional flow of electrons marked by
periods of non-current flow
• Electrons flow on both sides of the
baseline (positive and negative)
12

13. Biphasic Current Types
Symmetrical
– Mirror images on each side of the baseline
– No net positive or negative charges under the electrodes
Balanced Asymmetrical
– The shape of the pulse allows for anodal (positive) or
cathodal (negative) effects
– No net positive or negative charge
Unbalanced Asymmetrical
– Positive or negative effects

14. Waveform Shapes

15. 15
The sine wave
has gradual
increase &
decrease in
Amplitude for
Altenating,
direct and
polyphasic
current

16. 16
The rectangular
wave has an
almost
instantaneous
increase in
amplitude which
plateaus for a
period of time
and then
abruptly falls

17. 17
The triangular
wave has a rapid
increase and
decrease in
amplitude

18. 18
The shape of these
waveforms as they reach
their max. amplitude or
intensity is directly
related to the excitability
of the nervous tissue.
The more rapid the
increase in amplitude, or
the rate of rise,
the greater
the current’s ability to
excite the nervous tissue

19. The rate of rise & decay time
• The rate of rise in amplitude, or the rise time
refers to how quickly the pulse reaches its
maximum aplitude in each phase.
• Decay time refers to the time in which pulse
goes from paek amplitude to 0 V.
19

20. Pulse Duration
• The duration of each pulse indicates the length
of time current, is flowing in one cycle.
• The time (horizontal distance) from when the
pulse rises to the baseline to the point where it
terminates on the baseline.
20
Monophasic Pulse Biphasic Pulse

21. Pulse Duration
• Very short pulse durations with low intensities
can depolarize sensory nerves
• Longer pulse durations are required to
stimulate motor nerves
• Very long pulse durations with high intensities
are needed to elicit a response from a
denervated muscle.
21

22. Phase Duration
• Phases are individual portions of the pulse that appear on one side of the baseline
• For monophasic currents, pulse duration and phase duration are same (only 1 phase).
• Biphasic pulses have two phase durations so the pulse duration is dertermined by the
combined phase durations.
• The phase duration may be as short as a few microseconds or may be a long duration direct
current that flows fro several minutes.
22
1 1
Monophasic Pulse Biphasic Pulse
2

23. Interpulse Interval
• The time between the end of one pulse and the start of the next pulse
• Increasing the pulse frequency decreases the interpulse interval and vice-
versa
23
Two Monophasic Pulses Two Biphasic Pulses

24. Intrapulse Interval
• Intrapulse intervals are brief interruptions of current flow.
• Are always shorter than the interpulse interval.
• They allow for physiologic adaptations to the current
• Are normally not adjustable on the unit.
24
Biphasic Pulse

25. Pulse Frequency
• The number of times a pulse occurs per second
• With alternating currents this measure is described as cycles per second
• The muscular and nervous systems responses depend on the length of time
between pulses and on how the pulse or waveforms modulated.
• Muscles responds with individual twitch contraction to pulse rates of less than 50
pulses per second.
• At 50 pulses per second or greater a tetanic contraction will result, regardless of
whether the current is biphasic, monophasic, or polyphasic
25

26. Pulse Period
• The pulse period is the amount of time from the start of one pulse to the start of
the next pulse.
• Means the combined time of the pulse duration and the interpulse interval.
• Includes the phase durations, intrapulse interval,and interpulse interval.
• Inversely proportional to pulse frequency. As the pulse frequency increases, the
pulse period decreases and vice-versa.
26
Two Monophasic Pulses Two Biphasic Pulses

27. Pulse Trains (Bursts)
• Trains contain individual pulses
• Pulses in the train still have time-dependent characteristics:
pulse duration, interpulse interval, etc.
• Each train is separated by “off” times – the intertrain (or
interburst) interval
27

28. Pulse Charge & Phase Charge
• Refers to the total amount of electricity being
delivered to the patient during each pulse
• With monophasic current, the phase charge and the
pulse charge are the same and always greater than
zero
• In biphasic current, the pulse charge is equal to the
sum of the phase charges.
• If the pulse is symmetric, the net pulse charge is zero
28

29. Current Modulation
• Modulation refers to any alteration in the
magnitude or any variation in duration of
these pulses.
• Modulation may be continuous, interrupted,
burst or ramped.
• The parameters of this modulation must be
established according to various treatment
goals.
29

30. Pulse Ramp
• Gradually increases the current
• Produces a more natural contraction
• More comfortable
30

31. Electrical Stimulation Techniques

32. Current Flow
• Electron Flow
(shown in red)
– Between the generators and
electrodes
– To and from the generator
• Ion Flow
(shown in yellow)
– Occurs within the tissues
– Negative ions flow towards the
anode and away from the
cathode
– Positive ions flow towards the
cathode and away from the
anode
+
+
-
-

33. Electrodes
• Purpose
– Completes the circuit between the generator and body
– Interface between electron and ion flow
– Primary site of resistance to current
• Materials
– Metallic (uses sponges)
– Silver
– Carbon rubber
– Self-adhesive

34. Electrode Size
• Determines the Current Density
• Equal size
– Bipolar arrangement
– Approximately equal effects under exach

35. Electrode Arrangements
• Based on:
Current Density
Proximity to Each Other
Anatomic Location (Stimulation Points)

36. Current Density
• Bipolar Technique
– Equal current densities
– Equal effects under each electrode
(all other factors being equal)
• Monopolar Technique
– Unequal current densities
• At least 4:1 difference
– Effects are concentrated under the smaller electrode
• “Active” electrode(s)
– No effects under larger electrode
• “Dispersive” electrode
• Quadripolar Technique
– Two bipolar electrode arrangements
– Two independent electrical channels
– TENS is a common example
“Active” “Dispersive”

37. Electrode Proximity
• Determines the number
of parallel paths
• The farther apart the
electrodes the more
parallel paths are formed
• More current is required
to produce effects as the
number of paths
increases

38. Stimulation Points
• Motor Points
– Superficial location of motor nerve
– Predictably located
– Motor nerve charts
• Trigger Points
– Localized, hypersensitive muscle spasm
– Trigger referred pain
– Arise secondary to pathology
• Acupuncture Points
– Areas of skin having decreased electrical resistance
– May result in pain reduction
• Traumatized Areas
– Decreased electrical resistance (increased current flow)

39. Path of Least Resistance
• Ion flow will follow the path of
least resistance
– Nerves
– Blood vessels
• The current usually does not
flow from electrode-to-
electrode (the shortest path)
• The path of least resistance is
not necessarily the shortest
path

40. Selective Stimulation of Nerves
• Nerves always depolarize in the same order
– Sensory nerves
– Motor nerves
– Pain nerves
– Muscle fiber
• Based on the cross-sectional diameter
– Large-diameter nerves depolarize first
• Location of the nerve
– Superficial nerves depolarize first

41. Phase Duration and
Nerve Depolarization
• Phase duration selectively depolarizes tissues
Phase Duration Tissue
Short Sensory nerves
Medium Motor nerves
Long Pain nerves
DC Muscle fiber

42. Adaptations
• Patients “get used” to the treatment
• More intense output needed
• Habituation
– Central nervous system
– Brain filters out nonmeaningful, repetitive information
• Accommodation
– Peripheral nervous system
– Depolarization threshold increases
• Preventing Adaptation
– Vary output (output modulation) to prevent
– The longer the current is flowing, the more the current must be
modulated.

43. Electrical Stimulation Goals

44. Motor-level Stimulation
Comparison of Voluntary and Electrically-Induced Contractions
Voluntary
• Type I fibers recruited
first
• Asynchronous
– Decreases fatigue
• GTO protect muscles
Electrically-induced
• Type II fibers recruited
first
• Synchronous
recruitment
– Based on PPS
• GTOs do not limit
contraction

45. Motor-level Stimulation
• Parameters:
Amplitude: Contraction strength increases as
amplitude increases
Phase duration: 300 to 500 µsec targets motor
nerves:
– The shorter the phase duration, the more amplitude
required
– Longer durations will also depolarize pain nerves
– Pain often limits quality and quantity of the contraction
Pulse frequency: Determines the type of contraction

46. Pulse Frequency
• Frequency determines the time for mechanical
adaptation
• Lower pps allows more time (longer interpulse
interverals)
Label Range Result
Low < 15 pps* Twitch: Individual contractions
Medium 15-40 pps* Summation: Contractions blend
High >40 pps* Tonic: Constant contraction
* Approximate values. The actual range varies from person-to-person and
between muscle groups

47. Effect of Pulse Frequency on Muscle
Contractions
1 pulse per second
Twitch Contraction
The amount of time
between pulses – the
interpulse interval – is
long enough to allow the
muscle fibers to return to
their original position
20 pulses per second
Summation
The amount of time
between pulses allows
some elongation of the
fibers, but not to their
starting point.
40 pulses per second
Tonic Contraction
The current is flowing so
rapidly that there is not
sufficient time to allow the
fibers to elongate

48. Electrical Stimulation Goals
Pain Control

49. Pain Control
Sensory-level Motor-Level Noxious Level
Target A-beta fibers Motor nerves A-delta
Tissue C fibers
Phase < 60 µsec 120 to 250 µsec 1 msec
Duration
Pulse 60 to 100 pps 2 to 4 pps Variable
Frequency 80 to 120 pps
Intensity Submotor Moderate to To tolerance
Strong contraction

50. Electrical Stimulation Goals
Edema Control and Reduction

51. Edema Control
• Cathode placed over
injured tissues
• High pulse frequency
• Submotor intensity
• Thought to decrease
capillary permeability
• Do not use if edema has
already formed

52. Edema Reduction
• Muscle contractions
“milk” edema from
extremity
• Electrodes follow the
vein’s path
• Alternating rate targets
muscle groups
• Elevate during treatment

53. Electrical Stimulation Goals
Fracture Healing

54. Contraindications and
Precautions

55. Contraindications and Precautions
• Areas of sensitivity
– Carotid sinus
– Esophagus
– Larynx
– Pharynx
– Around the eyes
– Temporal region
– Upper thorax
• Severe obesity
• Epilepsy
• In the presence of
electronic monitoring
equipment
• Cardiac disability
• Demand-type pacemakers
• Pregnancy (over lumbar and
abdominal area)
• Menstruation (over lumbar
and abdominal area)
• Cancerous lesions (over
area)
• Sites of infection (over area)
• Exposed metal implants

56. Current density
• Amount of current flow per cubic volume
– If the electrodes are place closely together, the
area of highest current density is relatively
superficial.
– If the electrodes are spaced farther apart the
current density will be higher in deeper tissues,
including nerve and muscles.
56

57. Electrode size
& Placement
• Electrode size and placement are key elements which the therapist controls
that will have great influence on results.
• Electrode size will also change current intensity
• If one electrode is larger and the other is smaller, the current density beneath
the smaller electrode is increased.
• Using a large (dispersive) electrode remote form the treatment area while
placing a smaller (active) electrode as close as possible to the nerve or
muscle motor point will gibe greatest effect at the small electrode.
• The larger electrode disperses the current over the large area
• The small electrode concentrates the current in the area of the motor point
• High current density close to the neural structure makes it more certain that
the treatment will be successful with the least amount of current.
57

58. 58

59. 59

60. 60

61. 61

62. 62

63. 63

64. 64

65. 65

66. 66

67. 67

68. 68