Electrical stimulation
Notes
What is electricity?
 A form of that exhibits magnetic, chemical, mechanical, and thermal effects; formed from the interaction of positive (+) and negative (−) charges
 The physical phenomena associated with the existence and interaction of electrical charge, either static charges (electrostatics) or moving streams of charge (
Types of electricity
 Static
 Current
)
Static electricity
 Static electricity is electricity.
 One body gains electrons; the other loses electrons.
Current electricity
 A stream of along a conductor
 Current types:
 Direct current (DC)
 Alternating current (AC)
 Pulsed current
Direct current
 One-directional flow of electrons
 Constant and
passing
Alternating current
 Bidirectional flow of electrons
 No true positive and negative poles
 Two terminals of generator (source)
poles
from positive to negative
Pulsed currents
 Direct flow of current marked by periods of
Current attributes
 Calculated as the
Duty cycle
 The of time that the current is flowing relative to the time it is not
 ON / (ON + OFF) *100
 Example:
 20 μsec on, 40 μsec off
 20 μsec/ (20 μsec + 40 μsec) * 100
 20/60 *100 = 33.3% duty cycle
Pulse width
 The length of time a pulse is ON
 Measured in micro seconds (μsec)
=
Pulse rate (frequency)
 The number of times a
 Described as cycles per second
 Units of Mega Hertz (MHz)
= millions/second
Current density
 The amount of current in the tissues
 The higher the current density, the more
Medical devices
Muscle stimulator
Neuromuscular electrical stimulation, NMES
 A therapeutic device that delivers current to the body to cause and nerve depolarization
 Causes
Nerve stimulator
Transcutaneous electrical nerve stimulator; TENS
 Therapeutic device that delivers current to the
 body to cause nerve depolarization
Stimulate sensory nerves to
 Muscle contraction may occur, but this is not the
purpose of TENS.
What’s the purpose?
Effects
 and , which result from the stimulation of sensory and motor nerves
 Nerves are polarized – either positive or negative
 The electrical current alters the polarization =
 Depolarization causes an action potential
 Action potential causes a muscle contraction
 Single contraction =
 Continuous contraction =
Nerve stimulation
 Nerves always depolarize in the same order
 Sensory
 Motor

 Muscle fiber
 Based on the diameter of the nerve
 = depolarize first
 Based on location of the nerve
 = depolarize first
 By stimulating sensory nerves first, the
 By stimulating motor nerves, a
is diminished
occurs
 By stimulating pain nerves, the feeling of pain is

Electrical stimulation
Notes
Indications
 Acute injuries causing pain or edema
 Muscle re-education after injury
Contraindications
 Areas of (sensory nerve fiber excitement)
 Cardiac disability – pacemaker, etc.
 Pregnancy
 Over the lumbar spine (
 Cancerous lesions/tumors
 Sites of infection
 Exposed metal implants
Treatment parameters & protocols
Electrodes
 Completes the circuit between the generator and body
 Materials
 Metallic (uses sponges)
 Silver
 Carbon rubber
 Self-adhesive
 Shape is
 Size and placement are of main concern
 Determines the and
 Current density
of nerves stimulated
 Arrangement is based on
 Current density
 Proximity to each other
 Anatomical location
 Moving further apart current density in tissues
 The electrical current will take the
– not the shortest path possible
Intensity
 Increasing intensity causes the current to reach
into the tissue
 Usually use an intensity level that is
Duration
 Increasing treatment duration the number of nerves stimulated
 Depolarization & action potentials
 Typical treatment duration is
– ice pack, hot pack, etc.
)
Pre-modulated current
 of current with electrodes placed near the site of treatment
 Direction of flow is to muscle fibers
– not perpendicular
 Machine determines pulse width, duration, frequency
Interferential current
 Two channels of different frequencies at the site of treatment
 Allows for increased due to
 increased amplitude
of equal size
 Pair from each of two channels
 Crisscross the target tissue
 Machine determines pulse width, duration, frequencies
Russian current
 Used to
 A
after injury
is forced by electrically stimulating the muscle
 Patient feels muscle contract, sees muscle contract, and duplicates the response
 Intensity is set at while generating a muscle contraction
 Pulse width & frequency are set to a duration
 needed for
Hold each pulse for minute off
 Total treatment time of 15-20 minutes
, with 1