Electrical Stimulation Flashcards
What are the physiological effects of electrical stimulation?
1 decrease pain 2 decrease muscle spasm 3 reduce edema 4 stimulate exercise by muscle contraction 5 stimulate healing
By what concept does electrical stimulation decrease overall pain?
Gate-Control theory/endorphin release
What is the gate control theory and how does it work?
Theory that explains how non-painful input closes the “gates” to painful input, therefore preventing pain sensation from traveling to the CNS.
What 3 things are required for electricity to work?
1 source of electrons
2 driving force
3 path (conductor)
What is the river analogy in terms of electricity?
Electrons = drops of water in a river
Current (Amp) = flow of the river
Voltage = waterfall
Resistance = water flow through hose
Is there more or less resistance with a short smooth large diameter hose/wire?
Least
What does the term capacitance mean?
ability of a material to store a charge (to release later)
What is Ohm’s Law?
V = IR
What is another name for a monophasic current?
Direct current (DC) or Galvanic
What type of current has current flow in one direction?
Monophasic/direct current (Galvanic)
What is another name for a biphasic current?
Alternating current
What type of current has an electron flow that changes directions regularly?
Biphasic current/alternating current
Which type of wave form has the same shape in both phases? Different shapes?
Symmetrical = same shapes Asymmetrical = different shapes positive and negative
What are the shape variations possible with a biphasic current?
Sinusoidal, square, rectangular, triangular
What is the term for the time it takes the current to leave the isoelectric line to when it returns to that line?
Phase duration
In what type of current are the phase duration and pulse duration the same?
Monophasic
What type of current has two phase duration for each pulse?
Biphasic current
Do tissues respond to phase duration or pulse duration?
Phase duration
The phase duration must be how long (in general) to cause an action potential?
Long enough to overcome capacitance
Do small or large diameter nerves have low capacitance and therefor reach threshold quickly?
Large diameter
What is the space called in between each pulse duration?
InterPulse duration
What is the term used to describe the intensity or magnitude of the current?
Amplitude
Which fibers are close to the skin and have a lower threshold, so they are stimulated first?
A-beta
Which response is elicited first: sensory or motor?
Sensory
What is the term for the amount of current supplied over a period of time?
Average current
Why can too high average current be an issue?
Can cause tissue damage
What measurement describes the relationship between the amplitude (strength) of the electrical current and the phase duration?
Strength duration curve
Does a short or long duration require a higher amplitude for the nerve response?
Short
What kind of duration allows for a lower intensity for the same nerve response?
Long
How can the phase charge be altered?
Changing the phase duration and amplitude
When the patient reports tingling but no muscle twitch, what fibers have been exceeded and which fibers have not been reached?
A-beta fibers exceeded
A-alpha motor neurons not reached
What happens when A-alpha motor neurons are reached?
Muscle contraction
When the patient reports a burning, needling sensation, the capacitance of which fibers have been exceeded?
A-delta fibers
Does electrical stimulation target nerves or the actual muscle?
Nerves (targeting the actual muscle would be painful)
What is the order in which fibers are reached via electrical stimulation to initiate certain responses?
1 A-beta (tingling)
2 A-alpha (muscle contraction/twitch)
3 A-delta (discomfort)
4 C (PAIN)
What is rheobase?
Minimum amplitude needed to depolarize a nerve fiber when phase duration is infinite
What happens if the peak amplitude fails to exceed rheobase?
the nerve will not depolarize regardless of phase duration
What is chronaxie?
The time (or phase duration) required to depolarize a nerve fiber when the peak current is twice rheobase
When will the patients reach the greatest amount of comfort in terms of phase duration and amplitude?
When amplitude is twice rheobase and phase duration is slightly greater than chronaxie
What is the term for the number of pulses or cycles generated per second?
Frequency
What affects the number of action potentials elected during the stimulation?
Frequency
Does a higher or lower frequency lead to summation?
Higher
What is the rate limiting factor of the number of impulses that can be generated by a nerve?
Absolute refractory period
What occurs with stimulation at high frequency near the refractory period of the sensory nerve (official name)?
Wedenski’s inhibition
What are the most common treatment frequencies?
1-10 Hz or 60-100 Hz
What are the values for low, medium, and high frequency generators?
Low = up to 1,000 Hz Medium = 1,000-100,000 Hz High = greater than 100,000 Hz
What is the frequency for interferential current generators?
4,000-5,000 Hz
What is the main purpose for using high frequency generators?
Thermal purposes (ex. = diathermy)
What is the normal frequency level for Russian stimulation?
2,500 Hz
What structure attaches the electrodes to the current generator?
Leads
How many leads must there be to complete a circuit?
Two
If the electrodes are unequal sizes, to where will the current concentrate?
In the smaller electrode (perception of increased intensity)
What happens to the larger electrode when the sizes vary greatly?
Unable to perceive current - becomes dispersal electrode
What is the main target when two pads are placed close together?
Most concentration in superficial tissues
How does the target change when the pads are further apart?
Current has potential to take deeper path through the nerve and blood vessels that have less resistance
What is the general rule for selecting the size of the electrodes?
Largest possible but small enough to selectively target tissue
What is the size of the electrodes during monopolar electrode configuration?
Two or more unequal sizes (one active, one dispersal)
Monopolar electrode configuration can be used with what types of current?
Biphasic (AC) or monophasic (DC)
Which is found at the target site, and which is found away from the target site: active or dispersal electrode?
At target site = active
Away from target site = dispersal
Bipolar electrode configuration can be used with which types of currents?
Monophasic (DC) and biphasic (AC)
What is the size and location of the electrodes with a bipolar electrode configuration?
Equal size both placed over treatment site
Bipolar electrode configuration is most common for what kind of treatment?
TENS (transcutaneous electrical nerve stimulation)
Quadripolar electrode configuration is most common with what kind of treatment?
Interferential current
How are the electrodes arranged during quadripolar configuration?
Two separate medium frequency current with electrodes placed as cross currents
What is the significance of the cross currents of quadripolar configuration?
Current is interfered with in the center of the two currents