ES 547- electrical stimulation techniques

electrical stimulation relies on __________ _________________

tissue depolarization

how does coloumb's law explain what is happening in the body during electrical stimulation?

-ions replace the flow of electrons

-like charges repel, opposites attract

what kind of nerves depolarize first? what is the order of stimulation from first to last?

-large, superficial nerves with longer phase durations

-sensory (a-beta), motor, pain (a-delta and c-fibers)

what are the electrical stimulation parameters for gate control theory of pain?

-high frequency (80-150 pps)

-short phase duration (

what are the electrical stimulation parameters for opioid/endorphin release?

-low frequency (1-10 pps)

-longer phase duration (200-400 microseconds)

-at motor or noxious levels

how does acute sensory stimulation prevent edema formation?

tetany/"muscle pumping" clears existing edema by facilitating venous and lymphatic return

what are the safety measures taken when using stim?

-script from physician required

-avoid chemical burns under the cathode during DC application

-prepare skin to lower impedance

-adhere strictly to contraindications

__________ ______ move toward the negative pole (cathode) and _____________ _____ move toward the positive pole (anode)

-positive ions (Na+, K+)

-negative ions (Cl-)

direct current causes ____ ___ _____________ in one direction. alternating current/biphasic current moves ions ______ ____ _______

-net ion migration

-back and forth

what path do electrons follow? what in the body acts as the primary resistor?

-the path of least resistance

-the skin

how does ohm's law relate to the application of stim?

says that higher voltage or superior coupling (ge, moisture, wet sponges) is required to drive the current

conductive pathways are 4x more conductive ________ muscle fibers than _______ them

-along

-across

what is accomodation?

-peripheral nervous system response when a nerve's rate of depolarization decreases while the stimulus remains unchanged

-patients "get used to" electrical sensation

-requires intensity adjustments

what is habituation?

-central nervous system filtration of benign, continuous sensory input

what are the 3 categories that affect nerve depolarization recruitment?

diameter: large-diameter fibers depolarize before smaller ones

depth: nerves closer to the electrode depolarize first

phase duration: longer phase durations recruit deeper/smaller fibers

what is the stimulus level for depolarization for A-beta fibers? A-delta and C-fibers?

A-beta: low

A-delta and C-fibers: high

subsensory level definition

output intensity is between 0 and a the point of first discrete sensation

does the literature support the use of microcurrent?

no proven clinical/therapeutic benefits

sensory level definition

depolarizes sensory nerves (A-beta) without muscle contraction

motor level definition

produces a visible muscle contraction without causing pain

noxious level definition

stimulates pain fibers (A-delta and C-fibers) to activate descending inhibitory pathways

what are the characteristics of silicon/carbon-rubber pads?

-deliver the highest current at the lowest skin impedance

-requires a wet sponge or gel interface to protect the skin

-high risk of hot spots and chemical/electrical burns if poorly coupled

what are the characteristics of self-adhesive electrodes?

-most common in modern clinical settings

-pre-gelled

-higher resistance to current flow than carbon pads

how does size affect function of the pads?

-smaller pads have a higher current density and requires less overall current to stimulate tissue, but carries a higher risk of localized burns

-larger pads have a lower current density, more comfortable, lower impedance

what is a monopolar placement technique?

-one or more small "active" electrodes placed over target tissue

-much larger "dispersive" electrode placed elsewhere to complete the circuit

-focuses current density under the active pad

what is a bipolar placement technique?

-two electrodes of equal or near equal size placed within the target treatment area

-equal stimulation occurs under both

what is a quadripolar placement technique?

-two independant channels using two pairs of electrodes

-cross patterned

-common in IFC

what is spatial summation?

-increase in phase duration and intensity

-recruits a higher number of motor nerves

what is temporal summation?

-increase in pulse frequency

-increases the rate of contractions per unit of time

-leads to tetany

what is tetany and when it is achieved?

-steady contraction

-typically achieved at 30-40 pps

what are the effects of low, medium, and high pulse frequencies?

low (

how does electrical stimulation affect neuromuscular reeducation?

-reestablishes neural pathways for voluntary contraction

-uses a low duty cycle, ramping, and a pulse frequency around 60 pps

-patient may experience DOMS

how does electrical stimulation affect strength augmentation?

-via muscle overload and the reversal of normal motor unit recruitment

-recruits type II fast-twitch fibers first

how does electrical stimulation affect motor edema control? what are the parameters?

-tetanic contraction followed by relaxation "milks" fluid out of the area

-electrodes placed along a vein exiting the swollen area

-low pulse frequency

-50% duty cycle

what is the mechanism for utilizing gate control theory with stim? what are the parameters?

-stimulating large sensory (A-beta) fibers inhibits pain transmission at the dorsal horn of the spinal cord (closes the gate)

-pulse frequency: high (60-150 pps)

-phase duration : short (

what is the mechanism for utilizing opiate pain control with stim? what are the parameters?

-releases beta-endorphins (anterior pituitary) and enkephalins (spinal cord) for long lasting pain relief

-pulse frequency: low (2-10 pps)

-phase duration: moderate to long (200-400 microseconds)

-intensity: motor level (strong, non-painful contraction)

what alternative can stimulate enkephalin release?

high frequency (>80 pps) motor level

what is the mechanism for utilizing noxious level stim? what are the parameters?

-brief, intense stimulation of pain fibers to trigger descending pathways of inhibition

-pain to relieve pain

-pulse frequency: variable (1-100 pps)

-phase duration: 1-100 microseconds

-intensity: as painful as can be tolerated

what kind of current is used with high volt pulsed stimulation (HVPS)? what are its indications?

- alternating monophasic current

-acute and chronic edema

-wound healing

what kind of current is used with a TENS unit? what are the indications?

-alternating current (biphasic waveform)

-acute and chronic pain

what kind of current is used for interferential current (IFC)? what are its indications?

-two ACs criss cross

-acute and chronic pain

-muscle spasm

what kind of current is used with russian/nmes current? what are its indications?

-alternating current (biphasic waveform)

-disuse atrophy

-muscle reeducation

-muscle spasm

-subacute edema

what is direct current used for? what are the precautions?

-used to stimulate denervated muscles directly (depolarizes muscle fibers rather than nerves)

-high risk of chemical burn due to tissue under cathode becomes alkaline

what is low intensity pulsed ultrasound? what are the indications?

-acoustic rather than electrical energy

-used for bone fracture healing

-mimics electrical signals of bone to trigger osteoblastic activity

what is required before the use of electrical stimulation? what are the contraindications?

-script from a physician

-cardiac disability

-demand type pacemakers

-arterial disease

-uncontrolled hemorrhage

-sites of infection

-blood clots

-pregnancy (areas near fetus)

-active cancer

-exposed metal implants

-history of seizures

-sensory or mental impairment

-unstable fractures

what are the precautions of electrical stimulation?

-menstruation

-areas of sensitivity

-unfused epiphyseal plates

-communication impairments

-severe obesity

-electronic monitoring equipment (ankle monitor)