clinical effects of es

Pain relief
Transcutaneous electrical nerve stimulation (TENS)
Sensory TENS (high-rate TENS)
Used mostly in acute phase of pain or postoperatively
Pain reduction due to spinal gate mechanism
Depolarization results in a tingling sensation
Desirable to avoid muscle contraction
Motor TENS (low-rate TENS)
To treat subacute pain or trigger points
Targets the motor pain modulation theory
Pain relief may be delayed in comparison to that with sensory TENS
Pain relief lasts longer than with sensory TENS
Noxious TENS
Pain relief through central biasing mechanism
Commonly used with point stimulators
Portable TENS
Units are battery operated and can be self-administered
Clinician presets phase duration and pulse rate
Interferential stimulation (IFC)
Used for pain relief, increased circulation, and muscle stimulation
Applies two medium-frequency currents simultaneously
Waveforms of the two are superimposed on each other, which causes interference
Interference creates a “beat” mode
Wedenski’s inhibition—cutaneous nerve inhibition
Sweep frequency—feature available on some units that causes a rhythmical frequency change to reduce accommodation
Uses four electrodes in a quadripolar configuration
Allows for centralized concentration of current
Maximized by electrode placement so that intensity is perceived in area of pain
Can be used with other modalities
Premodulated interferential method easier to set up, but differs slightly
Bipolar electrode configuration
Currents are mixed in the machine, not the tissues
High-voltage stimulation (HVS)
Must be able to transmit a voltage of at least 150 V
Must use a twin-peaked monophasic current
High peak, but low average current provides deep penetration of a comfortable current
Used for pain control, edema reduction, tissue healing, and reduction of muscle spasm
Key feature of this unit is ability to be used with appendage submersion treatments
Muscle reeducation
Neuromuscular electrical stimulation (NMES)
Goal of treatment is to elicit a strong muscle contraction through stimulation of the alpha motor nerve
Can be used to slow disuse atrophy in innervated muscle
Assists neuromuscular function by enhancing force capacity (ability of muscle to contract) versus true “strengthening” of the muscle
Electrically produced contractions cause greater fatigue than physiological contractions
Duty cycle (rest time) must be imposed
Uses of galvanic current
Iontophoresis
Ions in solution are transferred through the intact skin via an electrical potential (like charges are repelled)
Uses DC generator
Most commonly used to suppress inflammation and pain
Treatment guidelines not well defined
Difficult to quantify amount of medication delivered into the tissues
Treatment should be physician prescribed
Safe application requires proper equipment and observation of cautions and contraindications
Direct stimulation of denervated muscle
Can occur secondary to trauma
Upper motor neurons—injury results in permanent paralysis; lower motor neuron is still intact and stimulation can still occur through the nerve
Alpha motor neurons—can regenerate, and active control of muscle can be restored
Electrical stimulation does not reinnervate, but maintains the contractile proteins in the muscle
Microcurrent
Effects and benefits
Evidence is limited
Only application shown to be effective is in treatment of slow-healing skin lesions
Summary
Electrical stimulation that crosses the skin to excite a nerve is considered TENS—transcutaneous electrical nerve stimulation.
Many types of units are available to the clinician, allowing many parameters and waveforms to be manipulated in order to achieve a treatment goal.
The clinical uses of electrical stimulation include pain management, muscle stimulation for alpha motor nerve, stimulation of denervated muscle, iontophoresis, edema reduction, and wound healing.
Electrical stimulation in any form of TENS (sensory, motor, noxious, portable, and interferential) is used primarily for pain relief.
Neuromuscular electrical stimulation (NMES) is used primarily to reeducate muscle contraction of the strengthening muscle.
Iontophoresis is used primarily to decrease inflammation, pain, or both.