NMES Flashcards
How is NMES initiated?
With the excitation of peripheral nervous tissue
Definition: defines the LOWEST level of electrical charge that generates an action potential
stimulus threshold
definition: phenomenon of the action potential produced by natural physiologic means is identical to the action potential induced by NMES
all or none phenomenon
(true/false) You can have a peripheral lesion and still use NMES
FALSE – MUST have an intact LMN
The threshold for eliciting a nerve fiber action potential is (less/more) than the threshold for muscle fiber stimulation.
LESS (100-1000x less)
(true/false) Clinical NMES systems stimulate either the nerve directly or the motor point of the nerve proximal to the neuromuscular junction
true
definition: The most electrically excitable area of the muscle wherein a minimum amount of electrical stimulation will easily excite this portion of the muscle
motor point
What principle does nerve fiber recruitment mediated by NMES follow?
Reverse recruitment order
The nerve stimulus threshold with the principle of reverse recruitment order used with NMES (is/is not) inversely proportional to the diameter of the neuron
It is
–> Larger fibers that innervate larger motor units are recruited first
(true/false) The nerve fiber recruitment properties elicited by NMES differ from those elicited by normal physiologic means
true
An action potential produced by normal physiologic mechanisms initially recruits the (smaller/larger) diameter neurons prior to recruitment of the other.
smaller diameter neurons
Alpha motor neurons are (small/large) fibers
large fibers
Type ___ fiber:
- smaller motor units
- low forces
- resistant to fatigue
type I
Type ___ fibers:
- larger motor units
- higher force
- rapidly fatigue
Type II
What is NMES dependent on?
An intact (alpha) low motor neuron
Clinical application of NMES is presently limited to neurologic injuries involving (UMN/LMN.
UMN
Several studies document the therapeutic benefit of electrical stimulation on muscle-fiber regeneration in _____ denervation
LMN degeneration
What determines the numbers of muscle fibers recruited when using NMES?
amplitude and pulse width
What is the minimum stimulus frequency that generates a fused muscle response?
12.5 Hz
What is the result of higher stimulus frequencies?
generate higher forces but result in fatigue and decreased contractile force of a muscle
An optimal NMES system utilizes the (minimal/maximal) stimulus frequency that produces a fused response and not just “twitching”
minimal stimulus frequency
What is the ideal stimulation frequency range for UEs?
12-16 Hz
What is the ideal stimulation frequency range for LEs?
18-25 Hz
What is the frequency range for NMES units?
10-50 Hz
NMES is delivered as a waveform of electrical current characterized by what?
- stimulus frequency
- amplitude
- pulse width
Temporal summation is determined by what?
the rate at which stimulus pulses are applied to muscle
How does temporal (wave) summation occur?
Occurs if consecutive stimuli are applied during the relaxation period of each preceding muscle contraction.
In this case, each subsequent contraction builds upon the previous contraction before its relaxation period ends.
definition: occurs when the frequency of stimuli increases and successive muscle contractions begin to blend, almost appearing as a single large contraction.
incomplete tetanus (unfused tetanus)
definition: occurs when the frequency of stimuli increases further.
In this case, individual muscle contractions completely fuse to produce one large muscle contraction.
complete tetanus (fused tetanus)
(true/false) The optimal pulse frequency for a muscle contraction is one that produces a “fused” response without discomfort
true
Why is clinical application of NMES complicated?
- the contractile force of muscle is variable over time
- muscle force generation is impacted by multiple factors distinct from the stimulation parameters of the NMES system
(true/false) NMES can activate paralyzed muscles in precise sequence and magnitude to accomplish functional tasks
true
definition: An artificial system bypassing the neural system to restore lost body functions by providing functional movement patterns using electrical stimulation.
neural prosthesis
ex: drop foot
definition: Changing normal and abnormal neural activity in both sensory and motor nerves to manipulate function
(pain, neural plasticity)
neuromodulation
–> most common neuromodulation treatment is spinal cord stimulation for chronic neuropathic pain
What is the indication for NMES?
UMN lesions
What warrants precautions when using NMES?
- impaired sensation
- edema (can interfere with adequate stimulation)
What are contraindications for NMES?
- healing FX
- wounds
- pacemaker
- malignancy or phlebitis in the treatment area
- superficial metal implants
Electromyographic findings of muscle dysfunction can occur within _______ IF they are cosncious.
a few days
Electromyographic findings of muscle dysfunction would take ______ IF the person is unconscious.
3 weeks
(true/false) Electronic equipment such as ECG monitors and alarms may not operate properly when TENS/NMES in use
true
DO NOT use ______ to assist paraplegic patients into the standing position
FES
What is the electrode placement for shoulder subluxation?
Negative/black: proximal 1/3 over posterior deltoid
Positive/red: superior to the spine of the scapula (critical to prevent the activation of the upper trapezius muscle)
When placing electrodes, select the (smallest/largest) possible electrode that minimizes overflow to other muscles and conforms to the treatment area
largest electrode
How should muscular fatigue be measured with NMES for shoulder subluxation?
by palpating the amount of subluxation present at the end of the stimulation session
What is the NMES electrode placement for gait training?
Negative/black: over anterior tibialis slightly overlapping the peroneous longus
Positive/red: distal mid-lower leg over the peroneal muscles and tendons
What is the goal of NMES use while gait training?
facilitate DF without excessive inversion and eversion
What is the electrode placement for finger EXT when using NMES?
Negative/black: over motor point of muscle mass most likely to produce finger EXT without activating wrist EXT
Positive/red: distal aspect of extensor muscle belly
(true/false) There is an on-off cycle when using a hand-triggered switch
FALSE (there is not)
How is a heel switch triggered with NMES during gait training?
heel strike
What does an asymmetrical waveform do?
Allows the negative electrode to be more active
