L10/11: Functional Electrical Stimulation Flashcards
1
Q
What is the purpose of Functional electrical stimulation (FES)?
A
Uses ES to produce a functional movement or series of movements
2
Q
What is ES?
EXAM QUESTION
A
Any type of electrical stimulation
3
Q
What is EMS?
EXAM QUESTION
A
Electrical muscle stimulation to excite denervated muscle directly
4
Q
What is NMES?
EXAM QUESTION
A
Neuromuscular electrical stim used to stim a peripheral nerve & to cause a sensory, motor or noxious response
5
Q
What is TENS?
EXAM QUESTION
A
Transcutaneous electrical nerve stimulation used as an analgesic without causing muscle contraction
6
Q
What is TES?
EXAM QUESTION
A
Therapeutic electrical stimulation causing a muscle contraction which aims to improve impairments after stimulation
7
Q
What is FES?
EXAM QUESTION
A
Functional electrical stimulation causing a muscle contraction to assist the performance of function during stimulation
8
Q
When are 2 scenarios when ES is used?
EXAM QUESTION
A
- Stimulation of motor nerves (e.g. Stroke)
- Stimulation of denervated muscle (e.g. Spinal cord injury)
9
Q
What are the 6 uses of FES?
A
- When individuals do not have ‘enough movement to work with’ – insufficient motor drive to produce an active movement
- Used during physiotherapy treatment / rehabilitation – to facilitate / activate / exercise the muscle (therapeutic)
- Used during everyday life to replace lost function
- Upper and lower limb function
- Bowel and bladder function
- Respiratory functon
10
Q
What are the 3 types of FES?
A
- Surface vs. intramuscular
- Single vs. multi-channel
- Applications – manual vs. cyclic vs. triggered vs. controlled
11
Q
What are 4 characteritics surface FES?
A
- Most common clinical application
- Non-invasive, low cost
- Easy to apply and remove electrodes
- Electrodes &stimulators available
12
Q
What are 3 disadvantages of surface FES?
A
- Pain from stimulation intensity used
- Lack of muscle selectivity- deep muscles & in severe
- Reproducibility affects by accuracy of electrode placement
13
Q
What is Surface FES similar to?
A
TENS
14
Q
Why do you need to draw around the electrodes (on the skin) when using surface FES?
A
- Usually draw on electrodes
- Able to maintain consistency
- Spend time on first time (good placement)
15
Q
What are 4 characteristics of intramuscular FES?
A
- Percutaneous – indwelling wires through the skin
- Fully implanted electrodes and circuits
- Bypass skin and cutaneous sensory fibres so less painful contractions, more efficient, less current
- More selective & sensitive to small EMG signals
16
Q
What are the 3 disadvantages of intramuscular FES?
A
- Research applications or research trials
- Invasive – percutaneous or surgical
- Maybe only used in spinal cord injuries -Activate muscles long term
17
Q
What are the 2 types of channel FES?
A
- Single
- Multichannel
18
Q
What is single channel FES?
A
Single ES to one muscle group for therapeutic use (to exercise / activate)
19
Q
What is multi-channel FES?
A
Multi-channel ES to several muscle groups (simultaneous, alternating) for therapeutic use (to exercise / activate
20
Q
What are 4 applications of FES?
A
- Manual
- Cyclic
- Triggered
- Controlled
21
Q
What is the manual application of FES?
A
operator controlled
22
Q
What is the cyclic application of FES?
A
activates paretic muscle at set duty cycle for set time period.
Patent is passive recipient.
23
Q
What is the triggered application of FES?
A
stimulation is triggered by an event
24
Q
What is the controlled application of FES?
A
ES is controlled by events like initiation, maintenance and termination of a contraction
25
What are 6 characteristics of manual ES?
1. Stimulation controlled by a hand-switch
2. Hand switch controls work and rest timing
3. Allows timing of muscle contraction to co- incide with activities
4. Allows active engagement
5. Allows client to control the movement
6. Needs someone who understands movement trying to achieve to be present at all times
26
What is important for the person controlling the machine in manual ES?
Person controlling machine needs to know parameters
27
What are 3 characteristics of cyclic ES?
1. Mild to moderate, chronic paresis
2. Single joint movements
3. No to minimal cognitive investment
28
What is the purpose of cyclic ES?
* Prevention of shoulder subluxation
* Muscle activation
* No need to think about it (not consciously comtrolled)
29
What are 3 outcomes of cyclic ES?
✔ Impairments – ROM, strength
✔ Impairments – Shoulder sublux
**X** Activity
30
What is the clinical implication of cyclic ES?
Cyclic ES machines are simple &cheap BUT ... need to incorporate into active task oriented practice
31
What are the 6 types of triggered ES?
1. Positional feedback ES
2. Pressure-switch triggered ES
3. Electromyogram-triggered ES
4. Contralateral-triggered ES
5. Outcome-triggered ES
6. Accelerometer-triggered ES
32
What are 3 characteristics of positional feedback ES?
1. Achievement of a preset degree of wrist extension triggered ES
2. Moderate to severe, chronic paresis
3. Single joint movements + \> cognitive investment & goal setting ? greater potential for motor learning
33
What is the outcome of positional feedback ES?
Good outcome
34
What are the clinical implications of the positive feedback ES?
* Research undertaken in 1970’s
* Not commercially available
35
What are 4 characteristics of pressure-switch triggered ES?
1. Pressure switch connected by wires or wireless technology inserted into footwear – must wear footwear
2. Allows for timing of stimulation to match gait cycle Allows for augmented muscle activity during weightshift or standing exercises
3. Most commonly worn under heel
36
Where are pressure-switched triggered ES usually worn?
Worn under the heel
37
Why is pressure-switch triggered ES usually worn under the heel?
Used (bioness) for foot drop
'
Activates TA when heel is up, TA turns off when heel touches the ground
When TA is not working --\> chronic problem --\> use FES (neuro-prosthesis) C
ompensating = increase energy cost and risk of falling
Circumduction
Bolting (lift hip up higher)
38
What does EMG-triggered ES look like?
* Detect what is happening at the muscles
* Certain threshold of activity --\> stimulate the stimulation to come on --\> activity
* Need some activity in target muscle for the EMG (to begin)
39
What is required from the beginning for EMG-triggered to work?
* cognitive engagement
* some activity in target muscle
* Some activity in the target muscle (otherwise, muscles can't be activated)
40
How does EMG-triggered Eswork? List the 4 steps.
1. Electrodes placed over target muscle
2. Patient voluntarily contracts muscle
3. Needs to reach a preset level of activity to then make the stimulation work
4. Stimulation then helps to complete full movement
41
How does automatic adjustment work in EMG-triggered ES?
Automatic adjustment – if patient can’t achieve set level – device automatically reduces threshold – or if does meet it – automatically raises threshold
42
When is EMG-triggered ES used?
Motor learning based --\> retraining motor tasks (eg. reaching)
* Mild, moderate, chronic paresis
* Moderate to severe, acute paresis
* Single joint mulG joint
43
What are the 2 outcomes of EMG-triggered ES?
1. Impairment (wr & fingers) – level 1 - 3RCTs
2. AcGvity (UL) (improves activity but no benefit over usual care) – 8 RCTs – mixture severity levels ´
44
What is contralateral triggered ES?
Unaffected arm triggers delivery of stimulation to affected arm
45
What are the 5 clinical implications of contralateral triggered ES?
1. Not available outside research
2. Unimpaired hand is engaged – loss of good hand functionally
3. Does it work partly due to bilateral facilitation of movement?
4. Synchronous bilateral v asynchronous bilateral task
5. Only can do bilateral symmetrical task --\> might not be functional
46
What are 4 characteristics of outcome-triggered ES?
1. Moderate to severe, acute paresis
2. Multiple and severe impairments
3. Multi joint movement
4. Combined with an ancillary device
47
How does outcome-triggered ES work?
Had to reach a certain distance
48
Why is outcome-triggered ES good?
Sometimes cheating when activating muscle --\> reward poor performance (false)
49
What are the 4 clinical implications of outcome-triggered ES?
1. Promotes normal pattern of movement – reaching in a straight line
2. Rewards movement in the direction of the goal
3. Training based on motor learning principles
4. Commercially not available as yet
Stimulation rewards what the outcome is
50
What are the 3 outcomes of outcome triggered ES?
✔ Impairments
✔ AcGvity
**?** Participation
51
What is an accelerometer triggered ES?
Anterior simulation --\> arm swing (mvt)
52
What are 2 characteristics of accelerometer triggered ES?
1. Moderate, chronic paresis
2. Multi joint movement
53
When is accelerometer triggered ES used?
Moderate, chronic paresis
54
What are 3 outcomes of accelerometer triggered ES?
✔ Impairment
✔ Activity
✔ Participation
55
What are 4 clinical implications of accelerometer triggered ES?
1. Rewards movement in the direction of the goal
2. Training based on motor learning principles
3. Commercially not available as yet
4. Issues with reliability & set-up
56
What is iterative learning control-mediated ES?
* ES with a robotic device to retrain reaching
* Accuracy of tracking & force exerted used to control ES delivery
57
What are the 2 outcomes of iterative learning control-mediated ES?
✔ Impairments
**X** AcGvity
58
What are the 2 clinical implications of iterative learning control-mediated ES?
1. Not commercially available
2. Cost
59
How does a neuro- prosthesis work?
Activates specific muscles in a specific sequence to replace lost function – to use during a functional task
60
When is neuroprosthesis used?
Used in upper limb for wrist extension
* Grasping and reaching
61
What are the 3 characteristics of the Bioness H200 (neuro-prosthesis)
1. Single & multi joint tasks:
1. Cyclic
2. Contralateral-triggered
2. Mild, moderate & severe paresis
3. Acute, subacute & chronic
62
What are the 3 outcomes of the Bioness H200 (neuro-prosthesis)?
✔ Impairment
✔ Activity
✔ Participation
63
What are 4 clinical implications of neuro-prosthesis?
1. Neuroprostheses can be used to retrain UL function
2. Commercially available
3. Cost & accessibility
4. ‘gateway’ or ‘bridge’ to participation in therapy regimes that demand greater volitional activity
64
What does the research say about neuroprothesis?
* Increases activity – Level I
* Mainly wrist &hand with limited research in those with severe impairment
* Reduces impairment – Level I
* Increases strength (Level I)
* Prevents subluxation (Level I)
65
What are the 3 guidelines for improving muscle strength in regards to duration, frequency and machine frequency and intensity?
1. Regularly 1-2 times a day
2. Freq of 35 – 50 Hz (PD best 100 -300 μs / 0.1-0.3ms)
3. Up to an hour a session, max intensity, 6 weeks or more
66
How does the neuroprothesis work physiologically?
* Improve strength of remaining motor units, improve fibre crosssectional area, facilitation of voluntary motor control – synapse strengthened by coincident pre and post synaptic activity, reciprocal inhibition of spasticity
* Increasing signal strength across synapse
67
How does the neuroprothesis work mechanically?
Mediate/augment muscle activity through full range during task, maintain / improve ROM, reduce oedema
Eg. Post stroke
Stimulate more muscle fibres and full range
68
How does the neuroprothesis work motivational?
Gives people hope/potential Stroke survivors can see movement, continue training until stim off
69
How does the neuroprothesis work motor learning?
Promotes normal movement, reinstates appropriate proprioceptive input sensory-motor integration – sensory input directly influences motor output, cognitive intent converges with sensory input, sensory-motor cycle reinstated – motor learning resumes, repeated input-use-dependent cortical reorganization
70
What are the 5 steps of how neuroprothesis work physiologically?
1. Voluntary movement activates nerve fibres orthodrmically (brain to hand)
2. ES activates nerve fibres antidromically (hand to ant horn cell)
3. Synapse strenthened by co-indicisent pre and post synaptic activity
4. FES + voluntary effort may help promote synaptic modifications at ant horn
5. FES can result in \> fatigue as it alters normal motor recruitment order and results in simulatenous stim of muscle fibres
71
What are 2 indications for using FES?
1. Peripheral nervous system intact
2. Can tolerate stimulation
72
What are the 4 contraindications for using FES?
1. Superficial metal, open wounds, broken skin, eczema, infective lesions
2. Pacemakers, implantable defibrillators, deep brain stimulation, cardiac monitoring, pregnancy, undiagnosed pain
3. Increased metabolic activity, neoplasms, carotid sinus
4. Confused patients, trans-cerebral, trans-thoracic
73
Why are open wounds are contraindications?
1. Infection
2. More difficulty to penetrate skin
74
What is increased metabolic activity?
1. In sepsis
2. Higher immune response
75
Why is Confusion/delirium a contraindication?
Might rip things off = dangerous
76
What are 2 precautions?
1. Frequent skin checks when sensation, cognition, communication impaired (Just need to keep checking and monitoring)
2. Avoid loss of skin contact–predisposes to burning; No water, no MRI
77
What are the important things when making goals for FES?
* Have a goal/reason for using ES
* E.g.to increase strength wr E for grasp and release
* E.g.to activate rotator cuffto prevent shoulder subluxation
* Know what is tobe achieve and how Grade3 wr extensors
* Work through full range repetively
* Measure activity pre and post training
78
What is the set up for FES to strengthen wrist extensors?
* Support limb proximally – only want wr E
* Ensure antigravity position that enables full ROM
* A target will help
79
What is the set up for FES to activate rotator cuff to prevent shoulder subluxation?
* Support limb under elbow
* Posterior and lateral shoulder exposed
80
What is the set up for FES to activate ankle DF during gait?
Seated position with appropriate footwear
81
What are 5 questions to ask for muscles to stimulate?
1. What muscles perform desired action?
2. Knowledge of anatomy/kinesiology
1. Aretheysufficientlysuperficial?
2. Single muscle group or multiple?
3. Locate muscle for stimulation–from Knowledge of surface anatomy
4. Visual inspection palpation during contraction and release with guidance /resistance
5. Resist movement on unaffected side
82
What are 4 ways to optimise motor response for FES?
1. Minimse skin impedance
2. Optimise electrode size and placement
3. Determine whihc neural fibre are to be stimulated
1. Intensity/amplitude (mAmp)
2. Duration /pulse width (msec/sec)
3. Shape of stimulus/waveform (rectangular)
4. Determine rate at whihc fibres fire
1. Frequency- single twitch (low Hz) to tetany (high Hx or pps)
83
What are 2 characteristics of skin preparation for FES?
1. Check no broken skin/eczema
2. Decrease skin impedance in area over electrode sites by preparing skin
* Shave if particularly hairy
* Scrib with nu-prep or alcohol wipe
84
What are 5 characteristics for electrode size for FES?
1. Consider size of muscle and person–largest possible electrodes without electrodes touching and without spread to unwanted muscles
2. Small electrodes–current density increased and localised uncomfortable
3. Large electrodes–current density decreased, increased current spread increased comfort
4. If use two sizes of electrodes–current will concentrate under the smaller electrode
5. Current density greatest near electrode-skin interface
85
With Smallelectrodes–currentdensity _______ (increased/decreased) andlocalised . This means it is _____ (comfortable/uncomfortable)
increased; uncomfortable
86
Large electrodes–current density\_\_\_\_\_ (increased/decreased) currents spread ____ (increased/decreased) comfort
decreased; increased
87
If use two sizes of electrodes–current will concentrate under the \_\_\_\_\_(larger/smaller) electrode
smaller
88
Is same size electrodes or difference sized electrodes more common? Why?
same size; max. activation of all fibre
89
What are 4 characteristics of the electrode placement when using FES?
1. Where strongest comfortable contraction felt/observed
2. Over motor point supplying muscle(black)and distal to it(red)
3. Close together= superficial current flow
4. Far apart=deeper currentflow
90
What are 4 characteristics of electrode contact when using FES?
1. need good electrode contact toavoid concentration of current and risk of skin / tisssue injury
2. Adhesiveelectrodes–ensure stickingon entire electrode, replace when ageing – if need to use tape – need to replace
3. Non-adhesive electrodes–adequate gel–note dries out Wiring& stimsecure to avoid electrodes being pulledoff
4. Electrodeparameters Duraton/pulsewidth
1. Shorter width = increased comfort due to decreased average current
2. 200 μsec recommended
91
What are the 2 wave forms when using FES?
1. Monophasic
2. Biphasic
92
What are 2 characteristics of the monophasic waveform?
1. moves in one direction, results in a charge build up – if prolonged can cause electrode deterioration and skin irritation
2. More excitation under black electrode – negative or active
93
What are 3 characteristics of the biphasic waveform?
1. moves in both directions, so no charge accumulation
2. Assymetric - small muscles – more charge under waveform with \> area
3. Symmetric –large muscle More common in FES
94
What are the 3 characteristics of the frequency for FES?
1. Rate at which fibres will fire – single twitch to tetany
2. Tetany required for muscle contraction (recommended 35-50 Hz)
3. Difference between physiologically and artificially (FES) induced contraction
* Normal motor neurons asynchronously recruited (5 – 25 Hz)
* FES uses a higher frequency than normal (35 – 50 Hz)
* FES causes all motor neurons to fire at one and therefore fatigue faster
* FES preferentially activates fast twitch fibres which fatigue faster
95
What is the purpose of the on/off time in FES?
To prevent fatigue ...
* Start with much greater off time than on time i.e. 2:1
* As muscle conditions, decrease off and increase on
* BUT off always longer than on
* Check fatigue – contracGon reduces with the same intensity
* Do not use overnight
96
What are 5 characteristics of the on/off time to prevent fatigue in FES?
1. Start with much greater off time than on time i.e. 2:1
2. As muscle condiGons, decrease off and increase on
3. BUT off always longer than on
4. Check fatigue – contraction reduces with the same intensity
5. Do not use overnight
97
Is a high or low frequency better in FES? Why?
Lower frequency = need higher intensity --\> Might be too uncomfortable
Thus, better to have a higher frequency = lower intensity • More comfortable
98
What is the purpose of ramp up in FES?
* Ramp up increase comfort by recruiting motor units gradually rather than abruptly
* Not turning on to 100% straight away (intensity) --\> more physiological with movements (slowly to max. activation)
99
What is the purpose of ramp down in FES?
Ramp down allows the limb time to return to starting position in a controlled manner – especially important when used for subluxation
100
What should the intensity b like in FES?
Needs to be sufficient to create a contraction but want the least electrical current possible – least current = greater paGent comfort and safety
As low as possible while still giving sufficient result
101
What are 4 characteristics of how intensity in FES can be maintained?
1. Correct electrode placement – stimulation over motor point requires least amount of current to produce a contration
2. Clean skin – no creams, lotions – good skin prep
3. Reduce hair resistance - shaving
4. Depends on individual patient sensation – skin resistance/impedance
102
You will need \_\_\_\_\_(higher/lower) current to stimulate muscles with extra layers of adipose tissue or tough skin/weathered skin
higher
103
FES machines may limit to
50
104
What is the basic frequency parameter for FES?
30-50Hz
105
What is the basic pulse width parameter for FES?
200usecs
106
What is the basic on time parameter for FES?
5 seconds
107
What is the basic off time parameter for FES?
10 seconds
108
What is the basic ramp up parameter for FES?
1 sec
109
What is the basic wave form parameter for FES?
Biphasic
110
What is the basic intensity parameter for FES?
To achieve goal- limited by max. stimulation tolerable
111
What are the 8 basic stimulation parameters for FES?
**EXAM QUESTION**
112
How long are each session for FES for shoulder subluxation?
2 hrs
113
How many sessions a day/week for FES for shoulder subluxation?
1-days
114
How long should the session continue for for FES for shoulder subluxation?
6 weeks
115
What are 3 ways to progression training in FES?
1. Gradually reduce dose so as to minimise dependence on stimulation to achieve movement
2. Add weight/resistance, increase task difficulty
3. Type of stimulation: Cyclic – EMG triggered - Active
116
What are the 7 steps in the process of the FES application?
1. Explain to stroke survivor what they might feel Prickly-ness and then muscle activation
2. Begin turning intensity up slowly
3. Ask them to tell you when they can feel something
4. Ask when intensity has reached highest point they can tolerate
* Start to see movements --\> Check if they can more --\> try for full ROM
5. Will accommodate so check during session-may tolerate more
6. Watch for fatigue–smaller contraction with same intensity
* Do 2 shorter session rather than 1 longer session
7. After use of FES, check skin condition below the electrode
117
When should be FES be done in the session? Why?
* Do FES earlier in the session
* Show some redness (sensitive skin) --\> die down ○
* Due to increased circulation
118
Why should you do a shorter session for the first time?
* Do shorter session for first time
* Can increase tolerance
119
What are 3 DOs when using FES?
1. Do regularly check the machine on yourself
2. Do set up and check on yourself prior to use on stroke survivor
3. Do check before, during and aqer training– ask, look, feel Sources of uneven resistance e.g., electrodes loosening, breaks in skin
120
What are 4 DON'Ts when using FES?
1. Do NOT turn up during ‘off’ period or when ramping
2. Do NOT touch electrode during ‘on’ or when ramping
3. Do NOT allow electrodes to come loose
4. Do NOT take electrodes off during ‘on’ period
