surface EMG biofeedback Flashcards
motor unit
body, axon, end plate
smallest unit of movement the CNS can control
MUAP
motor unit action potential
excitatory stimulation to reach threshold of depolarization
Is measured action potential the contraction
no its a phenomenon
Ep testing
where neuro/mm abnormalities suspected. Not entry level
techniques of Ep evaluation
SD curves
evoked potentials (motor / sensory nerve conduction test)
EMG
motor nerve conduction test
indirect
estimates velocity of depolarization
measures mm action potential not the impulse
determines latency n velocity
latency
duration between impulse and mm response
estimates rate of travel along alpha motor neuron # of motor units in evokes mm action potential
can latency calculate velocity
no
velocity estimates what
conduction velocity along peripheral motor nerves
how is velocity achieved
by measures two latencies (distal, and proximal)
residual latency
proximal minus distal +
difference sensory and motor evoked potentials
sensory smaller amplitude, single, negative phase. no delay (accurate latency)
motor are bi or trip phasic
sensory / motor testing can only be carried out___ over peripheral nerve
distally
to measure proximal conduction use ___
electronic reflex testing
two ways to do electronic reflex testing
H reflex
F wave
H reflex
electrically induced equivalent of tendon tap reflex
monosynpatic reflex arc
direct and latent
assess proximal nerve conduction
Abnormal h wave
other than triceps its hard to elicit
f wave
uses afferent / efferent components of same peripheral motor nerve
what measures proximal conduction
H reflex and F wave
difference in F and H
f wave is in most mm
H reflex in slow twitch mm
abnormal F wave
slower conduction of motor axons
centrally recorded evokes potentials
somatosensory evoked potentials
brainstems auditory evoked potential
visual evoked potentials
somatosensory evoked potentials
stimulate distal peripheral motor nerve to minimal motor threshold
Diagnose CNS disorder in early stage showing latency in central pathways
brainstem auditory evoked potentials
assess auditory pathways
used when demyelination, tumours are suspected
mostly be audiologists
visual evoked potentials
detects compromise of optic nerve in early stage of disease (i.e MS)
differentiates true and hysterical blindness
EMG / voluntary potentials
compares electrical action of mm at rest vs voluntary
Types of EMG electrodes
needle and surface
__ amplitude seen before __ amplitudes in active contraction as force increases
smaller
larger
is more than 500 usec rise time abnormal
yes
is <60 per second normal in firing rate
yes
is mm activity at rest normal
no
whats discharge frequency
firing rate
usual discharge frequency
5-15 per second
whats normal discharge frequency
<60 per second
electrical activity in mm is normal __ at rest
silent
what happens to irritable mm vs fibrotic/ atrophied mm
increased insertional activity if irratable
abnormal mm activity at rest suggests
neuropathy or myopathy
what causes fibrillation potentials
motor nerve disruption
types of abnormal mm activity
fibrillation potentials
postiive sharp waves
fasciculation potentials
causes positive sharp waves
denervation or myopathy
fasciculation potentials
spontaneous repetitive twitch like contraction
looks same as MUAP
causes fasciculation potentials
alpha motor neuron disease
radiculopathies
entrapment neuropathies
when is fasciculation potentials considered significant
if associated w pos sharp waves and fibrillation
Recruitment of motor units
lowest threshold first
Type S
FR
FF
type S motor units
slow contracting
fatigue resistant (type1)
small alpha motor neurone
as force requirements increase, type S motor units ___ discharge frequency and __ motor units are recruits
increase more
when stronger contractions are required the discharge frequency of type S and FR __
increase
FR motor units
fast twitch
fatigue resistant
Type 2A slightly larger alpha motor neurone
Type FF
fast twitch
readily fatiguable
2b and largest alpha motoneurons
the third class of motor neurone recruited
Type FF
the most common PT clinical application of EMG is
surface EMG biofeedback (SEMG BFB)
SEMG BFB
detects and ample mm motor unit potential
surface electrodes
gives feedback info to client to inc/dec mm training
SEMG BFB uses
improves control over defective mm action / coordination
imporoves control over stress related conditions
commonly treated conditions SEMG BFB
hemiplegia SCI partial spasticity dystonic conditions recovering peripheral nerve injuries retraining mm
candidate selection SEMG BFB
condition cognition motivation visual / auditory perception potential for improvement
Is Guillain barre, post CVA suitable condition for SEMG BFB
yes
how do you know if condition is suitable for SEMG BFB
weak
goes too much, too little too fast w motor control
reduced intrinsic feedback (sensory loss)
pain
stress or urge incontinece
can you do SEMG BFB is neglect or aphasia
you need to consider how severe they are
do you know someones potential for SEMG BFB right away
not always apparent need to trial the intervention
they need minimal voluntary control tho
electrodes for SEMG BFB
larger for lower impedance and more signal
along mm fibres
on neutral site (bone or between two active sites)
Leads on SEMG BFB
keep short and avoid movement to prefect artifact
how to progression SEMG in uptraining
active to resisted to active
lower sensitive
move electrodes closer
how to relax or down train SEMG BFB
position gravity assisted - resisted functional task increase sensitivity electrodes further adjust threshold
evaluating SEMF BFB
changes in EMG output , frequency of target goal, length of time to activity is sustained , time required to reach threshold
when to use SEMF BFB
inc vastus medialis activity in knee extension or controlled flexion
reduce upper trap, scalene, TMJ, forehead activity
