EMG Flashcards
what is the second part of the ENMG that uses a needle electrode directly into the ms belly?
EMG
EMG tells us a lot about the _____ _____
motor units
what is a disadvantage of the EMG?
the needle
it can be somewhat uncomfortable and pts tend to get scared by it
what kind of needle is used in EMG?
a Teflon coated monopolar electrode that goes into the ms more easily
t/f: NCS can reveal a demyelinated lesion, but cannot determine the particular status of the MUs
true
t/f: NCS cannot accurately tell whether some axons have been injured in addition to the focal demyelination
false
what is needed to assess the integrity of the MU?
EMG
t/f: the pattern of EMG ms involvement confirms the location of the problem, severity of ms involvement, and info on prognosis
true
what test can tell us if a ms is normally, partially, or completely innervated?
EMG
what test can tell use if there is evidence of MU recovery?
EMG
t/f: EMG can tell us if there is a neuropathic or myopathic disorder going on and the location of it
true
pattern of EMG abnormality in the anterior horn cell indicates what conditions may be present?
Polio
ALS
pattern of EMG abnormality in the nerve root indicates what conditions may be present?
HNP
tumor
pattern of EMG abnormality in the plexus could indicate what conditions may be present?
stretch, compression, or tumor disorders
Erb’s palsy from getting pulled
pattern of EMG abnormality in mixed nerves could indicate that what conditions may be present?
carpal/cubital tunnel syndrome
t/f: EMG helps us determine if there is a nerve or ms problem
true
when doing EMG studies, what muscles should we test?
muscles innervated by the site of suspected root or nerve pathology and muscles above and below
muscles innervated by other nerves in the same extremity
t/f: we should sample several sites in each muscle tested in EMG
true
why do we want to examine the CL muscles in EMG?
to see if the issue is systemic
what is the proper time frame for testing with EMG?
3 weeks after injury for signs of denervation and EMG abnormalities to show up
t/f: the needle can be used to test various quadrants of the same ms belly through one insertion site on EMG
true
what are the 4 segments of examination in EMG?
insertion
rest
minimal activation
maximal activation
what is the insertional activity (IA) on an EMG?
the normal brief burst of electrical activity with needle movt
the initial ms rxn to needle insertion
what is normal IA?
lasts bw 50-300msec and end abruptly when the needle stops moving
what is increased IA?
ms membrane is more irritable (denervation) leading to prolonged IA of >500msec
what is sustained IA?
severe denervation, extreme instability leads to IA that will continue unabated
what is decreased/absent IA?
long standing denervation (possibly complete denervation) leads to no activity with insertion
what is normal resting EMG activity?
after IA, the examiner ceases needle movt and the ms should return to electrical silence
what is abnormal resting EMG activity?
after IA, when the examiner ceases needle movt, there are spontaneous potentials that occur
what are the normal spontaneous electrical activities that can occur with resting EMG activity?
miniature end plate potentials (MEPPs)
end plate noise
what are miniature end plate potentials (MEPPs)?
at rest during the EMG, with the tip of the elecetrode near the NMJ, there is a transient depolarization of rapid firing (2000-3000Hz), low amplitude (10-50uV), and initial upward deflection (-)
what sound is associated with MEPPs?
holding a large seashell to the ear
what is end plate noise?
during resting EMG activity, there is an upward deflection of larger amplitude (100-200uV) firing at 100-300 Hz
t/f: end plate noise is often painful
true
how can we relieve the pain associated with end plate noise?
with slight movt of the needle
what is the sound associated with end plate noise?
a low level murmur
what are the abnormal spontaneous potentials that can be seen during resting EMG activity?
positive sharp waves
fibrillations
fasciculations
complex repetitive discharge
myotonic discharge
myokymic discharge
what are positive sharp waves (PSWs) during resting EMG activity?
single ms fiber activity of initial positive deflection f/b low amplitude (10-1mV) delivered at discharge rate of 1-200 Hz, long duration neg phase
what sound is associated with PSWs?
motor boat on low idle
PSWs result from what?
abnormally sensitive ms cell membranes
PSWs are seen with what conditions?
neuropathic/myopathic conditions
anterior horn cell disease
what are fibrillations?
single ms fiber firing causing an initial pos deflection, short duration, <5msec, amplitude of 20uV-1mV at 1-30 Hz
what sound is associated with fibrillations?
rain on a tin roof
fibrillations on an EMG represent what?
denervation potentials
when are fibrillations seen on EMG?
with myopathic conditions and anterior horn cell disease
how are fibrillations graded with PSWs?
0-4 with 3-4 being more severe membrane instability than 1-2
what is a fasciculation in resting EMG activity?
non-voluntary MU firing that has the appearance of normal MUs
what sound is associated with fasciculations activated in isolation?
popping sound
what sound is associated with fasciculations of another MU in the distance?
a thud sound
are fasciculations graded?
nope, just note their presence
t/f: fasciculations are normal unless attended by other spontaneous potentials, then it is considered abnormal
true
what conditions may have fasciculations present?
entrapment neuropathies and radiculopathies
may be observed in pts with anterior horn disease
what are complex repetitive discharges (CRDs)?
spontaneous potentials associated with chronic neuropathic processes
polyphasic like waveform firing at up to 100Hz
evoked by moving/tapping the needle, then it wanes down to a lower frequency (20-30 Hz)
what is the sound associated with CRDs?
machine gun firing
what is a key element of CRDs?
they fire at a high frequency then wane to lower frequency (ABILITY TO RETURN TO BASELINE)
what is myotonic discharge during resting EMG activity?
rhythmic spontaneous potentials initiated with needle movt or tapping with a waveform silimar to CRDs and fibrillations with an initial high frequency (150 hz) that fades to 20-30 hz then waxes again at high frequency
how is myotonic discharge dif from CDRs?
frequency is initially high then lowers then gets high again in myotonic discharge
frequency is initially high then lowers to baseline and doesn’t go back up in CDRs
what sound is associated with myotonic discharge?
WWII dive bomber sound
when would we see myotonic discharge on resting EMG activity?
with myotonic dystrophy, myotonia congenita, chronic radiculopathies
what is myokymic discharge during resting EMG activity?
non-volitional worm-like contractions of long sections of ms that appears like consecutively firing fasciculations with no wax/wane
what is myokymia?
ms disorder that produces worm-like contractions of long sections of ms
what sound is associated with myokymic discharge?
marching sound
does myokymic discharge have waxing/waning phases?
nope
does volitional activity alter the abnormal potentials seen in myokymic discharges?
nope
what is myokymic discharge associated with?
unstable ms membrane
chronic conditions
radiation plexopathies
bells palsy
facial ms of MS pts
what is the minimal activation component of the EMG?
when the person creates a normal ms contraction to assess the MUs volitionally recruited by the pt
what is normal MU potential?
biphasic/triphasic
duration of 5-15msec
amplitude of 250uV-5mV
firing frequency of 5-15Hz per sec (upper range <60 Hz)
what are polyphasic MUs?
MUs with 4 phases
t/f: polyphasic MUP is considered abnormal
true
polyphasic MUP is normal in young to middle age up to ____% allowed and up to ____% allowed in those over 60yo
15, 30
polyphasic MUPs can occur during what process?
denervation process
what are nascent potentials?
small, low amplitude, long duration polyphasics
polyphasic MUPs usually indicate what?
recent attempt to reinnervate an injured or disease MU
t/f: polyphasics are only seen during early reinnervation
true
polyphasics are often seen after what occurs in injured/diseased axons?
after collateral or terminal sprouting by injured/diseased axons
when are large amplitude polyphasics observed?
in chronic neuropathies
small amplitude, short duration polyphasics are a Hallmark sign of what?
myopathic disease
t/f: polyphasics can be a sign that the nerves are regenerating
true
what is the maximal activation component of the EMG?
seeing how many MUs the pt can recruited at once to evaluate the recruitment or interference pattern of each ms
t/f: we should go right to a max contraction with EMG studies
false, we should begin with the minimal/interference pattern for each ms then build to maximal contraction
what kind of ms activation is when we “fill the screen” with activity?
maximal activation
what type of activation is characterized by a full interference pattern where we are unable to ID the baseline?
maximal activation
what is the amplitude of maximal EMG activation?
4mV peak to peak
when looking at an EMG, what should we be paying attention to?
look for a wave/image and listen to the distinct sound of the responses
what is a neuropathic recruitment pattern?
decreased recruitment of the entire ms bc a significant # of MUs have been lost through denervation
what recruitment pattern is characterized by decreased MU recruitment and increased firing rates?
neuropathic recruitment pattern
what is the sound associated with neuropathic recruitment pattern?
playing cards shuffling
t/f: pts can fake a neuropathic recruitment pattern on EMG
false, they can’t fake it
what is a myopathic recruitment pattern on the EMG?
small amplitude, short duration polyphasic MUs that appear almost immediately with little effort
why does myopathic recruitment pattern occur in pts with myopathic processes?
bc they are unable to isolate individual MUs due to recruiting their existing MUs so readily
(no clue what this means, so if you do, send help!)
what is normal ms activity during insertional activity?
brief
what is normal ms activity during spontaneous activity?
none
what is normal ms activity during minimal MU activation?
normal
(queenie what??? that’s literally what the chart says)
what is normal ms activity during maximal MU activation?
full interference
what insertional activity would indicate a peripheral nerve disorder?
increased/prolonged insertional activity
what spontaneous activity would indicate a peripheral nerve disorder?
any spontaneous activity present
what minimal MU activation activity would indicate a peripheral nerve disorder?
polyphasics
increased duration
large/small amplitude
what maximal MU activation activity would indicate a peripheral nerve disorder?
reduced max activation
what insertional activity would indicate a myopathic process?
brief/increased insertional activity
what spontaneous activity would indicate a myopathic process?
usually none
what minimal activation activity would indicate a myopathic process?
polyphasics
decreased duration
small amplitude
what maximal activation activity would indicate a myopathic process?
full with no nominal activity
t/f: ENMG can determine the cause of the findings
false
to arrive at a dx from ENMG, what else needs to be done?
hx taking
clinical examination
imaging
blood analysis
what are common peripheral entrapment neuropathies?
carpal tunnel syndrome
cubital tunnel syndrome
radial tunnel syndrome
axillary tunnel syndrome
suprascapular nerve entrapment
what are the s/s of CTS?
sx in affected hand while driving (shaking out hands)
sx in BL hands
waking at night due to sx
hx of trigger finger
numbness and tingling in lateral hand
dropping items out of affected hand(s)
ipsi neck, shoulder, forearm pain
(+) Tinel and/or Phalen
APB ms atrophy
grip strength weakness
t/f: (+) Tinel/Phalen is only effective for recognizing CTS if caught up to about 6 months
true
is grip strength a strong indicator or carpal or cubital tunnel?
cubital tunnel
t/f: hand dominance is a good indicator of CTS
false, bc carpal tunnel can be on either hand
what would NCS/EMG show with CTS with neuroprxia?
normal CMAP (amplitude preserved)
normal EMG (ms remain innervated)
what is neurapraxia?
myelin impaired motor nerve conduction at the wrist
what does neurapraxia result in with CTS?
slowed distal motor latency of the APB
what is normal onset of APB at the wrist?
<4.2ms
what is normal amplitude of the APB at the wrist?
> 5mV
if there is an axon impairment in CTS, what would we see on NCS?
decreased amplitude (<5mV) bc not all axon potentials are getting through
if there is an axon impairment in CTS, what would we see on EMG?
fibrillation potentials and PSWs in APB and OP
in mild CTS, what is involved in treatment?
bracing
PNG
ergonomic changes to minimize pressure in the carpal tunnel
modalities
in mild CTS, what is the px for improvement?
good
in moderate CTS, what is involved in treatment
bracing
PNG
ergonomic changes to minimize pressure in the carpal tunnel
modalities
in moderate CTS, what is the px for improvement?
fair
is surgery needed for moderate CTS?
probably
is surgery needed for mild CTS?
nope
is surgery needed for severe CTS
definitely
what is the px for improvement in severe CTS?
dependent on the duration of sx
what modalities can we use to improve CTS?
US, laser
what is a strong indicator that surgery may be necessary for CTS management?
thenar eminence atrophy
t/f: suprascapular neuropathy is uncommon but often misdiagnosed
true
what are the s/s of suprascapular neuropathy?
diffuse aching
burning in post/lat shoulder and scap
atrophy
what are the typical exam findings with suprascapular neuropathy?
supraspinatus/infraspinatus weakness (atrophy)
worsening pain with elevation (SSN and SAIS)
(+) impingement signs (SAIS)
(-) cervical provocation weakness
no myotomal weakness
normal sensation and reflexes
what is peripheral neuropathy?
a global pattern of nerve impairment affecting the LEs first in a glove and stocking distribution
peripheral neuropathy is often confused with what?
entrapment syndromes
t/f: distal axonopathy is the most common peripheral neuropathy
true
what are the causes of peripheral neuropathy?
DM (#1 cause)
ETOH
low thyroid
kidney disease
chemo (CIPN)
low vit B6, B12, folic acid
exposure to organophosphates (common in farmers)
inherited
what is the strongest indicator of peripheral neuropathy?
“my socks feel like they’re bunched up in my shoes”
vascular impairment
what are the signs of vascular impairment?
hemosiderin staining
spider veins
skin lesions
nail deformities
other than the feeling of bunched up socks, what are some indicators of peripheral neuropathy?
the sensation starting in the toes
balance issues
lots of paresthesias, esp at night
strength is typically normal
what peripheral neuropathy would show most sensory nerves having a low amplitude on EMG/NCS?
sensory axonopathy
what peripheral neuropathy would show most motor and sensory nerves having slow CVs and DLs on EMG/NCS?
sensorimotor myelinopathy
what peripheral neuropathy would show EMG changes distally?
mixed severe peripheral neuropathy
are we necessarily going to see peripheral nerve involvement on EMG/NCS with MS?
no, and if we do it likely signal disease progression
t/f: MS is primarily a CNS disease, yet progressive forms can demyelinate the brain and SC tissues
true
what lesions in MS can interfere with the nerve transmission and NCV at the interneuron synapses in the SC?
SC lesions
facial MSK issues associated with MS would appear on the EMG as what?
myokymic discharges (marching sound) due to ms membrane damage
why may EMG results be altered with MS?
bc of ms denervation and disuse atrophy
if the SC or BS are affected in MS, what may be evident on EMG/NCS?
abnormal volitional motor control with abnormal MU recruitment
what is the UMN presentation of MS?
spasticity
hyperreflexia (3+ DTRs)
possible signs of reinnervation (chronic cases)
what can EMG/NCS help PTs do with MS?
distinguish the type of MS to guide treatments
helps determine where the progression is occurring (sensory, balance, MSK)
what does PT do for acute phase/relapse MS?
control the fxnal and acute sx (pain, spasticity, positional/contracture management, integ compromise, and fall risk prevention)
what might relapsing/remitting MS show on NCS?
increased latencies (take long for info to get to brain)
t/f: bc we do EMG on peripheral nerve, NCS is typically WNL in MS
true
with chronic MS, what would EMG/NCS show?
depending on severity, we could see regression from previous studies
what is the gold standard for diagnosing MS?
MRI
what tests can we use for fxnal assessment for pts with MS?
TUG
EDSS
MSIS-29
FSS
Berg
