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279 Cards in this Set

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Innervation of the rhomboid (nerve)
dorsal scapular nerve
The dorsal scapular nerve innervates
rhomboid
Segment(s) for innervation of the rhomboid
C5
Segment(s) for
Dorsal scapular nerve
Innervation of supraspinatus (nerve)
suprascapular nerve
Innervation of infraspinatus (nerve)
suprascapular nerve
Suprascapular nerve innervates
supraspinatus, infraspinatus
Main segment(s) for innervation of the supraspinatus
C5
Main segment(s) for innervation of the infraspinatus
C5
Secondary segment(s) for innervation of the supraspinatus
C6
Secondary segment(s) for innervation of the infraspinatus
C6
Innervation of the deltoid (nerve)
axillary nerve
The axillary nerve innervates
the deltoid
Main segment(s) for innervation of the deltoid
C5
Secondary segment(s) for innervation of the deltoid
C6
Main segment(s) of axillary nerve
C5
Secondary segment(s) of axillary nerve
C6
Innervation of biceps (nerve)
musculocutaneous
The musculocutaneous nerve innervates
the biceps
Main segment(s) of musculocutaneous nerve
C5, C6
Muscles with dominant or significant contribution from C5
- rhomboid
- supraspinatus
- infraspinatus
- deltoid
- biceps
- brachioradialis
Nerves with dominat or significant contribution from C5
- dorsal scapular n.
- suprascapular n.
- axillary n.
- musculocutaneous n.
- radial n.
Only muscle innervated by radial nerve with a C5 major component
brachioradialis
Motor branch off the median nerve
anterior interosseous nerve
Muscle innervated by the median nerve (proper)
- pronator teres
- flexor carpi radialis
- palmaris longus
- flexor digitorum superficialis
- 1st lumbrical
- 2nd lumbrical
- abductor pollicis brevis
- opponens pollicis
- flexor pollicis brevis
Muscles innervated by the anterior interosseous nerve
- flexor digitorum profundus to digits 2 and 3
- flexor pollici longus
- pronator quadratus
Median nerve comes from which cords of the brachial plexus?
medial and lateral
Muscles innervated by the recurrent branch of the median nerve
- abductor pollicis brevis
- flexor pollicis brevis superficial head
- opponens pollicis
Compression of the median nerve proximal to pronator teres likely occurs at
the ligament of struther's
What goes through the carpal tunnel?
- median nerve
- 8 tendons of superficial and deep finger flexors
- flexor pollicis longus tendon
% of population that has a palmaris longus
87%
Location of origin of the anterior interosseous nerve
Averages 5cm distal to medial epicondyle
most distal innervation by anterior interosseous nerve
pronator quadratus
Does the recurrent motor branch of the median nerve pass through the carpal tunnel?
Yes
Describe Benediction sign
unable to flex digits 1-3, but 4 and 5 flex nicely - median nerve lesion; position only occurs with attempts at movement
How can you abduct the thumb if there is a median nerve lesion?
May still be some action with the deep head of the abductor pollicis longus (from radial nerve)
Innervation of the deep head of the abductor pollicis longus
radial nerve
This muscle may substitute for some pronation after complete pronator loss
brachioradialis (start pronation from supinated position)
2 most common comparative muscles studied for the median nerve
- ABM (ulnar)
- extensor indicis (radial)
Most common entrapment neuropathy in the upper limb
carpal tunnel syndrome
Incidence and prevelance of carpal tunnel syndrome vary widely in studies, largely because of these two factors
- age
- occupation
Incidence of carpal tunnel syndrome
100-300 cases per 100,000 person years in USA
Prevalance of carpal tunnel syndrome
3-6%
Describe age relationships to carpal tunnel syndrome in women
Increases with age to a peak between 50-59 and then declines
Describe age relationships to carpal tunnel syndrome in men
Bimodal with peaks between 50-59 and 70-79
How does geography effect carpal tunnel syndrome?
higher in rural and industrial areas likely because of occupation
Relative risk of developing carpal tunnel syndrome with rheumatoid arthritis
3.6 time
Relative risk of developing carpal tunnel syndrome with diabetes mellitus
2.3 times
Relative risk of developing carpal tunnel syndrome with pregnancy
2.5 times
Relative risk of developing carpal tunnel syndrome with obesity (BMI 29 vs. under 20)
2.5 times
Key feature in occupational risk for carpal tunnel
hand motions with high force and high frequency of repititions as well as vibration
Relative risk of developing carpal tunnel syndrome with frequent use of vibrating hand tools
2 times
Day/night patterns of carpal tunnel syndrome
symptoms often worse at night
Name 2 things that commonly bring on carpal tunnel syndrome symptoms for patients
- hand use
- driving
Typical order in which fibers are effected in carpal tunnel syndrome
- sensory first (large myelinated) then...
- motor (smaller)
Why is it important to study motor conduction in carpal tunnel syndrome even if sensory latencies are normal
sometimes the motor fibers are preferentially effected
Sensitivity and specificity for combined sensory index (CSI) for carpal tunnel syndrome
- sensitivity: 83%
- specificity: 95%
When is the combined sensory index (CSI) for carpal tunnel syndrome the most useful?
When the difference at the ring finger is between 0.1 and 0.4msec
What interval change in the combined sensory index (CSI) for carpal tunnel syndrome indicates significant change?
more than 0.3msec
Give 2 reasons why someone might have motor involvement and not sensory involvememnt in carpal tunnel
- most distal involvement that hits the recurrent motor branch
- selective involvement of motor fibers in the mixed nerve
Conduction block = neur____
neurapraxia
Location of deep ulnar nerve to the recurrent median nerve
within 1.2 cm on average
Thenar response that is bigger or faster at the elbow over the wrist is suggestive of
a Martin Gruber anastamosis
Alternative to measuring APB for motor in carpal tunnel
use first lumbrical (median) and second palmar interosseous (ulnar)
List the 3 times when needle EMG is likely to be helpful in carpal tunnel screen
1. abnormal median motor response
2. history of trauma (axon loss more likely)
3. clinical presentation suggests dx other than carpal tunnel
Is there a correlation between latency and severity of disease in carpal tunnel syndrome?
no, not clearly
What is the one time when electrodiagnostics ARE likely to indicate severity of disease in carpal tunnel?
When there is evidence of motor axon loss
Describe typical changes in latencies after carpal tunnel release surgery
latencies usually improve maximally within 6 months after surgery (often NOT returning to normal)
Radiculopathies are typically caused by
root compression
Radiculopathy has really only been clinically known since
1950s
Number of spinal nerves
31 pairs
Most of the axons composing the ventral roots originate from
cells from anterior and lateral gray columns
Location of DRG
within ostium of the bony intervertebral foramina
Posterior primary rami of spinal nerves supply
skin and deep/intrinsic muscles of nueck and trunk
Anterior primary rami of spinal nerves supply
the trunk or limb muscles depending on level
2 regions where roots and spinal nerves are the fattest
cervical and lumbar
Are sensory fibers composing the cauda equina preganglionic or postganglionic?
preganglionic
Define myotome
all the muscles that share innervation from the same spinal cord segment (ventral root)
Define dermatone
the region of skin receiving sensory innervation from a single dorsal root
2 most common causes of root compression by age
- intervertebral disk protrusions/ruptures (40-50 yrs old)
- complex degenerative changes with osseoligamentous hypertrophy(over 50)
Why does compression of the same nerve root cause different radicular symptoms in different patients?
likely secondary to differences in compression site, fibers affected and nature of pathology
Fiber type involvement in radiculopathy from most common to least common
- sensory only
- sensory and motor
- motor only
General evidence of axon loss in radiculopahty
- fibrilations in a myotomal distribution
- MUAPs suggestive of dennervation/reinervation
Prominent short lived weakness in radiculopathy often indicates what pathologically?
focal demylelination with conduction block of motor fibers
What is synchronized slowing?
When all axons affected to same degree
What is desynchronized or differential slowing?
When axons are affected to different degrees
What kind of slowing is expected when reflexes are lost but there is not clinical weakness or or fixed sensory deficits?
desynchronized or differential slowing
Subtotal root involvement is characteristic of what?
radiculopathy
In radiculopathy, site of injury along sensory fibers is in what location relative to the dorsal root ganglion?
proximal
Root levels for tibial nerve
L4, L5, S1, S2, S3
General course of the tibial nerve
Posterior thigh to popliteal fossa -> medial leg (more superficial distal 3rd of leg) -> medial malleolus -> under flexor retinaculum -> branches to med and lat plantar nerves
Does the tibial nerve innervate the knee?
yes, mostly nociceptive
Cutaneous calcaneal nerve come from the
tibial nerve
Cutaneous innervation of the calcaneal nerve
heel and medial sole
Muscular branches of the medial plantar nerve
- abductor hallucis
- flexor digitorum brevis
- flexor hallucis brevis
- first lumbrical
The medial plantar nerve is from the
tibial nerve
The medial plantar nerve in the foot is analagous to the ______ nerve in the hand
median
Cutaneous innervation for the medial plantar nerve
Sole of the foot including hallux, second, third and medial half of 4th toe
The lateral plantar nerve in the foot is analagous to the ______ nerve in the hand
ulnar
Cutaneous innervation for the lateral plantar nerve
skin of 5th toe, lateral 4th toe and lateral sole
Muscular innervation for the lateral plantar nerve
(*most of the deep muscles of the foot)
- flexor digitorum accessorius
- abdunctor digiti minimi
- flexor digiti minimi brevis
- interossei
- 2nd to 4th lumbricals
- adductor hallucis
Which terminal branch of the sciatic nerve is better protected from trauma?
The tibial nerve
Where is the tarsal tunner?
The flexor retinaculum
Muscles innervated by the tibial nerve (perior to plantar branches)
- gastrocnemius (med and lat)
- popliteus
- soleus
- tibialis posterior
- flexor digitorum longus
- flexor hallucis longus
Is tarsal tunnel usually unilateral or bilateral?
unilateral
Is tarsal tunnel syndrome common or rare?
rare
Factors that predispose to tarsal tunnel syndrome
- trauma
- deformity at the ankle
- hypermobility at the ankle
- peripheral neuropathy
- rheumatoid arthritis
- hyperlipidemia
Radiologic studies in tarsal tunnel syndrome
May show:
- degenerative arthritis
- old fractures
- old spicules
- accessory ossicals
Signs/symptoms of tarsal tunnel syndrome
- burning pain on sole of the foot
- nocturnal paresthesias
- Tinel's over the tarsal tunnel
- weakness/atrophy of the intrinsic foot muscles
How can tibialis POSTERIOR help you in ddx of cause of foot drop?
tibialis posterior is often also weak in severe foot drop from L5 radiculopathy but should be normal in periphera. mononeuropathy
MUAP =
motor unit action potential
Normal duration of MUAP =
6-15ms
MEPP=
miniature end plate potential
MEPP are due to
non-propagated sub-threshold depolarizations due to spontaneous release of acetylcholine quanta
Shape of MEPPs
brief, monophasic negative spikes
on EMG negative is ____
up
on EMG positive is ___
down
Sound characteristics of MEPPs
- hissing
- buzzing
- static
- sea shell
SNAP =
sensory nerve action potential
What are the key features to look at in SNAPs
- PEAK latency
- amplitude
CMAP =
compound muscle action potential
M-response =
CMAP
What are the key features to look at in CMAPs
- ONSET latency
- amplitude
- conduction velocity
How was the h-reflex named
discovered by Hoffman in 1918
H-relfex is like ____ on physical exam
DTRs
What are the afferents and efferents for the h-reflex
afferents: 1A fibers
Efferents: alpha motor neurons
What is the h-reflex amplitude compared to the m-wamve
h-reflex amplitude is larger
Is the h-reflex an early or late response?
It's a late motor response/potential
At what stimulation do you record the h-reflex?
SUBmaximal
What are the general size and latency of an h-reflex?
consistent size and latency
When is the h-reflex typically used?
In S1 radiculopathy screen (to soleus)
How was the f-wave named?
First found in the foot
Is the f-wave a reflex?
no
Describe the general idea of the f-wave
if you stimulate motor axon backwards, you get about 3-5% of fibers backfiring
If the f-wave an early or late response?
Late
At what stimulation do you record the f-wave?
SUPRAmaximal
What is the general amplitude of the f-wave compared to the m-wave
small, about 3-5%
What are the general size and latency of the f-wave?
variable; each time a different set of neurons are firing
In general, what nerves do you use an f-wave to evaluate?
distal: fibular, tibial, ulnar, median
In general when do you use the f-wave?
Peripheral neuropathies and proximal-segment (nerve root) diseases
Why do you get insertional activity?
The needle causes mechanical depolarization of the muscle when you insert/move it.
Describe normal insertional activity
brief bursts of activity upon needle insertion that last less than 300ms
Describe when you see decreased insertional activity
* atrophied muscle
There are smaller shorter bursts
Describe when you see increased insertional activity and what that is like
* dennervated muscle
too much sustained spontaneous activity
Where is spontaneous activity normal?
at the endplate
How are endplate spike usually described?
- irregular rhythm
- high pitched clicks
- fat in frying pan
What is normal spontaneous activity?
a single motor action potential in the endplate zone triggered by needle movememnt
Is an endplate spike normal or abnormal?
normal
Define fibrillation potential
spontaneous action potential recorded froma single muscle fiber
Fibrillation potential aka
denervation hypersensitivity
Denervation hypersensitivity aka
fibrillation potentials
Fibrillation potentials sound like
raindrops on a tin roof
Are fibrillation potentions regular or irregular?
regular
Duration of fibrillation potential
short, less than 5ms
Why is a fibrillation duration short?
only one muscle fiber firing
Amplitude of fibrillation potential
small, less than 1mv
Define positive sharp waves
spontaneous action potential of a single muscle fiber
2 types of denervation hypersensitivity
- fibrillations
- positive sharp waves
Are positive sharp waves regular or irregular?
regular
Typical duration of positive sharp wave
wide, ofen >20ms
What do positive sharp waves sound like?
pop or dull thud
Define a fasciculation potential
spontaneous discharge of an entire motor unit
Which is wider - a fib or a fascicultion?
Fasciculation because there are many muscle fibers firing
Most common cause of fasciculations
benign fasciculations in normal muscle
What do fasciculation potentials sound like?
loud "snaps"
Amplitude for motor unit that is typical abnormal
>5mV
Normal duration in general for a motor unit
10-15ms
What is the rule of 5s for motor units?
The next motor unit is usually recruited at 5 Hz when the preceeding motor unit is firing at 10 Hz...
How many motor units should be firing when the first recruited motor unit is firing at 20Hz?
4 motor units
What is the recruitment ratio?
rate of fastest firing unit/number of units firing
High recruitment ratio = _______ recruitment
decreased
Low recruitment ratio = _______ recruitment
increased
What's a ghigh recruitment ratio?
above 10
What's a low recruitment ratio?
below 5
NCS test what type of fibers?
large myelinated fibers
The ground should be located...
between the active electrode and the stimulator
What's the only time where you flip the anode around so that the red anode is closest to the black electrode?
The f-wave
Typical distance to measure for motor studies
8cm
Typical distance to measure for sensory NCS
4cm
Name 2 major exceptions to the measuring rule in NCS
- Transpalmar sensory: 8cm
- Median/radial sensory to thumb: 10cm
Normal temperature for NCS
32 degrees C
Effect of cold on conduction velocity in NCS
decrease
Effect of hot on conduction velocity in NCS
increase
Effect of cold on onset/peak latency
increase
Effect of hot on onset/peak latency
decrease
Effect of cold on amplitude in NCS
increase
Effect of heat on amplitude in NCS
decrease
Adjustment of temperature for latency
subtract 0.2mg for each degree below 32 degrees C
Adjustment of temperature for conduction velocity
add 2m/s for each degree below 32 degrees C
Most common causes of peripheral nerve injuries in peacetime
- MVCs
- penetrating trauma
- falls
- industrial accidents
% of patients admitted to level I trauma centers with peripheral nerve inuries
2-3% (5% if include plexus and root injuries)
Most common traumatic peripheral nerve injuries in the UE
radial > ulnar > median
Which is more common, UE or LE traumatic peripheral nerve injuries?
UE
Most common traumatic peripheral nerve injuries in the LE
sciatic > fibular; tibial and femoral are rare
Peripheral nerve injury from trauma is often associated with
fractures
How does war impact rates of peripheral nerve injuries
much higher during wartime
% of patient with trauma peripheral nerve injury that also have a TBI
60%
Number of patients with TBI admitted to rehab who also have traumatic peripheral nerve injuries
10-34%
How does kinetic energy relate to mass and velocity?
KE = 1/2 m * v^2
What are the names for the two most commonly used classifications of systems for nerve injury?
Seddon and Sunderland
Describe neurapraxia
- mild
- motor and sensory loss
- no Wallerian degeneration
Etiology of dysfunction in neurapraxia injuries
focal demyelination and/or ischemia
Prognisis for neurapraxia
excellent recovery in (hours, day) weeks to months
When is axonotmesis commonly seen?
- crush injuries
- nerve stretch
- percussion injuries (GSW)
Describe what is damaged in axonotmesis
axons
Does Wallerian degeneration occur in axonotmesis?
Yes, but regrowth may also occur through intact endoneurial tubes.
Recovery after axonotmesis depends on
- degree of internal disorganization
- distance to the end organ
Main differences between Seddon and Sunderland classifications
Sunderland classification subdivides axonotmesis
Describe neurotmesis
nerve has been completely severed or there is so much scar tissue that it will not regrow
What is secondary degree nerve injury in Sunderland classification?
transection of the axon with intact endoneurium and stroma
What is third degree nerve injury in Sunderland classification?
transection of the axon and endoneurial tubes but surrounding perineurium is intact.
When there is a traumatic injury, axonal regrowth depends on
ability of axon to find endoneurial tubes to guide regrowth.
Describe fourth degree traumatic nerve injury in the Sunderland classification
- loss of continuity of axons
- loss of endoneuria tubes
- loss of perineurium
- continuity maintained only by epineurium
Prognosis of neural recovery in axonotmesis
- good to poor depending on integrity of supporting structures and distance to the muscle
Prognosis of neural recovery in Sunderland classification 3rd and 4th degree
poor, surgery may be required
Is there spontaneous recovery in neurotmesis/5th degree nerve injury?
No, surgery required and even then prognosis guarded
Difference in pathology between Sunderland 4th and 5th degree nerve injury
in 5th degree the epineurium is severed.
What is a "6th degree" traumatic nerve injury
mixed lesion with both axon loss and conduction block (probably quite common)
In localization of individual muscle bellies for injection of FDS, what is used as the "landmarking line."
Line draw between the medial epicondyle to the pisoform
General organization of the FDS muscle bellies
FDS 3 and 4 lie superficial to FDS 2 and 5
For preferential injection of FDS 3, give the % along the landmarking line and mm lateral where you would inject
54%, 17mm
For preferential injection of FDS 4, give the % along the landmarking line and mm lateral where you would inject
49%, 7mm
For preferential injection of FDS 2, give the % along the landmarking line and mm lateral where you would inject
72%, 14mm
For preferential injection of FDS 5, give the % along the landmarking line and mm lateral where you would inject
76%, 6mm
Which of the FDS muscle bellies has the most variability in location?
FDS5
How are SEPs and EEGs different in what they measure?
- SEP is response to stimulation
- EEG is spontaneous brain activity
What does SSEP stand for?
shor latency somatosensory evoked potentials
What are the general latencies for SSEPs for upper limb, peroneal and tibial
- uppser limb: 25msec
- peroneal: 40msec
- tibial: 50msec
What's the latency for a long latency SEP?
greater than 100msec
What are the effects of a patient being asleep or under anesthesia on SEPs of mixed peripheral nerves vs. dermatomes
- peripheral nerves: pt make be awake or asleep
- dermatomes: pt must be awake
How do you find the location for the Cz recording electrode for SEPs
intersection of ear-ear and nasion-inion measurements
SEPs with electrical stimulation mainly activate which fibers?
- Group II cutaneous afferents
- Group IA afferent from the muscle spindle
What are the general features of group IA afferent fibers?
- muscle spindle
- large diameter
- fast conducting
What types of sensation are carried by Group II cutaneous afferent fibers?
- vibration
- pressure (light and high threshold)
Where is the meduallary synapse for SEPs from the UE?
nucleus cuneatus
Where is the meduallary synapse for SEPs from the LE?
Nucleus gracilis
Describe the anatomy of the pathway traveled for a mixed nerve SEP stimulus
group II and IA afferent fibers -> cell bodies in DRG -> ipsilateral dorsal column -> synapse in medulla -> cross in medial lemniscus -> ventral posterolateral sulcus of thalamus -> somatosensory cortex based on homunculus
Where is the somatosensory cortex?
post-central gyrus of the parietal lobe
What is the typical amplitude of a response in an SEP?
1-3 microvolts
What is the key factor about the number of stimuli delivered for SEPs?
Need to average to remove background EEG and other noise

Often hundreds/thousands stimuli
What are the typical filter settings for SEPs?
10Hz to 1.5kHz
What's the typical stimulus frequency for SEPs?
3.1Hz
What's the typical stimulus duration for SEPs?
0.2msec
2 major sources of noise in SEPs
- the patient (muscle activity)
- electrical noise from the environment
What are the features of the "best" cortical trace in SEPs
Biggest amplitude and shortest latency
What's the easiest way to mark N1, P1 and N2 on the SEP response?
Mark P1 first (1st large positive/downward spike); then mark N1 and N2 on each side.
How are normal/abnormal values for SEPs determined?
Within 3SD are normal (larger normal range than NCS)
Describe in general the "new" and "old" labeling systems in SEPs
- old: each wave has N1, P1, (P2)
- new: labeled for each nerve based on expected latency for that waveform
Give the typical latency labels for median/ulnar SEP at the cortex
N20, P25, N35
Give the typical latency labels for median/ulnar SEP at the mastoid
N10, P14
Give the typical latency labels for median/ulnar SEP at the cervical recording site
N13
Give the typical latency labels for tibial SEP at the cortex
N33, P37
In general, what can SEPs detect?
Physiologic impairment of the central sensory transmission through the peripheral nerve, roots, spinal cord, brainstem and cortex; via the dorsal column pathway
List 7 major reasons for ordering an SEP.
- lumbar spinal stenosis
- coma studies
- MS diagnosis
- Meralgia parasthetica
- surgical monitoring
- cervical myelopathy/stenosis
- radiculopathy
Which test is more sensitive in lumbar spinal stenosis: needle EMG or SEP?
SEP
What is the sensitivity of dermatomal SEPs for detecting single and multi-level disease in lumbar spinal stenosis that is evident on imaging?
- single root: 93%
- multiple root: 78%

(difficult gold standard, more of a correlation with imaging)
In general, what are the parameters for considering a dermatomal SEP abnormal?
- N1 or P1 greater than 3SD of normal
- Amplitude of N1 or P1 less than 0.2 microvolts
- Amplitude of N1 or P1 less than 1/3 of contralateral side
- N1 or P1 latency 4.5 or more milliseconds longer than contralateral side
What is the sensitivity of SEPs for detecting cervical stenosis compared with imaging?
30-70% sensitivity
What are the SEP findings typical in cervical stenosis?
- small amplitude N13 peak for tibial, median, or ulnar nerve
- asymmetric dermatomal SEPs

* often normal
* cortical recording often normal even when cervical recording slow
If cervical recorded dermatomal SEPs are symmetrically abnormal, you should consider...
polyneuropathy
What percentage of adults with hypoxic-ischemic encephalopathy with absent SEPs will awake from coma?
<1%
What percentage of adults with hypoxic-ischemic encephalopathy with abnormal SEPs will awake from coma?
~25%
What percentage of adults with hypoxic-ischemic encephalopathy with normal SEPs will awake from coma?
~50%
What percentage of adult patients with intracranial hemorrhage with absent SEPs will awake from coma?
1%
What percentage of adult patients with intracranial hemorrhage with SEPs present will awake from coma?
38%
What percentage of adult/teen patients with traumatic brain injury with SEPs absent will awake from coma?
5%
What percentage of adult/teen patients with traumatic brain injury with SEPs abnormal will awake from coma?
70%
What percentage of adult/teen patients with traumatic brain injury with SEPs normal will awake from coma?
89%
What percentage of pediatric patients with traumatic brain injury with SEPs absent will awake from coma?
7%
What percentage of pediatric patients with traumatic brain injury with SEPs abnromal will awake from coma?
69%
What percentage of pediatric patients with traumatic brain injury with SEPs normal will awake from coma?
86%
What is the best timing for coma SEP study for patients with anoxic injury?
wait 24-48 hours
What is the best timing for coma SEP study for patients with traumatic injury
wait 12 hours
What nerve is typically stimulated for SEPs in coma studies and where do you record?
- median nerve
- record: axilla, C7, mastoid, cortex
In a coma study, if all responses are absent is this helpful?
No, can't draw any conclusions
Is there a difference in prognosis for waking from coma if SEPs are present bilaterally vs. unilaterally?
No, about the same
SEPs are abnormal in what % of patients with MS
77%
What are the general AAN guidelines regarding using evoked potentials in the diagnosis of MS?
- VEPs: probably useful
- SEPs: possibly useful
- BAER: insuffecient evidence
Sensitivity and specificity of SEPs for diagnosis of meralgia parasthetics
- sensitivity: 52%
- specificity: 76%