Clinical Neurophysiology Flashcards
TEst that determines distribution of sweating?
Thermoregulatory sweat test
what is quantitative sudomotor axon reflex testing (QSART)
test postganglionic sympathetic failure seen in small fiber neuropathies AND
excessive sweating in reflex sympathetic dystrophy
2 signs of SNS dysfunction during valsalva test?
- exaggerated drop in BP in early phase 2 as venous return drops b/c lack of vasoconstrix
- no overshoot of BP after relaxation due to increased venous return
How do you test parasympathetic function during valsalva?
You should get a reflex bradycardia as BP increases in final overshoot BP due to vagal tone. Absent in PNS dysfunction.
What should HR do w/ breathing and what does it test?
should increase with inspiration due to cardiovagal reflex
autonomic neuropathy with orthostasis, bradycardia, megaesophagus, megacolon, and congestive cardiomyopathy found in South America/Central America patients
Chagas’ disease from trypanosomiasis
dopamine beta hydroxylase deficiency
- what does it cause in adults (2 sx)
- what NT pattern do you see
- what chromosome
- what tx?
Increased dopamine, lack of NE
chromosome 9q34
causes ptosis, orthostatic hypotension
tx: L-DOPS which can be decarboxylated into NE instead
Dopamine hydroxylase deficiency causes what in neonates?
3Hys: hypothermia, hypoglycemia, hypotension episodes
Disease with hypohidrosis, decreased tear/saliva, GI dysmotility, impotence, severe lancinating pain in extremities, renal disease
Cause
Genetics?
Fabry’s
alpha galactosidase def
X-linked recessive
What is familial amyloid polyneuropathy caused by and what is the disease path and sx?
small fiber neuropathy due to transthyretin defect FAP1
causes pain/temp sensation loss, autonomic sx and CHF
Disease causing lack of sensitivity to pain?
Hereditary sensory and autonomic neuropathies (HSAN) particularly
Riley-Day syndrome: HSAN III autosomal recessive in Ashkenazi jews (familial dysautonomia)
Genetic cause of Riley Day?
autosomal recessive mutation in kappaBkinase complex assoc protein on chrom 9q31
Distinctive feature of Riley day? (2 sx/si)
absence of fungiform papillae on tongue and no overflow emotional tears
EEG frequencies: the order from slow to fast
Delta, Theta, Alpha, Beta
*Dig that awesome beat
Alpha freq EEG?
8-13
Theta freq EEG
4-7
Beta freq EEG
> 13
Delta freq EEG
<4
negative deflection on EEG means what
That the first input is positive compared to second
pos to neg is down
What is the layout of bipolar montage?
inputs 1 and 2 are adjacent:
Channel 1: Fp1-F3
Channel 2: F3-C3
Channel 3: C3…
What is a referential montage?
There is a reference electrode that is presumably inactive
Channel 1: Fp1-Cz
Channel 2: F3-Cz
Channel 3: C3-Cz
Hyperventilation shouldn’t be performed w/ EEG on which 3 (non resp dz)
- cerebrovascular dz
- sickle cell trait/dz
- moymoya
Normal EEG response to hypervent?
generalized background slowing
photic response w/ epileptiform discharges seen in what major epilepsy? Actual photoconvulsive response seen with what?
JME (photoparoxysmal response)
primary generalized epilepsy - pts can have seizure w/ photic
Background rhythm norms at 3 mos and 5 mos?
3 mos: 3 HZ
5 mos: 5 Hz
background alpha rhythm of at least 8HZ by what age?
3 yr
What is a kappa wave in EEG and when does it occur?
low amplitude in temporal regions, either alpha or theta during THINKING (phi beta kappa)
what is lambda waves and when do you seen them?
positive sharp transients in occipital area during visual scanning (if you are looking around at a bunch of lambs)
What is the mu rhythm
where and when does it occur?
arciform 7-11 Hz in centroparietal regions, attenuated by moving or thinking about moving the contralat body
spikes seen 6-11 hz in temporal region, during drowsy/light sleep in adults?
wicket spikes/waves
delta activity in kids/adol w/ overriding alpha that attenuates with eye opening
posterior slow waves of youth
WHo gets 14 and 6 positive bursts of arciform activity over posterior temporal for < 3 sec and when?
adolescents in light sleep
What do you see in teens/adults with wakefulness and drowsiness that disapper with sleep?
bursts of diffuse 6hz very small spike and higher amplitude wave discharges for a couple of seconds (phantom spike/wave)
What are small sharp spikes of sleep in adults
brief low voltage (<50mv) spikes over temporal region in drowsy/light sleep: small sharp spikes of sleep
5-7 Hz sharp countoured theta in bursts over temporal region in drowsy young adults
rhythmic temporal theta bursts of drowsiness/psychomotor variant pattern
WHat are the two types of alpha coma?
- posterior dominant alpha: poorly reactive: pontine strokes/brainstem lesions
- diffuse frontal alpha: poorly reactive: after anoxia
*Alpha coma: anoxia/arrest
what is bancaud’s phenomenon
when alpha activity over one hemisphere doesn’t attenuate w/ eye opening (non reactive hemisphere is abnormal)
What causes beta coma
Bzd, Barbs: better buzzed encephalopathy or brainstem lesion
high amplitude generalized beta
What rhythm on EEG with skull defect with higher amplitude spiky looking EEG activity?
Breach rhythm
What causes focal delta activity on EEG
continuous and polymorphic delta due to structural lesion
define spike on EEG?
< 70ms
define sharp wave on EEG
70-200msec
WHat is FIRDA? and what does it mean?
Frontal Intermittent Rhythmic Delta Activity
seen in encephalopathy, incr ICP. deep midline lesions
What is pattern do you see in kids with encephalopathy instead of FIRDA?
Occipital (OIRDA)
WHat are PLEDS and what causes them?
Sharp activity at regular intervals over a hemisphere
usually from stroke or Herpes encephalitis
What are triphasic waves?
frontal dominant waves with an anterior to posterior lag seen in hepatic encephalopathy and others
What EEG findings can Clozapine cause?
Clozapine: clonic activity:
Interictal discharges, GTCs, myoclonus
Two meds that can cause seizures in people w/o epilepsy?
Bupropion (Wellbutrin) and DEmorol (meperidine) OD
Two meds that can cause seizures in patients with epilepsy and one med that causes interictal discharges in patients w/ epilepsy?
Seizures: Ultram (tramadol) and Benadryl
Discharges: Lithium
Sharp or sharp/slow wave complexes every 1-3 sec and PLEDS?
What dz?
herpes encephalitis
EEG showing high amplitude periodic sharp wave complexes every 4-15 seconds generalized occurs in what stage of post-measles?
subacute sclerosing panencephalitis, stage 2.
Stages of SSPE (post measles)
I: personality change/lose academics
II: EEG findings, myoclonic jerks, cognitive decline
III: stupor, EPS, autonomic sx, hyperreflexia, rigidity
IV: chronic vegetative state
generalized periodic sharp wave complexes every 0.5-1.6 seconds in what disease
CJD NOT variant (mad cow)
EEG criteria for brain death? (7)
- 8 electrodes
- 2microvolt sensitivity
- electodes at least 10cm apart
- impedance 100-5000 ohms
- low freq filter set < 1Hz
- high freq filter set >30 Hz
- Duration 30 min
QUiet and active sleep in neonates is found when and what are the stages like?
between 30-36wk
active: like REM (go straight to it)
quiet: similar to nonREM, less synchrony than in younger babies
What is active moyenne in neonatal EEG?
appears at 36 wks and is a continuous pattern of mixed freq during awake and active sleep (REM sleep)
EEG development in quiet sleep in neonate?
TD (trace discontinu) –>TA (trace alternans) –>CSWS (continuous slow wave sleep) –>CSWS and spindles
Active sleep - awake - quiet sleep.
What is a CMAP represent?
the sum of all the individual muscle fiber action potentials
Draw the CMAP and label the parts
latency: time from stimulus to initial CMAP
amplitude: peak of wave
duration: length of time on x axis from when waves return to original start before overshoot
What does latency reflect?
fastest conducting motor fibers
What does amplitude reflect?
number of muscle fibers
what does duration reflect on EMG?
synchrony of muscle fiber firing
what would a significant drop in area comparing CMAPs with distal and proximal stimulation suggest?
a conduction block
Do you see a conduction block in acquired vs inherited demyelinating polyneuropathies
only in acquired.
what do you see in multifocal motor neuropathy with conduction block?
Marker?
you see conduction blocks in sites w/o compression, asymmetric weakness and atrophy beginning distally.
Marker is anti-GM1 antibodies
What is a martin gruber anastomosis? what does it look like?
when recording from abductor digiti minimi, shows apparent conduction block between wrist and below elbow during ulnar motor studies
-from fibers crossing median nerve to innervate some muscles usually innervated from ulnar nerve
How does low temp affect EMG?
increased latency, duration, amplitude, area of motor and sensory action potentials
What do you use to measure the conduction velocity with regards to latency
onset latency (not peak latency) / distance from stimulation point
what does EMG/NCS show in small fiber neuropathies
its normal
EMG findings in demyelinating neuropathy?
- prolonged distal latency
- normal/reduced amplitude
- reduced conduction velocity by about 50%
- conduction block
- increased temporal dispersion
EMG findings in axonal neuropathy
- decreased amplitude
2. only mild slowing
if you have loss of sensation but normal sensory nerve action potentials, where is the lesion?
proximal to the DRG
if you have loss of sensation and lost SNAP, where is lesion?
plexus
what is more sensitive test for picking up carpal tunnel on EMG?
median nerve palmar sensory response b/c routine NCS may be normal
What is the F response and what does it mean?
late response when the AP travels back in the antidromic direction to the anterior horn cell via ventral root and then back down the motor nerve *shows integrity of the proximal motor neuron pathway)
F responses are in motor only, not sensory neurons
Earliest GBS finding on EMG/NCS?
loss of F response
What is the H reflex and what does it mean?
monosynaptic reflex involving alpha motor neurons: stimulate tibial nerve w/ submaximal stimulus in popilteal fossa and record in gastroc/soleus
tests integrity of proximal sensory and motor pathways
compare/contrast H reflex and F response
H reflex: involves synapse adn mixed nerves
F response: motor nerves only: no sensory or synapse
What is increased or decreased insertional activity on EMG?
waveform lasting more than 200msec when you insert needle.
Seen in neuropathic denervation and myopathic polymyositis
Decreased insertional activity is seen when muscle is replaced by fat/CT
What are fibrillation potentials on EMG
from single muscle fiber
Best test for NMJ d/o?
single fiber EMG
Repetitive nerve stim test used for what?
NMJ d/o of myasthenia, LEMS, botulism
What do you see on Repetitive nerve stim in LEMS and Myasthenia and Botulism?
CMAP decrement at 2-5 HZ with LEMS and MG
CMAP increment at 20-50Hz w/ LEMS and botulism
What is neurapraxia?
nerve injury with loss of conduction but axon intact: conduction block with proximal stimulation
What is axonotmesis?
axon disrupted but sheat intact in axonotmesis: failure to conduct and wallerian degeneration of part of axon removed from cell body
What is neuronotmesis?
axon and connective tissues disrupted: most severe injury
Peaks in BAERS? What is most prominent?
NCSLIMA:
Nerve, cochlear nuclei, superior olivary complex (pons), lateral lemniscus (pons), inferior coliculus (mb), MGN (thal), auditory radiations (thalamocortical)
Waveform V: inferior colliculus should be most prominent
What is delayed in VEPs for lesion anterior to optic chiasm?
p100
Somatosensory evoked potentials (SSEPS) what are N9, N11, P14, N18, N20 of median nerve?
N9: erb's point, brachial plexus N11: cervical cord P14: caudal brainstem N18: upper brainstem N20: primary somatosensory cortex
What are median nerve SSEPs useful for?
to identify lesion in dorsal column medial lemniscal system
*ie p14-N20 latency suggests defect conduction between brainstem and cortex
Tibial nerve SSPEs? N8, N19, N22, P31, N34, P38
N8: tibial nerve N19: cauda equina N22: lumbar gray matter P31: medial lemniscus N34: multiple brainstem P38: primary somatosensory cortex
Neurotransmitters that promote wakefulness?
NE, Histamine, Dopamine, Serotonin
and ACh is also increased in wakefulness (and REM()
WHat neurons promote wakefulness? from where?
orexin/hypocretin neurons in posterior/lateral hypothal
What NT promotes sleep and what blocks it?
Adenosine: receptors blocked by caffeine and theophylline
what neurons important for sleep onset?
basal forebrain and anterior thalamus
What helps with initiation of sleep?
inhibition of hypocretin By GABA from preoptic and basal forebrain neurons
VErtex waves seen in what stage of sleep
Stage 1: with slowing of background
Stage II sleep characterized by onset of what?
sleep spindles and K complexes
What parts of sleep are characterized by NREM vs REM
NREM in beginnning 1/3, REM in last 1/3
What is hypnagogic and hypnopompic hypersynchrony?
bursts of synchronous theta/delta in children mostly during drowsiness
What are POSTS and when are they seen?
positive occipital sharp transients in occipital region looking like checkmarks in runs occur in drowsiness and light sleep, max in adolescents
What can elicit K complexes during sleep?
noise
Sawtooth waves and theta frequency waves in brief runs found in frontocentral region in what?
REM sleep
When do sleep spindles and vertex waves appear in stage II sleep in babies?
spindles by 2 mos
vertex by 3-4 mos, well formed at 5 mos
In adulthood, what perentage of time in each stage of sleep?
Elderly?
1 <5% 2. 40-60% 3/4. 10-20% REM: up to 25% Elderly: increase stage 1, decrease slow wave
WHen do nightmares occur (stage of sleepP)
REM
When do confused arousals and night terrors occur in sleep?
slow wave sleep
when do periodic limb movements occur in sleep?
light sleep stage 1-2
When does sleep walking occur in sleep?
slow wave sleep
So what half of sleep due sleep walking, terrors, confused arousals present in?
1st half
WHat is periodic limb movement disorder?
> 5 PLMS / hour of sleep, PSN diagnosis *not clinical
When do periodic limb movmeents occur in sleep?
light sleep
Hypnagogic vs hypnopompic hallucinations
gogic: when goes to sleep
pompic: when wakes
What biochemical test is abnormal in people with narcolepsy
low CSF orexin/hypocretin
what bug causes sleeping sickness?
african trypanosomnias from trypanosoma brucei (tse tse fly)
when is peripheral myelination complete?
by age 3-5y. conduction velocity should be same as adults
What is the deal with height and conduction velocity and what is most affected?
Taller –> slower CV
affects the F waves
what are two stimulation errors?
- submaximal stimulation (large fibers have highest threshold and are evoked last)
- costim of adjacent nerves leading to too large amplitudes
what fibers are measured in nerve conduction studies?
large myelinated fibers
Basic neuropathic patterns of NCS? (2) and how they are differentiated?
- axonal loss: reduced amplitude, basically normal conduction velocity and distal latency
- demyelination: marked slowing of conduction velocity (<30-35) and markedly prolonged distal latency
what does temporal dispersion indicate and what else happens with wave forms? when is this most prominent?
Demyelination b/c slow fibers lag behind fast ones, can cause amplitude to drop by >50% too.
More prominent with sensory than motor and proximal stimulation
What do you see in conduction block?
What is definitely indicative of conduction block?
drop in CMAP of at least 20% and increased duration of at least 15%. Area drop of at least 50% is definite conduction block
myokymic discharges seen in what?
post radiation plexopathy (pathognomonic)
what makes a hissing or seashell noise on EMG needle study due to small monophasic negative potentials?
end plate noise near NMJ - normal
what makes a fat in the frying pan sound on needle EMG that is negative deflections and irregular?
end plate spikes
What makes a rain sound with positive regular deflections (downward)
fibrillations on needle EMG
What do you see EMG fibrillations in? (4)
- neuropathic disorders
- inflammatory myopathies
- muscular dystrophies
- botulism
What kind of spontaneous needle EMG activity do you see in active denervation?
positive waves from spontaneous depolarization of muscle fiber, regular pattern making dull pop
regular rain on roof needle EMG sound with downward (positive) deflections
fibrillations
what are myotonic discharges and what are they seen in most commonly?
spontaneous d/c of muscle fiber with waxing/waning pattern, similar to p waves with brief positive spike. Revving engine sound in myotonic dystrophy but many others
what dx with eyelid, arm, leg, feet, tongue fasciculations but otherwise normal exam, some cramping
benign fasciculation syndrome
3 conditions assoc w/ myokymia
1, radiation injury
- facial myokymia in GBS, MS, pontine tumors
- low serum Calcium
needle EMG pattern for neuropathy vs myopathy?
neuropathy: decreased recruitment, large amp Motor unit APs
myopathy: early recruitment of small, polyphasic units
What three nerves come off of the first half of the brachial plexus, supraclavicular portion and what are they made of?
- dorsal scapular from C5 root only
- suprascapular from C5 and C6 upper trunk
- long thoracic from C5 C6, C7
WHat are the two divisions of the sciatic nerve and what do they innervate?
tibial: semiteninous, semimembranous biceps femoris long head;
Peroneal: biceps femoris short head
major role of obturator and root supply?
adduction of lower extremity
L2-4
major action and root supply of femoral nerve?
hip flexion, knee extension L2-4
What is the dx and tx for acute onset shoulder and arm pain then weakness and sensory loss w/ no trauma hx?
parsonage turner, neuralgic amyotrophy
subacute onset of weakness and atrophy of pelvic and femoral muscles with lots of hip / thigh pain, absent patellar reflexes
Dx and course?
diabetic amyotrophy, gradual recovery over 6 mos
median nerve mononeuropathy with what sx?
LOAF weakness and atropy, numbness in digits 1-3.5
LOAF: lumbricals 1/2, opponens pollicis, APB, FPB
most common radial neuropathy
causes what, spares what?
spiral groove causes wrist drop, spares ticeps
nerve responsible for foot eversion?
tibial
NMJ presynaptic EMG and repetitive stim findings?
facilitation of CMAP amplitudes after exercise and high freq (30HZ) stim
-may have p waves / fibs
(LEMS, Botulism)
EMG rapid stim findings in post synaptic NMJ dz/
> 10-20% decrement after exercise, unstable MUAP on EMG needle study
what characterizes juvenile absence seizures
- absence on wakening
- myclonic sz
- EEG 3-5HZ
myoclonus in AM, GTCs, college student? Dx and tx?
JME, VPA
EEG w/ symmetric, bilateral polyspike generalized spike/wave complexes 4-6Hz, maximal at frontal, and photosensitivity
JME
slow spike and wave < 3Hz discharges
Dx and tx?
LGS, lamotrigine, VPA, VNS
post traumatic epilepsy
% w/ sz at 6 mos, and at 2 yrs
50% at 6 mos, 80% at 2 y
75% remain sz free after 1yr, 90% after 2 yrs
Best associated with poor outcome after cardiac arrest? evoked potential?
median SSEP N20 (Thalamocortical radiations)
absence of wave V on brainstem auditory evoked potential?
lesion of auditory pathway above caudal pons (lateral lemniscus/inferior colliculus)
what exactly does EEG measure
voltages between electrodes on scalp. Detects extracellular currents of large groups of radially oriented pyramidal cells in cortex
yield of single routine EEG to be abnormal in pt w/ epilepsy
1 vs 4 and w/ sleep
1 50%
4 92%
w/ sleep 80%
Evoked Potentials, examples of near vs far fields
near: near the recording electrode w/ restricted distribution
(P100, Wave I, N20)
Far: recorded further from source, Waves II-V of BAERS
What is the order of the VEP waves and what do they represent (2 main)
N75 is the turn at the Meyers loop of radiations after LGN
P100/N100 is the calcarine fissure/visual cortex
Reduced P100 amplitude indicates what
ocular or retinal lesion (think of half as much light getting in)
Increased P100 latency and decreased amplitude is due to what
usually demyelinating optic neuropatphy like optic neuritis
Pattern on VEP expected in acute optic neuritis
loss of P100
expected VEP with anterior ophtho pathway compressive lesion
abnormal P100 morphology AND latency
expected VEP with ischemic or toxic optic neuropathy that isn’t necessarily demyelinating
P100 amplitude diminished (axon damaged, myelin isn’t)
6 stops of the auditory pathway mnemonic
CNS LIMA:
Cochlea –> Nerve/Nucleus VIII –> Superior olive –>Lateral lemniscus –> Inferior colliculus –> MGN –> auditory cortex
5 Waves of BAERS and three most important and what they represent
*I: distal CN VIII / spiral ganglia II: proximal nerve/cochlear nucleus VIII *III: superior olive or ventral pons IV: upper pons - inferior lateral lemniscus in pons *V: inferior Colliculus MIDBRAIN
IF BAERS are absent bilaterally?
technical, braindeath, or bilateral CN VIII lesions
absent unilateral BAERs
think CNVIII or cochlear lesion
BAERS:
One side normal
Other side only peak 1
CP angle lesion affecting rest of signal
BAERS
increased wave I latency, normal waves the rest
peripheral hearing loss or partial CN VII lesion
BAERS Increased latency of waves I-III, rest are normal
lower brainstem lesion
BAERS w/ delayed latency waves III-V
upper brainstem lesion
Somatosensory evoked potentials do what?
measure integrity of the dorsal column pathway by stimulating median or tibial nerve and assessing potentials in spine and scalp
What are the waves for median nerve SSEP?
N9: plexus / Erb's point N13: cervical cord / DRG N18: Brainstem **N20: primary somatosensory cortex: most prognostic P22: cortical positivity after N20
Tibial SSEPs
PP/PF: popliteal fossa N22: lumbar spine P31: cervical medullary cunction N34: brainstem P37: primary somatosensory cortex
Absent N20 suggests what?
poor prognosis in hypoxic ischemic coma
On Nerve conduction study:
What is the F wave and what does it represent
Is there a synapse
When is it abnormal?
measure from ANY motor nerve with supramaximal stimulus and look at backfiring responds
reflects conduction along the entire length of the motor nerve (proximal)
Does NOT involve synapse
Abnormal early in demyelinating neuropathies
In NCS what is the H reflex what does it represent synapse? equivalent of what clinically where is it measured
Measured only in the tibial nerve
it measures a REFLEX arc with sensory and motor and a synapse (monosynaptic in cord)
Reflects conduction along sensory nerve and motor nerve
Equivalent of subtle ankle jerk
If you lose axons what basically happens on the nerve conduction study?
you reduce the amplitudes of the CMAP and SNAP
perhaps slightly decrease the Conduction velocity only because you may lose the fastest ones
You NEVER see conduction block or abnormal temporal dispersion
What do you basically see on Nerve Conduction Study in Demyelination?
You see massively reduced conduction velocity with prolonged distal motor latencies and F wave latencies
You may see conduction block and/or temporal dispersion if acquired
What does conduction block look like on NCS?
If partial, you see Massively diminished amplitude and area under the curve in proximal compared to distal areas
What does temporal dispersion look like on Nerve conduction study?
increased duration of the CMAP
What is a motor unit
the motor neuron and all the muscle fibers it supplies
What is a motor unit action potential
summation of fraction of muscle fiber action potentials of that motor unit, at recording electrode tip (8-20 muscle fibers)
Motor unit action potential height is increased in what and decreased in what
increased in neurogenic disorders with axonal collateral sprouting and decrease in myopathic disorders when just can’t get enough force
motor unit action potential is increased in what and decreased in what
increased in neurogenic disorders w/ axonal collateral sprouting and severe chronic myopathies
decreased in myopathic disorders or severe disorders of NMJ
recruitment is reduced in what and increased in what conditions on EMG
decreased in neurogenic
increased in myopathic: abnormally increased early recruitment
the non “Myotonia” clinical condition that can have myotonic discharges on EMG
hyperkalemic periodic paralysis
generalized myokymia is seen in what
limb myokymia is seen in what
face myokymia is seen in what
Isaac’s syndrome
facial in brainstem lesions
limb in radiation plexopathies
