Notes 3A Flashcards
F wave?
obtained after super maximal stimulation of a motor nerve
electrical impulse travels antidromically (conduction along the axon opposite to the normal direction of the impulses) along the motor axons toward the motor neuron, backfiring and then orthodromically (conduction along the motor axon in the normal direction) down the nerve to be recorded at the muscle.
H reflex?
electrophysiologic equivalent of the ankle reflex (S1 reflex arc) and is obtained by stimulating the tibial nerve at the popliteal fossa while recording at the soleus.
The electrical impulse travels orthodromically through a sensory afferent, enters the spinal cord, and synapses with the anterior horn cell, traveling down the motor nerve to be recorded at the muscle
Siponimod? MOA and SE?
sphingosine 1 -P inhibitor
Need to check CYP2A9 prior to initiating treatment
Ocrelizumab MOA? only DMT approved for?
Anti-CD20
Only one approved for PPMS
*can have infusion reactions, tx with tylenol and solumedrol*
Large polyphasic motor unit potentials are seen in?
chronic re-innervation
Types of spontaneous activity?
fibrillation potentials
fasciculation potentials
myokymia
myotonic potentials
What is recruitment?
measure of the number of MUPs firing during inc force of voluntary muscle contractionm
myopathic MUAPs are
small and short in duration
neurogenic MUAPs are
large and prolonged
Fibrillation potentials
occur when an individual muscle is denervated. Fibrillation potentials are small (<500 µV), short (<5 ms in duration), biphasic or triphasic, and fire regularly or sometimes irregularly.
Positive sharp waves
emanate from denervated muscle fibers and have the same clinical significance as fibrillations. They have a sharp initial positive deflection followed by a longer, lower amplitude negative phase than fibrillation potentials.
Myokymia
Myokymia consists of bursts of MUAPs, usually 2 to 10, firing at rates of 20 to 150 Hz. The bursts consist of regular or irregular doublets, triplets, or multiplets. Between bursts there is electrical silence.
Reduced recruitment is when there is? seen in
less than expected MUPs firing more rapidly than expected
axonal loss, conduction block, end stage myopathy
Early or rapid recruitment is when there is?
myopathic processes with lots of muscle fibers in which an excessive number of short-duration and small amplitude MUPs fire during contraction
With poor effort or with CNS disorders causing weakness, recruitment is?
reduced, with normal MUPs firing at slow or moderate rates
In neuropathic disorders with denervation and re-innervation, MUPs are
inc duration and amplitude, and may be polyphasic
In a radiculopathy, SNAPs are
normal (SNAPs are recorded distally to the lesion, in the postganglionic projections from the DRG)
EMG findings in radiculopathy?
An axon loss radiculopathy will also injure motor fibers in the intraspinal canal region affecting the respective myotome.
This leads to denervation, with fibrillation potentials seen 3 weeks after the onset of motor axon loss, decreased recruitment, and 3 to 6 months later, large and polyphasic motor unit potentials (MUPs). The presence of these large and polyphasic MUPs is dependent on reinnervation and collateral innervation, typically occurring in a proximal to distal fashion, with proximal muscles more successfully reinnervated as compared to distal muscles.
Mg dx with EMG/NCS
NCS is normal EMG with slow repetitive nerve stimulation showing more than 10% decremental response in CMAP amplitude
Lambert Eaton Dx with EMG/NCS
rapid stimulation produces an incremental increase in CMAP amplitude (>50% inc)
- this occurs with rapid stimulation (20 to 50 Hz) because the frequency of stimulation is faster than the time it takes for calcium to leave the presynaptic terminal (100 to 200 ms), leading to higher levels of calcium influx and larger end-plate potentials
Skeletal muscle Type 1
slow-oxidative
- slow ATPase activity and large oxidative capacity
- Large num of mitochondria
- Red in color, small diameter
Skeletal muscle type 2A
fast oxidative glycolytic fibers
- Fast ATPase
- High glycolytic capacity
- Moderate oxidative capacity
- Fast and resistant to fatigue
- Red and large
Skeletal muscle type 2B
fast oxidative glycolytic fibers
- Fast ATPase
- High glycolytic capacity
- Low oxidative capacity
- Fast and fatigable
- Pale and large
CIDP
features
timeline
EMG/NCS shows
Biopsy?
symmetric demyelination with proximal and distal weakness with or without sensory loss and hypo/areflexia.
progressive, needs to be for 8 weeks for dx
demyelinating polyneuropathy with prolongation of distal motor latencies, reduction of motor conduction velocities, prolongation of F-wave latencies/absence of F-wave, partial motor conduction block, abnormal temporal dispersion
onion-bulb formation
normal latency should be? conduction velocity?
<4 ms
>50
The presence of a conduction block suggests?
demyelination
Wallerian degeneration is completed in ___ days from the injury
7-10
Fibrillation potentials (sign of spontaneous muscle activity) appear in ___ days from injury
3 weeks( 21 days)
Carpal tunnel
where is sensation spared?
thenar eminence because the palmar sensory branch that innervates the thenar eminence travels outside the carpal tunnel
Sign of severe CTS is
thenar muscle atrophy
GBS: which variant has worse prog
axonal variant
NIF of less than ___ or vital capacity less than ___ supports elective intubation in GBS
-30
15-20
Which nerves branch off the roots of the brachial plexus
dorsal scapular nerve (innervates the rhomboids and elevator scapulae)
long thoracic nerve (innervates the serratus anterior)
Trunks of the brachial plexus
Upper: C5-6
Middle C7
Lower C8-T1
cords of the brachial plexus: Lateral
named in reference to the axillary artery
Lateral (C5-7): gives rise to lateral pectoral nerve, median nerve, musculocutaneous
cords of the brachial plexus: Posterior
Posterior C5-T1: Gives rise to upper subscapular nerve, lower subscapular nerve, thoracodorsal nerve, axillary nerve, radial nerve
cords of the brachial plexus: Medial
C8-T1
medial pectoral nerve, medial brachial cutaneous nerve, medial antebrachial cutaneous + median, ulnar nerve
Familial amyloid polyneuropathy
mutation, inheritance
Type 1 vs Type 2
AD
transythretin mutation
Type 1: Polyneuropathy + autonomic features
Type 2: carpal tunnel syndrome, mild sensory polyneuropathy + absence of prominent autonomic features
CMT
features
nerve biopsy shows
heriditary sensorimotor polyneuropathy , high arched foot
onion bulb appearance
Demyelinating types of CMT
CMT1, CMTx, CMT4
CMT1
inheritance
mutation
features
CSF may show
AD (most common type)
DUPLICATION OF PMP22 on chromosome 17
hammertoes, high arched feet, palpably enlarged nerves and pes cavus
can see elevated protein in CSF
CMTx
inheritance
mutation
X linked
Connexion-32 gene
CMT2
inheritance
features
AD
axonal neuropathy (not demyelinating)
sx appear later in life, more UE than LE
can see optic atrophy (CMT2A), foot ulcerations, vocal cord paralysis, no peripheral nerve hypertrophy
CMT3 (Dejerine Sottas Syndrome)
features
most severe form, AD and AR
presents in infancy with proximal weakness, absent DTRs, hypertrophy of the peripheral nerves
HNPP (hereditary neuropathy with pressure palsy)
inheritance
mutation
features
biopsy
AD
deletion in PMP22
focal mononeuropathies (most commonly peroneal nerve, followed by ulnar nerve)
biopsy shows tomacula (myelin thickening)
Lesion in deep peroneal nerve presents with?
inability to dorsiflex (eversion is intact)
Superficial = eversion
Common = dorsiflexion and eversion
Foot drop + eversion impaired + inversion impaired ?
L5 radiculopathy
Foot drop + eversion impaired + intact inversion?
common peroneal neuropathy
Tangier’s disease
inheritance
features
unique PE finding
AR
defect with deposition of triglycerides causes sensory neuropathy with disassociated sensory loss (loss of pain and temp with preservation of the posterior column)
Deposition of TG can cause yellow/orange tonsils
Anti-Hu is seen in some sensory neuropathies and is assoc with?
Small cell lung ca
Anti-Yo is seen in some cerebellar degenerations and is assoc with?
ovarian ca
Sciatic nerve gives rise to
tibial and common peroneal nerve
Multifocal motor neuropathy (MMN)
features
AB assoc
treatment
purely motor demyelinating neuropathy, presents with asymmetric weakness from involvement of individual peripheral nerves + hypo/areflexia. no sensory deficits
anti-GM1
IVIG, no response to steroids or plasmapharesis
Hypokalemic periodic paralysis
Inheritance
Types
presents with
triggered by
tx
AD
Type 1: Ca channel mutation (CACN), Type 2: Na channel (SCN4A)
presents with episodes of weakness without myotonia, during attack K is low.
exercise, carb high meals, alcohol, emotional stress, cold
diet + acetazolamide and K sparing diuretics
Hyperkalemic periodic paralysis
inheritance
mutation
presents with
tx
AD
Sodium channel SCN4A
episodes of weakness triggered by exercise and fasting
can give glucose during attacks
tx with thiazides
Anderson-Tawil Syndrome
mutation
features
K channel mutation in gene KCNJ2
periodic paralysis, ventricular arrhthymia, dystrophic features
Paramyotonia
inheritance
mutation
features
AD
SCNA4
exercise induced myotonia most appreciated in the eyelids (in contrast to myotonia congenita)
in steroid induced myopathy, there is atrophy of?
EMG? CK?
Type 2 fibers
EMG and CK nonspecific
3 types of Anti-ACH Abs in MG
binding
blocking
modulating
most common ACH Ab assoc with MG
binding (causing a complement mediated destruction of the receptor
MOA of tensilon test
ACHesterase inhibitor = causes transient improvement of weakness
Dystrophic myotonia Type 2 (aka proximal myotonic myopathy)
Inheritance, mutation
features
AD
CCTG repeat expansion in intron of zinc finger protein 9 gene on chromosome 3
myotonia of proximal muscles (type 1 is distal)
Dystrophic myotonia Type 1
inheritance, mutation
features
AD
CTG repeat expansion in myotonic dystrophy protein kinase gene on chrom 1
myotonia of the distal muscles: ptosis, facial weakness, frontal balding, atrophy of the masters and temporals, weakness and atrophy of small muscles of the hands and extensor of the forearm and peroneal muscles, testicular atrophy, infertility, intellectual delay
Facioscapulohumeral muscular dystrophy (FSHD)
inheritance, mut
features
AD
D4Z4 mutation on chromosome 4
- Predominantly affects the face and shoulder
- Presents with difficulty lifting their arms above their head with relative sparing of deltoid muscles + weakness of lower abdominal muscles (Beevor sign)
- Forearm more atrophic than the arm—> Popeye
- Weakness of foot dorsiflexion with preservation of plantar flexion is characteristic
Symptoms that distinguish cholinergic crisis (pyridostigmine overdose) from myasthenic crisis
In pyridostigmine overdose: nausea, vomiting, diaphoresis sialorrhea, excessive bronchial secretions, mitosis, bradycardia and diarrhea
Central core myopathy
inheritance, mut
features
pathology
AD
RYR1 (ryanodine receptor gene) on chrom 19
- Can print with weakness and hypotonia after soon after birth and delay in motor development
- Pelvic girdle more affected than shoulder girdle
- Pathology: loss of oxidative activity of NADH within the center of muscle fibers (pale areas)
Autonomic ganglionopathy
caused by
features
Ab
Tx
dysfunction in the parasympathetic and sympathetic nervous system
- orthostatic hypoT, absent HR variability, hypo or anhidrosis, dry mouth and eyes, pupillary abnormalities, sexual dysfunctions, early satiety, constipation, and diarrhea due ti abnormal gastric and intestinal motility
may have Ab against ganglionic nicotinic ACH rec
PLEX and or IVIG
In 50% of patients with clinic MG and Ab-ACH negative, what is pos
Anti-MUSK (muscle specific tyrosine kinase)
Significance of Anti-MUSK (+) MG?
does not respond to pyridostigmine
Features of congenital muscular dystrophies at birth?
- hypotonic and weak, rest failure, bulbar dysfunction, scoliosis, developmental delay and anomaly of cerebral cortex causing seizures
Pure autonomic failure (Bradbury-Eggleston Syndrome)
caused by
features
loss of intermediolateral cell column neurons, results in deposition of alpha-synuclein in autonomic nervous system (Lewy Bodies)
autonomic sx that are worse in the morning, after meals, with exertion and heat exposure
What is seen in dermatomyositis and not seen in polymyositis
perifasicular atrophy
Inclusion body myositis
features
pathology
myopathy affecting those >50yo
asymmetric weakness and atrophy of the wrist and finger flexors, quads, anterior tibial muscle → painless weakness that is distal leading to thumb flexing weakness with relative preservation of finger abductors (dorsal interossei)
Pathology: endomysial inflammation, intracytoplapmic vacuoles with granular material known as rimmed vacuoles
Limb Girdle Muscular Dystrophy
features
assoc with
proximal weakness with involvement of shoulder or pelvic girdle with sparing of facial muscles
assoc with cardiomyopathy and conduction defects → need cardiac screening
Difference between LEMS / MG
LEMS is less likely to have ocular or bulbar sx than MG
LEMS also more likely to have depressed DTRs
Tx of LEMS? autoimmune LEMS
3,4 DAP (diaminopyridine)
steroids, IVIG, PLEX
Nemaline myopathy
features
path
- Proximal weakness, cardiomyopathy and prominent compromise of rest muscles
Fibers have rod like structures (nemaline rods)below the sarcolemma
Pompe Disease (glycogen storage disease Type 2) is a deficiency of
Acid Maltase
McArdles Disease (glycogen storage disease type 5) is a def of
myophosphorylase
Cori’s Disease (glycogen storage disease Type 3) is a def of
glycogen debranching enzyme
Congenital MG
caused by
features
difference in Tx from regs MG
- Due to acetylcholine receptor deficiency
- Most commonly present a birth (> males)
- Typical presentation: ophthalmoparesis in infancy with facial diparesis
- Not immune mediated, so not treated like MG
Emery-Dreifuss muscular dystrophy
gene, inheritance
presents with
assoc with
- AD, LMNA
- Presents with contractures in elbows, ankles and neck.
- Muscles weakness tends to affect the UE and shoulder girdle first and layer the pelvic girdle and distal legs
- Cardiac involvement
Difference between nerve structures (pre and post ganglion) in parasympathetic vs sympathetic
PARA: (ganglia are close to the target site) long pre and short post
SYMP: short pre and long post
The neurotransmitter for all sympathetic and parasympathetic preganglionic fibers is _____ (acts on ____ receptors). Postgang in parasym release ______ while postgan in sympathetic release ________.
The neurotransmitter for all sympathetic and parasympathetic preganglionic fibers is acetylcholine (acts on nicotinic receptors. Postgang in parasym release acetylcholine while postgan in sympathetic release norepinephrine
Autonomic system in the spine: Para vs symp
Parasympathetic - Onuf’s nucleus S2-S4 (GU and distal colon: controls the urethral and anal sphincters)
Sympathetic: intermediolateral cell column from T1-L2
With lesion of the cauda equina, a flaccid bladder results from?
Loss of detrusor tone, sensation of bladder fullness is lost, voluntary control over urination is lost → overflow incontinence
with lesions affecting the paracentral lobule (such as hydrocephalus or tumors), what is affected
voluntary control over the external urethral sphincter is lost
- Lesion above the conus medullaris lead initially to
- a flaccid bladder leading to urinary retention with or without overflow incontinence.
BUZZWORDS: acute onset dysautonomia in a smoker with a lung mass
Paraneoplastic autonomic ganglionopathy
Ab against ganglionic nicotinic ACH receptors
BUZZWORDS: Duchenne muscular dystrophy (protein, inheritance)
dystrophin
X linked rec
BUZZWORDS: tongue, ear, throat pain assoc with syncope
glossopharyngeal neuralgia
BUZZWORDS: tilt table test showing inc in HR >30 from baseline, or more than 120 within 10 mins of head up tilt, without significant changes in BP but with sx of orthostasis
POTS
most common form of dysautonomia
BUZZWORDS: Emery Dreifuss gene and inheritance
LMNA
AD
(could also be X linked and emerin
BUZZWORDS: central core myopathy gene, path, assoc clinically
RYR1
central pare cores in NADH stains from absence of mitochondria
assoc with malignant hyperthermia
BUZZWORDS: Tarul disease (enzyme)
phosphofructokinase def
BUZZWORDS: cause of Hirschsprungs Disease
maldevelopment and absence of the myenteric plexus, sometimes due to RET proto-oncogene mutation
BUZZWORDS: Becker’s muscular dystrophy protein, inheritance
abnormal or reduced dystrophin
XLR
BUZZWORDS: syncope with hypotension and bradycardia after putting on a tight neck tie
carotid sinus hypersensitivity
BUZZWORDS: Ab assoc with LEMS
presynaptic P/Q type voltage gated calcium channel antibodies
BUZZWORDS: oculopharyngeal dystrophy (gene affected)
CTG repeat on PABP2 gene
BUZZWORDS: pathologic finding in critical illness myopathy
myosin loss
BUZZWORDS: Anderson’s disease (enzyme)
Branching enzyme deficiency
ALS affects what parts of the brain
anterior horn cells, motor cortex, brainstem
Split hand phenomenon in ALS?
weakness and atrophy of the lateral hand (thenar and FDI muscles) with relative sparing of the medial hand (hypothenar)
Tx for psuedobulbar affect in ALS
dextromethorphan-quinidine
What cognitive impairment is assoc with ALS?
FTD - have TDP-43(+) tau inclusion
Familial ALS-FTD is assoc with what mutation?
C9ORF72 on chromosome 9
Familial ALS mutation?
copper/zinc superoxide dismutase (SOD1) on chromosome 21
Things usually spared in ALS?
bladder/sphincter issues - Onuf’s nucleus is spared
sensation
autonomic sx
PLS (primary lateral sclerosis)
features
UMN signs at least 3 years from symptom onset wihtout evidence of LMN dysfunction. Presents in the 60s with progressive spastic tetraparesis and later cranial nerve involvement
Most common cause of spinal cord involvement in patients with HIV
HIV-related myelopathy: vaculoar myelopathy in which there is lateral and posterior column demyelination with microvacuolar changes and axonal preservation (upper extremities typically spared)
HTLV-1: tropical spastic paraparesis
features
MRI
labs
Tx
chronic progressive myelopathy endemic to equatorial and south Africa as well as parts of Asia, south america and caribbean. Transmitted via blood, sex, breast feeding.
p/w slow spastic paraparesis, LE paresthesias, painful sensory neuropathy and bladder dysfunction
MRI with inc T2 signal and atrophy of the thoracic cord
Dx with serum and CSF PCR
no tx at the moment
Hereditary Spastic Paraparesis
inheritance, mut
features
AD
SPAST gene encoding spastin protein
Progressively worsening spasticity of the LE with variable weakness and difficulty walking
What spinal levels are most susceptible to watershed injury?
T4-T8: blood supply is scarce
Artery of Adamkiewicz: supplies and affected in
T8-L3 levels
can get infected in aortic arch dissection
oculopharyngeal dystrophy: mutation
GCG repeat, PABP2 gene
Duchenne MD
inheritance
mutation
features
X linked
dystrophin gene mutation
proximal muscles weaken with sparing of ocular, facial, bulbar
All should get cardiac checkup
