Neuromuscular Flashcards
Infantile neuroaxonal dystrophy
- what is it characterized by?
- Symptoms
- MRI findings
- Large axonal eosinophilic spheroids (from axonal swelling)
- Symptoms
- Normal development until ~9 months
- Hypotonia, weakness, hyporeflexia
- Progressis to spastic quadraparesis, optic atrophy, cognitive reression, and involuntary movements
- MRI: high iron content in BG > progressive cerebellar atrophy
Ullrich’s congenital muscular dystrophy: main features (4)
- Main symptoms
- Persistent global hypotonia
- absent reflexes
- proximal joint contractures
- distal joint hyperlaxity
Mechanism by which Statins can cause myopathy (2)
- Direct toxic attack on muscle
- Immune-mediated
- anti-HMG-CoA reductase antibodies
- Anti-SRP
Miller-Fisher syndrome
Antibodies to ____
Symptoms (3)
- Antibodies to GQ1B
- Symptoms
- Ataxia
- Areflexia
- opthalmoplegia
Herpes Zoster vasculopathy
Affected vessels Clinical syndromes (6)
CSF findings (5)
- Large and small
- Clinical syndromes
- Stroke
- TIA
- Carotid dissection
- aneurysm
- SAH
- cerebral hemorrhage
- CSF findings
- Mononuclear pleocytosis
- oligoclonal bands
- elevated protein
- Normal glucose
- Normal protein
Most common extraocular muscle affected in myastenia gravis
Medial rectus
Percentage of patients with ocular-only MG who will eventually develop generalized MG
80%
Anderson Syndrome
Onset:
Timeline of attacks
Situation
Other features (3)
- Onset within first two decades of life
- Timeline: Occurs monthly, lasts for days at a time
- Situation: rest after periods of exercise (like hypokemic periodic paralysis)
- Other features
- Dysmorphic features
- long QT interval
- Ventricular arrythmias
Electrodiagnostic findings for radiculopathy
Dermatomal somatosensory evoked potentials
Diabetic Amyotrophy
Population (2)
Features (5)
Biopsy finding
- population
- DM II > DM I
- Unrelated to glycemic control
- Features
- Pain, weakness, and wasting of pelvifemoral muscles (MC thigh)
- Typically asymmetric but may affect contralateral side at some point
- minimal / absent sensory impairment
- Reduced / absent DTR
- Ankle jerk normal / slightly diminished
- Nerve biopsy features
- microvasculitis
Polymyalgia rheumatica
Onset
Features (3)
Associated disease
Diagnostic findings (4)
Treatment
- Onset after 50
- Can be seen in isolation or with patients with giant cell arteritis
- Features
- stiffness
- pain
- NO muscle weakness
- Diagnostic findings
- EMG = Normal
- Biopsy = Normal
- CK = normal
- ESR = elevated
- Treatment: Low-dose prednisone
Parsonage-Turner syndrome
AKA
timeline (2)
Most common affected nerves (5)
Prognosis
- AKA Neuralgic Amyotrophy
- Symptoms
- sudden-onset upper shoulder / girdle pain
- >>followed by weakness of 1+ brachail plexus nervesover 1 day to 2 weeks after onset
- MC affected nerves
- long thoracic
- suprascapular
- radial
- axillary
- anterior interosseus
- Prognosis
- pain usually resolves around time of onset of weakness, but strength recovery can take months to years
Oculopharyngeal muscular dystrophy
Inheritance
Common population
Mutation / Gene
symptoms (4)
- Mostly autosomal Dominant, rare early onset variant is AR
- Common among french canadian ancestry
- Mutation
- GCN repeat expansion in PABPN1 gene
- Symptoms
- Dysphagia
- Dysarthria
- ptosis
- Distal and proximal muscle weakness
Features (6) of diabetic peripheral autonomic neropathy
- Hyperthermia (most common early sign)
- skin color changes
- periopheral edema
- Pruritis
- aching / cramping
- dry skin
Features of Cardiovascular autonomic neuropathy
(6)
- Resting tachycardia
- Postural tachycardia
- Orthostatic hypotension / syncope
- exercise intolerance
- silent MI
- (late) fixed heart rate at 80-90
Features of genitourinary autonomic neuropathy
(4)
- urinary retention with overflow incontinence
- erectile dysfunction
- retrograde ejaculation
- decreased vaginal lubrication
mechanism behind malignant hyperthermia
- mutation in ryanodine receptor in skeletal muscle
- Excess calcium release from sarcoplasmic reticulum during muscle contraction
Multifocal acquired demyelinating sensory and motor neuropathy
AKA
Features (2)
Diagnostic findings (2)
Treatment
- AKA MADSAM or Lewis-Summer syndrome
- Features
- asymmetric motor and sensory loss affecting UE first
- multifocal Conduction block affecting distal limbs
- Diagnostic findings
- CSF protein normal, no pleocytosis
- EMG
- sensorimotor abnormalities suggesting demyelination and conduction block
- Treatment
- Steroid / IgG therapy
Muscle fiber characteristics
Type I
Type II
- Type I (“slow”)
- predominately aerobic / oxidative metabolism > more vascular
- Type II (“fast”)
- Higher rate of myosin ATPase hydrolesis (2-3x)
Monomeilic Amyotrophy
AKA
etiology
+ clinical features (4)
does NOT __(3)__
Helpful test (1) and findings (2)
- Hirayama disease
- etiology unknown
- Features
- typically teenage / 20’s males
- Slowly progressive painless weakness / atrophy in one arm (75%) or leg, typically distally
- Limited to few myotomes in one limb
- CL limb may be affected subclinically
- does NOT
- affect cranial nerves
- progress after 3-4 yeras
- have UMN signs
- Helpful test
- Flexion MRI of cervical spine
- would show engorgement of posterior epideural venous plexus
- +/- T2 signal in anterior horn
- Flexion MRI of cervical spine
First muscle fiber type to atrophy with lack of use
Type 1
Centronuclear Myopathy
Inheritance
Gene
features
EMG findings (4)
Histopathology findings
- aka myotubular myopathy
- X-linked recessive
- MTMM1 gene (myotubularin)
- Features
- often fatal infantile hypotonia w/ respiratory failure
- EMG findings
- fibrillation potentials
- positive sharp waves
- complex repetitive discharges
- occasionally myotonic discharges
- Histology findings
- muscle fibers with central nuclei (below)
Anti-striated muscle antibodies are a helpful marker for ____
Thymoma in patients with early onset Myasthenia gravis (between ages 20 and 50)
Clinical features of Chronic inflammatory demyelinating polyneuropathy (6)
Features
- Duration >2 months
- Proximal and distal involvement
- weakness > sensory symptoms
- decreased or absent reflexes
- increased CSF protein w/o pleocytosis
- Improvement after immunomodulatory treatment
Exclusionary criteria for chronic inflammatory demyelinating polyneuropathy (CIDP)
(5)
- Prominent sphincter disturbance
- neuropathy due to other causes (including borrelia burdorferi)
- drug / toxin exposure
- diphtheria
- multifocal motor neuropathy and/or IgM monoclonal gammopathy with AB to myelin-associated glycoprotein
Supercategories of Neuromuscular Disorders
anterior horn cell:
Stimulated by ____, inhibited by ____
Stimulated by glutamate, inhibited by GABA / Glycine
Expected clinical findings of motor neuron diseases (4)
-
Painless muscle weakness and atrophy
- 50% of LMN are usually lost before weakness is clinically detected
- Fasciculations and muscle cramps
- Hyporeflexia
- Hypotonia
Motor Neuron Disease:
EMG Findings:
sensory neuron action potential (SNAP) response
compound motor action potential (CMAP)
EMG
(benign condition) Trip-up for seeing fasciculations on EMG
Benign fasciculation syndrome
- most cmmon in eyelids, arms, legs, and feet
- NO pathologic findings on exam
- Muscle cramping / pain may occur
Treatment for bening muscle cramps by AAN
- Quinine derivatives should be avoided for routine use (can be considered on an individual trial)
- Vitamin B complex, naftidrofuryl, and calcium channel blockers are possibly effective.
EMG features: Fasciculations versus Fibrillations
Fasciculations
- What are they?
- Associated with ____
- Buzz-word
Fibrillations
- what are they?
- What do they indicate
- Buzzword
- when are they seen?
Fasciculations
- spontaneous involuntary discharges of a single motor unit
- associated with diseases of anterior horn cell and proximal root
- “corn-popping” sound
Fibrillations
- spontaneous discharge of one muscle fiber
- indicates acute or active denervation
- “rain on the roof” or “metronome”
- Seen in
- Neuropathic disorders
- inflammatory myopathies
- muscular dystrophies
- botulism
EMG findings: Doublets / Triplets
characteristically seen in ____
Tetany from hypocalcemia
ALS
Onset / sex preference
Features (5)
Prognosis (2)
- Onset / Sex preference
- Onset typically in 60’s, but can occur at almost any age
- M:F 2:1
- features
- progressive, painless weakness
- Spares eyes and bladder
- Can involve bulbar muscles (nasal voice”
- brisk reflexes
- fasciculations (motor neuron disease)
- Live expectancy
- 3-5 years (median 36 months)
- worse prognosis with bulbar symptoms
subtypes of ALS
A (2)
B (2)
C (3)
- Progressive bulbar palsy
- Often menopausal women
- poor prognosis
- Primary lateral sclerosis
- Pure UMN signs 4 y. after onset
- slow progression
- Progressive muscular atrophy
- Pure LMN
- men aged 64+
- longer survival time (48 months)
Familial ALS:
- Percentage of all ALS cases
- Mutations (3)
- onset / sex
- Clinical features (3)
- mutation associated with rapid disease
- 10% of all ALS cases
- Mutations
- SOD-1 (15-20%) AD
- c9orf72
- TARDBP (may have FTD features)
- Clinical features
- limb onset more common
- more bulbar features
- significant phenotypic variability, even within same family
- Onset ~46 (10 years earlier than sALS)
- A4V mutation associated with rapid disease course
Revised El Escrial criteria for ALS
Definite (1)
probable (2)
probable, lab supported (2)
Possible (3)
Suspected (1)
- Definite:
- UMN and LMN signs in 3 regions
- Probable
- UMN and LMN signs in 2 regions
- Some UMN signs must be rostral to LMN signs
- Probable, lab supported
- UMN and LMN signs in 1 region OR
- UMN signs alone in 1 region AND LMN signs defined by EMG in 2 limbs
- Possible
- UMN and LMN signs in 1 region OR
- UMN signs alone in 2 regions OR
- LMN rostral to UMN signs
- Suspected
- only LMN signs in 2+ regions
Diagnostic workup for ALS:
EMG findings (2)
Imaging (2)
“routine” lab studies (7)
“specialized: lab studies (2)
- EMG / NCV
- mortor NCV either normal or without demyelinating features
- normal SNAPs
- Imaging
- Neuroimaging of brain + spinal cord (rule out compression)
- CXR (r/o paraneoplastic from lymphoma-related MND associated with LAD; especially NHL)
- Routine blood studies
- CBC, CMP
- ESR, CPK
- TFT, PTH
- RPR
- B12
- ANA, SPEP/IFE
- CSF
- “specialized” lab studies
- GM1 abs (multifocal motor neuropathy)
- Hexoseaminidase A (pt <40; r/o tay-sachs
Medication approved for treatment for ALS
- MoA
- unknown, may block Na channels and prevent release of glutamic acid
- Adverse effects
- elevated LFT’s
- nausea
- abdominal pain
- HTN
AAN 2009 rec’s for treatment of ALS
7
- Riluzole should be offered (level A)
- PEG tube considered to stabilize weight and prolong survival (level B)
- NIV should be considered to treat respiratory insufficiency and lengthen survival (level B)Early NIV may increase compliance and insufflation / exsufflation may be considered to help clear secretions (Level C)
- Considere multidisciplinary clinc referral (level B)
- Botox can be considered for refractory sialorrhea (level B) as well as radiation (level C)
- Dextrmethorphan + quinidine scan be considered for pseudobulbar effect (level C)
- screen for cognitive impairment)
Adult-onset Tay-sachs
Inheritance
epidemiology note
Onset
Symptoms (3)
Biopsy buzzword
- autosomal recessive
- frequently in ashkenazi jews
- Onset <40, but may show intention tremor in first decade
- Features
- proximal weakness w/ fasciculations and atrophy
- cerebellar symptoms (ataxia)
- Psychiatric symptoms (50%) - manic-depression like d/o
- Biopsy
- pyknotic nuclear clumps
Post-polio syndrome
Onset
manifestations (3)
- Onset years to decades after illness (8-71 years)
- Features
- typically in spinal / bulbar segments most severely affected by initial illness
- can affect respiratory muscles
- (rarely) can have UMN signs
SMA I, II, and III, for each:
Gene
Onset
Motor Sx
+/- Tremor
life expectancy
For all: Survival motor neuron protein (chromosome 5)
Kennedy’s Disease
Inheritance
mutation
Neurologic features
non-neurologic features
EMG features (4)
- X-linked recessive
- CAG repeat dosrder of androgen receptor
- Neurologic features
- facial fasciculations virutually pathognomonic
- Proximal > distal weakness
- Tremor
- (female carriers) cramps / fasciculations
- Non-neurologic features
- Gynecomastia
- testicular atrophy
- EMG features
- Positive waves / fibrillations / fasciculations
- large amplitude, long-duration, polyphasic MUAPs
- May have abnormal SNAPs (atypical for MND)
ALS mimics (3) and what can differentiate them
- cervical myelopathy
- may have LMN findings in arms and UMN findings in legs
- Normal jaw jerk
- Benign fasciculations
- especially in young / anxious person w/ no other findings
- Multifocal motor neuropathy with conduction block
- no UMN findings
- Evidence of conduction block
- Can be associated with GM-1 Ab
How to distinguish sensory neuronopathies from sensory axonopathies
- Ganglionopathies present in non-length dependent manner
- Sensory neuropathies are often patchy and asymmetric
- Gait ataxia is common as a presenting feature in neuronopathies but never presenting feature an axonopathies
- Diminished joint position sense early (“pseudo-athetosis”; “piano hands”)
EMG/NCS features of Sensory Neuron disease
- SNAP
- CMAP
- EMG
Friedrichs ataxia
Inheritance
mutation
onset
Clinical features (9)
MRI features
- Autosomal recessive, GAA repeat on FXN gene (9q21.11)
- only autosomal recessive trinucleotide repeat
- Onset: 2-16 years
- Features
- UE > LE
- Dysarthria
- nystagmus
- trunkal / appendicular ataxia
- absent DTR
- axonal neuropathy
- cardiomyopathy
- DM
- Scoliosis
- MRI findings
- Atrophic cerebellum, brainstem, posterior columns, and CST tract
Features typically associated with axonal loss
(4)
- Symmetric__al, length dependent
- Sensory typically before motor
- (-) ankle reflexes
- distal muscle loss often present
Trip-ups: Axonal neuropathies that can be asymmetric (3)
All are rare
- mononeuropathy multiplex
- variants of CIDP
- Radiculopathy / entrapment neuropathy
EMG findings:
Axonal neuropathy
SNAP
CMAP(3)
EMG (4)
Feautres of this EMG finding (5)
Grading
Positive waves
- Spontaneous depolarization of a muscle fiber
- signify active denervation
- reglar pattern
- “dull pop”
- knife-like appearance
Grading
- 0: none
- 1+: persistent in single trains (>2-3 seconds) in at least 2 areas
- 2+: moderate number or potentials in 3+ areas
- 3+: many potentials in all areas
- 4+: full interference pattern (trauma, vasculitis, infarction)
EMG: Motor Unit Action Potential (MUAP)
(visual aid)
- Duration reflects number of muscle fibers iwthin a motor unit
- from initial reflection to time it returns to baseline
- Normal 5-15 milliseconds
- Longer duration occurs with number of reinnervation
Common gene mutations associated with length-dependent polyneuropathy (3)
- CMT1A dupication / HNPP deletion
- CX32
- MFN2
Abetalipoproteinemia
Inheritance
Gene
Features (4)
- Inheritance (AR)
- mutation: MTTN gene
- Features
- opthalmoplegia
- pigmented retinopathy
- acanthocytosis
- progressive ataxia
Features of toxic neuropathies
Most common exposure
Features of neuropathy
- Most common exposure: Fumes
- Features
- multifocal neuropathy (wrist drop or foot drop)
- GI / psych disturbance
- burton lines: bluish pigmentation at gum line
3.
Strachan syndrome and related disorders
AKA
Features (4)
- “tropical myeloneuropathies” due to mulifactorial nutritional difficulties
- Features
- Spinal cord lesion and axonal sensory > motor neuropathy
- severe burning pain in palms of hands and soles of feet
- Skin changes
- (less common) retrobulbar neuritis
paraneoplastic Ab’s (3) and non-malignant autoimmune dz (3) associated with sensory neuronopathy
- Paraneoplastic
- Anti-Hu
- ANNA-1
- +/- CRMP-5
- Autoimmune
- sjogren’s disease
- Chronic autoimmune hepatitis
- MGUS
- high IgM
- may be associated with anti GD1b
Non-0Chemo Drugs commonly associated with neuropathy (5)
- Isoniazide (preventable with B6 supplementation)
- Metronidazole
- Nitrofurantoin
- Chloroquine / hydroxychloroquine
- Lithium
Dystproteinemic neuropathies
- % of patients with peripheral neuropathy with monoclonal gammopathy
- Most common Ig subtype
- Specific disease associations with certiain Ig subtypes:
- IgM Kappa (2)
- IgG > IgA
- Lambda (2)
- 5-10% (though may not be associated with neuropathy)
- Most commonly associated with IgM (though igG and IgA are commonly found)
- Associated Ig subtypes
- IgM kappa:
- MGUS
- Waldenstrom macroglobulinemia
- IgG>IgA
- multiple myeloma
- Lambda
- POEMS (almost always)
- AL amyloidosis
- IgM kappa:
Distal acquired demyelinating syndrome associated with MGUS (DADS-M)
Typical Ig subtype
Features (3)
Ab note
EMG note
Treatment note
- Typically IgM-Kappa
- Features
- slow/insidious sensory loss and gait imbalance
- minimal pain
- intention tremor
- AB note: 50% have Ab to MAG
- EMG note: Very prolonged distal latencies
- Poor response to IVIG and steroids
Primary Symmetric Amyloidosis
What is it / mechanism (2)
general rule about when to consider
Features (7)
pathology
- What are they?
- group of disorders resulting from extracellular deposition of amyloid
- AKA “AL” > light chain protein misfolds and forms beta-pleated sheet > organ dysfunction
- Consider in any patient w/ peripheral neuropathy and prominent autonomic features, particularly with no hx of diabetes
- Features
- Typically male (2/3) > 60 years old
- Fatigue / weight loss
- Peripheral neuropathy
- nephrotic syndrome / renal failure
- hepatomegaly
- CHF
- Autonomic neuropathy w/ prominent orthostatic hypotension
- Pathologic hallmark
- congo-red stained deposits = apple green birefringence
Familial amyloid polyneuropathy
Inheritance
Features (5)
treatment
Inheritance: AD (for most common type, TTR-related FAP)
Features
- Small-fiber neuropathy w/ autonomic features
- carpal tunnel is common
- cardiac dysfunction (arrythmia, heart block, heart failure)
- vitreous involvement
- renal involvement
Treatment: liver transplant
Characteristics of Demyelinating neuropathies
Type of neuropathy (2)
Pathologic findings and results (1)
Clincial clues (4)
- Segmental demyelination
- Implies injury of either myelin sheath or schwann cells
- Axons are spared
- Pathologic findings
- “onion bulb” resulting remyelination of multiple layers of schwann cells around Axon
- Clinical clues
- early, generalized loss of reflexes
- Disproportionately mild muscle atrophy in presence of both proximal and distal weakness.
- neuropathic tremor
- palpably enlarged nerves (possibly)