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Neurology Lectures > Myopathy (Lozowska) > Flashcards

Myopathy (Lozowska) Flashcards

1
Q

When evaluating a patient with generalized weakness, what should you ask?

  • _____ is the lesion?
  • if the lesion is in the muscle, what is the _____?
  • What is the _____?
  • What is the ____?
  • Is it ____ or _____
  • Any associated __, __, __
A
  • Where
  • Pattern
  • Age of onset
  • tempo (time course)
  • hereditary or acquired
  • Sx, complications, medications
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2
Q

What are some potential locations for the lesion?

A
  • corticospinal
  • anterior horn cell (spinal cord)
  • peripheral nerve (motor, sensory, sensorimotor, autonomic)
  • NMJ
  • MUSCLE
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3
Q

Describe the potential patterns of involvement:

A
  • Symmetric, asymmetric
  • Cranial (bulbar weakness) vs axial vs limb
  • proximal, distal, generalized
  • ocular vs fascioscapulohumeral vs scapulohumeral vs forearm flexor and knee extensor
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4
Q

What is the time course? Can include?

A
  • Acute: hrs to wks
  • Subacute: 4 wks to 2 mos
  • Insidious (>2 mos)
  • Relapsing - fluctuating
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5
Q

These help to distinguish?

  • Examining affected and asymptomatic relatives
  • Drawing a pedigree
A

If hereditary vs acquired

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6
Q

What are some associated symptoms that go along with myopathies?

A
  • cardiomyopathy
  • pulmonary
  • rheumatologic
  • renal
  • liver
  • infectious
  • malignancy
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7
Q

If myopathy is toxin related, what could it be from?

A
  • Medications
  • Alcohol
  • Illicit drugs
  • Environmental
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8
Q

What are some differential diagnoses for myopathy in infancy?

A
  • congenital myopathy
  • muscular dystrophy (anticipation)
  • Mitochondrial
  • Metabolic (glycogen and lipid storage defects)
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9
Q

What are some differential diagnoses for myopathy in childhood?

A
  • Congenital myopathy
  • Muscular dystrophy
  • Mitochondrial
  • Metabolic (glycogen and lipid storage defects)
  • Periodic paralysis
  • Toxic
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10
Q

What are some differential diagnoses for myopathy presenting in adulthood?

A
  • Inflammatory myopathy [dermatomyositis, polymyositis, IBM]
  • Toxic
  • Sarcopenia [diffuse atrophy related to age, systemic illness, steroids]
  • Mitochondrial
  • Metabolic (glycogen and lipid storage defects)
  • Muscular dystrophy
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11
Q

See photo for patterns of distal weakness - but these include?

A
  • FSH
  • Scapuloperoneal
  • EDMD - emery dreifuss
  • IBM
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12
Q

These following disorders present with ___ or ___?

  • Mitochondrial myopathy
  • OPMD
  • Myotonic dystrophy
  • Congenital myopathy
A

ptosis or ophthalmoparesis

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13
Q

With suspected myopathy - how should you evaluate?

A
  • Look, listen, feel myotonia and rippling muscle
  • Detailed history
  • EMG/NCS for myopathic vs neuropathic
  • Lab work up (CPK)
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14
Q 
Ask about... 
- grip strength, turning door knobs
- opening jars
- standing on tip-toes
- tripping
- fatiguing easily
- getting up from the floor
- losing complex motor function, up from kneeling, jump on one foot, squat
.... to assess?
A

assess LEVEL OF FUNCTION

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15
Q

What are the neuromuscular symptoms to ask about?

A
  • Myalgias, cramps
  • muscle stiffness
  • fasciculations
  • myoglobinuria, pigmenturia
  • hypertrophy, atrophy
  • **typically lack of bowel, bladder, sensory complaints
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16
Q

FYI:

  • clinical examination
    • CN involvement - jaw movement, dysarthria, ophthalmoparesis, ptosis
    • Shoulder girdle weakness
    • LE weakness
    • Motor: tone, bulk, myokymia, paramyotonia/myotonia, myoedema
A 
Labs: 
- CK
- AST, ALT, LDH, Aldolase
[10% of myotonic dystrophy has normal CK, but high aldolase]
- DNA analysis
- Dried blood spot for pope disease
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17
Q

What test?

  • confirms a clinical impression
  • provides insight into underlying pathophysiology
  • helps localize the lesion when its not apparent by HPI
  • Can tell if its acute, chronic, both
  • Can “hear” myotonia, myokymia

*** What muscles to do?

A

EMG

*** 2 muscles in arm, leg, thoracic paraspinals, checking for insertional activity, spontaneous activity, MUAP morphology, recruitment

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18
Q

What test?

  • Fat suppression STIR images show distinct patterns in various myopathies
  • Radiologists and neurologists are able to interpret these
A

MRI in muscle

19
Q

What test?

  • Use this in weak muscle, MRC grade 4 or above
  • EMG can be used to help guide
  • Different stains to diagnose inflammatory, dystrophy, mitochondrial, metabolic, neurogenic
  • Not useful in subjective complaints
A

Muscle biopsy

20
Q

Diagnosis?

  • X-linked recessive disorder, 1/3 result from spontaneous mutations
  • Rare: hypotonic and weak boys at birth
  • Wide based, waddling gait and noted by about 2-6 yoa
  • Calf hypertrophy
  • Difficulty climbing stairs by age 8
  • Arms and trunk are affected by age 6-12
  • Ambulation becomes progressively difficult - wheelchair by 12
  • Progressive scoliosis, often spinal fusion required

***GOWER’s sign - weakness of proximal muscles in lower limb

***Trendelenburg gait - [gluteus muscle lurch] abnormal gait caused by weakness of the abductor muscles of the lower limb, gluteus medius and minimus - weakness of abducting thigh at the hip

A

Duchenne Muscular Dystrophy

21
Q

What leads to death in most DMD patients by early 20’s

  • What other muscle can be involved?
  • Most patients are asymptomatic early in the course, but these later develop.
  • Serum CK is elevated 50-100x normal, peak around what age? Never normalize, but decrease about 20% per year
  • Western blot analysis of muscle usually reveals reduced or absent ____ in DMD
A

Respiratory function decline

  • Cardiac muscle - dysrhythmias, CHF
  • age 3!
  • Dystrophin
22
Q

Diagnosis?

  • Milder form of dystrophinopathy, slower rate of progression than DMD
  • Ambulatory past 15, by age 40 50% can’t
  • Western blot shows abnormal quantity/size of dystrophin protein

*** What is the treatment of DMD?

A

Becker Muscular Dystrophy

***Prednisone 0.75 mg/kg daily; Exondys51 (eterplirsen)

23
Q

Diagnosis?

  • _______ - weakness early on, contractors of joints, hyper extensible distal joints, high arch palate
  • ______ - allelic (collagen V!)
  • ______ - classic type
  • ______ - associated with brain abnormalities
  • Walker Warburg syndrome
A
  • Ulrich dystrophy
  • Bethlehem
  • Merosin
  • Fukuyama
24
Q

Diagnosis?

  • Caused by mutations in calpain, sarcoglycan (4 types), mersin, dystroglycan, titin, caveolin, desmin
  • Type 1, AD
  • Type 2, AR
  • CK levels elevated from 10-30x of normal
A

Limb Girdle Muscular Dystrophy

25
Q

Limb girdle muscular dystrophy 2B

  • _______ myopathy
  • type ? with ?
A

Myioshi myopathy

Type 1, dysferlin

26
Q

Diagnosis?

  • FSHD2: About 5% of individuals with this have a mutation found on SMCHD1 gene
  • FSHD1: onset of weakness is usually appreciated between 3 and 44 years, although onset as late as 75 years has been reported
  • telomere region of chromosome ______
  • EcoRI polymorphism is reduced compared to normal 10-30 (normally 50-300), within lies a tandem array of D4Z4
A

Fascioscapulohumeral muscular dystrophy
- 4q35

(downsloping shoulders, protruding scapula)

27
Q

What sign in FSH?

Umbilicus is displaced towards the head due to paralysis of inferior rectus abdomens (95% sensitive, 93% specific

A

Beevor sign

  • paralysis of lower rectus abdominis
28
Q

Diagnosis?
Atrophy of the finger flexors and knee extensors
- most common myopathy in patients with age > 50 years
- distinctive pattern of weakness
- gradual progression, no generally effective treatment
- “looks like refractory polymyositis”

A

Inclusion body myositis

29
Q

Diagnosis?

  • Disorders of carbohydrate metabolism
  • ATP yields energy
  • _______ defined by the presence of fixed or progressive weakness
  • _______ associated with exercise intolerance
A

Metabolic myopathy

  • Static myopathies
  • Dynamic myopathies
30
Q

Metabolic myopathies:

  • Long chain acylCoA must link with carnitine to cross over the outer mitochondrial membrane
  • __________: AR. Symptoms are bouts of rhabdomyolysis, with recurrent myoglobinuria. Precipitated by fasting or prolonged exertion by second decade of life.
  • Mutation in _______ (genetic testing available). Light microscopy can show increased lipid content of muscle
  • A high protein, low-fat diet with frequent meals and avoidance of prolonged stenuous activity, cold temperatures, and fasting may prevent episodes of rhabdomyolysis
  • During febrile illness, patients should be instructed to increase their intake of ________ and again avoid _____
A
  • CPT2 deficiency
  • CPT2 gene
  • complex carbohydrates, fasting
31
Q

What test?
- test can be used to diagnosis various disorders of glycolysis like myophosphorylase, phosphofructokinase, phosphoglycerase mutase, phosphoglycerase kinase, phosphorylase b kinase, debrancher, and lactate dehydrogenase deficienciesDo without a cuff

  • Check blood samples immediately, 1, 2, 4 min after 1 min exercise
  • Lactic acid doesn’t rise but NH3 does (normally both should rise)
A

Exercise Forearm Test

32
Q

Diagnosis?

  • the most common disorder of carbohydrate metabolism that usually presents with exercise intolerance in childhood or young adults
  • Patients complain of exertional muscle pain and cramps induced by brief, but very intense, activities but they can also occur following prolonged low-intensity exercises
  • Second wind phenomena (after the onset of mild exertional myalgias or cramps muscle pain eases and the individual may continue with the exercise at a slightly reduced level)
  • Elevated CK, normal EMG, biopsy shows accumulated glycogen
  • Do warm up exercises, avoid weight lifting or sprinting
A

McArdle’s Disease

33
Q

Diagnosis?

  • Accumulation of glycogen vacuoles in muscle fibers
  • Symptoms are macroglossia in infants, generalized weakness, cardiomegaly, hepatomegaly, Feeding difficulty
  • Fatal by age 2 due to cardiorespiratory failure
  • Adult onset in third decade with proximal>distal weakness and respiratory insufficiency
  • check ___________ activity
  • CK moderately elevated but may be normal, - Echo and PFT are abnormal, EMG and EKG abnormal

Treatment: ________ (rhGAA) produced by recombinant technology
Recommended dose: 20 mg/kg q2wk by IV infusion

A

Pompe Disease

  • alpha glucosidase

Tx. Alglucosidase

34
Q

Diagnosis?
- Decreased ATP production in mitochondria causes cellular energy failure
- Symptoms are decreased exercise capacity, decreased stamina cramps
(red-rimmed vacuoles)

Tx. Supportive care, cofactors, vitamin cocktail and diet therapy

A

Mitochondrial Myopathy

35
Q

______: delayed relaxation following contraction, improves with repeated activity

___________ = paramyotonia: worsens with repeated activity

________ – firing waxing and waning after needle movement

Symptoms: can’t open eyes after forcible closure, or open hands

A

Myotonia

Paradoxical myotonia

Electrical myotonia

36
Q

________ is the recognized, distinguishing hallmark of myotonic dystrophy. There is abnormality of the muscle fiber membrane (sarcolemma) that results in an extended delay before muscles can relax after a contraction. The electrical activity continues after the nerve signal has ended, causing a stiffness or “locking up” of the muscle.

  • may be related to decreased chloride ion conduction across the sarcolemma.
A

Myotonia

37
Q

Myotonic disorders:

Dystrophic myotonia
Type 1: ___ repeats in ____ on chrom __
Type 2 (PROMM): ___ repeats in ____ on chrom __

Non-dystrophic myotonia

  • ___channel (ClCn1) myotonia congenita
  • ___channel (ScN4) paramyotonia congenita, K sensitive periodic paralysis
A

Dystrophic myotonia
Type 1: CTG repeats in DMPK on chrom 19
Type 2 (PROMM): CCTG repeats in ZNF9 on chrom3

Non-dystrophic myotonia

  • Cl channel (ClCn1) myotonia congenita
  • Na channel (ScN4) paramyotonia congenita, K sensitive periodic paralysis
38
Q

Myotonic dystrophy _____: muscle weakness, myotonia, cataracts, cardiac conduction abnormality, early sudden death
-congenital: hypotonia, MR, facial diplegia, early death

Myotonic dystrophy____: onset 20-60 years, myotonia inlimb and facial muscles, neck flexion weakness

  • -Work up for both: genetic testing, muscle biopsy
  • -Facial diplegia (triangular face, fish mouth)
A

Type 1

type 2

39
Q

How is myotonic dystrophy managed?

  • Medications?
  • Annual ___ and cardiology visit
  • PFT for OSA
  • Warn about general anesthesia complications due to neuromuscular blocking agents (succinylcholine)
  • _______ excision
A
  • phenytoin, carbamazepine, mexilletine, procainamide
  • EKG
  • Cataract
40
Q

Diagnosis?

ClCn1 gene mutation:
Thomsen is dominant myotonia congenita
Becker is recessive myotonia congenita

SCN4A mutation:
Paramyotonia congenita
K aggrevated myotonia: sensitive to exercise and K
Periodic paralysis: episodic attacks.

  • Tx: ?
A

Non-dystrophic myotonia

  • Tx: acetazolamide, dichlorphenamide
41
Q

Diagnosis?

  • Proximal limb weakness
  • CK is normal in dermatomyositis, always high in polymiositis and modestly increased in IBM
  • Polymiositis is painful to palpation and causes myalgias
  • In IBM there is atrophy of thighs and forearms
  • Check _______ ab (interstitial lung disease)
  • Malignancy evaluation in dermatomyositis
  • PFT
  • EMG and muscle biopsy
A

Inflammatory myopathy

Anti Jo1 ab

42
Q

Medications to treat?

  • Long term steroids
  • Steroid sparing agents
  • MTX, imuran , cell sept,
  • IVIG
A

Polymyositis, dermatomyositis (will see cutaneous and subcutaneous calcification, Grotton’s papules, heliotrope rash, miniaturization of fibers on the periphery)

43
Q

Diagnosis?

  • Subacute or chronic predominantly proximal weakness
  • Very heterogeneous – can be in association with other connective tissue disorders (overlap syndrome)
  • Need to carefully exclude inclusion body myositis and limb‐girdle muscular dystrophies

*with endomysial inflammation

A

Polymyositis

Neurology Lectures (12 decks)

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