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Neuro Clerkship > Myopathy > Flashcards

Myopathy Flashcards

1
Q

What are the three major groups of myopathies?

A
  • Muscular dystrophies (dystrophic: fiber splitting + ^ CT)
  • Inflammatory myopathies
  • Metabolic myopathies
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2
Q

Duchenne Muscular Dystrophy:

  • Inheritance
  • Chromosome
  • Onset
  • Initial Weakness
  • Rate of progression
  • CK
  • EKG
  • Muscle biopsy?
A
  • XR; 1/3 spontaneous
  • Xp21, large deletion
  • Onset 5 yoa
  • Pelvic weakness first; (+) Gower’s sign
  • Rapidly progressive
  • ^^^CK
  • Abnormal EKG
  • Muscle biopsy shows MQ invasion, necrotic fibers
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3
Q

Becker Muscular Dystrophy:

  • Inheritance
  • Chromosome
  • Onset
  • Initial Weakness
  • Rate of progression
  • CK
  • EKG
A
  • XR; Xp21
  • Onset 10 yoa
  • Pelvic weakness first
  • Slower progression
  • ^^CK (more moderate)
  • Abnormal EKG
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4
Q

Face-Scapulo-Humoral

  • Inheritance
  • Chromosome
  • Onset
  • Initial Weakness
  • Rate of progression
  • CK
  • EKG
A
  • AD; chromosome 4
  • Onset 10-20 yoa
  • Initial shoulder weakness w/ early facial weakness
  • Slow progression
  • Normal CK and EKG
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5
Q

Myotonic Muscular Dystrophy

  • Inheritance
  • Chromosome
  • Onset
  • Initial Weakness
  • Rate of progression
  • CK
  • EKG
A
  • AD; chromosome 19
  • Onset 15-30 yoa
  • DISTAL weakness first** w/ early facial weakness
  • Slow progression
  • Normal CK w/ abnormal EKG
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6
Q

Limb Girdle Muscular Dystrophy

  • Inheritance
  • Chromosome
  • Onset
  • Initial Weakness
  • Rate of progression
  • CK
  • EKG
A
  • AR or AD; mult. chroms
  • Onset 10-30 yoa
  • Pelvic- shoulder weakness first; spares the face
  • Slowly progressive
  • ^ CK
  • Occasionally abnormal EKG
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7
Q

Compare the pathophys of Duchenne and Becker’s musculodystrophy: which mutations are in frame vs. out of frame?

A
  • Duchenne is out of frame
  • Beckers is in frame

Both result in deficient dystrophin, weak sarcolemma, and muscle necrosis

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8
Q

What are the clinical features of Duchenne’s Muscular Dystrophy?

A
  • Waddling gait, pseudo hypertrophy of calves, lumbar lordosis, weak neck flexors
  • Wheel chair at 13 yoa
  • Cognitive impairment
  • GI pseudoobstruction
  • Cardiomyopathy and death by 20yoa form cardio/resp failure
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9
Q

How do we treat Duchennes?

A

Steroids; delazacort at 4yoa

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10
Q

What are the clinical features of a DMD carrier; how many carriers demonstrate sx?

A
  • 8% have sx
  • Asstd with X inactivation: patients have mild myalgia, CVD, Cognitive, bx issues
  • ^ CK, ^ aldolase
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11
Q

Describe how Beckers differed from DMD:

A
  • Onset 12 yoa; ambulatory into adulthood; live beyond 30 yoa
  • Less likely cognitive, CVD, contractors, scoliosis, GI issues
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12
Q

Facioscapulomumoral MD:

What are the clinical features?

A

Slowly progressive wasting of facial, scapular, humeral, and perineal muscles (winged scapula)

No reduction in life expectancy

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13
Q

List some features of Myotonic Dystrophy 1 that differentiate it from Myotonic dystrophy 2: (4)

A

MD1:

  • Distal weakness
  • Congenital; DMPK gene; anticipation
  • Cataracts, Cardio problems
  • MR, avoidant personality
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14
Q

What differentiates Myotonic Dystrophy 2 from Myotonic dystrophy 1?

A

MD2:

  • Proximal weakness
  • Rare; zinc finger protein 9 gene mutation
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15
Q

Limb Girdle MD:

  • What are the general features of this disease
  • Two common comorbidities
  • Pace of the typical course
  • Which is dominant and which is recessive?
A

Slowly progressive hip and shoulder weakness

Commonly comorbid with cardiorespiratory problems

Slowly progressive, symmetric, proximal

Type 1 is dominant; type 2 is recessive

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16
Q

Emmy Dreifuss MD, Type 1 vs Type 2:

  • What are the mutant proteins
  • What is the inheritance pattern
  • Which has contractures?
  • What is a common comorbidity associated with both?
A
  • 1 = Emerin; 2 = Lamin A/C
  • Type 1 always XR; type 2 may be dominant or recessive
  • Type 1 has contractures before weakness
  • Both have cardiac comorbitities; type 1 specifically conduction abnormalities
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17
Q

Oculopharyngeal Muscular Dystrophy:

  • Inheritance pattern
  • Age of onset
  • Clinical features
  • Treatment
A
  • AD; onset in middle age
  • Ptosis, EOM and limb weakness, dysphagia
  • Treat with oculoplasty and PEG
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18
Q

Dermatomyositis:

  • Rash?
  • Location of weakness?
  • Age of onset? Population?
  • Asstd w cancer?
  • Response to steroids?
  • CK?
  • EMG
  • Muscle biopsy findings
A
  • Rash present
  • Proximal weakness
  • Bimodal onset: kids, 40+
  • Asstd w breast cancer; Women»>
  • Good response to steroids
  • ^ CK
  • Myopathic EMG
  • Muscle biopsy = perifasicular atrophy
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19
Q

Polymyositis:

  • Rash?
  • Location of weakness?
  • Age of onset? Population?
  • Asstd w cancer?
  • Response to steroids?
  • CK?
  • EMG
  • Muscle biopsy findings
A
  • NO RASH
  • Proximal weakness
  • Adult onset; Women»>
  • Asstd w cancer
  • Variable response to steroids
  • ^ CK
  • Myopathic EMG
  • Endopysial Inflammation
20
Q

Inclusion Body Myositis:

  • Rash?
  • Location of weakness?
  • Agoe of onset? Population
  • Asstd w cancer?
  • Response to steroids?
  • EMG
  • Muscle biopsy findings
A
  • NO RASH
  • DISTAL–> Proximal weakness; asymmetric
  • Onset 50+ yoa; Men»>
  • NO assn w cancer
  • Myopathic + neuropathic EMG findings
  • Amyloid Inclusion bodies + rimmed vacuoles on biopsy
21
Q

Which of the inflammatory myopathies can not be treated with immunosuppression?

A

Inclusion body; does not respond well

22
Q

List the three glycogenoses myopathies:

A
  • McArgles (myophosphorylase)
  • Pompe’s (acid maltase)
  • PFK deficiency
23
Q

List the 2 lipidoses myopathies:

A
  • Carnitine Deficiency

- Carnitines Palmityl Transferase Deficiency

24
Q

What are the two channelopathies that cause myopathy?

What are the channels that they compromise?

What are the triggers for sx?

A
  • Hyperkalemic periodic paralysis (SCN4A channels)–triggered by rest after fasting or exercise; better w/ fasting and exercise
  • Hypokalemic periodic paralysis (L type Ca channels):
    Weakness lasting hrs or days w carboloading or exercise
25
Q

Three metabolic myopathies:

A
  • Kearns-Sayre Syndrome
  • MERRF
  • MELAS
26
Q

Glycogen and Lipid Myopathies:

  • Inheritance pattern
  • Clinical présentation
A
  • Most are AR

- Present w exercise intolerance, post-exercise myoglobinuria, ^ CK

27
Q

How does Pompe’s present?

A

Proximal weakness; resp insufficiency

28
Q

How does Cori’s present?

A

Distal weakness; cardiomyopathy, PN

29
Q

Which glycogen storage diseases present with exercise intolerance and myoglobinuria?

How are they differentiated?

A

McArdles, PFK

McArdles has second wind phenomenon

30
Q

When do patients with lipid storage diseases experience symptoms?

What are the sx? (5)

A

Flare ups w fasting

Proximal weakness, tender muscles, ^ CK, recurrent myoglobinuria, lipid vacuoles on biopsy

31
Q

Provoked necrotizing polymyopathy/ Rhabdomyolysis with myoglobinuria

What is the cause?
What are the sx?
How do we treat it?

A

Caused by ETOH abuse or crush injury

Presents with pihgmeturia, swollen/ tender muscles

Treat with IVF, CK monitoring, +/- dialysis

32
Q

Patients with a defect in what enzyme are predisposed to malignant hyperthermia?

A

Phosphodiesterase

33
Q

How does hypothyroid myopathy present? (5)

A
  • muscle cramps
  • mild proximal weakness
  • delayed reflexes
  • myoedema on percussion
  • ^ CK
34
Q

How does Critical Illness Myopathy present?

What is the cause?

A

Patients with sepsis/ malnutrition/ etc + paralytics, steroid tx in ICU–> Myopathy w loss of myosin on biopsy

35
Q

What type of weakness is caused by acromegaly and cushings?

A

proximal; Cushing’s is more in lower extremities

36
Q

Describe the findings on a myopathic EMG

A

Low amplitude, short duration, polyphasic waves with rapid recruitment

37
Q

Steroid myopathy results in what type of weakness?

A

proximal

38
Q

What are some drugs other than steroids that result in myopathy (3)

A
  • Statins (no mevalonic acid)
  • AZT
  • Rheumatology drugs
39
Q

Which is the most common overall muscular dystrophy?

A

Duchenne

40
Q

Which is the most common muscular dystrophy in adults?

A

Myotonic Dystrophy 1

41
Q

Which dystrophy is normally recessively inherited?

A

LGMD type II

42
Q

Which type of dystrophy does not involve the cardiac muscle?

A

Oculopharyngeal muscular dystrophy

43
Q

In a patient with “biopsy proven polymyositis” who does not respond to conventional treatments, what alternative disorder is most likely?

A

Inclusion body myositis

44
Q

Which muscular dystrophy is associated with a triplet repeat?

A

Oculopharyngeal muscular dystrophy; GCG

45
Q

Which muscular dystrophy is associated with rimmed vacuoles on muscle biopsy?

A

Inclusion body myositis

Neuro Clerkship (13 decks)

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