AWABS - Myopathies Flashcards

1
Q

Classification of myopathies

A

Primary
Secondary

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2
Q

Primary myopathies

A

Muscular (muscular dystrophy)
Congenital
Metabolic

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3
Q

Acquired myopathies

A

Metabolic and endocrine
Dermato- and poly- myositis
Drug induced
Infectious
?Polymyalgia ?Fibromyalgia

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4
Q

Metabolic myopathies

A

Glycogen storage
Lipid storage

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5
Q

Muscular dystrophy features

A

Involves dystrophin
Inherited
Progressive

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6
Q

Muscular dystrophy synptoms

A

Inability to regenerate
Proximal weakness
Respiratory involvement eventually
Myotonia

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7
Q

Types of muscular dystrophy

A

Dystrophia myotonica
Becker’s
Thomsen’s
Duschenne’s muscular / myotonic dystrophy

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8
Q

Congenital myopathy features

A

Rare
Genetic defects lead to protein defects
Non progressive
Reduced contractile ability

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9
Q

Metabolic myopathy features

A

Hereditary enzyme defects
Errors in metabolism of ATP

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10
Q

Examples of glycogen storage diseases

A

Pompe’s disease
McArdle’s disease

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11
Q

Enzyme affected in Pompe’s disease

A

Acid maltase

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12
Q

Enzyme affected in McArdle disease

A

Myophosphorylase

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13
Q

Examples of lipid storage diseases

A

Carnitine palmitoyltransferase deficiency
Myopathic carnitine deficiency

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14
Q

Examples of acquired metabolic and endocrine myopathies

A

Thyroid disease
Parathyroid disease
Pituitary disease eg Addison’s
Corticosteroids eg Cushing’s
Diabetes

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15
Q

Acquired infectious causes of myopathy

A

Trichinosis
Toxoplasmosis
HIV
Coxsackie
Lyme disease
Influenza

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16
Q

Acquired drug induced causes of myopathy

A

Statins
Steroids
Alcohol
Cocaine
Colchicine

17
Q

Most common form of myopathy

A

Drug induced

18
Q

Incidence of Duchenne’s muscular dystrophy

A

1:4000 in boys

19
Q

Features of Duchenne’s

A

Progressive muscular wasting
Poor balance
Drooping eyelids
Atrophy
Scoliosis
Waddling gait
Cardiomyopathy

20
Q

Genetics of Duchenne’s

A

X linked recessive

Mutation on dystrophin gene at locus Xp21

21
Q

Ix for Duchenne’s

A

Raised CK
EMG
Genetic testing
Muscle biopsy

22
Q

Rx of Duchenne’s

A

High dose steroids
Ataluren
Exercise / Physio

23
Q

Role of steroids in Duchenne’s

A

Increase muscle strength
Reduce Symptoms
Prolong life

24
Q

Dystrophin features

A

Large cytosolic protein
Hydrophobic
Rod shaped
Connects cytoskeleton to extracellular matrix

25
Q

Becker’s dystrophy genetics

A

Same as Duchenne’s

26
Q

Features of Becker’s

A

More rare than Duchenne’s
Later onset (teens)
Milder
Normal life expectancy
Dilated cardiomyopathy

27
Q

Features of dystrophia myotonica (myotonic dystrophy)

A

Inherited
Slow progressing
Difficulty initiating movement
Cataracts
Cardiac conduction defects

28
Q

Categories of Dystrophia myotonica

A

DM1
DM2

29
Q

Features of DM1

A

Steinert disease
Severe congenital
Childhood

30
Q

Features of DM2

A

Proximal myotonic myopathy
Adult onset
Rare

31
Q

Genetics of dystrophia myotonica

A

Autosomal dominant

32
Q

Features of acid maltase deficiency

A

Resp failure
Pulmonary HTN
Cardiomegaly
Aspiration risk

33
Q

Lipid storage myopathy features

A

Hypoglycaemia
Acidosis
Rhabdomyolysis
Cardiac failure

34
Q

Management of lipid storage myopathies in perioperative period

A

Require administration of supportive substrates

35
Q

Implication of mitochondrial myopathies for anaesthetics

A

Worsened by depressant anaesthetics
Maintain normoglycaemia
Avoid suxamethonium
Sensitive to non depolarising NMB so give 10-20% dose
Risk of heart block and seizures
Risk of rhabdo with volatiles - ?use TIVA

36
Q

Features of peripheral neuropathy to distinguish from myopathy

A

Distal muscles affected
Fasciculations
Somatosensory abnormalities
Reduced reflexes