58 Musculoskeletal 3 Flashcards

1
Q

Which investigations are use in muscle diseases? (5).

A
Clinical exam.
Electromyograph.
Nerve conductions studies.
MRI.
Serum/Blood investigations.
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2
Q

Name two diseases of the basal lamina:

A

Merlin deficiency.

Integrin VII deficiency (limb girdle syndrome).

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3
Q

What is motor neurone disease?

Which cells does it involve? (3).

A

Widespread degeneration of motor neurones.

Anterior horn cells, brain stem nuclei, Betz cells.

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4
Q

What are the signs of motor neurone disease? (4).

A

Fasciculation.
Wasting.
Spasticity.
Brisk reflexes.

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5
Q

Which gene is responsible for spinal muscular atrophy?

What is the course of SMA?

A

SMN1 gene.
Begins very young to aged 15.
3 severities: very early death to adult survival with disability.

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6
Q

What is the genetic and molecular basis of Duchenne muscular dystrophy?

A

X linked recessive disorder.

Dystrophin protein - uncontrolled Ca entry into cell.

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7
Q

When and how does Duchenne muscular dystrophy present?

A

2-4 years of age.

Proximal muscle weakness with calf muscle hypertrophy. Elevated CPK.

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8
Q

What is the prognosis for Duchenne muscular dystrophy?

A

Wheelchair by 12.

Dead by 25 due to cardiomyopathy.

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9
Q

What is Becker dystrophy?

A

Variant of DMD, with later onset and slower progression.

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10
Q

Which proteins are affected in limb girdle dystrophy? (3)

A

Nuclear membrane related proteins.

Emerins, laminin A/C.

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11
Q

What is limb girdle dystrophy?

Genetic basis?

A

Dystrophy of pelvic/shoulder girdle.

Autosomal recessive condition.

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12
Q

What is the genetic defect seen in facioscapulohumeral dystrophy?
Fibre changes?

A

Large telomeric deletion.
Autosomal dominant.
Angular, atrophic fibres.

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13
Q

What are the effects of facioscapulohumeral dystrophy?

Associated with?

A

Weakness of face + shoulder.

Progressive deafness, retinal vasculopathy.

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14
Q

What is the genetic basis of myotonic dystrophy?

A

CTG repeat expansion in X19.

Autosomal dominant.

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15
Q

When is the onset of myotonic dystrophy?

What are the effects? (4)

A

Onset 20-30 years.
Weakness of face, limb girdle + proximal muscles.
Myotonia (persistent contraction after voluntary effort has ceased).

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16
Q

What are the histological changes seen in myotonic dystrophy? (4)

A

Type 1 fibre atrophy.
Type 2 fibre hypertrophy (compensation).
Central nuclei.
Motheaten, targetoid + ring fibres.

17
Q

What is polymyositis?

How does it present?

A

Inflammatory muscle disorder.

Weakness, pain and swelling of proximal muscles.

18
Q

What is dermatomyositis?

A

Complement deposition in capillaries causes muscle ischaemia.

19
Q

What are the histological findings in polymyositis and dermatomyositis?

A

Perimysial inflammation with B cells.

Endomysial inflammation with T cells.

20
Q

How is polymyositis treated?

A

Corticosteroids and azathioprine.

21
Q

What is inclusion body myositis? (3)

A

Clinically like polymyositis. But…
Shows filamentous intracellular inclusions.
Responds poorly to corticosteroid + azathioprine.

22
Q

How do congenital myopathies present? (2)

Name two:

A

Hypotonia + floppiness in infancy.
Congenital fibre type disproportion.
Congenital nuclear myopathy.

23
Q

What is the cause of malignant hyperthermia?

A

Prolonged rise in intracellular calcium ions.

24
Q

How does myasthenia graves present?

Age/sex, effects (3)

A

Female 20-30.

Fluctuating weakness affecting ocular, bulbar and proximal muscles.

25
Q

What is the molecular basis of myasthenia graves?

What is it commonly associated with?

A

IgG against ACh receptor proteins.

Thymus hyperplasia.

26
Q

What is Lambert-Eaton myasthenic syndrome?

How does it present?

A

Paraneoplastic disorder associated with small cell carcinoma of lung (oat cell cancer).
Weakness of proximal muscle and girdles.

27
Q

What is the molecular basis of Lambert-Eaton myasthenia syndrome?

A

IgG binds to pre-synaptic calcium channels, preventing release of ACh.

28
Q

What changes are seen on muscle biopsy in myasthenia syndromes?

A

No specific/little changes.

29
Q

Where are muscle biopsies taken from? (3).

A

Deltoid.
Biceps.
Quadriceps.

30
Q

What is core disease:
Genetics:
Histology:
Presentation?

A

Autosomal dominant.
Cores of inactivity to NADH-Tr in type 1 fibres.
When child starts to walk.

31
Q

How does nemaline myopathy present? (4)

Genetics?

A

Neonatal hypotonia.
Respiratory insufficiency.
High arched palate.
Kyphoscoliosis.

Autosomal recessive.

32
Q

What histological changes are seen in mitochondrial myopathies?

A

Whorled cristae.

Accumulation of lipid on Oil Red O stain.

33
Q

Which drugs can induce myopathy? (3).

A

Statins.
Steroid.
Heroin/ecstasy:

34
Q

What type of myopathy does heroin and ecstasy precipitate?

Features? (3).

A

Acute necrotising myopathy.

Rhabdomyolysis.
Myoglobinuria.
Renal failure.