Diseases of muscle

Question 1

Give the 5 limited symptoms of muscle disease?

Answer 1

1) Wasting
2) Pain
3) Cramping
4) Fasciculations
5) Weakness

Question 2

What are the 5 clinical muscle investigations?

Answer 2

1) Clinical examination (neurological)
2) Electromyograph
3) Nerve conduction studies
4) MRI
5) Serum/ Blood investigations

Question 3

Give 3 common sights of muscle biopsy?

Answer 3

1) Deltoid
2) Biceps
3) Quadriceps

Question 4

What does the term limb-girdle muscular dystrophy refer to?

Answer 4

Group of rare inherited disorders which predominantly affect the muscles around the shoulder girdle and hip girdle causing progressive muscle weakness eg. Duchenne muscular dystrophy

Question 5

What is the pattern of inheritance of Duchenne muscular dystrophy?

Answer 5

X linked recessive

Question 6

What are the 4 clinical features of Duchenne muscular dystrophy?

Answer 6

1) Relentlessly progressive muscle wasting
2) Chair-bound by 12 years
3) Proximal muscle weakness
4) Hypertrophy of calves

Question 7

What is the pattern of inheritance of Emery-Dreifuss Muscular dystrophy?

Answer 7

X linked recessive

Question 8

What are the 3 clinical features of emery-dreifuss muscle dystrophy?

Answer 8

1) Weakness of proximal arm and distal leg muscles
2) Early contractures
3) Cardiomyopathy

Question 9

What is the pattern of inheritance of core disease?

Answer 9

Autosomal dominance

Question 10

Core disease is a defect of what kind of protein?

Answer 10

Myofribilar and internal cytoskeletal proteins

Question 11

Duchenne muscular dystrophy is a disease of which part of the muscle?

Answer 11

Plasma membrane

Question 12

When is core disease usually detected?

Answer 12

When the child starts walking

Question 13

How is core disease defined?

Answer 13

The central core is a well demarcated zone in the center of a muscle fibre, devoid of normal histochemical activity.

Question 14

In core disease, cores only occur in what type of fibres?

Answer 14

Type 1 fibres

Question 15

Nemaline myopathy is a disease of what proteins?

Answer 15

Myofibrillar and internal cytoskeletal proteins

Question 16

Nemaline myopathy has what kind of inheritance pattern?

Answer 16

Autosomal recessive

Question 17

What are the 4 clinical features of nemaline myopathy?

Answer 17

1) Generalised neonatal hypotonia
2) Resp insufficiency
3) High arched palate
4) Kyphoscolioisis

Question 18

Malignant hyperthermia is a disorder of what part of the muscle?

Answer 18

Ion channels and ion transporters

Question 19

What is malignant hyperthermia?

Answer 19

Abnormal susceptibility to certain inhalational anaesthetics which leads to a prolonged rise in intracellular calcium ions leading to rigid contractions and elevation in body temp

Question 20

What are the muscle biopsy changes in malignant hyperthermia?

Answer 20

Mild and non specific

Question 21

Myotonic dystrophies are due to what kind of genetic defect?

Answer 21

Repeat expansion

Question 22

What is the pattern of inheritance of myotonic dystrophy?

Answer 22

Autosomal dominant

Question 23

What is the age of onset of myotonic dystrophy?

Answer 23

20-30 years

Question 24

What are the 2 clinical features of myotonic dystrophy?

Answer 24

1) Myotonia and progressive weakness of facial muscles

2) Cardiac conduction defects

Question 25

Fascioscapulohumeral dystrophy has what kind of inheritance pattern?

Answer 25

Autosomal domiant

Question 26

When does fascioscapulohumeral dystrophy present?

Answer 26

In early adult life

Question 27

In addition to the skeletal muscle effects, what are the 3 other clinical features of fascioscapulohumeral dystrophy?

Answer 27

1) Myocardium affected
2) Progressive deafness
3) Retinal vasculopathy

Question 28

What is the pathology of myasthenia gravis?

Answer 28

Autoimmune disease with Ab usually IgG, against the acetylcholine receptor

Question 29

Is muscle biopsy an appropriate diagnostic test for myasthenia gravis? What changes may be seen on biopsy?

Answer 29

NOT an appropriate diagnostic test

May see mild changes of denervation atrophy

Question 30

What is Eaton-Lambert Myasthenic Syndrome?

Answer 30

Rare, non metastatic manifestation of malignancy - usually oat cell carcinoma of the bronchus

Question 31

Are any changes seen on biopsy in Eaton-lambert Myasthenic Syndrome?

Answer 31

No specific changes seen

Question 32

Mitochondrial myopathies are related to what defect?

Answer 32

Respiratory chain defects

Question 33

What are the 3 histological changes in mitochondrial myopathy?

Answer 33

1) Ragged red fibres
2) Accumulation of lipid on Oil red O stain
3) Biopsy may be relatively normal

Question 34

What is dermatomyositis?

Answer 34

Inflammatory myopathy responsible for chronic debilitating disease, associated with a scaly rash

Question 35

What is the most common type of drug-induced myopathy?

Answer 35

Steroid induced myopathy

Question 36

Steroid induced myopathy leads to what 2 histological changes?

Answer 36

1) type 2 fibre atrophy

2) Increase in lipid droplets

Question 37

What is the most serious drug induced myopathy caused by?

Answer 37

Heroin and ecstasy

Question 38

What are the 3 clinical features of heroin and ecstasy induced myopathies?

Answer 38

1) Necrotising myopathy causing: rhabdomyolysis
2) Myoglobinuria
3) Renal failure

Question 39

In addition to steroids, heroin and ecstasy what other drug can cause myopathy?

Answer 39

Statins

Question 40

What is motor neuron disease characterised by?

Answer 40

Progressive disease of middle to old age which is characterised by widespread degeneration of motor neurons

Question 41

What cells are involved in MND? 3

Answer 41

1) Anterior horn cells
2) Brain stem nuclei
3) Betz cells

Question 42

What are the clinical features of MND?

Answer 42

Upper and lower motor neuron signs with wasting associated with spasticity and brisk reflexes

Question 43

Which 3 endocrine disorders can lead to myopathies?

Answer 43

1) Glucocorticoid
2) Thyroid
3) Parathyroid
4) Growth hormone
5) Insulin