3: Myopathy

Question 1

Define myopathy

Answer 1

symmetrical muscle weakness

Question 2

What are inherited myopathies

Answer 2

muscular dystrophies

Question 3

When does duchenne muscular palsy present

Answer 3

5-years

Question 4

When does Becker muscle dystrophy present

Answer 4

10-years, with milder symptoms

Question 5

What is mcardles disease

Answer 5

Autosomal recessive glycogen storage disease that presents with muscle pain following exercise

Question 6

Describe muscle weakness in myopathies (compared to neuropathies)

Answer 6

• Proximal muscles affected

- Weakness in muscles, wasting is a very late feature

Question 7

Describe reflexes in myopathies

Answer 7

Normal

Question 8

What is a stereotypical story of a myopathy

Answer 8

Person struggles to get out of a chair

Question 9

What test is raised in myopathy

Answer 9

Creatnine kinase

Question 10

What are the inheritance patterns of myotonic dystrophies

Answer 10

Autosomal dominant

Question 11

How many types of myotonic dystrophies are there

Answer 11

2

Question 12

What chromosome is affected in myotonic dystrophy 1

Answer 12

Chromosome 19

Question 13

What chromosome is affected in myotonic dystrophy 2

Answer 13

Chromosome 3

Question 14

In myotonic dystrophy 1, what feature is present

Answer 14

Distal muscle weakness

Question 15

In myotonic dystrophy 2, what feature is present

Answer 15

Proximal muscle weakness

Question 16

What are features of myotonic dystrophies

Answer 16

• Myotonic facies (long haggard appearance)
• Frontal balding
• Bilateral ptosis
• Cataracts
• Dysyarthritis
• Myotonia = tonic muscle spasm
• Weakness arm and legs
• DM
• Testicular atrophy

Question 17

What is myasthenia gravis

Answer 17

Autoimmune condition caused by antibodies raised to postsynaptic acetylcholine receptors

Question 18

Describe epidemiology of myasthenia gravis

Answer 18

Young Females : 20-30 years

Old men: 60-70 years

Question 19

In women, what age are affected by myasthenia gravis

Answer 19

20-30 years

Question 20

In men, what age are affected by myasthenia gravis

Answer 20

60-70

Question 21

What causes myasthenia gravis

Answer 21

Autoantibodies against acetylcholine receptors on post-synaptic membrane

Question 22

What two conditions is myasthenia gravis associated with

Answer 22

• Thymoma

- Thymic hyperplasia

Question 23

What exacerbates symptoms in myasthenia gravis

Answer 23

Exertion

Quinine 
B-blockers 
Penicillamines 
Lithium 
Phenytoin 
Antibiotics

Question 24

Describe diurnal variation in symptoms of myasthenia gravis

Answer 24

Symptoms worsen throughout day with repetitive use

Question 25

What muscles are affected first in myasthenia gravis

Answer 25

Extra-ocular muscles

Question 26

How do eye symptoms of myasthenia gravis present

Answer 26

Ptosis Diplopia Blurred vision

Question 27

What does bulbar nerve involvement cause in myasthenia gravis

Answer 27

Difficultly swallowing, slurred speech, chewing

Question 28

What muscle weakness is present in myasthenia gravis

Answer 28

Proximal muscle weakness

Question 29

How does proximal muscle weakness present

Answer 29

- Difficultly standing from sitting | - Difficultly climbing stairs

Question 30

What is a serious complication of myasthenia gravis

Answer 30

Respiratory muscle involvement

Question 31

What are two signs of myasthenia gravis

Answer 31

Snarl sign | Peep sign

Question 32

What is snarl sign

Answer 32

When patients attempt to smile it appears as a snarl

Question 33

What is peep sign

Answer 33

When patient close their eyes. White of sclera is visible

Question 34

What type of hypersensitivity reaction is myasthenia gravis

Answer 34

Type 2 (IgG mediated)

Question 35

What is myasthenia crisis

Answer 35

Essential muscles - including diaphragm are affected

Question 36

What investigations a performed in myasthenia gravis

Answer 36

Repetitive nerve stimulation AChR antibody testing EMG CT thorax - look for thymoma

Question 37

What are two management options added to all patients with myasthenia gravis

Answer 37

Pyridostigmine (acetyl choline esterase inhibitor) Thymectomy - remove gland

Question 38

what is a myasthenia crisis

Answer 38

acute life-threatening exacerbation of myasthenia gravis with resp muscle involvement

Question 39

how is myasthenia crisis managed

Answer 39

intubation IVIg plasmapheresis

Question 40

what is lambort-eaton myasthenic syndrome

Answer 40

paraneoplastic syndrome caused by antibodies to pre-synaptic voltage-gated calcium channels

Question 41

what cancer is Lambert-eaton myasthenic syndrome most commonly associated with

Answer 41

small cell lung cancer

Question 42

what 3 cancers is lambert-eaton myasthenic syndrome

Answer 42

small cell lung cancer breast ovarian

Question 43

explain symptoms in Lambert eaton myasthenic syndrome

Answer 43

- repeated muscle contraction leads to increase in strength. - Limb girdle weakness - Hyper-reflexia Autonomic symptoms: - Dry mouth - ED - Difficultly micturating

Question 44

what investigation is ordered for Lambert eaton myasthenic syndrome

Answer 44

repetitive nerve stimulation

Question 45

how is lamber eaton myasthenic syndrome managed

Answer 45

- treat cancer | - immunosuppressants (prednisolone, azathioprine)