Neuromuscular Disorders Flashcards

1
Q

What are the two main mechanisms by which NMJ disorders occur?

A

Failure to release ACh

Failure to respond to ACh

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2
Q

What is myasthenia gravis?

A

Autoimmune disorder caused by autoantibodies against ACh receptors on the post synaptic end plate

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3
Q

How does myasthenia gravis present?

A

Fatigable muscle weakness worse on activity, better in morning
Slurred speech
Difficulty chewing/swallowing/blinking
Transient double vision

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4
Q

Why is a CT of mediastinum performed in myasthenia gravis?

A

To look for thymoma

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5
Q

How is myasthenia gravis investigated?

A

CT
Autoantibody screen
Nerve conduction study

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6
Q

What antibodies are present in myasthenia gravis?

A

Anti-ACh receptor antibodies

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7
Q

What do nerve conduction studies show in myasthenia gravis?

A

Decreasing response of muscle through repetitive stimulation

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8
Q

How is myasthenia gravis treated?

A

Prednisolone
Pyridostigmine
Azathioprine
Thymectomy

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9
Q

What does pyridostigmine do?

A

Prevents ACh breakdown

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10
Q

What can be used in myasthenia gravis if prednisolone and pyridostigmine are unsuccessful?

A

IV immunoglobulins

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11
Q

What are the main side effects of pyridostigmine?

A

GI upset

Excess saliva

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12
Q

What is Lambert-Eaton Myasthenic Syndrome?

A

Autoimmune NMJ disorder involving antibodies against voltage gated Ca2+ channels

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13
Q

What condition is Lambert-Eaton Myasthenic Syndrome associated with?

A

Small cell lung cancers

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14
Q

How does Lambert-Eaton Myasthenic Syndrome present?

A

Proximal limb weakness, lower limbs affected first

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15
Q

How is Lambert-Eaton Myasthenic Syndrome investigated?

A

Nerve conduction studies and CXR

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16
Q

How is Lambert-Eaton Myasthenic Syndrome managed?

A

3,4-dipyradamine

17
Q

How does 3,4-dipyradamie work?

A

Blocks K+ channels to prolong Ca2+ influx

18
Q

What can be used in resistant Lambert-Eaton Myasthenic Syndrome?

A

IV immunoglobulins or plasma exchange

19
Q

How is Duchenne’s Muscular Dystrophy inherited?

A

X-linked recessive

20
Q

Where is the mutation in duchennes muscular dystrophy?

A

Dystrophin gene

21
Q

How does Duchenne’s present?

A

Delayed motor milestones
Gower’s manoeuvre
Calf pseudohypertrophy

22
Q

How is Becker’s muscular dystrophy inherited?

A

X-linked

23
Q

What conditions do people with Becker’s muscular dystrophy get in their 20s?

A

Cardiomyopathies

24
Q

How is myotonic dystrophy inherited?

A

AD

25
Q

How does myotonic dystrophy mostly commonly present?

A

Distal limb weakness
Stiffness
Myotonia

26
Q

What endocrine conditions are associated with myotonic dystrophy?

A

Diabetes mellitus

Pituitary dysfunction