Clinical Approach to Disorders of the Neuromuscular Junction (Hon) Flashcards

1
Q

What are some disorders that act at the presynaptic region of the NMJ?

A

1) Lambert-Eaton myasthenic syndrome (LEMS)

2) Botulism

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2
Q

What are some disorders that act at the postsynaptic region of the NMJ?

A

Myasthenia gravis

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3
Q

Myasthenia gravis is caused by a defect of neuromuscular transmission due to?

A

An antibody mediated attack upon nicotinic acetylcholine receptors (AChR)

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4
Q

Myasthenia gravis has a high frequency of what HLA haplotypes?

A

1) HLA-B8

2) HLA-DR3

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5
Q

What are general characteristic symptoms of Myasthenia gravis?

A

1) Fluctuating weakness
2) Ocular muscle weakness leading to ptosis and diplopia
3) Clinical response to cholinergic drugs

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6
Q

What antibodies are found with Myasthenia gravis?

A

Acetylcholine receptor antibodies

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7
Q

What EMG finding is seen with Myasthenia gravis?

A

Decremental response on repetitive stimulation

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8
Q

What test can be used to diagnose Myasthenia gravis?

A

Ice Bag Test

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9
Q

What is unique when it comes to prednisone (steroid) treatment with myasthenia gravis?

A

Start with low dose and gradually increase if needed

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10
Q

What antibiotic is the most significant in avoiding with Myasthenia gravis patients?

A

Aminoglycosides

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11
Q

What is Myasthenic crisis?

How does it present?

What is done to treat it?

A

1) Rapid deterioration of the disease
2) Aspirations, respiratory failure
3) Stop anticholinesterase meds and give plasma exchange and IVIg

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12
Q

What is the big clue regarding cholinergic crisis?

A

Presence of miosis and or fasciculations

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13
Q

In Myasthenia Gravis patients that have no detectable anti-AChR Abs, what Antibody can be found instead?

Which sex is more common with this?

A

1) MuSK

2) Women

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14
Q

Lambert – Eaton Myasthenic Syndrome (LEMS) is due to an autoimmune attack against?

What is it often associated with?

A

1) Voltage-gated calcium channels on presynaptic nerve terminal
2) Small cell lung cancer

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15
Q

What is the clinical presentation of LEMS?

A

1) Proximal weakness
2) Loss of DTR
3) Myalgia
4) Dry mouth
5) Impotence
6) Strength improve after exercise

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16
Q

What EMG finding is seen with LEMS?

A

Incremental response on fast repetitive stimulation

17
Q

With Botulism, the toxin blocks?

A

Presynaptic mechanisms for release of ACh

18
Q

What is the clinical presentation of Botulism?

A

1) Dry, sore mouth and throat
2) Blurred vision
3) N/V

19
Q

Nerve “Gases” such as Sarin acts by?

What does this cause?

Death is due to?

A

1) Inhibiting Ach esterase at NM junction
2) End organ overstimulation
3) Respiratory failure