Neuromuscular Diseases and Disorders Flashcards

1
Q

What is the inheritance pattern of hypokalemic periodic paralysis? Hyperkalemic periodic paralysis?

A

autosomal dominant for both

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2
Q

What precipitates hyperkalemic periodic paralysis?

A

dehydration (exercise and fasting)

potassium-rich foods

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3
Q

What precipitates hypokalemic periodic paralysis?

A

hyperglycemia (insulin burst leads to hypokalemia)

hyperventilation (alkalosis leads to hypokalemia)

viral illness

rest following exercise

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4
Q

Is an extremity affected by a stroke more or less sensitive to non-depolarizing muscle relaxants?

A

less sensitive due to extrajunctional receptors

*true of all upper motor neuron conditions*

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5
Q

Is cerebral palsy a contraindication for succinylcholine?

A

No

*CP patients do not develop extrajunctional receptors*

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6
Q

Is MS a contraindication to succinylcholine?

A

a relative contraindication, more absolute in the presence of significant paresis

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7
Q

Why is succinylcholine contraindicated in Duchenne’s muscular dystrophy? Myotonic dystrophy? ALS? Guillain Barre syndrome?

A

DMD: hyperkalemia from disrupted myocyte membrane

MyoD: persistent contractures preventing intubation and ventilation

ALS and GBS: hyperkalemia from extrajunctional receptors

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8
Q

What should be avoided to prevent sustained contractures in patients with myotonic dystrophy?

A

succinylcholine

anti-cholinesterases (e.g., neostigmine)

hypothermia

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9
Q

Does myasthenia gravis affect skeletal muscle, smooth muscle, or both?

A

only skeletal muscle

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10
Q

How do you distinguish between weakness from worsening myasthenia and a cholinergic crisis?

A

edrophonium challenge (e.g., tensilon test)

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11
Q

Which factors increase the risk of post-op ventilation in pateints with myasthenia gravis?

A

disease duration > 6 years

vital capacity < 2.9 L

pyridostigmine dose > 750 mg/day

concomitant respiratory disease

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12
Q

How are infants of mothers with myasthenia gravis affected?

A

They can have myasthenia for up to 3 weeks.

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13
Q

How does Eaton-Lambert myasthenia syndrome affect sensitivity to muscle relaxants?

A

More sensitive to succinylcholine due to upregulated AChRs

More sensitive to non-depolarizing agents due to less ACh to compete with

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