NMJ Disorders Flashcards Preview

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Flashcards in NMJ Disorders Deck (12):
1

Myasthenia Gravis
What are the two variants of the disease?

Ocular MG (10-20%)

Generalized MG (80-90%)

2

Myasthenia Gravis
Clinical Signs and Symptoms

Ocular-- ptosis, diplopia

Generalized--ptosis, diplopia, dysarthria, dysphagia, respiratory, facial, neck, limb weakness

PRESERVED sensation and reflexes

3

What causes MG?

Autoantibodies form against the Ach receptor

Loss of functional AchR leads to weakness

4

Myasthenia Gravis
How does the NMJ appear in this disease?

Lose the folds of the muscle due to loss of AchR

5

Myasthenia Gravis
What diagnostic tests may be performed?

Tensilon (Edrophonium) test -- give an acetylcholinesterase inhibitor to see if there is short-term symptom improvement

EMG evidence can indicate abnormal NMJ transmission

Elevated serum Ab titer against AchR

6

Myasthenia Gravis
Treatment

Acetylcholinesterase inhibitors may be used to improve symptoms

Thymectomy

Immunosuppressant drugs-- corticosteroids, cyclosporine, azathioprine, mycophenolate mofetil, plasmapharesis or IVIG

7

Why is a thymectomy considered in the treatment of MG?

Thymus contains AchR-like material, which could be where the autoimmune response is initiated?

8

Lambert-Eaton Myasthenic Syndrome (LEMS)
Clinical Signs and Symptoms

Fatiguable weakness of proximal limbs, trunk (mimicking a myopathy)

Hyporeflexia

Dry mouth
Orthostasis

9

Lambert-Eaton Myasthenic Syndrome (LEMS)
What is the cause?

Autoantibodies formed against presynaptic Ca2+ channels

10

Lambert-Eaton Myasthenic Syndrome (LEMS)
What disease is it often related to?

Small Cell Lung Cancer

11

Lambert-Eaton Myasthenic Syndrome (LEMS)
How is it diagnosed?

Nerve stimulation tests

EMG

Sometimes detect specific antibodies

12

Lambert-Eaton Myasthenic Syndrome (LEMS)
Treatment

Find and treat underlying cancer

Drugs to enhance Ach release-- guanidine or 3,4 diaminopyridine

Immunosuppressive therapy

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