Sx: fluctuating weakness of commonly used voluntary muscles, weakness increased by activity
- diplopia
- ptosis
- difficulty swallowing
- respiratory and limb muscles may be involved
Dx: Tensilon test (edrophonium chloride test): short acting (min) anticholinesterase, transiently improves symptoms of Myasthenia gravis
Associated conditions: thymic tumor, thyrotoxicosis, rheumatoid arthritis, lupus erythematosus
Mechanism: anti-Ach-R antibodies made
Tx: 1st line: anticholinesterases (symptomatic), recommended if pt <60>
Admit indications: acute exacerbation, plasmaphoresis, thymectomy, starting corticosteroids
Interactions: aminoglycosides worsen symptoms
Lambert-Eaton
sx: variable weakness, improved with activity
- dysautonomic symptoms present
associated conditions: h/o malignant disease (small cell carcinoma)
Mechanims: antibodies against voltage gated Ca++ channel
Tx: combined plasmaphoresis and immunosuppressive therapy (prednisone, azathioprine), tx underlying malignancy, response to anticholinesterases is variable
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