Autoimmune disorder of the peripheral nerves.  Antibodies are formed against the acetylcholine postsynaptic receptors at the myoneural junction. The ACh receptors are destroyed resulting progressively reduced muscle strength with repeated use of the muscle with recovery of muscle strength after rest.
     The bulbar muscles are most common and most severely affected. The bulbar muscles are the ones that deal with speech and swallowing. Patients can often have normal strength but have airway compromise, but most patients will have generalized weakness at some time.
     Exacerbation of disease can be due to noncompliance, infection, and other stressors
Some medications are known for causing exacerbations

• Antibiotics: Macrolides, fluoroquinolones, aminoglycosides
• Antidysrhythmics: Beta blockers, CCBs, lidocaine, procainamide
• Miscellaneous: muscle relaxants, levothyroxine, and corticosteroids

Look for signs of cholinergic crisis from excess of cholinesterase inhibitors which can mimic myasthenic crisis. Both present with muscle weakness and can be indistinguishable. Look for signs of Miosis and the SLUDGE syndrome

Severe exacerbation: expressionless face, unable to support head, nasally voice, limp body, absent gag reflex and respiratory distress.