What leads to insufficient endplate potentials (EPP) in the pathophysiology of myasthenia gravis (MG)?

Updated: Aug 27, 2018
  • Author: Abbas Jowkar, MD; Chief Editor: Nicholas Lorenzo, MD, MHA, CPE  more...
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Answer

In MG, there are anti-AChR-ab against AChR available at the post-synaptic folds, which become flattened or simplified by the immunopathological mechanism. This, on top of the gradual reduction of AChRs that are released with repeated use of the muscle, leads to insufficient endplate potentials (EPP), which may fall below the threshold value for generation of an action potential. The end result of this process is inefficient neuromuscular transmission. When this failure occurs at enough muscle fibers, it can manifest clinically and can be demonstrated electrophysiologically through low-frequency repetitive nerve stimulation (3 Hz RNS). However, if it occurs in only a few muscle fibers it can be detected on single-fiber electromyography (SFEMG).


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