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Single fiber EMG and repetitive stimulation of the same muscle in myasthenia gravis
Author(s) -
Gilchrist James M.,
Massey Janice M.,
Sanders Donald B.
Publication year - 1994
Publication title -
muscle and nerve
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.025
H-Index - 145
eISSN - 1097-4598
pISSN - 0148-639X
DOI - 10.1002/mus.880170207
Subject(s) - myasthenia gravis , neuromuscular transmission , medicine , jitter , stimulation , blocking (statistics) , neuromuscular junction , compound muscle action potential , electromyography , anesthesia , electrophysiology , neuroscience , physical medicine and rehabilitation , psychology , mathematics , telecommunications , statistics , computer science
We performed RNS and SFEMG studies of the same muscle in 46 patients with myasthenia gravis. Maximum decrement to 3–5‐Hz stimulation before and after maximum voluntary exercise, percentage of action potential pairs with increased jitter and blocking, and mean MCD in each study were compared. A significant decrement (> 10% decrease in CMAP area or amplitude between the first and fourth response) was never found without increased jitter and impulse blocking on SFEMG. Increased jitter, blocking, and mean MCD were each correlated with maximum decrement ( r > 0.61, P < 0.0001). We conclude that decrement to RNS and impulse blocking on SFEMG result from the same physiologic phenomenon, and that SFEMG is more sensitive at detecting disordered neuromuscular transmission given its ability to detect impulse blocking at levels below the resolution of RNS and increased neuromuscular jitter when there is not blocking. © 1994 John Wiley & Sons, Inc.