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The effect of anticholinesterases on motor unit potentials in myasthenia gravis
Author(s) -
Pinelli Paolo
Publication year - 1978
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.880010521
Subject(s) - extensor digitorum communis , myasthenia gravis , motor unit , neuromuscular transmission , edrophonium , repetitive nerve stimulation , anesthesia , extraocular muscles , medicine , reflex , electromyography , duration (music) , electrophysiology , anatomy , physical medicine and rehabilitation , physics , acoustics
In most patients with myasthenia gravis, the mean duration and amplitude of motor unit potentials sampled in the extensor digitorum communis muscle, as well as the amplitude of the pattern of activity during full effort, increased after application of anticholinesterase. This appears to be a sensitive test for early detection of failure in neuromuscular transmission. In a series of 12 patients, the mean amplitude of motor unit potentials increased 30%–130% in 9, and the mean duration increased 10%–25% in 7. In 3 patients who failed to show an increase in amplitude in the extensor digitorum communis muscle, the amplitude of motor unit potentials increased in a facial or extraocular muscle after intravenous application of edrophonium. This increase in the amplitude or duration of motor unit potentials was even evident in 4 patients who failed to show a decrement in response of the opponens pollicis muscle to repetitive stimuli delivered to the median nerve at 3/sec and 5/sec. In 5 patients, responses evoked by stimuli delivered at 15/sec showed marked facilitation.