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Magnetically induced muscle contraction is caused by motor nerve stimulation and not by direct muscle activation
Author(s) -
Machetanz Jochen,
Bischoff Christian,
Pichlmeier Reiner,
Riescher Hermann,
Meyer BerndUllrich,
Sader Astrio,
Conrad Bastian
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.880171007
Subject(s) - depolarization , neuromuscular transmission , contraction (grammar) , stimulation , muscle contraction , motor nerve , wrist , electromyography , anatomy , neuromuscular junction , medicine , chemistry , neuroscience , biology , physical medicine and rehabilitation
When magnetically stimulating peripheral nerves, a local cocontraction of muscle under the coil is observed. We assessed whether this contraction results from: (1) magnetic stimulation of motor nerves, or (2) direct depolarization of the muscle membrane. Wrist extensor muscles of normal subjects were magnetically stimulated with the coil placed directly above the muscle. Neuromuscular transmission was then blocked by atracurium using a technique of local curarization. As a reference, the radial nerve was stimulated electrically. Magnetic and electrical stimuli were applied alternatingly every 10 s. Twitch force of wrist extension was measured isometrically over a period of about 70 min including the phase of complete neuromuscular block. Twitch amplitudes elicited by magnetic and electrical stimuli were equivalent during the whole experiment. These results suggest that muscle cocontraction following magnetic stimulation results from depolarization of terminal motor nerve branches. © 1994 John Wiley & Sons, Inc.