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Updated: Aug 24, 2026

Assessment of Neuromuscular Function Using Percutaneous Electrical Nerve Stimulation
Published on: September 13, 2015
Compound muscle action potentials during repetitive nerve stimulation
Teruko Asawa1, Masaomi Shindo, Hiroki Momoi
1Department of Laboratory Medicine, Shinshu University Hospital, Matsumoto, Japan. teasawa@hsp.md.shinshu-u.ac.jp
Abstract:
When using repetitive nerve stimulation to examine neuromuscular transmission, the change in compound muscle action potential (CMAP) size is usually assessed by measurement of negative-peak or peak-to-peak amplitude. Technological developments now allow automatic measurement of CMAP area, but some patients show increment of CMAP amplitude and decrement of CMAP area. This study systematically analyzed the changes in these CMAP parameters in 23 neurologically healthy subjects. CMAPs were recorded when the ulnar nerve was stimulated at frequencies of 1, 2, 5, 10, 20, 30, and 50 HZ (five pulses per train). CMAP amplitude showed significant increment within a train when stimulus frequency was above 5 HZ (probably due to increased muscle-fiber conduction velocity), whereas CMAP area hardly changed at any frequencies. Measurement of CMAP area produces less ambiguous results than amplitude measurement in repetitive nerve stimulation studies.
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