Single fiber electromyography.

Journal Article (Journal Article;Review)

Single fiber electromyography (SFEMG) is a highly selective technique that permits assessment of individual muscle fiber action potentials (MFAPs). This selectivity is achieved with a specialized concentric needle electrode with a 25-μm diameter recording surface located in a side port 3mm from the needle tip. Additional selectivity is achieved with 500-Hz low-frequency filtering. An oscilloscope with a trigger and delay line enables identification of time-locked MFAPs within the same motor unit. SFEMG techniques allow assessment of two important features of the motor unit: jitter and fiber density (FD). Neuromuscular jitter is a direct measure of neuromuscular transmission and reflects the temporal variation in end-plate potentials reaching threshold to elicit a MFAP. SFEMG may be used to assess paired jitter with voluntary activation or by axonal stimulation of motor nerve branches to individual end plates. SFEMG is the most sensitive clinical test for neuromuscular junction disease and is often abnormal in clinically unaffected muscles in patients with myasthenia gravis (MG) and Lambert-Eaton myasthenia (LEM). Normal jitter findings in a clinically weak muscle exclude neuromuscular junction disease as a cause for weakness in that muscle. FD measurements assess the local concentration of muscle fibers within a motor unit and provide a sensitive in vivo assessment of reinnervation.

Full Text

Duke Authors

Cited Authors

  • Juel, VC

Published Date

  • 2019

Published In

Volume / Issue

  • 160 /

Start / End Page

  • 303 - 310

PubMed ID

  • 31277856

International Standard Serial Number (ISSN)

  • 0072-9752

Digital Object Identifier (DOI)

  • 10.1016/B978-0-444-64032-1.00019-9


  • eng

Conference Location

  • Netherlands