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Monograph: Single fiber electromyography and measuring jitter with concentric needle electrodes
Monograph: Single fiber electromyography and measuring jitter with concentric needle electrodes
Abstract: Abstract
This monograph contains descriptions of the single fiber electromyography (SFEMG) method and of the more recently implemented method of recording jitter with concentric needle electrodes (CNEs). SFEMG records action potentials from single muscle fibers (SFAPs), which permits measuring fiber density (FD), a sensitive measure of reinnervation, and jitter, a sensitive measure of abnormal neuromuscular transmission
(NMT). With voluntary activation, jitter is measured between two SFAPs with acceptable amplitude and rise time. With activation by axon  stimulation, jitter is measured between the stimulus and individual SFAPs. Pitfalls due to unstable triggers and inconstant firing rates during voluntary activation and subliminal stimulation during axon stimulation should be identified and avoided. In CNE recordings, spikes with
shoulders or rising phases that are not parallel are produced by summation of SFAPS; these should be excluded and reference values for CNE jitter should be used. CNE and SFEMG have similar and very high sensitivity in detecting increased jitter, as in myasthenia gravis and other myasthenic conditions. However, jitter is also seen in ongoing reinnervation and some myopathic conditions. With SFEMG, these can be identified by increased FD; however, FD cannot be measured with CNE, and conventional electromyography should be performed in muscles with increased jitter to detect neurogenic or myogenic abnormalities. Jitter is abnormal after injections of botulinum toxin, even in muscles remote from the injection site, and can persist for 6 mo or more. This can complicate the detection or exclusion of abnormal NMT.

ACCREDITATION STATEMENT
The AANEM is accredited by the Accreditation Council for Continuing Medical Education (ACCME) to provide continuing medical education for physicians.

DISCLOSURE INFORMATION
Drs. Sanders and Stålberg receive royalties for the book “Single Fiber EMG.” Dr. Kouyoumdjian has nothing to disclose.All conflicts of interest have been resolved according to ACCME standards. 

CREDIT DESIGNATION
The AANEM designates this enduring material for a maximum of 2.0 AMA PRA Category 1 Credits TM. Physicians should claim only the credit commensurate with the extent of their participation in the activity. Credit expires 08/01/2025.
Author
Donald B. Sanders, MD; Joao A. Kouyoumdjian MD, PhD; Erik V. Stålberg MD, PhD.
Summary
Availability: On-Demand
Expires on Aug 01, 2025
Cost: Member: $0.00
Non-Member: $15.00
Credit Offered:
2 CME Credits
2 CEU Credits
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