What is concentric needle electromyography (CNEMG)?

Updated: Mar 13, 2019
  • Author: Pradeep C Bollu, MD; Chief Editor: Nicholas Lorenzo, MD, MHA, CPE  more...
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Answer

Answer

Several studies have examined the quantitative evaluation of neuromuscular transmission using concentric needle electrodes (CNE). [1]  Concentric needle EMG (CNEMG) offers the advantage of using disposable electrodes that are cheaper, safer, and well tolerated by the patients.

  • A larger recording area results in potentials that are easier to acquire.

  • This larger area is more likely to produce recordings with overlapping pairs.

  • The overlapping pairs, along with contributions from more distant motor units within the recording area, probably results in an underestimation of the true jitter value.

  • The several studies available suggest that the specificity may be similar to recordings performed with a single-fiber electrode.

  • CNE with the smallest possible recording surface should be used.

  • A high-pass filter setting of 1–2 Hz is recommended.

  • Normative data studies now exist for CNE jitter studies. The mean MCD is lower for CNE jitter recording compared to classic SFEMG.

  • CNE studies cannot measure fiber density.

It should be noted that CNEMG jitter may be comparable to SFEMG jitter, although the two techniques have not been compared adequately in the same patients. Moreover, the use of any particular high-pass filter setting for CNEMG jitter has not been validated fully. 


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