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Updated: May 18, 2026
Determining the Functional Status of the Corticospinal Tract Within One Week of Stroke
Published on: February 22, 2020
Discharge rates in electromyography distinguish early between peripheral and central paresis
Tim P Jürgens1, Christoph Puchner, Wilhelm J Schulte-Mattler
1Department of Systems Neuroscience, University Medical Centre Hamburg-Eppendorf, Martinistrasse 52, D-20246 Hamburg, Germany. t.juergens@uke.de
Introduction:
Abnormally increased discharge rates (DRs) of motor unit potentials on concentric needle electromyography (CNEMG) indicate a loss of motor units in peripheral neurogenic lesions.
Methods:
To determine when increased DRs occur during the course of a peripheral nerve lesion, we retrospectively analyzed CNEMG recordings of 19 patients with acute weakness of peripheral origin.
Results:
The initial CNEMG studies took place from 3.7 hours to 10 days after the onset of the lesion. Abnormally increased DRs (≥20/s) were found in all but 1 of the muscles in which MRC grade was <4. Peripheral neurogenic damage was confirmed in all patients thereafter. The DRs depended on neither the kind of lesion nor the time between onset and CNEMG examination.
Conclusions:
The measurement of DRs of motor unit potentials is helpful immediately after a sudden paresis of MRC grade 3 or worse to differentiate between a central and a peripheral lesion.
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