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Updated: Feb 8, 2026

Extraction of the EPP Component from the Surface EMG
Published on: December 16, 2009
Excitability tests using high-density surface-EMG: A novel approach to studying single motor units
Boudewijn T H M Sleutjes1, Judith Drenthen2, Ernest Boskovic3
1Department of Neurology and Neurosurgery, Brain Center Rudolf Magnus, The Netherlands.
Objective:
To study excitability of single motor units (MUs) using high-density surface-EMG.
Methods:
Motor unit action potentials (MUAPs) were evoked by submaximal stimulation of the median nerve at the wrist and recorded with a 9 × 14 electrode grid on the skin overlying the thenar muscles. For excitability tests of single MUs, the most optimal specific single-channel surface-EMG signal was selected based on the spatiotemporal profile of single MUs.
Results:
Axonal excitability measures were successfully obtained from 14 single MUs derived from ten healthy subjects. Selecting the optimal single-channel surface-EMG signals minimized interference from other single MUs and improved signal-to-noise ratio. The muscle fiber conduction velocity (MFCV) could also be derived from the unique spatiotemporal profile of single MUs.
Conclusion:
High-density surface-EMG helps to isolate single MUAP responses, making it a suitable technique for assessing excitability in multiple single motor axons per nerve.
Significance:
Our method enables the reliable study of ion-channel dysfunction in single motor axons of nerves without any requirement for specific conditions, such as prominent MU loss or enlarged MUAPs due to collateral sprouting.
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