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Updated: Sep 7, 2025
Assessment of Neuromuscular Function Using Percutaneous Electrical Nerve Stimulation
Published on: September 13, 2015
Effects of 10-kHz Subthreshold Stimulation on Human Peripheral Nerve Activation
Vedran Deletis1, Jay Shils2, Juan Anso3
1Albert Einstein College of Medicine, New York, NY, USA; Department of Neurosurgery, University Hospital Dubrava, Zagreb, Croatia.
Objective:
The mechanisms of action of high-frequency stimulation (HFS) are unknown. We investigated the possible mechanism of subthreshold superexcitability of HFS on the excitability of the peripheral nerve.
Materials And Methods:
The ulnar nerve was stimulated at the wrist in six healthy participants with a single (control) stimulus, and the responses were compared with the responses to a continuous train of 5 seconds at frequencies of 500 Hz, 2.5 kHz, 5 kHz, and 10 kHz. Threshold intensity for compound muscle action potential (CMAP) was defined as intensity producing a 100-μV amplitude in ten sequential trials and "subthreshold" as 10% below the CMAP threshold. HFS threshold was defined as stimulation intensity eliciting visible tetanic contraction.
Results:
Comparing the threshold of single pulse stimulation for eliciting CMAP vs threshold for HFS response and pooling data at different frequencies (500 Hz-10 kHz) revealed a significant difference (p = 0.00015). This difference was most obvious at 10 kHz, with a mean value for threshold reduction of 42.2%.
Conclusions:
HFS with a stimulation intensity below the threshold for a single pulse induces axonal superexcitability if applied in a train. It can activate the peripheral nerve and produce a tetanic muscle response. Subthreshold superexcitability may allow new insights into the mechanism of HFS.
