Conflict of interest: The author has no financial interest and no conflicts of interest to report.
Neurophysiological characteristics of human leg muscle action potentials evoked by transcutaneous magnetic stimulation of the spine†
Version of Record online: 28 NOV 2012
Copyright © 2012 Wiley Periodicals, Inc.
Volume 34, Issue 3, pages 200–210, April 2013
How to Cite
Knikou, M. (2013), Neurophysiological characteristics of human leg muscle action potentials evoked by transcutaneous magnetic stimulation of the spine. Bioelectromagnetics, 34: 200–210. doi: 10.1002/bem.21768
- Issue online: 7 MAR 2013
- Version of Record online: 28 NOV 2012
- Manuscript Accepted: 13 OCT 2012
- Manuscript Received: 17 JAN 2012
- Professional Staff Congress of the City University of New York. Grant Number: 63159-00-41
- low-frequency depression;
- magnetic stimulation;
- multisegmental responses;
- thoracolumbar region
The objectives of this study were to establish the neurophysiological properties of the compound muscle action potentials (CMAPs) evoked by transcutaneous magnetic stimulation of the spine (tsMSS) and the effects of tsMSS on the soleus H-reflex. In semi-prone seated subjects with trunk semi-flexed, the epicenter of a figure-of-eight magnetic coil was placed at Thoracic 10 with the handle on the midline of the vertebral column. The magnetic stimulator was triggered by monophasic single pulses of 1 ms, and the intensity ranged from 90% to 100% of the stimulator output across subjects. CMAPs were recorded bilaterally from ankle and knee muscles at the interstimulus intervals of 1, 3, 5, 8, and 10 s. The CMAPs evoked were also conditioned by posterior tibial and common peroneal nerve stimulation at a conditioning-test (C-T) interval of 50 ms. The soleus H-reflex was conditioned by tsMSS at the C-T intervals of 50, 20, −20, and −50 ms. The amplitude of the CMAPs was not decreased when evoked at low stimulation frequencies, excitation of group I afferents from mixed peripheral nerves in the leg affected the CMAPs in a non-somatotopical neural organization pattern, and tsMSS depressed soleus H-reflex excitability. These CMAPs are likely due to orthodromic excitation of nerve motor fibers and antidromic depolarization of different types of afferents. The latency of these CMAPs may be utilized to establish the spine-to-muscle conduction time in central and peripheral nervous system disorders in humans. tsMSS may constitute a non-invasive modality to decrease spinal reflex hyperexcitability and treat hypertonia in neurological disorders. Bioelectromagnetics 34:200–210, 2013. © 2012 Wiley Periodicals, Inc.