Brain Advance Access originally published online on January 28, 2004
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Brain, Vol. 127, No. 3, 660-670, 2004
© 2004 Guarantors of Brain
doi: 10.1093/brain/awh073
Forces consistent with plateau-like behaviour of spinal neurons evoked in patients with spinal cord injuries
1 Spinal Injuries Research Centre, Prince of Wales Medical Research Institute and University of New South Wales, 2 College of Health Sciences, University of Sydney, Sydney, Australia and 3 Faculty of Physical Education and Recreation, University of Alberta, Canada
Correspondence to: Dr Peter Nickolls, Prince of Wales Medical Research Institute, Barker St, Randwick, NSW 2031, Australia E-mail: p.nickolls{at}unsw.edu.au
Percutaneous electrical stimulation over tibialis anterior and triceps surae was performed in 14 patients with traumatic spinal cord injury (SCI) to look for evidence that ‘extra contractions’ can develop, beyond those due to activation of the motor axons beneath the stimulating electrodes. Criteria for the extra contractions included marked asymmetry of force with respect to stimulation, progressively rising force during stimulation of constant amplitude and frequency, and force remaining high after stimulation frequency had returned to the control level following a high-frequency burst. Twelve of the 14 patients showed evidence of such behaviour, more frequently in triceps surae than tibialis anterior. Force or electromyographic activity commonly outlasted the stimulation in these patients. There was no apparent correlation between the completeness or level of injury and the ability to induce the behaviour. Evidence of force potentiation and ‘habituation’ was also seen. Eleven of the 14 patients exhibited hyper-reflexia and reported spontaneous spasms, but there was no obvious association with the extra contractions. It is concluded that non-classical behaviour of neurons within the spinal cord can contribute to the extra contractions evoked by electrical stimulation over muscles in spinal cord-injured subjects. This central contribution is less easy to obtain than in intact healthy subjects, all of whom showed the phenomenon. These contractions are consistent with the activation of plateau potentials in spinal neurons and, if so, plateau potentials may contribute to a patient’s clinical manifestations.
Key Words: spinal cord injury; plateau potentials; triceps surae; tibialis anterior
Abbreviations: EMG= electromyographic activity; SCI = spinal cord injury; TA = tibialis anterior; TS = triceps surae
Received June 30, 2003. Revised November 2, 2003. Accepted November 9, 2003.
CiteULike 
Connotea 
Del.icio.us What's this?
This article has been cited by other articles:
|
|
 |
|
  C.J. Heckman, M. Johnson, C. Mottram, and J. Schuster Persistent Inward Currents in Spinal Motoneurons and Their Influence on Human Motoneuron Firing Patterns Neuroscientist, June 1, 2008; 14(3): 264 - 275. [Abstract] [PDF]
|
|
|
|
 |
|
 J. A. Norton, D. J. Bennett, M. E. Knash, K. C. Murray, and M. A. Gorassini Changes in sensory-evoked synaptic activation of motoneurons after spinal cord injury in man Brain, June 1, 2008; 131(6): 1478 - 1491. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 Z. A. Riley, A. H. Maerz, J. C. Litsey, and R. M. Enoka Motor unit recruitment in human biceps brachii during sustained voluntary contractions J. Physiol., April 15, 2008; 586(8): 2183 - 2193. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 J. C. Dean, L. M. Yates, and D. F. Collins Turning on the central contribution to contractions evoked by neuromuscular electrical stimulation J Appl Physiol, July 1, 2007; 103(1): 170 - 176. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
S. K. Jankelowitz, J. Howells, and D. Burke Plasticity of inwardly rectifying conductances following a corticospinal lesion in human subjects J. Physiol., June 15, 2007; 581(3): 927 - 940. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 P. M. Klakowicz, E. R. L. Baldwin, and D. F. Collins Contribution of M-Waves and H-Reflexes to Contractions Evoked by Tetanic Nerve Stimulation in Humans J Neurophysiol, September 1, 2006; 96(3): 1293 - 1302. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
E. R. L. Baldwin, P. M. Klakowicz, and D. F. Collins Wide-pulse-width, high-frequency neuromuscular stimulation: implications for functional electrical stimulation J Appl Physiol, July 1, 2006; 101(1): 228 - 240. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
T. G. Hornby, J. H. Kahn, M. Wu, and B. D. Schmit Temporal facilitation of spastic stretch reflexes following human spinal cord injury J. Physiol., March 15, 2006; 571(3): 593 - 604. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. K. Floeter, P. Zhai, R. Saigal, Y. Kim, and J. Statland Motor Neuron Firing Dysfunction in Spastic Patients With Primary Lateral Sclerosis J Neurophysiol, August 1, 2005; 94(2): 919 - 927. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 A J Thompson, L Jarrett, L Lockley, J Marsden, and V L Stevenson Clinical management of spasticity J. Neurol. Neurosurg. Psychiatry, April 1, 2005; 76(4): 459 - 463. [Full Text] [PDF]
|
|