Department of Exercise Sciences


The contribution of cervical propriospinal premotoneurons in recovering hemiparetic stroke patients

James W. Stinear and Winston D. Byblow.
J. Clin. Neurophysiol. (2004) 21, 6, 426-434

Introduction and Aim

  • There is evidence in humans that the cervical (C3/4) level of the spinal cord is a site for sensorimotor integration, analogous to the C3/4 propriospinal system (PS) in cat.
  • Although the clinical relevance of the putative C3/4 PS in humans is not clear, there is some evidence indicating that drive to upper limb muscles via this non-monosynaptic pathway is up-regulated as a compensatory mechanism in stroke and in Parkinson’s disease.
  • Here we ask whether descending drive via the C3/4 PS to affected limb wrist flexors of moderately- to well-recovered chronic stroke patients is up- regulated compared with controls.

Methods

  • The extent of descending drive via the C3/4 PS was assessed in seven patients and seven controls during the onset of co-contraction of the biceps brachii and flexor carpi radialis (FCR), during which transcranial magnetic stimulation was used to evoke motor potentials in FCR.
  • Responses were conditioned by subthreshold stimulation of the musculocutaneous nerve.
  • The extent of this facilitation was taken as a measure of the proportion of drive to FCR motoneurons being transmitted via the C3/4 PS.

Results

Patients revealed greater facilitation than control subjects (see Figure 1).

c3to4Stroke
Figure 1 - The extent of facilitation and inhibition in lesioned, non-lesioned, dominant and subdominant FCR responses. Filled bars represent facilitated responses, open bars inhibited responses. Error bars represent one s.e.m. Asterisks (without lines) indicate the level of significance for the difference in means from unity (paired t-tests). Asterisks between lines indicate the level of significance for the difference in means between pathways (ANOVA). **, p = < 0.01; d.f. 1,12.

Conclusions

The results suggest that descending drive to forearm flexors was being transmitted via the C3/4 PS as a compensation mechanism following stroke.

For more information on this project contact:

Winston Bublow
Email: w.byblow@auckland.ac.nz