Facilitation of transmission in heteronymous group II pathways in spastic hemiplegic patients
- aInserm U455 CHU Purpan Pavillon Riser place du Dr Baylac 31059 Toulouse cx France, and Laboratoire de Physiologie, Faculté de Médecine Rangueil, 133 route de Narbonne 31062, Toulouse, France, bService de Médecine Physique et Réadaptation CHU Rangueil, 1 av J. Poulhès 31403 Toulouse cx France
- Dr M S Moreaumoreauma{at}cict.fr
- Received 20 April 2000
- Revised 8 August 2000
- Accepted 30 August 2000
Abstract
OBJECTIVE A potent heteronymous group II excitation of quadriceps motor neurons has been recently demonstrated in normal subjects. The present study was undertaken to investigate whether this heteronymous group II excitation also contributes to spasticity in hemiplegic patients.
METHOD The early and late facilitations of the quadriceps H reflex elicited by a conditioning volley to the common peroneal nerve at three times motor threshold, attributed to non-monosynaptic group I and group II excitations respectively, were investigated. The comparison was drawn between results obtained in 20 patients after stroke, with hemiplegia due to a vascular lesion in the territory of the middle cerebral artery, and 20 age and sex matched normal subjects.
RESULTS A significant increase in the group I as well as in the group II common peroneal nerve induced facilitation of the quadriceps H reflex was seen on the spastic side of the patients (group I: 159 (SEM 10)% of control H reflex; group II: 165 (SEM 8)%) compared with their unaffected side (group I: 126 (SEM 4)%; group II: 128 (SEM 5)%) (Wilcoxon signed rank test, p<0.01), or to the right (group I: 132 (SEM 4)%; group II: 131 (SEM 5)%) or left (group I: 130 (SEM 3)%; group II: 135 (SEM 6)%) side of controls (Mann-Whitney U test, p<0.01). No significant correlation (Spearman rank test) was found between the degree of group I and group II induced facilitations on the spastic side of the patients and the degree of clinically assessed spasticity (Ashworth scale).
CONCLUSION These results reflect a facilitation of the transmission in the interneuronal pathway coactivated by group I and group II afferents, probably resulting from a change in their descending control in spastic hemiplegic patients.
