Effect of intrathecal baclofen on the monosynaptic reflex in humans: evidence for a postsynaptic action.
Intrathecal baclofen is a very powerful antispastic agent. Its mechanism of action on the monosynaptic H-reflex in spinal patients was investigated. It could inhibit rapidly and profoundly monosynaptic reflexes in lower limbs, but did not modify Ia vibratory inhibition of the soleus H-reflex. To assess more precisely its effect on Ia afferents, an experimental paradigm using Ia heteronymous facilitation of the soleus H-reflex was used. Intrathecal baclofen did not modify the amount of monosynaptic facilitation of the soleus H-reflex brought about by stimulation of the femoral nerve. This demonstrates that the main part of the inhibitory effect of baclofen on the H-reflex in spinal patients is not due to a presynaptic effect, suggesting a postsynaptic site of action.
Department of Neurological Rehabilitation, INSERM U215, Raymond Poincaré Hospital, Garches, France.
P
P
Azouvi
A
A
Roby-Brami
A
A
Biraben
J B
JB
Thiebaut
C
C
Thurel
B
B
Bussel
D000293:Adolescent; D000328:Adult; D001418:Baclofen / Q000008:administration & dosage / Q000627:therapeutic use*; D005260:Female; D006801:Humans; D007278:Injections, Spinal; D007866:Leg / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D009128:Muscle Spasticity; D012023:Reflex, Monosynaptic; D013118:Spinal Cord Diseases / Q000188:drug therapy* / Q000503:physiopathology
D001418:Baclofen