The effect of quadriceps-electrocutaneous stimulation on the T-reflex and the H-reflex of the soleus muscle

Objective: To investigate the effect of ipsilateral quadriceps-electrocutaneous stimulation on the T-reflex and the H-reflex of the soleus muscle, and to examine the interactions in human cutaneous sensation - the soleus motoneuron pathway. Methods: The T-reflex and H-reflex tests were performed bilaterally on 50 able-bodied adults with a standardized technique using the soleus muscle. The reflexes were conditioned by electrocutaneous stimuli applied to the ipsilateral quadriceps using the optimal transcutaneous electrical nerve stimulation (TENS) machine (3 x perception, intensity 15 - 30 mA). The conditioning stimuli were followed by reflex tests by 30-50 ms (conditioning A) and 80-100 ms (conditioning 13). The latency and amplitude of the T-reflex and H-reflex were measured before (control) and after conditioning stimuli (A and B) and at sham (placebo). Results: There were no significant differences between the right and left sides and between the control and placebo in both T-reflex and H-reflex. There were significant differences in both latency and amplitude of the T-reflex only between control and conditioning A. There were no significant differences between control and conditioning tests in the H-reflex. Conclusions: The above results suggest that supraspinal center and cutaneous fusimotor reflexes, which increase the sensitivity of the soleus muscle spindle, mediate the observed motoneuron excitability changes. (C) 2003 International Federation of Clinical Neurophysiology. Published by Elsevier Science Ireland Ltd. All rights reserved.