REFLEXES FROM THE SUPERFICIAL PERONEAL NERVE DURING WALKING IN STROKESUBJECTS

The function of ipsilateral cutaneous reflexes was studied with short trains of stimuli presented pseudo-randomly to the superficial peronea l nerve (SP; innervates the top of the foot) during treadmill walking in neurologically intact (NI) subjects and subjects who had had a stro ke. Ankle and knee joint angles together with electromyograms (EMG) of tibialis anterior (TA), soleus (SOL), medial gastrocnemius (MG), vast us lateralis (VL), and biceps femoris (BF) muscles were recorded. Net reflex EMG and kinematic responses to stimulation were quantified in e ach of the 15 parts of the step cycle and responses compared between t he stroke and NI subjects. Stimulation strongly suppressed extensor mu scles throughout stance in the stroke subjects. TA muscle showed a sig nificant suppression during swing phase that was correlated with reduc ed ankle dorsiflexion in both stroke and NI subjects. BF reflexes were facilitatory during parts of swing and VL reflexes were suppressive t hroughout stance in the stroke subjects. There was a significant corre lation between BF facilitation and knee flexion during swing, which wa s stronger in NI subjects. We conclude that only part of the stumble c orrection to foot dorsum electrical stimulation observed in NI subject s is maintained after stroke. and that new, suppressive responses are seen.