Suppression of flexor reflex by transcutaneous electrical nerve stimulation in spinal cord injured patients

The effect of transcutaneous electrical nerve stimulation (TENS) applied to the area of the sural nerve on the early and late electromyographic component of the flexor reflex was studied in 20 patients with complete and incomplete transversal spinal cord injuries. A marked, progressive, and prolonged decrease of both reflex components was observed in most patients. The early component was decreased less than the late reflex component immediately following the end of TENS, while further decrement of both components was observed 30 min after the end of TENS. The placebo stimulation in 4 patients revealed no decrease, or only a less marked decrease in reflex responses. The marked suppressive effect of TENS cannot be attributed to the potentiated habituation of the reflex responses alone. The induced inhibitory processes seem to be at least partially localized at the segmental level of the spinal interneuron system.