Electrophysiologic Responses to the Electrical Stimulation: A Peripheral Nerve Conditioning Near the Spinal Cord

Lee, Chyung Ki; Han, Soo Jung

Abstract

It has been reported that the electrical stimulation of nerves can cause the changes of anterior horn cell excitability and conduction velocity of the nerves in vivo and vitro studies. The purpose of this study is to evaluate the electrophysiologic changes of the peripheral nerves near the spinal cord by the electrical stimulation. Subjects were 20 healthy volunteers, with the age of 21 to 27 years. The conditioning current was an interferential current of 10 Hz and 100 Hz with the maximal tolerable intensity (18~20 mA). Conditioning stimulation was applied to the paraspinal area between T9 and T12 for 15 minutes. Before and after the conditioning stimulation, we measured the peripheral nerve conduction, H-reflex, F-wave, and somatosensory evoked potential (SEP) of the tibial nerve. The results after the conditioning revealed that the tibial motor and sensory conductions were unchanged but the latency of the H-reflex was significantly prolonged with a significant reduction of H amplitude and H/M ratio (p<0.01). The latency, duration, and F-ratio of the F-wave were significantly increased and the amplitude of the F-wave was significantly reduced (p<0.01). P1 latency was significantly prolonged in the cortical tibial SEP (p<0.01). Change of N1P1 amplitude was not meaningful (p>0.05). There was no statistical difference between the changes by a high or low frequency stimulation. These results suggest that a certain conditioned electrical stimulation of peripheral nerves near the spinal cord may cause the decrement of anterior horn cell excitability, and the inhibition of the alpha motor nerve and sensory nerve conductions near the spinal cord.