Electrophysiologic Changes of Tibial Nerve by Low Frequency Stimulation in Peripheral Polyneuropathic Patients

ABSTRACT

The changes of anterior horn cell excitability and conduction of the nervous system by the electrical stimulation of nerve have been reported in both vivo and vitro studies. Purpose of this study is to observe the neurophysiologic changes of nerves by 10 Hz electrical stimulation on polyneuropathic peripheral nerves. Subjects were 18 diabetic polyneuropathic patients diagnosed by the conduction studies. Electrophysiologic studies were performed in both right and left tibial nerves before and after conditioning of the right tibial nerve. Electrophysiologic studies included five tests which were the sural sensory and tibial motor conduction(abductor hallucis), F response(abductor hallucis), H reflex(gastrosoleus) and somatosensory evoked potential(ankle, SEP). Ten Hz rectangular electrical current was used for the conditioning stimulation. It was applied to the popliteal tibial nerve with the tolerable maximal intensity(10-24 mA) for 5 minutes. Following changes were statistically significant in statistics after the conditioning. Prolongation of F latency (p<0.05), increases of F chronodispersion, duration and area(p<0.05), prolongation of H latency(p<0.05), increase of H amplitude(p<0.05), decrease of P1 latency of SEP(p<0.01) and increase of P1N1 amplitude of SEP(p<0.01) were seen in both conditioned and unconditioned legs. Increase of F wave conduction time(FWCT) and decrease of F wave conduction velocity (FWCV) were seen in conditioned leg(p<0.05). Above findings suggest that certain electrical stimulation of polyneuropathic nerve may cause increase of the anterior horn cell excitability, fascilitation of the SEP conduction and slowness of alpha motor conduction to and from the spinal cord.