Objective To investigate the effects of various stimulus waveforms in low frequency (0-10Hz) on the inhibition of overactive bladder, caused by detrusor hyperreflexia after spinal cord injury, and find a new stimulus waveform which can inhibit the bladder overactivity effectively.Methods According to the McNeal’s lumped circuit model theory of the myelinated axon, a simulation system based on the Frankenhaeuser-Huxley (FH) equations was built at first, to study the nerve fiber’s responses of several stimulus waveforms. Four kinds of stimulus waveforms were anodal pulse, cathodal pulse, biphasic symmetrical pulse and biphasic asymmetrical pulse. The clinic performance of the best stimulus waveform from the simulation results was also validated by stimulating pudendal nerve of the male Beagle dogs, which were spinal cord injured. The simulation results demonstrated that biphasic asymmetrical pulse was the best stimulus patternin the low frequency stimulation.Results From the animal experiment, the results also showed that the anodal-leading, biphasic asymmetrical pulse, which is composed of anodal pulse in 3V, 0.1ms and cathodal pulse in 1V, 0.3ms, had the best stimulation effect.Conclusion For pudendal nerve electrical stimulation, the anodal-leading, biphasic asymmetrical stimulus pattern has thebest simulation result, and is possible to apply in the clinic, which can inhibit overactive bladder effectively, and protect the nerve fiber from electrochemiscal injury.
|