An instrumentation system for therapeutic perpulse delivery

Abstract

High amplitude electrical muscle stimulation has been known to cause pain and discomfort among those receiving long duration stimulation treatments to build muscle strength. Recently, the use of prepulses in sensory tactile stimulation has been shown to increase the pain threshold in human subjects. The use of prepulses in surface motor point stimulation has not been tested or published in the literature. However, typical electrical stimulator cannot output a prepulse and have limited recording capabilities. This thesis presents the design and prototype of a novel muscle stimulator that can output any type of prepulse shape and duration. The system is fully computer controlled and provides muscle action potential recordings through a custom built electromyography amplifier. The system was tested with a series of single subject pilot studies that also looked at the merits of using ramped and rectangular prepulses during surface motor point stimulation. The results show that both ramped and rectangular prepulses are effective at augmenting the M-wave response. By keeping the stimulus amplitude fixed, the prepulses elicited M-waves responses that had much larger peak to peak amplitudes than those elicited with the control stimulus (no prepulse). Those studies used a single stimulus to elicit a response. A pulse train experiment was also conducted. Clinically, pulse trains are used in a rehabilatory setting to build muscle strength. The pulse train experiment also showed that both ramped and rectangular prepulses are effective at augmenting the M-wave response. By lowering stimulus amplitude requirements, pain associated with high amplitude stimulation may be reduced. Further studies that include multiple subjects should be carried out to evaluate the full merit of using prepulses for muscle stimulation.