The choice of pulse duration for chronic electrical stimulation via surface, nerve, and intramuscular electrodes

Abstract

The peak current, peak voltage, charge transfer and energy dissipation necessary for equivalent stimulation were measured for several pulse durations in the range from 0.01 to 1.0 msec. The unidirectional, regulated current, rectangular waveform was studied for subcutaneous nerve and intramuscular stimulation in animals and for surface stimulation in humans. In addition, the unidirectional, regulated current, exponential waveform was studied in humans and was compared with the rectangular waveform. The question of the relationship between charge transfer and energy dissipation and possible tissue damage due to the electrochemical formation of toxic compounds or a temperature rise in the surrounding tissue was examined. The optimal pulse duration for reducing the possibility of tissue damage was concluded to be less than or equal to 0.01 msec for intramuscular stimulation in the test situation. No conclusion was made as to the optimal duration for nerve or surface stimulation. Excitation of muscle fibers was found to take place indirectly by was of muscle nerves during intramuscular stimulation. The exponential waveform required less charge transfer and energy dissipation than the rectangular waveform, but higher peak currents. © 1974 Academic Press, Inc.