Relationship of selected clinical variables to current delivered during transcutaneous electrical nerve stimulation

Nineteen normal subjects were given transcutaneous electrical nerve stimulation to the hypothenar eminence, back, or legs, using a selected constant-current device. Stimulation characteristics from this unit were measured. Stimulation, at 20- microsec or 80- microsec pulse widths, was provided at increasing strengths until subject tolerance or muscle contraction was reached. The current delivered at each stimulus setting for single or repeated intrasubject trials was reliable at each anatomical landmark. For intersubject single trials, current levels proved reliable in the hand and back but not at any of the three interelectrode distances evaluated in the leg. Possible explanations for this latter finding are offered. This study showed that, for those stimulation settings evaluated, at least one constant-current transcutaneous electrical nerve stimulation unit reliably delivers current of specific stimulus strengths to the hypothenar eminence or back.