Transcutaneous electrical nerve stimulation (TENS) : effects of duration of stimulation on antinociception in man

Transcutaneous electrical nerve stimulation (TENS) has been employed for over 2 decades in pain management, however, definitive analgesic parameters have yet to be determined. The objective of this study was to determine the influence of 10, 30 and 60 min of TENS on the time course and magnitude of modulation on flexion reflex (FR) and on subjective pain estimates (visual analogue scale, VAS), as well as determining the relationship between FR responses and VAS scores following TENS of different durations.Ten (10) normal subjects received electrical stimuli of maximal tolerable intensity to the sole of their foot. Our results indicated that TENS could suppress the FR in 50% to 70% of subjects. However, longer durations (30 and 60 min) of TENS have a small, but discernible difference in the number of subjects that show inhibition of FR area and significant maximal FR suppression when compared to 10 min of TENS. Moreover, the 60 min of TENS generated significant depression of VAS scores in more subjects than 10 and 30 min of TENS and ensured that any increase in pain perception would not reach significance when compared to the shorter (10 and 30 min) durations of TENS.Our results suggested that longer durations of TENS could be applied to produce antinociceptive and analgesic effects. (Abstract shortened by UMI.