Analgesic effects of different pulse patterns of transcutaneous electrical nerve stimulation on cold-induced pain in normal subjects.

The analgesic efficacy of various pulse patterns of transcutaneous electrical nerve stimulation (TENS) were assessed in 84 normal healthy subjects using the cold pressor pain technique. Burst, modulation, random and continuous TENS all significantly elevated ice pain threshold. Continuous (80 Hz) TENS produced the greatest mean elevation in threshold but the response to random TENS showed the least inter-subject variation. Ice pain tolerance was increased by all modes of TENS, continuous TENS producing the greatest magnitude of response, although these changes did not reach statistical significance. Increasing the size of electrodes reduced the effect of continuous TENS. The clinical implications of these findings are discussed.