The lack of hypoalgesic efficacy of H-wave therapy on experimental ischaemic pain.

The hypoalgesic effect of H-wave therapy (HWT) at various frequencies (2-60 Hz) was assessed using a standardised form of the submaximal effort tourniquet technique (SETT). Healthy human volunteers (n = 112; 56 men, 56 women) were required to attend on two occasions; on the first, baseline pain scores were obtained and on the second, 48 h later, subjects were randomly assigned to control, placebo or 1 of 5 H-wave treatment conditions. In the treatment groups 2 self-adhesive electrodes were attached to the ipsilateral Erb's point and just lateral to the spinous processes of C6/C7. H-wave stimulation commenced 10 min prior to pain induction and continued throughout the 12-min duration of the technique. In the placebo group electrodes were attached as normal but leads were connected to a dummy power output. Analysis of variance of the differences in visual analogue scale and McGill Pain Questionnaire scores showed no significant differences in the treatment groups compared to placebo or controls. These results do not provide convincing evidence for any hypoalgesic effects of HWT at the frequency parameters stated on the experimental model of pain used.