The influence of mechanical vibratory stimulation and transcutaneous electrical nerve stimulation on experimental...

The effect of conditioning mechanical vibratory stimulation and transcutaneous electrical nerve stimulation (TENS) on experimentally induced pruritus was studied on 12 healthy subjects. Pruritus was provoked by intradermal injection of histamine on the upper arm. Vibration at 10, 100 and 200 Hz and TENS at 2 and 100 Hz were applied (i) over or (ii) proximal (in the same dermatome) to the pruritic area for a period of 5 min following itch elicitation. In addition the influence of a 5 min pre-stimulatory regimen of the injection area was investigated (iii). The results obtained were compared with unconditioned values and with those obtained following a placebo conditioning procedure (i, ii). It was found that vibratory as well as electrical stimulation, for all frequencies used, reduced subjective itch intensity. Vibration at 100 Hz was the most effective mode of stimulation especially when applied directly to the pruritic area. Conditioning with 100 Hz vibration was also the most effective mode for reducing the duration of the itch response as well as the total experience of pruritus (estimated as a total itch index). Induction time to partial and maximal itch alleviation was shortest for 100 Hz vibration. The results indicate that treatment of pruritic conditions with conditioning stimulation, especially vibration, may be of therapeutic interest.