The influence of extrasegmental mechanical vibratory stimulation and transcutaneous electrical nerve stimulation on histamine-induced itch.

The effect of peripheral conditioning stimulation on experimentally induced pruritus was studied in 12 healthy volunteers. Itch was induced by intradermal injections of histamine on the upper arms. Vibration at 100 Hz and transcutaneous electrical nerve stimulation (TENS) at 2 and 100 Hz were applied extrasegmentally (dorsal aspect of the lower part of the leg, ipsilateral to the injected arm) for a period of 5 min following induction of itch. The effect of a 5 and 30 min stimulation period before itch elicitation was also studied as well as the influence of placebo stimulation. No significant effects were obtained with 100 Hz vibration and 100 Hz TENS, and none with placebo stimulation, whereas significant itch reduction was seen using 2 Hz TENS. The local skin flare response following histamine injections was not altered following conditioning stimulation of any type.