Influence of natural sulphur baths on pain threshold of healthy subjects

In a controlled experimental study the cutaneous microcirculation (Laser-Doppler-Flowmeter) as well as thermic (Peltier-Thermode) and pressure pain thresholds were examined in 12 healthy test persons before, during and 20 minutes after thermodifferent natural H2S plain baths (20,4 mg H2S/l) and tap-water baths. All the measurements were taken on both forearms for comparison, each test person only having one arm bathed. As expected, the bathed skin showed a 37% significant increase of the mean cutaneous microcirculation (p < 0.001). This effect did not occur in the tap-water baths and with the unbathed skin in the sulphur baths. The thresholds of pain caused by pressure and cold also increased 30 and 25% respectively (p < 0.001 and p <0.01 respectively). Heat pain thresholds, however, showed no significant changes. It is of special interest that the effects on pain caused by pressure and cold also occurred on the untreated arm. The thresholds increased even further after the end of the bath to 43 and 33%, respectively. It can be concluded that natural thermoindifferent sulphur baths significantly reduce the sensitivity to pain caused. by pressure and cold. Since it was possible to prove these effects on an extremity that had not been bathed, they must have a systemic character.