Verification of the Therapeutic Pain Inhibition and Neurophysiological Response by Combined Vibration and Thermal Stimulation to the Abdomen

Abstract

This study investigated the pain inhibition and neurophysiological responses elicited by combined vibration and thermal stimulation applied to the abdomen. Eighteen healthy male volunteers participated in a crossover study comparing vibratory stimulation to the abdomen alone with combined vibratory and thermal stimulation. The primary outcomes measured were the pressure pain threshold (PPT), autonomic nervous function (using heart rate variability), and brain wave activity (using EEG). The results showed no significant differences between the conditions in PPT, comfort levels, autonomic nervous, or brain wave activities. However, significant correlations were observed between PPT and autonomic nervous activities and between brain waves and autonomic nervous activities in the combined condition, suggesting a neurophysiological interaction. Specifically, increased parasympathetic activity was associated with reduced pain perception, indicating potential vagus nerve involvement. This study suggests that while combined stimulation does not enhance pain inhibition more than vibration alone, it does indicate complex neurophysiological interactions. Further studies should explore these mechanisms and the clinical potential of combined stimulation for pain relief, particularly in cases where direct stimulation is challenging.