Activity of Corrugator Muscle with Pressure Pain Stimulation in Healthy People

Abstract

Corrugator muscle activity with pressure pain stimulation has not yet been studied. We recorded corrugator muscle activity at rest and before, during and after pressure pain stimulation to the shoulder three times each in 14 healthy adults (20.0 ± 2.1 years of age (mean ± SD)) without pain using surface electromyography. Corrugator muscle activity with pressure pain and the relationships between corrugator muscle activity and pressure pain or unpleasantness intensity on a visual analogue scale measured three times were examined. The corrugator muscle activity during pressure pain stimulation was significantly higher than that before (p < 0.001) and after (p = 0.019) stimulation. There were significant differences among the three measurements examining reproducibility in pain (p = 0.037) and unpleasantness (p = 0.014) but not among corrugator muscle activities before (p = 0.526), during (p = 0.145) and after (p = 0.109) stimulation. Significant correlations were revealed for corrugator muscle activity vs. pain (ρ = 0.465, p = 0.002) and corrugator muscle activity vs. unpleasantness (ρ = 0.558, p < 0.001). Pressure pain increased corrugator muscle activity with reproducibility and correlated with subjective pain assessments, which indicates the utility of corrugator muscle activity as an objective indication of pain assessment.