Effects of repeated electrocutaneous pain stimulation on facial blood flow.

The purpose of the study was to examine the effects of repeated electrocutaneous pain stimulation of the hand on facial blood flow responses in healthy human subjects (58 adult women). Finger blood flow, mean arterial blood pressure, and heart rate were also monitored. To investigate the influence of psychological factors, the subjects' affect states were assessed, and physiological responding was explored during cognitive distraction, i.e., when attention was turned away from the unpleasant stimulus. Consistently, electrocutaneous stimulation elicited vasodilatation in the cheek, together with finger vasoconstriction. This response pattern was evident even at non-painful stimulation intensities. The facial blood flow response showed habituation across stimulation trials and was largely unrelated to systemic cardiovascular changes, affect states, and attentional manipulation. These findings indicate (1) that the experimentally induced facial blood flow changes are part of a non-specific physiological response pattern elicited during noxious stimulation, and (2) that they are not dependent on regional (orofacial) stimulation for their occurrence.