Effects of repeated sensory stimulation sessions (electro-acupuncture) on skin temperature in chronic pain patients

Changes in skin temperature and haemodynamics were studied during experimentally administered electro-acupuncture before and after a 4-week period of electro-acupuncture (EA) treatments. Subjective pain intensity was evaluated using a pain questionnaire. Twelve patients with long-lasting nociceptive pain were included. Before clinical treatment, skin temperature tended to decrease after 30 minutes' stimulation. In contrast, a significant increase was seen after the clinical treatment. No significant changes were seen for blood pressure, heart rate or pain intensity before and after the clinical treatment. The data indicate that an increased skin vasoconstrictor sympathetic activity may be responsible for the decreased skin temperature during the electro-acupuncture in the initial test sessions, whereas an inhibition of skin sympathetic activity and/or a release of vasodilatory substances may be responsible for the increase in temperature after completed clinical treatment. Despite a small number of subjects and correction for multiple inference, the difference in temperature effects before and up to 3 months after acupuncture treatment was significant.