Sympathetic vasomotor changes induced by manual and electrical acupuncture of the Hoku point visualized by thermography.

Considerable evidence implicates sympathetic neural activity in acupuncture analgesia. However, the exact nature of these effects has not been specified in detail, and many experimental findings are contradictory. This study evaluated in normal conditions the specific sympathetic effects of both manual and electrical acupuncture applied to the same hand (Hoku) point. Thermographic measures of superficial skin temperature were used to assess sympathetic vasomotor tone in the face, hand and foot of 19 normal subjects. Baseline assessment, manual acupuncture and electrical acupuncture were performed in 3 separate sessions in a well controlled, 23 degrees C environment. Superficial skin temperature decreased slowly in the control condition. Both manual and electrical acupuncture produced a generalized long-lasting warming effect, indicating reduced sympathetic activity (sympatholytic effect). In addition, electrical acupuncture induced a localized short-term cooling effect, indicating a transient segmental increase in sympathetic activity (sympathomimetic effect).