The effect of brief electrical and manual acupuncture stimulation on mechanical experimental pain

Although manual and electrical stimulation are frequently used in acupuncture analgesia, studies comparing both stimulation modalities are contradictory. This blinded, placebo-controlled cross-over study investigates effects of brief manual and electrical acupuncture stimulation on pressure pain detection thresholds (PPDT) compared with nonpenetrating sham acupuncture (NPSA).

Forty-five healthy volunteers received electrically and manually stimulated acupuncture and NPSA at large intestine 4 and 11 in randomized order. PPDT was assessed using pressure algometry at the second toe before; during; and 0, 2, and 5 minutes after each intervention. Stimulus intensity during stimulation was rated on a 0-10 numeric rating scale (NRS).

PPDT rose from 316 kPa (standard deviation [SD] 149) to 398 kPa (SD 157) and 405 kPa (SD 184) immediately after acupuncture with manual and electrical stimulation, respectively, and to 380 kPa (SD 175) and 367 kPa (SD 168) after NPSA with simulated manual and electrical stimulation, respectively. During the intervention, electroacupuncture produced a higher PPDT increase than any other procedure (P<0.001). Immediately after, both acupuncture procedures were significantly more effective than NPSA (P<0.001) but did not mutually differ (P=0.082). NRS ratings differed significantly: manual acupuncture 4.1, electroacupuncture 2.7, manual NPSA 2.5, electro-NPSA 1.2 (P<0.001 except for electroacupuncture vs manual NPSA, P=0.271).

Electroacupuncture produced higher PPDT elevation than manual acupuncture, and acupuncture in general showed significantly greater analgesic effect than NPSA. These effects seem to be short lasting (<5 minutes) in the context of only brief acupuncture. The superiority of acupuncture to NPSA provides further evidence for acupuncture-specific analgesic effects.