Transcutaneous Electrical Acupoint Stimulation Potentiates Analgesic Effect of Morphine

Pain is the major complaint of patients who choose acupuncture treatment. Transcutaneous electrical acupoint stimulation (TEAS) provides a safe, standardized technique without needle insertion. TEAS can be tested with the cold‐pressor test, a simple, reliable, and widely used model in humans for the induction of tonic pain. In this controlled study, the effects of TEAS on cold‐pressor‐induced pain were evaluated in 20 healthy human subjects. Electrical stimulation electrodes were applied to He‐Gu (LI 4) and Nui‐Guan (P 6) acupoints. The effects of saline plus no TEAS, 15‐minute TEAS alone, 0.05 mg/kg morphine alone, and 15‐minute TEAS plus morphine were assessed. Pain score ratings were evaluated at four time points from 30 to 170 seconds during the cold‐pressor test. The authors observed analgesic effects in both TEAS‐alone and morphine‐alone sessions, and pain score rating reductions were statistically significant compared to unstimulated control (both p < 0.01). The degree of TEAS analgesia combined with 0.05 mg/kg morphine was significantly higher than TEAS alone (p < 0.01). The results support the efficacy of TEAS analgesia and suggest that combination of TEAS with low‐dose morphine can achieve better pain control in a variety of clinical settings.