[Mechanism of acupuncture anesthesia for analgesia of the operative region of thyroid gland]

OBJECTIVE: To probe into peripheral nervous mechanisms of analgesic effect of electroacupuncture (EA) at Hegu (LI 4) and Neiguan (PC 6) on cervical region. METHODS: Twenty cases of thyroid disease who wished to receive acupuncture anesthesia, were stimulated with electroacupuncture at bilateral Hegu (LI 4), Neiguan (PC 6) in continued wave, intensity of 6-8 V, frequency of 10-20 Hz. After stimulation for 40 min, the operation was made. Before EA stimulation, 10 min, 20 min and 30 min after EA stimulation, changes of the physiologi cal functions including latent period, conduction velocity, wave peak amplitude of great auricular nerve were monitored and changes of pain sense were detected. RESULTS: After EA given at Hegu (LI 4) and Neiguan (PC 6) for 10 min, 20 min and 30 min, the pain sense significantly decreased (P<0.01), the latent period of great auricular nerve was shortened, and the conduction velocity was fastened and the wave peak amplitude raised with significant changes as compared with those before EA stimulation (P<0.01). CONCLUSION: EA at Hegu (LI 4) and Neiguan (PC 6) can produce a better analgesic effect on cervical region; EA at Hegu (LI 4) and Neiguan (PC 6) induces electro-physio logic changes of the nerve innervating the cervical region, showing increase of excitability; the nerves innervating Hegu (LI 4) and Neiguan (PC 6) and the nerves of cervical region possibly are homologous nerves.