Zhonghua Yi Xue Za Zhi (Taipei). 2002 Jul; 65(7): 299-302.

The local mechanism of acupuncture.

Chu J.

Department of Rehabilitation Medicine, Hospital of the University of Pennsylvania, Philadelphia 19104, USA. [email protected]

Scientific development of acupuncture is described to increase its therapeutic efficacy and ultimate utilization. Acupuncture may have central, local and placebo effects. Little is known about the local effects of acupuncture specific to needle penetration and/or movement. Acupuncture points, muscle trigger points and motor end-plate zones are identical. Therefore, the benefit of acupuncture in musculoskeletal pain relief for which it is most commonly used, would not be limited to classical acupuncture points on the meridians. Intramuscular movements of the needle causes insertional activity which can be recorded on electromyography (EMG). The insertional activity occurs from depolarization of innervated single or grouped muscle fiber discharges which are micro-twitches and this is the basis of pain relief with EMG and intramuscular stimulation methods. Occasionally, needle penetration or manipulation in classical or electrical acupuncture may also evoke small local twitches. These observations suggest that needle induced local muscle twitches mediate musculoskeletal pain relief in acupuncture. These micro-twitches are capable of producing micro stretch effects on the adjacent shortened muscle fibers undergoing varying stages of denervation. This reduces the mechanical traction effect produced by these shortened muscle fibers on pain sensitive structures including intramuscular nerves and blood vessels. This theory of stretching shortened muscle fibers to produce pain relief would be justified when even more significant musculoskeletal pain relief can be obtained through inducing larger force twitches. Therefore, automated and electrical twitch-obtaining intramuscular stimulation methods were invented to elicit larger twitches. These methods allow the objective localization of the motor end-plate zones and allow recording of the number, frequency and force of the twitches. Therefore, by mechanism of action and associated therapeutic relief, the twitch may be the local key to pain relief, notjust a diagnostic sign for the localization of myofascial trigger points.