目的 :观察电针人体合谷穴和痛刺激正中神经时

其传入冲动在中枢神经系统内的相互作用。方法 :按照受试者、记录者、施针者三盲的方法

对 1 2例健康人进行 4系列试验。系列Ⅰ为非痛单独电刺激正中神经 ;系列Ⅱ为痛单独电刺激正中神经 ;系列Ⅲ为同时电刺激正中神经与合谷穴 ;系列Ⅳ为同时电刺激正中神经与合谷穴旁。刺激正中神经的电流强度在Ⅱ、Ⅲ、Ⅳ系列中相同。利用NeuroScan公司ESI 1 2 8脑电记录仪记录从 64个头皮电极点引出的体感诱发电位 (So matosensoryEvokedPotentials

SEP)

并比较各主波的绝对峰值和峰峰值及作二维地形图分析。结果 :系列Ⅰ未能引出明显的SEP晚成分 ;系列Ⅱ、Ⅲ、ⅣSEP中、晚成分N80 、P1 70 、N2 80 的绝对峰值大小关系为 :系列Ⅱ >系列Ⅳ >系列Ⅲ

而早成分在 3系列中变化不明显。二维地形图显示

SEP早成分发生源位于对侧半球

晚成分位于中央略偏对侧

向前额部扩伸

系列Ⅲ 87 40ms以后各时间窗口信号强度明显弱于系列Ⅱ和Ⅳ。结论 :电针合谷穴明显抑制痛刺激正中神经引起的痛觉诱发脑电位

穴位的镇痛效果好于非穴位

大脑皮质在针刺穴位镇痛过程中具有时间依赖的电活动

痛觉诱发电位可以实时反映电针穴位的镇痛效果Objective:This study was undertaken to observe changes of pain-related cerebral somatosensory evoked potentials (SEPs) following electroacupuncture (EA) stimulation of Hegu(LI 4) in volunteer subjects for elucidating the cerebral cortical mechanisms of EA analgesia. Methods: SEPs from 12 healthy volunteer subjects (7 males and 5 females) were recorded using 64 channels NeuroScan (ESI-128) following electrical stimulation of the left median nerve (MN)

Hegu (LI 4) and non-acupoint (1 cm beside LI-4

i.e.

the ulnar margin of the first metacarpal bone on the back palm and at the same level with LI-4) that included stimulus series of Ⅰ (4～6.8 mA

MN)

Ⅱ (10～13 mA

MN)

Ⅲ (10～13 mA

MN+LI-4) and Ⅳ (10～13 mA

MN+non-acupoint). Peak values of N 20

P 40

N 80

P 170 and N 280

and peak-peak (PP) values of N 20-P 40

N 80-P 170

P 170-N 280 of SEPs obtained from 64 scalp electrodes before and after stimulation were recorded and analyzed. Results: Late components of SEPs could not be gained during non-painful stimulation (series Ⅰ). During painful stimulation (series Ⅱ～Ⅳ)

the peak values of medium and late components (N 80

P 170 and N 280) of SEPs were the biggest for series Ⅱ

moderate for series Ⅳ and the lowest for series Ⅲ. The early components (N 20 and P 40) had no apparent changes during stimulus series Ⅲ. Two dimensions topography recording displayed that the early components of SEPs originated from the contralateral hemisphere(C4); and the late components from the slight contralateral part of the central hemisphere extending to the frontal cortex. The amplitude values of SEPs at different time courses after 87.4 ms during stimulus series Ⅲ were significantly lower than those of stimulus series Ⅱ and Ⅳ. The inhibitory effect of EA of Hegu (LI 4) on MN-stimulation induced SEPs became obvious at 87.4 ms

peaked at 170 ms and lasted for 337.4 ms. The peak values of N 20 and P 40 and the PP values of N 20-P 40 from CZ (the parietal-central zone) and C4 (the contralateral vertex zone) had no significant differences among series Ⅱ

Ⅲ and Ⅳ (P>0.05); the peak values of N 80 from CZ also had no significant difference between series Ⅲ and Ⅳ (P>0.05); while the peak value of N 80 from CZ

and those of P 170 and N 280 and the PP values of N 80- P 170 and P 170- N 280 from CZ and C4 of series Ⅲ were all considerably lower than those of series Ⅱ and Ⅳ (P<0.05). The peak and PP values of various components of SEPs from CZ

and P 170

N 280

N 80-P 170 and P 170-N 280 from C4 of series Ⅳ were all lower than those of series Ⅱ. Conclusion:Both EA of Hegu (LI 4) and non-acupoint can inhibit the medium and late components of MN-stimulation induced SEPs

and the effect of EA of Hegu (LI 4) is strikingly superior to that of non-acupoint

suggesting a specific action of the acupoint

and the human cerebral cortex is involved in EA analgesia.