BACKGROUND: F-wave is a late muscle response which results from the antidromic activation of spinal motorneurones following peripheral nerve supramaximal electrical stimulation,and influenced by the balance of excitatory and inhibitory postsynaptic potentials on spinal motomeurons. However, F-wave is low amplitude and unstable, so how to make the F-wave to be stable is the subject of electrophysiology.OBJECTIVE: To observe the effect of magnetic stimulation on the excitability of spinal anterior horn motor neuron.DESIGN: Healthy volunteers-controlled study.SETTING: Department of Neurology of the First Affiliated Hospital of Guangxi Medical University, China, and Kumamoto Kino Hospital, Japan.PARTICIPANTS: From March 2000 to March 2001, 13 healthy volunteers, including 6 males, 7 females, aged 20 to 54 years, most of which being members of kumamoto Kino Hospital' s staff were selected.METHODS: The magnetic stimulation was performed on the occipital protuberance and the electrical stimulation was performed on the tibial nerve in the right elbow joint. The muscle potential was recorded in the first dorsal intercostals muscle of the right hand. F-wave of before magnetic stimulation, and atan interval of 30, 50, 100, 300 ms magnetic and electrical stimulation were recorded.F-wave ≥0.05 mV).RESULTS: Data of 13 cases was entered the final analysis. Significant change of the duration was observed at ISI 50 ms [(8.39±1.59), (6.75±1.62) ms,P ＜ 0.001], Fmean/M ratio was increased (1.73±1.20, 0.87±0.78, P ＜ 0.001),Fmax/M ratio was increased (4.07±2.59, 2.19±1.76, P ＜ 0.05), frequency of Fwave was increased [(80.77±22.89)%, (61.82±23.16)%, P ＜ 0.01] and also at 100 ms (P ＜ 0.05). No changes were observed in the F-wave minimal latency in our data (P ＞ 0.05).CONCLUSION: Magnetic stimulation on the occipital protuberance might obviously increase the excitability of the spinal anterior horn motor neuron. With the interval of magnetic stimulation at tuberosity of occipital bone and electric stimulation of ulnar at wrist joint, amplitude of F-wave was lengthened and course was delayed. Meanwhile, the shortest latency of Fwave is not changed at any condition.%背景:F波是末梢神经接受最大电刺激,从肌肉诱发出来的后期合成活动电位之一,是脊髓运动神经元突触后电位的反映,对F波的研究已经被作为衡量脊髓运动神经元兴奋性的一种手段.但F波具有低波幅和出现不稳定的特点,如何使F波的出现更加稳定和明显且又不影响F波的最短潜伏期是神经电生理研究的方向.目的:了解枕骨粗隆处磁刺激对F波的影响,更进一步了解人类中枢神经系统对脊髓前角运动细胞兴奋性的影响.设计:自身对照实验.单位:广西医科大学第一附属医院神经内科,日本熊本机能医院.对象:选择2000-03/2001-03日本熊本机能医院的工作人员13名,男6名,女7名,年龄20～54岁,均排除神经系统疾病史,体内无植入金属体.方法:枕骨粗隆上或稍低处使用8字形磁刺激头进行磁刺激,右腕关节尺神经上进行电刺激,在右手的第一骨间肌记录肌电活动,每一个受试者均分别记录磁刺激前、磁刺激后间隔30,50,100和300 ms时电刺激的F波,每一个实验条件下记录10个F波.主要观察指标:①M波的波幅.②F波平均波幅与M波波幅比.③F波最大波幅与M波波幅比.④F波最小潜伏期.⑤F波平均持续时间.⑥F波出现频率(F 波波幅≥0.05 mV).结果:13名健康自愿者的实验数据均进入结果分析.磁-电刺激间隔50 ms时F波平均持续时间出现极显著性延长[(8.39±1.59),(6.75±1.62)ms,P＜0.001];F平均/M波幅出现极显著性升高[1.73±1.20,0.87±0.78,P＜0.001];F最大/M波幅出现显著性升高[4.07±2.59,2.19±1.76,P＜0.05];F波出现频率出现极显著性升高[(80.77±22.89),(61.82±23.16)%,P＜0.001];在磁-电刺激间隔100 ms亦出现显著性升高(P＜0.05).在整个实验过程中,任何实验条件下都没有观察到F波最短潜伏期有显著性改变(P＞0.05).结论:枕骨粗隆处磁刺激明显改变了脊髓前角细胞兴奋性,表现为当枕骨粗隆处施行的磁刺激和腕关节处尺神经电刺激间隔一定的时间时,F波波幅增高,时程延长.同时还发现无论在任何实验条件下,F波最短潜伏期都没有明显的变化.
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