大鼠脊髓诱发电位与脊髓损伤的关系 Ⅰ、刺激坐骨神经诱发脊髓电位的特征与分布

RELATION BETWEEN SPINAL EVOKED POTENTIALS AND SPINAL INJURY IN RAT.1.CHARACTERISTIC AND DISTRIBUTION OF SPINAL POTENTIALS EVOKED BY SCIATIC NERVE STIMULATION

本工作用电刺激大鼠的坐骨神经,双极引导硬膜外脊髓诱发电位,观察电位的特征与分布。结果表明,大鼠脊髓对刺激坐骨神经的反应分布于L5到T10椎体水平。反应潜伏时自L5向T11有规律地依次增加,由0.35ms延长到1.17ms。电位的基本波形为正(P1)、负(N1)、正(P2)三相电位的早期反应和随后的负(N2)、正(P3)双相晚期反应。不同节段水平的电位存在各自的特征。其中,T13与L1水平的电位大而稳定,晚期反应的波幅平均高达394μv和432μv左右,且波形互为反相,呈现明显的传入神经投射节段的电位特征。上述结果及对电位诸参数的分析为识别损伤后电位提供了依据。

In order to study the characteristics, distributions and parameters of spinal potentials evoked by sciatic nerve stimulation, epidural bipolar recording over the thoracic and lumbar levels of spinal cord were made in rats. The results may be summarized as follows: 1. Spinal evoked potentials in response to sciatic nerve stimulation could be recorded epidurally from L5-T10 in rat.The basic waveforms of SEP consist of early positive(P1), negative(N1)and positive(P2) triphasic responses followed by delayed negatige-positive components. 2. Comparison of SEP obtained at different segmental level showed that the recordings made from L5-L2 levels were similar in waveform and topography and the responses recorded at L1-T13 levels were characterized by a remarkable early triphasic compound action potentials followed by a large late component which varied in shape, amplitude and polarity according to the spatial relationship between the position of the electrodes and the spinal cord at L1-T13 levels. As recording electrodes were moved rostrally, the latencies of responses were increased. 3. The amplitude of SEP were related to stimulus intensity and could be increased by stimulating both side sciatic nerve at the same time. 4. Some parameters on SEP of normal rats were obtained in the present study. On the basis of the above mentioned results we suggest that the segmental responses, evoked by sciatic nerve stimulation might be at L1-T13 levels in rats and others were conductive responses. The possible explanations of the waveforms recorded were discussed.