探讨经颅电刺激运动诱发电位(TceMEP)对发现兔急性坐骨神经根损伤的敏感性及TceMEP早期波形变化对急性坐骨神经根部损伤的评估价值。

新西兰大白兔12只24条坐骨神经随机区组法分3组，实验组分为1个血管夹组(n＝8)，2个血管夹组(n＝8)和对照组(n＝8)；实验组分别应用1个或2个血管夹夹压坐骨神经根部建立急性坐骨神经损伤模型，观察并记录2 h坐骨神经根部受夹压损伤急性期TceMEP的变化特点，并记录TceMEP波形稳定后的波幅与基线波幅比值和潜伏期；对照组仅手术分离出坐骨神经而不夹压坐骨神经，用于排除麻醉药和手术操作对TceMEP的影响；2 d后应用Tarlov评分对各组兔下肢运动功能进行评估。应用配对t检验，单因素方差分析，秩和检验和Speraman相关性进行统计学分析。

实验组1个血管夹组经过[0.20(0.00，0.431)]min TceMEP波形开始变化，经过[2.60(1.40，3.35)]min波形平稳；2个血管夹组经过[0.35(0.05，1.63)]min TceMEP波形开始变化，经过[4.45(2.83，5.65)]min波形平稳。1个和2个血管夹组手术后TceMEP波形平稳后波幅与基线波幅百分比[(49.84±15.27)%，(15.47±12.64)%]均低于手术前[(100.00±0.00)%，(100.00±0.00)%]，均差异有统计学意义(t＝9.293，18.912；均P<0.01)；对照组和实验各组手术后TceMEP波形平稳后波幅与基线波幅百分比比较，差异有统计学意义(F＝110.196，P<0.05)。1个和2个血管夹组手术后TceMEP波形平稳后潜伏期[(12.60±0.61)ms，(14.29±1.24)ms]高于手术前TceMEP潜伏期[(12.21±0.59)ms，(12.31±1.10)ms]，均差异有统计学意义(t＝7.519，5.721；均P<0.05)；对照组和实验各组手术后TceMEP波形平稳后潜伏期比较，差异有统计学意义(F＝6.702，P<0.05)。1个血管夹组和2个血管夹组夹压后2 d下肢运动功能评分[4.00(3.00，4.00), 2.50(2.00，3.00)]，低于夹压前[5.00(5.00，5.00)，5.00(5.00，5.00)]，均差异有统计学意义(Z＝－2.598，－2.585；均P<0.05)，且均低于对照组[5.00(5.00，5.00)]，均差异有统计学意义(Z＝－3.664，－3.651；均P<0.05)。对照组和实验组各组手术后波形平稳后波幅与基线波幅百分比与各组坐骨神经损伤手术后2 d的运动功能评分呈显著性正相关(r＝0.844，P<0.01)。

TceMEP监测对发现急性坐骨神经根损伤非常敏感，表现为潜伏期延长和波幅降低，为采取保护性措施预防不可逆性神经根损伤的发生提供了可能；TceMEP波形变化可以预测下肢运动神经功能。

To explore the sensitivity of transcranial electrical stimulation motor evoked potential (TceMEP) after acute sciatic nerve root injury in rabbits and the evaluation value of its early waveform changes after acute sciatic nerve root injury.

Twelve New Zealand rabbits with 24 sciatic nerves were divided into 3 groups by random grouping method, one vascular clamping group (n=8), two vascular clamping groups (n=8) and the control group (n=8). The acute sciatic nerve injury model was established by using one or two vascular clamp compression of the sciatic nerve root, the TceMEP was recorded for 2 hours to observe the characteristics of TceMEP in the acute phase of sciatic nerve root compression injury, the percentage of TceMEP amplitude of stabilized waveform after compression injury to baseline amplitude and latency were recorded. The control group was used to exclude the effects of anesthetic and surgical operations on TceMEP. The lower limb motor function was evaluated using the Tarlov score after 2 days of clamping. Statistical analysis was performed using t-test, one-way ANOVA, rank sum test and spearman correlation analysis.

TceMEP waveform of 1 vascular clamping group was changed at [0.20(0.00, 0.43)]min and was stable at [2.60(1.40, 3.35)]min; TceMEP waveform of 2 vascular clamping group was changed at [(0.35(0.05, 1.63)]min and was stable at [4.45(2.83, 5.65)]min. The percentage of postoperative amplitude when the waveform was stable to baseline in 1 and 2 vascular clamping group [(49.84±15.27)%, (15.47±12.64)%] were lower than the percentage of preoperative amplitude [(100.00±0.00)%, (100.00±0.00)%], there were statistically significant differences (t=9.293, 18.912, all P<0.01). There was statistically significant difference between the control group and the experimental groups in the percentage of postoperative amplitude when the waveform was stable to baseline (F=110.196, P<0.05). The postoperative latency when the waveform was stable in 1 and 2 vascular clamping groups [(12.60±0.61)ms, (14.29±1.24) ms] were higher than the preoperative latency [(12.21±0.59)ms, (12.31±1.10)ms], there were statistically significant differences (t=7.519, 5.721, all P<0.05). There was statistically significant difference of the postoprative latency in the control group and the experimental groups (F=6.702, P<0.05). The lower limb motor function scores after 2 days of clamping in 1 and 2 vascular clamping groups [4.00(3.00, 4.00), 2.50(2.00, 3.00)] were lower than the control group [5.00(5.00, 5.00)], there were statistically significant differences (Z=-3.664, -3.651, all P<0.05), which were also lower than the motor function scores before clamping [5.00(5.00, 5.00), 5.00(5.00, 5.00)], there were statistically significant differences (Z=-2.598, -2.585, all P<0.05). The percentage of postoperative amplitude when the waveform was stable to baseline and the Tarlov motor function scores after 2 days of clamping were significantly positively correlated in the control group and experimental groups (r=0.844, P<0.01).

TceMEP monitoring is very sensitive to the detection of acute sciatic nerve root injury, which is manifested as prolonged latency and decreased ampilitude, it provides the possibility of taking protective measures to prevent the occurrence of irreversible nerve root injury. The motor function of lower limbs can be predicted by the change of TceMEP waveform.