大鼠分级脊髓损伤对经颅电刺激运动诱发电位的影响

The effects of graded spinal cord injuries on transcranial electric stimulation motor evoked potentials in the rat

目的了解不同程度脊髓损伤（ＳＣＩ）对运动诱发电位（ＭＥＰ）的影响以及ＭＥＰ对ＳＣＩ运动功能预后的价值。方法采用改良Ａｌｅｎｓ法，分别以３０ｇｃｆ、５０ｇｃｆ、８０ｇｃｆ和１００ｇｃｆ冲量打击４０只ＳＤ大鼠Ｔ８～９脊髓，造成不同程度ＳＣＩ，于伤前及伤后１个月连续记录Ｌ１～２脊髓硬膜外ＭＥＰ（ｓｃＭＥＰ）和双侧腓肠肌ＭＥＰ（ｍＭＥＰ），并采用斜板试验和Ｔａｒｌｏｖ评分评估运动神经功能。结果（１）不同程度ＳＣＩ可造成大鼠ＭＥＰ波幅明显变化，损伤越重，电位越低；（２）ｍＭＥＰ较ｓｃＭＥＰ更敏感，但ＳＣＩ早期ｍＭＥＰ消失并不说明大鼠不能恢复行走能力；（３）伤后早期ｓｃＭＥＰ波幅变化与１个月后的斜板试验（γ＝０．９６６５）和Ｔａｒｌｏｖ评分（γ＝０．８８９３）显著相关，可作为判断运动功能预后的长期指标；（４）伤后１个月１１只后肢无自主运动的大鼠中３只（２７．３％）仍保留ｓｃＭＥＰ，提示脊髓仍残留部分传导功能，属于非完全性损伤。结论ｓｃＭＥＰ能较为客观、敏感地反映ＳＣＩ后中枢运动神经纤维的损伤程度，可以作为判断远期运动功能预后的可靠指标。

Objective To study the effects of graded spinal cord injury (SCI) on the motor evoked potentials (MEP) characteristrcs and the prognostic value of MEP for the motor function. Method Modified Allens method was used by weight drop force of 30gcf, 50gcf, 80gcf and 100gcf on the T8～9 spinal cord of 40 SD rats in order to make SCI models. MEP was recorded continuously at L1～2 epidurally and bilateral gastrocnemius muscles before and after the spinal cord lesion was produced (followed up for 1 month). The inclined plane and Tarlov technique were used to assess clinical neurological function. Result The amplitude of rat′s MEP changed significantly with graded SCI, the more sever the lesion, the lower the potentials. mMEP was more sensitive than scMEP, though the abolishment of mMEP soon after SCI didn′t indicate that the animals could not regain ambulation. Changes in amplitude of scMEP recorded early after SCI were collaborate significantly with inclined plane (γ=09665,P<001) and Tarlov scale (γ=08893,P<001) assessed 1 month later, and can be used as a chronic measure parameter of motor function prognosis. scMEP still existed 1 month after SCI in 3 of 11 rats (273%) without any voluntary movement in bilateral hindlimbs, suggesting that some parts of conductive function still existed in the spinal cord. So it should be called “discomplete SCI”. Conclusion scMEP can be used as a reliable parameter for motor function prognosis, because it reflects objectively and sensitivetly the severity of central motor neurol fiber injury.