奥卡西平对癫痫患者运动皮质兴奋性的影响

目的：利用经颅磁刺激（transcranial magnetic stimulation, TMS）技术来研究奥卡西平（oxcarbazepine, OXC）对部分性癫痫患者运动皮质兴奋性的影响，并与卡马西平(carbamazepine, CBZ)的作用相比较。方法：对38例头颅MRI正常的部分性癫痫患者和20例正常对照进行磁刺激，并记录双侧大脑的静息期运动皮质阈值(rest motor threshold, rMT)、运动诱发电位波幅（motor evoked potential amplitude，MEP amplitude）、皮质潜伏期(cortical latency, CL)和中枢传导时间（central motor conduction time, CMCT）。癫痫组中18例给予OXC治疗，20例给予CBZ治疗，在治疗后第2周末、第4周末分别给予TMS。结果： 癫痫组38例治疗前可能致痫灶同侧大脑rMT高于对侧大脑，但差异无显著(P>0.05)。奥卡西平组可能致痫灶同侧大脑rMT在第2周末和第4周末均明显高于治疗前(P<0.05)，卡马西平组可能致痫灶同侧大脑rMT仅在第4周末时高于治疗前(P<0.05)。癫痫组治疗前后同侧大脑MEP amplitude、CL和CMCT差别均无显著，两侧大脑半球间比较差别也无显著。结论： 头颅MRI正常的部分性癫痫患者可能致痫灶所在半球和对侧半球的大脑皮质兴奋性可能存在差异，OXC和CBZ均能降低运动皮质兴奋性，可能机制为细胞膜钠离子通道阻滞。 TMS是从电生理角度研究大脑皮质兴奋性的可靠辅助工具。

Effect of oxcarbazepine on cortical excitability in patients with epilepsy

AIM:To evaluate the effect of monotherapy(oxcarbazepine and carbamazepine)on rest motor threshold(rMT),cortical latency(CL),central motor conduction time(CMCT)and motor evoked potential amplitude(MEP amplitude),using transcranial magnetic stimulation(TMS)in patients with partial epilepsy.METHODS:A single pulse transcranial magnetic stimulation was used for recording the motor-evoked potentials(MEP)from the thenar muscles of both hands in 38 patients with partial epilepsy,who were with normal brain MRI and treated with OXC or CBZ.The rMT,CL,CMCT and MEP amplitude were recorded and compared with 20 healthy controls.The recording sessions were performed before treatment and 2 and 4 weeks after treatment.RESULTS:The rMT were higher in the ipsilateral hemisphere in partial epilepsy compared with the contralateral hemisphere,but not statistically significant(P>0.05).Compared with the patients before treatment,the ipsilateral rMT in OXC group increased significantly 2 and 4 weeks after treatment,while that increased significantly only after 4 weeks in CBZ group.No significant interhemispheric difference was observed on MEP amplitude,CL and CMCT in both controls and patients before treatment.Also,no significant change was found on CL,CMCT and MEP amplitude among patients before and after treatment.CONCLUSION:Single pulse TMS is able to provide a valuable electrophysiologic insight into the interical excitatory state of cortex in patients with epilepsy.The excitability of motor cortical in partial epilepsy with normal brain MRI may be interhemispheric asymmetry.Both OXC and CBZ reduce the membrane excitability of human motor cortical neurons,possibly through changing Na channel activity.