Klimpe Sven, Behrang-Nia Mehrnousch, Bott Michael C, Werhahn Konrad J
Department of Neurology, University Medicine Mainz, Langenbeckstr. 1, 55131 Mainz, Germany.
Epilepsy Res. 2009 Apr;84(2-3):210-6. doi: 10.1016/j.eplepsyres.2009.02.013. Epub 2009 Mar 14.
Intracortical disinhibitory mechanisms play a crucial role in epilepsy. Therefore, the recruitment of motor cortical excitability was evaluated to distinct between focal and generalized epileptic syndromes. Twenty-five untreated patients with epilepsy and 20 controls were enrolled. Classification into focal (FE, n=10) or idiopathic generalized (IGE, n=15) epilepsy was based on seizure semiology, EEG and MRI. The recruitment of motor cortical inhibition and facilitation was measured by varying the stimulus intensity (SI) of the first conditioning stimulus in a paired-pulse transcranial magnetic stimulation (TMS) paradigm producing stimulus-response (S-R) curves of intracortical excitability. S-R curves were then compared with other commonly used TMS measures of cortical excitability [cortical silent period (CSP) and motor threshold (MT)]. In patients with IGE, inhibition occurred only at higher conditioning SIs compared to patients with focal epilepsy and controls. Recruitment of inhibition was unchanged in patients with focal epilepsy compared to controls. Recruitment of facilitation (ICF), CSP duration and MT, were not different between patients with FE or IGE or between patients and controls. These results suggest that the recruitment for motor cortical inhibition in patients with IGE is less effective. This may reflect a disturbed access to or an increased threshold of inhibitory neurons within the motor cortex. Impaired recruitment of inhibition might be a helpful parameter to access cortical excitability in newly diagnosed patients with generalized or focal epilepsy.
皮质内去抑制机制在癫痫中起关键作用。因此，对运动皮质兴奋性的募集进行评估，以区分局灶性和全身性癫痫综合征。招募了25例未经治疗的癫痫患者和20名对照。根据发作症状学、脑电图和磁共振成像将其分为局灶性癫痫（FE，n = 10）或特发性全身性癫痫（IGE，n = 15）。在配对脉冲经颅磁刺激（TMS）范式中，通过改变第一个条件刺激的刺激强度（SI）来测量运动皮质抑制和易化的募集情况，从而产生皮质内兴奋性的刺激-反应（S-R）曲线。然后将S-R曲线与其他常用的皮质兴奋性TMS测量指标[皮质静息期（CSP）和运动阈值（MT）]进行比较。与局灶性癫痫患者和对照相比，IGE患者仅在较高的条件刺激强度下才出现抑制。与对照相比，局灶性癫痫患者的抑制募集没有变化。FE或IGE患者之间以及患者与对照之间的易化募集（ICF）、CSP持续时间和MT没有差异。这些结果表明，IGE患者运动皮质抑制的募集效果较差。这可能反映了运动皮质内抑制性神经元的通路受到干扰或阈值升高。抑制募集受损可能是评估新诊断的全身性或局灶性癫痫患者皮质兴奋性的一个有用参数。
