Imaging studies showed that the structure of the corpus callosum (CC) is affected in amyotrophic lateral sclerosis (ALS). Some clinical studies also suggest that interhemispheric connectivity is altered, since mirror movements seem to occur in ALS. Finally, reduced interhemispheric inhibition (IHI), studied by transcranial magnetic stimulation (TMS), has been reported. It is not known whether there is any association between these findings. Here, we studied the integrity of the CC in ALS on the morphological, the functional, the electrophysiological, and the clinical level. Twenty-seven right-handed ALS patients and 21 healthy right-handed controls were included. Mirror activity (MA) was quantified using surface EMG. Diffusion tensor imaging tractography was used to segment the CC and quantify fractional anisotropy (FA). We studied the diffusivity of the intra-axonal markers N-acetylaspartate+N-acetyl aspartyl glutamate D(tNAA) within the CC. IHI was studied as a marker of CC function using a double-pulse TMS protocol. ALS patients showed significantly decreased FA in the motor segment of the CC (p < 0.01), and IHI was significantly reduced compared to controls (p = 0.01). However, no differences were observed regarding D(tNAA) and MA. The morphological as well as the functional integrity of the CC are altered in ALS. IHI was reduced in ALS, associated with decreased FA in the motor CC. Patients did not exhibit increased MA. Also, no differences within the CC were observed using diffusion-weighted spectroscopy. IHI might serve as a marker of transcallosal pathway disruption in ALS, even before clinical deficits become apparent.

中文翻译：

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ALS中经call肌运动纤维的功能和结构受损：使用经颅磁刺激，扩散张量成像和扩散加权光谱的研究。

影像学研究表明，在肌萎缩性侧索硬化症（ALS）中，call体（CC）的结构受到影响。一些临床研究还表明，由于镜运动似乎发生在ALS中，因此半球之间的连通性发生了变化。最后，已经报道了通过经颅磁刺激（TMS）研究的减少半球间抑制作用（IHI）。尚不清楚这些发现之间是否有任何关联。在这里，我们从形态，功能，电生理和临床水平研究了ALS中CC的完整性。包括27位右手ALS患者和21位健康的右手对照。使用表面肌电图定量镜象活性（MA）。弥散张量成像术成像用于分割CC和量化分数各向异性（FA）。我们研究了CC内部轴突内标记N-乙酰天冬氨酸+ N-乙酰天冬氨酰谷氨酸D（tNAA）的扩散性。使用双脉冲TMS协议研究了IHI作为CC功能的标志物。ALS患者的CC运动节段FA显着降低（p <0.01），与对照组相比IHI显着降低（p = 0.01）。但是，没有观察到关于D（tNAA）和MA的差异。CC的形态和功能完整性在ALS中发生了变化。IHI的ALS降低，与运动CC的FA降低有关。患者没有表现出增加的MA。而且，使用扩散加权光谱法未观察到CC内的差异。即使在临床缺陷变得明显之前，IHI仍可作为ALS跨信号途径中断的标志。