Department of Neurology, University Hospital Ulm, Ulm, Germany.
Department of Neurology, University Hospital Geneva, Rue Gabrielle-Perret-Gentil 4, 1205, Genève, Switzerland.
Brain Imaging Behav. 2021 Apr;15(2):748-757. doi: 10.1007/s11682-020-00282-x.
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.
影像学研究表明，肌萎缩侧索硬化症（ALS）会影响胼胝体（CC）的结构。一些临床研究还表明，大脑两半球间的连接发生了改变，因为在 ALS 中似乎会出现镜像运动。最后，经颅磁刺激（TMS）研究报道了减少的大脑两半球间抑制（IHI）。尚不清楚这些发现之间是否存在任何关联。在这里，我们从形态学、功能、电生理学和临床水平研究了 ALS 中 CC 的完整性。纳入 27 名右利手 ALS 患者和 21 名健康右利手对照者。使用表面肌电图定量镜像运动（MA）。使用扩散张量成像束追踪技术分割 CC 并量化分数各向异性（FA）。我们研究了 CC 内轴内标志物 N-乙酰天冬氨酸+N-乙酰天冬氨酸谷氨酸 D(tNAA)的扩散性。使用双脉冲 TMS 方案研究 IHI 作为 CC 功能的标志物。与对照组相比，ALS 患者的 CC 运动段 FA 明显降低（p<0.01），且 IHI 明显降低（p=0.01）。然而，D(tNAA)和 MA 无差异。CC 的形态和功能完整性在 ALS 中发生改变。IHI 在 ALS 中降低，与 CC 运动段 FA 降低相关。患者未表现出 MA 增加。另外，使用扩散加权光谱未观察到 CC 内的差异。即使在临床缺陷变得明显之前，IHI 也可能作为 ALS 中胼胝体通路中断的标志物。
