Translational Neurodegeneration Section "Albrecht Kossel", Department of Neurology, Rostock University Medical Center, Rostock, Germany; Deutsches Zentrum für Neurodegenerative Erkrankungen (DZNE), Rostock-Greifswald, Rostock, Germany.
Deutsches Zentrum für Neurodegenerative Erkrankungen (DZNE), Rostock-Greifswald, Rostock, Germany; Department of Neurology, Rostock University Medical Center, Rostock, Germany.
J Neurol Sci. 2024 Nov 15;466:123267. doi: 10.1016/j.jns.2024.123267. Epub 2024 Oct 4.
Interhemispheric neurons in the motor section of the corpus callosum have an inhibitory effect on neurons of the contralateral motor cortex. Three quarters of patients with amyotrophic laterals sclerosis (ALS) show impaired transcallosal inhibition. We aimed to investigate whether structural changes co-occur with this functional impairment and to explore its phenotypic correlates.
The demographic, clinical, and neuropsychological data of 127 ALS patients were analysed. Transcallosal inhibition was assessed with an ipsilateral silent period (iSP) protocol using transcranial magnetic stimulation. Patients were categorised based on an iSP response or its loss, and the groups were characterised by demographic, clinical, and neuropsychological variables. Diffusion-weighted images from a subset of 63 patients were analysed using tractography, and white matter (WM) structural integrity metrics were compared across groups.
54 % of patients displayed iSP loss. The average free-water-corrected fractional anisotropy values within the callosal tract between the primary motor cortices were lower for patients with iSP loss compared to patients with an iSP response. There were no group differences based on other diffusivity metrics. The groups did not differ regarding any of the demographic, clinical, or neuropsychological variables.
We found reduced WM integrity in the motor section of the corpus callosum that differentiated ALS patients with iSP loss from patients with an iSP response, but with a small effect size. Nevertheless, the underlying pathological substrate and potential genetic drivers for these structural and functional changes in a subset of ALS patients remain to be satisfactorily investigated.
胼胝体运动区的半球间神经元对对侧运动皮层神经元具有抑制作用。四分之三的肌萎缩侧索硬化症（ALS）患者表现出经胼胝体抑制受损。我们旨在研究这种功能障碍是否伴有结构变化，并探讨其表型相关性。
分析了 127 例 ALS 患者的人口统计学、临床和神经心理学数据。使用经颅磁刺激的同侧静息期（iSP）方案评估经胼胝体抑制。根据 iSP 反应或其缺失对患者进行分类，并对各组进行人口统计学、临床和神经心理学变量的特征描述。对 63 例患者的一部分进行了弥散加权成像分析，使用轨迹追踪法比较了各组的白质（WM）结构完整性指标。
54%的患者表现出 iSP 缺失。与 iSP 反应的患者相比，iSP 缺失的患者初级运动皮质之间胼胝体束的自由水校正分数各向异性值平均较低。各组间其他弥散度指标无差异。两组在人口统计学、临床或神经心理学变量方面没有差异。
我们发现，运动区胼胝体 WM 完整性降低，可将 iSP 缺失的 ALS 患者与 iSP 反应的患者区分开来，但效应量较小。然而，这些结构和功能变化在一小部分 ALS 患者中的潜在病理基础和潜在遗传驱动因素仍有待充分研究。
