Rajagopalan Venkateswaran, Pioro Erik P
Department of Electrical and Electronics Engineering, Birla Institute of Technology and Science Pilani, Hyderabad Campus, Hyderabad 500078, India.
Neuromuscular Center, Department of Neurology, Neurological Institute, Cleveland, OH 44195, USA.
Brain Sci. 2021 Mar 14;11(3):371. doi: 10.3390/brainsci11030371.
A pathological hallmark of amyotrophic lateral sclerosis (ALS) is corticospinal tract (CST) degeneration resulting in upper motor neuron (UMN) dysfunction. No quantitative test is available to easily assess UMN pathways. Brain neuroimaging in ALS promises to potentially change this through identifying biomarkers of UMN dysfunction that may accelerate diagnosis and track disease progression. Fractal dimension (FD) has successfully been used to quantify brain grey matter (GM) and white matter (WM) shape complexity in various neurological disorders. Therefore, we investigated CST and whole brain GM and WM morphometric changes using FD analyses in ALS patients with different phenotypes. We hypothesized that FD would detect differences between ALS patients and neurologic controls and even between the ALS subgroups. Neuroimaging was performed in neurologic controls ( = 14), and ALS patients ( = 75). ALS patients were assigned into four groups based on their clinical or radiographic phenotypes. FD values were estimated for brain WM and GM structures. Patients with ALS and frontotemporal dementia (ALS-FTD) showed significantly higher CST FD values and lower primary motor and sensory cortex GM FD values compared to other ALS groups. No other group of ALS patients revealed significant FD value changes when compared to neurologic controls or with other ALS patient groups. These findings support a more severe disease process in ALS-FTD patients compared to other ALS patient groups. FD value measures may be a sensitive index to evaluate GM and WM (including CST) degeneration in ALS patients.
肌萎缩侧索硬化症（ALS）的一个病理特征是皮质脊髓束（CST）退化，导致上运动神经元（UMN）功能障碍。目前尚无简单易行的定量测试来评估UMN通路。ALS患者的脑成像有望通过识别UMN功能障碍的生物标志物来改变这一现状，这些生物标志物可能会加速诊断并追踪疾病进展。分形维数（FD）已成功用于量化各种神经系统疾病中的脑灰质（GM）和白质（WM）形状复杂性。因此，我们使用FD分析研究了不同表型的ALS患者的CST以及全脑GM和WM形态计量学变化。我们假设FD能够检测出ALS患者与神经对照组之间甚至ALS亚组之间的差异。对神经对照组（n = 14）和ALS患者（n = 75）进行了神经成像检查。根据临床或影像学表型将ALS患者分为四组。估计脑WM和GM结构的FD值。与其他ALS组相比，患有ALS和额颞叶痴呆（ALS-FTD）的患者显示出显著更高的CST FD值以及更低的初级运动和感觉皮层GM FD值。与神经对照组或其他ALS患者组相比，没有其他ALS患者组显示出显著的FD值变化。这些发现支持了与其他ALS患者组相比，ALS-FTD患者的疾病进程更为严重。FD值测量可能是评估ALS患者GM和WM（包括CST）退化的一个敏感指标。
