Danish Research Centre for Magnetic Resonance, Centre for Functional and Diagnostic Imaging and Research, Copenhagen University Hospital Hvidovre, Hvidovre, Denmark.
Metropolitan University College, Copenhagen, Denmark.
PLoS One. 2018 Oct 24;13(10):e0201162. doi: 10.1371/journal.pone.0201162. eCollection 2018.
Fatigue is a common and highly disabling symptom of multiple sclerosis. Patients experience an effort-independent general subjective feeling of fatigue as well as excessive fatigability when engaging in physical or mental activity. Previous research using functional magnetic resonance imaging (fMRI) has revealed heterogeneous findings, but some evidence implicates the motor system. To identify brain correlates of fatigue, 44 mildly impaired patients with relapsing-remitting multiple sclerosis and 25 age- and gender-matched healthy controls underwent functional magnetic resonance imaging at 3 Tesla, while they performed alternating blocks of rest and a non-fatiguing precision grip task. We investigated neural correlates of fatigue using the motor subscore of Fatigue Scale for Motor and Cognitive Functions (FSMCMOTOR) using the bilateral motor cerebellum, putamen, and dorsal premotor cortex as regions of interest. Patients and healthy controls performed the grip force task equally well without being fatigued. In patients, task-related activity in lobule VI of right motor cerebellum changed in proportion with individual FSMCMOTOR scores. In right dorsal premotor cortex, linear increases in activity across consecutive task blocks scaled with individual FSMCMOTOR scores in healthy controls, but not in patients. In premotor and dorsomedial prefrontal areas, patients were impaired at upscaling task-related activity the more they were affected by motor fatigue. The results support the notion that increased sensorimotor processing in the cerebellum contributes to the experience of motor fatigue and fatigability in multiple sclerosis. Additionally, downscaling of motivational input or sensorimotor processing in prefrontal and premotor areas may constitute an additional pathophysiological factor.
疲劳是多发性硬化症的一种常见且高度致残的症状。患者在进行体力或脑力活动时会经历一种与努力无关的全身性主观疲劳感，以及过度疲劳。先前使用功能磁共振成像（fMRI）的研究结果存在异质性，但有一些证据表明与运动系统有关。为了确定疲劳的大脑相关性，44 名缓解-复发型多发性硬化症轻度受损患者和 25 名年龄和性别匹配的健康对照者在 3 Tesla 磁共振成像仪上进行了功能磁共振成像，同时他们进行了休息和非疲劳性精确握力任务的交替块。我们使用双侧运动小脑、壳核和背侧运动前皮质作为感兴趣区域，使用运动功能和认知功能疲劳量表（FSMCMOTOR）的运动子评分来研究疲劳的神经相关性。患者和健康对照者在不疲劳的情况下同样能够很好地执行握力任务。在患者中，右运动小脑 VI 叶的与任务相关的活动与个体 FSMCMOTOR 评分成比例变化。在右侧背侧运动前皮质中，活动在连续任务块中的线性增加与健康对照者的个体 FSMCMOTOR 评分相匹配，但在患者中则不然。在运动前和背内侧前额叶区域，患者在运动疲劳的影响下，其任务相关活动的上调能力受损。研究结果支持这样一种观点，即小脑中增加的感觉运动处理有助于多发性硬化症中运动疲劳和易疲劳感的产生。此外，前额叶和运动前区域中动机输入或感觉运动处理的下调可能构成另一个病理生理因素。
