White A T, Lee J N, Light A R, Light K C
Department of Exercise & Sport Science and Brain Institute, University of Utah, Salt Lake City, UT, USA.
Mult Scler. 2009 May;15(5):580-6. doi: 10.1177/1352458508100034. Epub 2009 Mar 19.
Multiple sclerosis (MS) patients experience fatigue as a chronic symptom that decreases quality of life. Commonly, fatigue in MS patients is manifested as decreased motor function during or after physical activity and is associated with changes in brain metabolism.
To determine brain activation patterns in MS patients and healthy controls during a simple motor task before and after fatiguing hand-grip exercise.
Functional magnetic resonance imaging (fMRI) scans were conducted on 10 MS patients and 13 healthy controls during 4-finger flexion and extension in rested and fatigued states.
Before the fatigue protocol, MS patients had greater activation in the contralateral primary motor cortex, insula, and cingulate gyrus than controls. Following fatiguing exercise, controls showed increased activation of precentral gyrus and insula while patients did not show any activation increases and actually decreased activity to the insula.
Results indicate that before fatiguing exercise, MS patients marshaled more brain activation compared to controls, which may represent functionally adaptive changes in response to demyelination. This increased activation may suggest that patients require more effort to perform even simple motor tasks, possibly because peripheral or central signals for fatigue are chronically enhanced. When fatigued further by muscle contraction, brain activation cannot be further increased.
多发性硬化症（MS）患者会经历疲劳这一降低生活质量的慢性症状。通常，MS患者的疲劳表现为体力活动期间或之后运动功能下降，并与脑代谢变化有关。
确定MS患者和健康对照者在疲劳性握力运动前后进行简单运动任务时的脑激活模式。
对10名MS患者和13名健康对照者在休息和疲劳状态下进行四指屈伸时进行功能磁共振成像（fMRI）扫描。
在疲劳方案之前，MS患者在对侧初级运动皮层、岛叶和扣带回的激活程度高于对照组。疲劳运动后，对照组中央前回和岛叶的激活增加，而患者未显示任何激活增加，实际上岛叶的活动减少。
结果表明，在疲劳运动之前，MS患者与对照组相比调动了更多的脑激活，这可能代表了对脱髓鞘的功能适应性变化。这种增加的激活可能表明患者即使执行简单的运动任务也需要更多努力，这可能是因为疲劳的外周或中枢信号长期增强。当因肌肉收缩而进一步疲劳时，脑激活无法进一步增加。
