Danish Research Centre for Magnetic Resonance, Centre for Functional and Diagnostic Imaging and Research, Copenhagen University Hospital Hvidovre, Kettegard Allé 30, 2650 Hvidovre, Denmark; Department of Neurology, Copenhagen University Hospital Bispebjerg, Bispebjerg Bakke 23, 2400 Copenhagen, NV, Denmark.
Danish Research Centre for Magnetic Resonance, Centre for Functional and Diagnostic Imaging and Research, Copenhagen University Hospital Hvidovre, Kettegard Allé 30, 2650 Hvidovre, Denmark.
Neuroimage. 2019 Apr 15;190:269-274. doi: 10.1016/j.neuroimage.2018.03.061. Epub 2018 Mar 27.
A patient with motor conversion disorder presented with a functional paresis of the left hand. After exclusion of structural brain damage, she was repeatedly examined with whole-brain functional magnetic resonance imaging, while she performed visually paced finger-tapping tasks. The dorsal premotor cortex showed a bilateral deactivation in the acute-subacute phase. Recovery from unilateral hand paresis was associated with a gradual increase in task-based activation of the dorsal premotor cortex bilaterally. The right medial prefrontal cortex displayed the opposite pattern, showing initial task-based activation that gradually diminished with recovery. The inverse dynamics of premotor and medial prefrontal activity over time were found during unimanual finger-tapping with the affected and non-affected hand as well as during bimanual finger-tapping. These observations suggest that reduced premotor and increased medial prefrontal activity reflect an effector-independent cortical dysfunction in conversion paresis which gradually disappears in parallel with clinical remission of paresis. The results link the medial prefrontal and dorsal premotor areas to the generation of intentional actions. We hypothesise that an excessive 'veto' signal generated in medial prefrontal cortex along with decreased premotor activity might constitute the functional substrate of conversion disorder. This notion warrants further examination in a larger group of affected patients.
一位患有运动转换障碍的患者出现左手功能性瘫痪。在排除结构性脑损伤后，她反复接受全脑功能磁共振成像检查，同时进行视觉引导的手指敲击任务。在急性亚急性期，背侧运动前皮质显示双侧去激活。单侧手瘫痪的恢复与双侧背侧运动前皮质基于任务的激活逐渐增加有关。右侧内侧前额叶皮质显示出相反的模式，表现为初始基于任务的激活，随着恢复逐渐减少。在使用受影响和未受影响的手进行单手手指敲击以及双手手指敲击时，发现运动前皮质和内侧前额叶皮质的活动在时间上呈现出相反的动态。这些观察结果表明，运动前皮质活动减少和内侧前额叶皮质活动增加反映了转换性瘫痪中的皮层功能障碍，这种障碍与瘫痪的临床缓解平行逐渐消失。研究结果将内侧前额叶和背侧运动前区域与意向性动作的产生联系起来。我们假设内侧前额叶皮质中产生的过度“否决”信号以及运动前皮质活动的减少可能构成转换障碍的功能基础。这一概念需要在更大的患者群体中进一步研究。
