Department of Neurology, Otto-von-Guericke University, 39120 Magdeburg, Germany.
Cereb Cortex. 2011 Oct;21(10):2394-8. doi: 10.1093/cercor/bhr026. Epub 2011 Mar 2.
The neural mechanisms underlying conversion disorders such as hysterical blindness are at present unknown. Typically, patients are diagnosed through exclusion of neurological disease and the absence of pathologic neurophysiological diagnostic findings. Here, we investigate the neural basis of this disorder by combining electrophysiological (event-related potentials) and hemodynamic measures (functional magnet resonance tomography) in a patient with hysterical blindness before and after successful treatment. Importantly, the blindness was limited to the left upper and right lower visual quadrant offering the possibility to use the other 2 sighted quadrants as controls. While the functional magnetic resonance imaging activations were normal for visual stimulation electrophysiological indices of visual processing were modulated in a specific manner. Before treatment, the amplitude of the N1 event-related potentials component had smaller amplitudes for stimuli presented in the blind quadrants of the visual field. Following successful treatment the N1 component elicited by stimuli presented in formerly blind quadrants had a normal distribution without any amplitude differences between the 4 quadrants. The current findings point out that dissociative disorders such as hysterical blindness may have neurophysiological correlates. Furthermore, the observed neurophysiological pattern suggests an involvement of attentional mechanisms in the neural basis hysterical blindness.
目前尚不清楚转换障碍（如癔症性失明）的神经机制。通常，通过排除神经疾病和没有病理神经生理诊断发现来诊断患者。在这里，我们通过对一名成功治疗前后癔症性失明患者进行电生理（事件相关电位）和血流动力学测量（功能磁共振成像），来研究这种疾病的神经基础。重要的是，失明仅限于左上和右下视野象限，这为使用其他两个视力正常的象限作为对照提供了可能性。虽然功能磁共振成像激活对于视觉刺激是正常的，但视觉处理的电生理指标以特定的方式发生了调制。在治疗前，对于呈现于视野中失明象限的刺激，N1 事件相关电位成分的振幅较小。在成功治疗后，由先前失明象限呈现的刺激诱发的 N1 成分具有正常的分布，四个象限之间没有任何振幅差异。目前的研究结果表明，分离性障碍（如癔症性失明）可能具有神经生理学相关性。此外，观察到的神经生理模式表明，注意机制可能参与了癔症性失明的神经基础。
