BACKGROUND Diagnosis of functional (psychogenic) movement disorders is challenging, causing concern for many clinicians. Here, we describe a case in which MRCP (movement related cortical potentials) was useful for understanding pathophysiology. CASE REPORT The patient was a 16-year-old male with history of glycogenosis and Crohn's disease. He also had a history of possible autism spectrum disorder and psychogenic gait disturbance at age 12. On admission, persistent abdominal jerk had appeared. Abdominal jerks presented like hiccups, appearing once every few seconds and reducing in amplitude and frequency with distraction. Surface electromyogram with EEG excluded epileptic spasms. MRCP, with rectus abdominis muscle contractions set as a trigger, showed slowly rising negative waves (Bereitschaftspotentials, BP) from 0.6 s prior to the trigger. The presence of BP suggests that the abnormal movement emerges through a voluntary motor pathway. We comprehensively diagnosed his involuntary jerks as functional abdominal myoclonus. DISCUSSION In a voluntary movement, after the drive to move from frontal and limbic regions, MRCP shows slow negative waves originating from pre-Supplementary Motor Area (SMA) and SMA, as BP, before real muscle contraction. The sense of agency is also simultaneously generated in this process by the collaborative work of the frontal and parietal lobes. Even though this abnormal movement goes through the voluntary motor pathway, the patient may not be aware of voluntariness due to lack of sense of agency. CONCLUSION MRCP is still challenging, but useful for the diagnosis of functional (psychogenic) movement disorders.

中文翻译：

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运动相关皮层电位分析腹部功能性肌阵挛一例

背景功能性（心因性）运动障碍的诊断具有挑战性，引起了许多临床医生的关注。在这里，我们描述了一个案例，其中 MRCP（运动相关皮层电位）有助于理解病理生理学。病例报告 患者是一名 16 岁男性，有糖原贮积症和克罗恩病史。他在 12 岁时也有可能患有自闭症谱系障碍和心因性步态障碍的病史。入院时，出现持续的腹部痉挛。腹部抽搐就像打嗝一样，每隔几秒钟出现一次，并且随着注意力的分散而降低幅度和频率。带脑电图的表面肌电图排除癫痫性痉挛。MRCP 以腹直肌收缩为触发，显示从触发前 0.6 秒开始缓慢上升的负波（Bereitschaftspotentials，BP）。BP 的存在表明异常运动是通过自主运动途径出现的。我们综合诊断他的不自主抽搐为功能性腹肌阵挛。讨论 在随意运动中，在从额叶和边缘区域移动后，MRCP 显示出缓慢的负波，该负波源自前辅助运动区 (SMA) 和 SMA，作为 BP，在真正的肌肉收缩之前。在这个过程中，额叶和顶叶的协同工作也同时产生了代理感。即使这种异常运动通过自主运动通路，由于缺乏代理感，患者可能不会意识到自主性。结论 MRCP 仍然具有挑战性，但可用于诊断功能性（心因性）运动障碍。