Dear editors,

Parkinsonism is a clinical syndrome characterized by tremor, rigidity, akinesia, and postural disturbances. Parkinson's disease is the most common cause of parkinsonism, but there are numerous other causes. Functional movement disorders (FMDs) comprise a broad range of clinical symptoms not explained by a classical neurological disease. Tremor is the most common symptom in FMDs^{1, 2} followed by dystonia, myoclonus, balance disorder, bradykinesia, cranial movement, hemifacial spasms, restless legs, and so on. FMDs are often categorized as “psychogenic,” and the psychological parkinsonism is about 10% of patients with FMDs.³

A 53-year-old woman presented with a 2-year history of bradykinesia and rigidity. This patient presented with cogwheel rigidity, shortened stride length, and a decrease in arms swing. But she had a good balance with no difficulty in turns and no decreased facial expressions. She claimed to have an operation because of low blood pressure 2 years ago. Orthostatic hypotension was not found on our examinations and external anal sphincter-electromyography was normal to exclude multiple system atrophy. The results of routine laboratory tests were normal, as well as the brain MRI. Also, her cerebrospinal fluid (CSF) revealed a normal leukocyte count, protein level, immunoglobulin G index, and no unique oligoclonal bands. Her condition got deteriorated after dopa treatment. Interestingly, her bradykinesia could be resolved after a specific action by herself, and her symptoms almost completely reversed after only 1 week of placebo. This patient was diagnosed with dissociative conversion disorder by a professional psychologist finally.

It is important to differentiate FMDs from Parkinson's disease or other neurodegenerative diseases, as the latter often progresses inexorably over a period of years. Although ignoring a suspicion of psychological disorder seems more acceptable than a diagnosis of organic disease, there are many clues to the FMDs, like the history, physical examination, laboratory assessment, and treatment response. Distractibility, abrupt onset, variability of manifestation over time, and selective disabilities are common clinical characteristics in FMDs.¹ Diagnosing patients with psychological movement disorders often met with anger. While functional, sometimes interchangeably with “psychological,” is the term used in the diagnostic and statistical manual of mental disorders (DSM-5) and seems more acceptable to patients. The DSM-5 added a clinical criterion in 2013, which allows a ‘‘rule-in’’ procedure in firming a diagnosis of FMDs so that it is no longer considered a diagnosis of exclusion.²

Functional movement disorders account for even 15% of neurology outpatient clinics, which are more common in women^{1, 2} and range from 17 to 83 years old.¹ The incidence of functional neurological disorders is 4 to 12 of 100,000 per year.² Definitely, the etiology of FMDs is multifactorial. The bio-psycho-social model is considered more convincing to understand the underlying mechanisms in FMDs. Although no specific gene has been associated with FMDs, there is a possible role of certain forms of genetic variants in predisposition to different movement disorders, like Potassium (K+) Channel Tetramerization Domain (KCTD)-related family and catechol O-methyltransferase (COMT) variants.^{4, 5} Increasing neuroimaging studies identified the hypoactivation of the cortical and subcortical motor pathways and increased modulation by the limbic system in FMDs, like strengthened connectivity between the limbic, cognitive, and motor networks in patient with FMDs.⁵ These abnormal cerebral regions were thought related to motor planning and execution.⁶ With F-dopa, PET is helpful in distinguishing FMDs from Parkinson's disease in which abnormalities of fluorine accumulation are typically pronounced in the putamen and spared in the caudate.^{3, 7} A growing body of evidence suggests that physical trauma or stressful event often precedes or triggers FMDs, like motor vehicle accidents, operations, or fractures.⁸ Their pathogenic mechanisms may be related to the overactivity of brain networks reported in patients with functional neurological disorders, including energy regulation, threat detection, and action preparation. Certainly, some patients did present with combined FMDs and organic movement disorders, which is about 10%.⁹

Functional movement disorders still remain an enormous therapeutic challenge. Patients present for repeated medical attention because their physical suffering is real. Currently, there is no consensus about the treatment of FMDs, psychotherapy and psychoactive medications are typically early treatment attempts. Although a striking improvement can be observed in FMDs patients with successful treatment, movement disorders often have poor outcomes in those persisting beyond 6 months.¹ The purpose of this study was to provide more data on functional movement disorder to emphasize its importance and to help reach a correct diagnosis.

 亲爱的编辑们，

帕金森症是一种以震颤、强直、运动不能和姿势障碍为特征的临床综合征。帕金森病是帕金森病的最常见原因，但还有许多其他原因。功能性运动障碍 (FMD) 包括一系列无法​​用经典神经系统疾病解释的临床症状。震颤是FMD ^1、2最常见的症状，其次是肌张力障碍、肌阵挛、平衡障碍、运动迟缓、颅骨运动、面肌痉挛、不安腿等。 FMD 通常被归类为“心理性”，约 10% 的 FMD 患者患有心理性帕金森症。 ³

一名 53 岁女性，有 2 年运动迟缓和强直病史。该患者表现为齿轮僵硬、步幅缩短和手臂摆动减少。但她的平衡感很好，转身没有困难，面部表情也没有下降。她自称2年前因低血压接受了手术。我们的检查未发现直立性低血压，肛门外括约肌肌电图正常，排除多系统萎缩。常规实验室检查和脑部核磁共振检查结果均正常。此外，她的脑脊液 (CSF) 显示白细胞计数、蛋白质水平、免疫球蛋白 G 指数正常，没有独特的寡克隆条带。多巴治疗后，她的病情恶化。有趣的是，她的运动迟缓在她自己采取特定行动后就能得到缓解，而且仅服用安慰剂1周后，她的症状就几乎完全逆转。该患者最终被专业心理学家诊断为分离性转换障碍。

将口蹄疫与帕金森病或其他神经退行性疾病区分开来非常重要，因为后者通常会在数年的时间内无情地发展。尽管忽略对心理障碍的怀疑似乎比诊断器质性疾病更容易被接受，但口蹄疫有很多线索，如病史、体检、实验室评估和治疗反应。注意力分散、突然发作、随着时间的推移表现的变化以及选择性残疾是 FMD 的常见临床特征。 ¹诊断心理运动障碍患者常遇到愤怒。虽然功能性（有时与“心理性”）可互换，但它是精神障碍诊断和统计手册（DSM-5）中使用的术语，似乎更容易被患者接受。 DSM-5 在 2013 年增加了一项临床标准，允许通过“规则”程序来确定 FMD 的诊断，从而不再将其视为排除诊断。 ²

功能性运动障碍甚至占神经内科门诊的15%，多见于女性^1、2 ，年龄范围为17岁至83岁。 ¹功能性神经系统疾病的发病率为每年 10 万人中的 4 至 12 人。 ²当然，FMD 的病因是多因素的。生物心理社会模型被认为更有说服力来理解口蹄疫的潜在机制。尽管没有特定基因与 FMD 相关，但某些形式的遗传变异可能在不同运动障碍的易感性中发挥作用，例如钾 (K+) 通道四聚化结构域 (KCTD) 相关家族和儿茶酚 O-甲基转移酶 (COMT)变种。 ^{4, 5}越来越多的神经影像学研究发现，FMD 患者的皮质和皮质下运动通路活性低下，边缘系统的调节增加，例如 FMD 患者边缘系统、认知和运动网络之间的连接性增强。 ⁵这些异常的大脑区域被认为与运动计划和执行有关。 ⁶对于氟多巴，PET 有助于区分口蹄疫和帕金森病，在帕金森病中，氟积累异常通常在壳核中很明显，而在尾状核中则不受影响。 ^{3, 7}越来越多的证据表明，身体创伤或压力事件通常先于或引发口蹄疫，例如机动车事故、手术或骨折。⁸其致病机制可能与功能性神经系统疾病患者的大脑网络过度活跃有关，包括能量调节、威胁检测和行动准备。当然，也有部分患者同时出现口蹄疫和器质性运动障碍，比例约为10%。⁹

功能性运动障碍仍然是一个巨大的治疗挑战。患者需要反复就医，因为他们的身体痛苦是真实存在的。目前，关于口蹄疫的治疗尚未达成共识，心理治疗和精神活性药物通常是早期治疗尝试。尽管成功治疗的 FMD 患者可以观察到显着的改善，但运动障碍持续超过 6 个月的患者往往预后不佳。 ¹本研究的目的是提供更多有关功能性运动障碍的数据，以强调其重要性并帮助做出正确的诊断。