Supplementary Material for: New-onset progressive ataxia in a 66-year-old woman with longstanding Parkinson’s disease – a case report

Introduction:
Parkinson’s disease (PD) is a common neurodegenerative disorder, and its diagnosis remains a clinical one. Hence, the emergence of new symptoms warrants consideration of a new diagnostic work-up even at later disease stages. Important differential diagnoses include atypical or symptomatic parkinsonism, like multiple system atrophy, normal pressure hydrocephalus, or rarely, superficial siderosis (SS).

Case Presentation:
A 66-year-old woman with longstanding PD presented to our clinic with a four-year history of progressive ataxia and gait impairment. The emergence of a new symptom (ataxia) prompted us to conduct a new, broad diagnostic work-up. Clinical examination revealed both parkinsonian (hypomimia, dyskinesias, right dominant bradykinesia and rigidity, intermittent resting tremor) and cerebellar signs (scanning dysarthria, gaze-evoked nystagmus, severe ataxia of extremities and gait). No signs or symptoms of autonomic dysfunction were present. Magnetic resonance imaging of brain and spine showed extensive hemosiderin depositions and ventral intraspinal fluid collection, establishing a diagnosis of SS. No apparent dural leak was detected in cerebrospinal fluid scintigraphy. The patient was treated with epidural blood patch.

Conclusion:
The occurrence of new symptoms in PD, especially “red flags” or exclusion criteria, calls for a repeated diagnostic work-up to exclude potentially treatable causes of parkinsonism. While SS has been reported as a cause of symptomatic parkinsonism, we favor a diagnosis of idiopathic PD and comorbid SS in this case. This case report highlights the clinical importance of diagnostic criteria in differentiating PD from atypical parkinsonian disorders or symptomatic parkinsonism as well as signs and symptoms, pathophysiological aspects, and treatment of SS.

引言：
帕金森病（Parkinson’s disease, PD）是一种常见的神经退行性疾病，目前其诊断仍依赖临床手段。因此，即便处于疾病后期，若出现新的症状，也需考虑开展新一轮全面的诊断排查。重要的鉴别诊断包括非典型帕金森综合征或症状性帕金森综合征，如多系统萎缩（multiple system atrophy）、正常压力脑积水（normal pressure hydrocephalus），极少数情况下还可见浅表铁质沉着症（superficial siderosis, SS）。

病例报告：
一名患有长期帕金森病的66岁女性患者，因渐进性共济失调与步态障碍病史4年前往我院门诊就诊。新出现的共济失调症状促使我们启动了全面的新诊断排查。临床检查同时发现帕金森样体征（面具脸、运动障碍、右侧为主的运动迟缓与肌强直，间断性静止性震颤）以及小脑体征（吟诗样构音障碍、凝视诱发性眼震、四肢与步态严重共济失调）。未观察到自主神经功能障碍的相关体征与症状。颅脑与脊柱磁共振成像（Magnetic resonance imaging）显示广泛的含铁血黄素沉积以及脊柱腹侧液体积聚，据此确诊为浅表铁质沉着症。脑脊液闪烁显像（cerebrospinal fluid scintigraphy）未发现明确的硬膜漏。患者接受了硬膜外血贴疗法。

结论：
帕金森病患者出现新症状，尤其是出现“警示征”或排除标准时，需重新开展诊断排查以排除潜在可治疗的症状性帕金森综合征病因。尽管已有浅表铁质沉着症作为症状性帕金森综合征病因的相关报道，但本例患者我们倾向于诊断为特发性帕金森病合并浅表铁质沉着症。本病例报告凸显了诊断标准在区分帕金森病与非典型帕金森综合征或症状性帕金森综合征中的临床重要性，同时也阐述了浅表铁质沉着症的临床表现、病理生理机制与治疗方案。