Parkinsonism is a clinical syndrome defined as bradykinesia, combined with rest tremor, rigidity, or both (Postuma et al., 2015). Parkinson's disease (PD) is the most common cause of parkinsonism and the fastest-growing neurodegenerative disorder worldwide with currently almost 1
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Parkinsonism is a clinical syndrome defined as bradykinesia, combined with rest tremor, rigidity, or both (Postuma et al., 2015). Parkinson's disease (PD) is the most common cause of parkinsonism and the fastest-growing neurodegenerative disorder worldwide with currently almost 12 million affected people worldwide (Bloem et al., 2021; Murray, 2024). Atypical parkinsonisms, including progressive supranuclear palsy (PSP), multiple system atrophy (MSA), corticobasal syndrome (CBS), and dementia with Lewy bodies (DLB), are collectively less prevalent than idiopathic PD. These disorders are classified as rare, with estimated prevalence rates ranging from 5 to 22 cases per 100,000 population depending on the specific subtype and diagnostic criteria used (Lo, 2022). MSA and PSP are the most frequently encountered atypical forms. For example, MSA has a reported prevalence of about 3–5 per 100,000, while PSP may reach up to 6 per 100,000 in some studies. DLB, often overlapping with both PD and Alzheimer's disease, appears to be more common, with estimates around 0.4 %–5 % of the elderly population, depending on whether clinical or neuropathological criteria are used (Nysetvold et al., 2024; Sekiya et al., 2024; Delpirou et al., 2024). Diagnosis is typically made based on clinical grounds, and several exclusion criteria as well as red flags have been defined that should urge the clinician to consider an atypical parkinsonian syndrome (Postuma et al., 2015). For instance, in case of early severe autonomic failure or frequent falls, the diagnosis of MSA or PSP should be considered respectively (Wenning et al., 2022; Höglinger et al., 2017). Atypical parkinsonism (AP) has a more aggressive disease course than PD, leading to earlier loss of independent functioning and shorter life spans. Moreover, dopamirgenic treatments are less effective when applied in persons with AP. Therefore, for appropriate guidance and treatment, a timely accurate diagnosis is crucial. However, AP diagnoses are frequently missed in the early stages with reported sensitivities for MSA and PSP below 65 % (Hughes et al., 2002; Joutsa et al., 2014). [...]
