Objective: To determine the prevalence of functional neurological signs in patients with PD through a standardized neurological examination. Secondary objectives are to quantify the number of positive functional neurological signs per patient, evaluating the association between the number of positive functional signs per patient and clinical characteristics, including demographics, disease duration, motor severity, and non-motor symptoms.

Background: Functional neurological disorders (FND) are increasingly recognized as clinically relevant comorbidities. in patients with established neurological disorders, including Parkinson’s disease (PD). However, there is uncertainty about the prevalence of functional neurological signs in PD, and systematic multicenter assessments using validated positive clinical signs are limited. Failure to recognize functional sources of disability in PD may contribute to inappropriate treatment and increased disease burden.

Method: This prospective, multicenter, cross-sectional observational study will enroll 500 patients with PD. All participants will undergo a standardized neurological examination assessing seven predefined positive functional neurological signs: Hoover’s sign, tremor entrainment, shoulder tap test, fixed dystonic posture, typical functional hemifacial overactivity, altered vibration sensation across the forehead, and arm drift without pronation. Clinical data collected will include demographic characteristics, disease duration, motor symptoms severity, and non-motor symptoms. Descriptive statistics will be used to estimate the prevalence of functional neurological signs, with 95% confidence intervals. Logistic regression analyses will be performed to identify demographic and clinical predictors of positive functional signs.

Results: This study is expected to provide reliable multicenter estimates of the prevalence of functional neurological signs in PD and to identify clinical factors associated with their presence.

Conclusion: Improved understanding of the prevalence and clinical correlates of functional neurological signs in PD may enhance diagnostic accuracy, optimize clinical management, and support appropriate referral to multidisciplinary care.

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3. Matar E, Tinazzi M, Edwards MJ, Bhatia KP. Functional movement disorder as a prodromal symptom of Parkinson’s disease—clinical and pathophysiological insights. Movement Disorders. 2024;39(11):1952-9.
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5. Tinazzi M, Geroin C, Erro R, Marcuzzo E, Cuoco S, Ceravolo R, et al. Functional motor disorders associated with other neurological diseases: beyond the boundaries of “organic” neurology. European journal of neurology. 2021;28(5):1752-8.
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MDS Abstracts - https://www.mdsabstracts.org/abstract/prevalence-of-functional-neurological-signs-in-parkinsons-disease-a-multicenter-cross-sectional-study/