Objective: Young onset Parkinson’s disease diagnosis can be challenging, and it is a rare subtype of a disease typically associated with older age. On the other hand, Functional movement disorders are recognized as a “crisis” in neurology since the diagnosis requires a lot of expertise and comprehensive evaluation. The current case highlights the utility of neurophysiology in differentiating Parkinson’s tremor and functional tremor with similar phenotype.

Background: Functional parkinsonism is observed in less than 10% of the case series of FMDs, with a female-male ratio of roughly 1:1. Functional tremors can be diagnosed based on clinical and physiologic criteria such as entrainment, suggestibility, distractibility, variable nature with the associated clinical history of psychosomatic co-morbidities.

Method: We report a 35 years old man with progressive parkinsonian tremor and other mimicking findings of Parkinson’s disease. We performed an extensive electrophysiological assessment tremor which was noted to be variable and entrainable, suggestive of a functional etiology.

Results: We describe a 35 years old man, with early onset left hand tremor resembling Parkinson’s disease, followed by right arm tremor and progressive gait changes with negative DaT scan and further work up, including tremor studies supporting functional movement disorder. Lack of amplitude decrement in repetitive movements and of cogwheel rigidity also can help to differentiate FMD from true parkinsonism.

Conclusion: Functional tremor can be differentiated from early-onset parkinsonism by clinical and ancillary studies such as neurophysiology testing as supportive evidence which will potentially improve disease prognosis and outcome.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/functional-movement-disorder-mimicking-parkinsons-disease-a-case-with-supporting-evidence/