Arm swing while walking and running: a new clinical feature to separate Parkinson's disease from functional parkinsonism

Background

Functional parkinsonism is an important differential diagnosis of Parkinson's disease (PD). Based on anecdotal experience, we hypothesized that arm swing while walking and running could differentiate these two conditions, but this assumption has not been previously explored systematically.

Objectives

To examine differences in arm swing while walking/running between patients with PD and functional parkinsonism.

Methods

We analyzed blinded video assessments of arm swing and other gait parameters in patients with asymmetrical PD (n=81) and functional parkinsonism (n=8) while walking and running. The groups were matched for age, sex and disease duration.

Results

In contrast to those with PD, patients with functional parkinsonism (i) were more likely to have a marked asymmetry in arm swing while walking (5/8 vs. 25/81; p=0.06), (ii) were less likely to improve arm swing while running with full effort (3/8 vs. 72/81; p<0.001) and (iii) demonstrated normal passive arm swing even when asymmetry of arm swing was marked during running/walking (6/6 vs. 9/33; p=0.002).

Conclusions

Assessment of arm swing while walking and running and passive arm swing could be important differentiating clinical features between functional parkinsonism and PD.

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