Neurophysiological Features of Tremor during Walking in Parkinson's Disease

Background: In Parkinson's Disease (PD), upper limb tremor during walking (TW) is observed and clinical observations suggest it may represent a variant of rest tremor. However, its neurophysiological characteristics remain unexplored. Objectives: This study compared the neurophysiological features of TW with other PD tremors and tested whether TW arises from reduced ipsilateral arm swing. Methods: Inertial measurement units were used to measure frequency and amplitude of tremors and arm swing during walking in 25 PD patients. Results: TW shared a similar frequency with rest and re-emergent tremor (RET) but showed significantly greater amplitude. A positive correlation was observed between the amplitude and frequency of TW with those of rest and RET on the same side. TW distribution was unrelated to reduced arm swing during walking, suggesting TW is not due to decreased ipsilateral arm movement. Conclusions: These findings suggest that walking may act as a provocation maneuver, triggering rest tremor.