Temporal synchronization during bilateral foot-tapping and its relationship with gait disturbance in patients with Parkinson's disease.

OBJECTIVE

Previous studies using finger-tapping tasks have shown that patients with Parkinson's disease (PD) exhibit a deficit of temporal processing linked to gait disturbance. In this study, we aimed to investigate abnormalities in lower-limb rhythmic control and their association with freezing of gait in PD using a bilateral foot-tapping task.

METHODS

Fifteen patients with PD and 25 healthy controls performed foot-tapping tasks synchronized with auditory tones at fixed intervals (500-2,400 ms). The tasks included unilateral and bilateral foot-tapping, with bilateral movements performed either in-phase (simultaneous) or antiphase (alternating). Data on synchronizing tapping error and inter-tap interval variability were analyzed and correlated with scores from clinical assessments, including the Unified Parkinson's Disease Rating Scale and Freezing of Gait Questionnaire.

RESULTS

Patients with PD showed greater negative synchronizing tapping error (negative asynchrony) and higher inter-tap interval variability than did controls, especially in antiphase condition. Exploratory within-PD-group analyses suggested associations between clinical severity and abnormalities in bilateral foot-tapping performance.

CONCLUSION

These findings indicate altered temporal accuracy and stability of rhythmic lower-limb movements in PD, particularly during bilateral antiphase foot-tapping. Bilateral foot-tapping measures may help characterize lower-limb timing deficits that are relevant to gait rehabilitation in PD.