Freezing of gait and quiet standing: Sensory and medication influences in Parkinson’s disease

BACKGROUND: Freezing of Gait (FoG) is a debilitating symptom of Parkinson's disease (PD), significantly impacting postural control and increasing fall risk. Traditional methods for assessing postural control, such as the equilibrium score (ES), face criticism for inaccuracies due to their limited sensitivity and reliance on fixed assumptions. AIM: This study aimed to evaluate the influence of FoG status on postural control using center of pressure (CoP) analysis under various sensory conditions and medication states. METHODS: The study analyzed data from 32 individuals with idiopathic PD (14 with FoG - freezers) using a force platform to measure CoP variables during quiet standing. Participants were assessed under four sensory conditions: rigid surface with eyes open, rigid surface with eyes closed, malleable surface with eyes open, and malleable surface with eyes closed. Measurements were taken in both medication ON and OFF states. Statistical analysis was performed using linear mixed-effects models. RESULTS: Significant differences were observed in the malleable surface with eyes closed (CoP velocity and frequency in the anteroposterior direction) when participants were in ON state. INTERPRETATION: This finding underscores the importance of investigating how dopaminergic medication affects sensory processing in individuals with FoG, as the effects of medication on postural control may vary depending on task demands and sensory conditions. The findings underscore the need to consider sensory conditions and medication status in clinical assessments and interventions to improve management strategies for postural instability and FoG in PD.