Postural control in Parkinsonisms during a short static sway

Abstract

Neurological diseases, such as Parkinsonisms, are often associated with static postural instability. Progressive supranuclear palsy (PSP) is a rare neurodegenerative disease classified among atypical Parkinsonisms. In the earliest stages, PSP is similar to Parkinson’s disease (PD) [1]. Static postural stability is an important contributor to the balance control framework and balance impairment can be quantified with a postural sway measure [2]. The main goal of our study was to compare postural sway changes in both PSP and PD subjects, using a standing single task of 5-6 seconds, in order to prove that a shorter sway time may be useful to distinguish Parkinsonisms. We assessed fifteen individuals with early PSP and fifteen individuals with recent diagnosis of PD (De Novo PD). Stabilometric analysis was performed for the evaluation of balance through a BTS Bioengineering system. The patient was instructed to stand on the force plate with the eyes open and measures of 5-6 seconds were taken. To find differences between the groups, univariate statistical analysis on sway data was conducted, and an alpha significance level was set to p-value < 0.05. The statistical analysis showed significant differences between De Novo PD and PSP groups for Medio- Lateral (M-L) sway (p-value=0.01), M-L range (p-value=0.023) and radius (p-value=0.026); minimum oscillation from the center of gravity and area showed a statistical trend with a p-value slightly above the 0.05 (p-value=0.056 and p-value=0.061, respectively). Several studies have demonstrated that balance dysfunction in PD is directionally dependent [2,3]. In agreement with our data, patients with atypical Parkinsonism show balance impairment on M-L direction as attested by augmented M-L sway, M-L range and radius. These results indicate that a short static sway of 5-6 seconds, could provide the clinician with a reliable and non-invasive tool to distinguish PSP from PD since the earliest stages.