The characteristics of body sway at the static standing position and postural instability in patients with progressive supranuclear palsy

Abstract

Progressive supranuclear palsy (PSP) is a neurodegenerative disease characterized by supranuclear gaze palsy, postural instability with frequent falls, gait disturbance, pseudobulbar palsy, and dementia. Although postural instability is one of the cardinal features of PSP, there are few reports about the features in detail. In this study, we investigated the characteristics of body sway and postural instability in patients with PSP. The subjects were 21 patients with PSP whose mobility were above the level of assistance gait level (PSP) and 25 healthy elderly people (CON). Age, sex, body mass index, duration of disease from onset of initial symptoms, modified Rankin Scale (mRS), progressive supranuclear palsy rating scale (PSPRS), pull test and body sway during resting standing position were evaluated. Comparison between groups and relationship between the pull test and other evaluation items in PSP were analyzed. In PSP, area of body sway (cm²) wad larger and their center of gravity position (cm) was deviated backward during standing compared to CON. Furthermore, locus length per unit area (cm/cm²), which reflected postural adjustments controlled by the spinal proprioceptive reflexes of the lower limbs, was lower compared to CON. Patients with longer duration, more severe mobility, and worse clinical status of PSP had more severe postural instability. In addition, the postural instability was related to the degree of body sway in the static standing position in PSP.