Laboratory based assessment of gait and balance impairment in patients with progressive supranuclear palsy

Background: Gait and balance abnormalities are a significant source of morbidity and mortality in progressive supranuclear palsy (PSP). Gait impairment in PSP is primarily assessed clinically on exam or with the use of rating scales. Three dimensional video based gait and balance analysis performed in a laboratory setting is a highly accurate method of motion analysis (Wren et al., 2020), however limited data is available in patients with PSP. Research question: In this study we assess the objective features of postural control, kinematics, kinetic and temporal-spatial gait metrics in PSP, using three-dimensional video motion analysis in a laboratory setting compared to normal controls. Methods: Three-dimensional motion was captured using a 10-camera motion capture system, 41 body markers and ground embedded force plates in 16 patients with PSP patients and compared to motorically normal controls. Results: Spatiotemporal, kinematic, and kinetic gait measures effectively differentiated patients with PSP from controls. Patients had slower gait velocity, lower cadence, increased double support time and abnormal antero-posterior sway. Joint kinematics and kinetics were reduced and showed less variation among patients with PSP compared to controls which is suggestive of bradykinesia. Objective gait measures of abnormality correlated with clinical disease severity. Postural sway metrics distinguished PSP from controls and captured gait imbalance. Significance: Objective measures of gait and balance abnormalities in patients with PSP provide an outcome measure that can be potentially used for early disease detection, in clinical trials and to validate portable motion capture devices in the future.