Quantifying postural instability in Parkinsonian gait from inertial sensor data during standardised clinical gait tests

Quantifying dynamic postural stability from inertial sensor data is clinically very relevant for treatment and therapy monitoring in neuromuscular diseases, e.g. Parkinson's disease (PD). We extract peak accelerations in movement direction during the loading phase and in vertical direction at ground contact from gravity-free acceleration signals captured at the patient's feet as novel markers of dynamic postural stability. The approach is tested on a dataset containing 100 idiopathic PD patients and 50 age- and weight-matched healthy controls. Experiments include group separation of the controls and PD patients with/without postural instability as assessed by the pull test and analysis of correlations to existing parameters from inertial sensor data. Both markers show significant clinical differences, specifically between the two conditions in the PD group. At least one parameter provides complementary information to the existing set of spatio-temporal gait parameters while the other one correlates highly to gait velocity but might be measurable more precisely. In conclusion, the inertial sensor derived markers can detect postural instability but further research in this domain is needed.