Development of a novel VR-based system for quantitative assessment of freezing of gait in Parkinson disease

Gait disturbances in Parkinson's Disease (PD) are highly susceptible to changes in patients' surrounding environment. It is empirically known that the gait disturbances tend to become worse in environments with doors, obstacles, or narrow pathways, often causing freezing of gait (FoG). FoG is defined as a state in which the soles of the feet are experienced to be stuck to the floor, making it difficult for the patients to walk. FoG is a major cause of falls, yet it is often challenging to elicit this symptom in standard clinical examination rooms.The present study proposes a VR-based novel system to experimentally induce FoG and quantitatively assess the degree of severity. We developed a VR-FoG system that allows users to experience walking through a corridor placed with an obstacle using a head-mounted display (HMD). Using the system, 20 PD patients and 11 healthy elderly people were asked to walk through the virtual corridor from a start to the end position by changing the obstacle state (ordered vs. messy) and passage width (narrow vs. wide). During the experiment, position and posture of the participant’s head were measured with the HMD to analyze the walking sate. The experimental results in PD patients demonstrated that the proposed system can induce FoG especially under messy and narrow conditions, and showed that walking velocity frequently become zero in FoG state, resulting in significant long walking time. These findings implied that the proposed system may give a breakthrough to quantitative evaluation of various walking impairments including FoG.