Thesis defense Jolanda Roelofs (Donders series 397)

19 November 2019

Promotor: prof. dr. A. Geurts
Co-promotors: dr. V. Weerdesteyn, dr. ir. A. Schouten

Static and dynamic standing balance in the chronic phase after stroke: how to recover?

Many persons in the chronic phase after stroke have deficits in standing balance. These balance deficits are associated with an increased fall risk in the post-stroke population. To identify persons with a high fall risk, it is of utmost importance to know which aspects of standing balance are critically deficient. This thesis provides more insight into both static and dynamic aspects of standing balance control in persons in the chronic phase after hemiparetic stroke. The results show that persons after stroke with (near-)complete clinical recovery of leg motor impairments (i.e., persons after ‘minor stroke’) are easily overestimated with regard to their quiet two-legged standing balance capacity, because clinical leg motor scores do not capture the subtle motor control needed for balance. In addition, persons after minor stroke may still show deficiencies in dynamic balance and gait, higher fall rates, and lower intensities of physical activity. Stroke-related deficits in the ability to recover balance from external perturbations (i.e., when standing on a moving platform) were more pronounced in stepping than in feet-in-place responses. With regard to reactive backward and side stepping, it appeared that the angle between the vertical and the stepping leg (i.e., leg angle) at first stepping-foot contact and perturbation intensity were the strongest predictors of successful balance recovery. As the backward leg angle could accurately be determined from a 2D video frame, it is a promising outcome measure for reactive step quality in clinical practice. Importantly, perturbation-based balance training improves reactive step quality in backward, forward, and both sideward directions in persons in the chronic phase after stroke.