Deficient recovery response and adaptive feedback potential in dynamic gait stability in unilateral peripheral vestibular disorder patients

Abstract

Unilateral peripheral vestibular disorder (UPVD) causes deficient locomotor responses to novel environments due to a lack of accurate vestibular sensory information, increasing fall risk. This study aimed to examine recovery response (stability recovery actions) and adaptive feedback potential in dynamic stability of UPVD‐patients and healthy control subjects during perturbed walking. 17 UPVD‐patients (>6 months since onset) and 17 matched healthy control participants walked on a treadmill and were subjected to eight unexpected perturbations during the swing phase of the right leg. For each perturbation, the margin of stability (MS; state of body's centre of mass in relation to the base of support), was determined at touchdown of the perturbed leg and during the following six recovery steps. The first perturbation caused a reduced MS at touchdown for the perturbed leg compared to baseline, indicating an unstable position, with controls requiring five recovery steps to return to MS baseline and UPVD‐patients not returning to baseline level within the analyzed six recovery steps. By the eighth perturbation, control subjects needed two steps, and UPVD‐patients required three recovery steps, both thereby improving their recovery response with practice. However, MS at touchdown of the perturbed leg increased only for the controls after repeated perturbations, indicating adaptive feedback‐driven locomotor improvements for the controls, but not for the UPVD‐patients. We concluded that UPVD‐patients have a diminished ability to control dynamic gait stability during unexpected perturbations, increasing their fall risk, and that vestibular dysfunction may inhibit the neuromotor system adapting the reactive motor response to perturbations.

Visual and proprioceptive contributions to postural control of upright stance in unilateral vestibulopathy

“…The base of support during dynamic gait tasks using three dimensional motion capture techniques is often calculated using the anterior toe markers which are placed at the same position on all subjects (McCrum et al 2014, Süptitz et al 2012, Süptitz et al 2013). Our findings suggest that previous studies using the base of support in …”

“…Previous studies have demonstrated negatively affected upper and lower body motor control during standing, sitting and perturbed walking in patients with UPVD (Borello-France et al 1999, McCrum et al 2014, Raptis et al 2007). Due to the stability and motor control issues seen in UPVD, posturography under different sensory disturbances represents a potential method to analyse postural control and sensory compensation in these patients.…”

Dynamic margin of stability during gait is altered in persons with multiple sclerosis

“…Previous studies have examined MoS at each heel strike (McAndrew Young et al, 2012; McCrum et al, 2014); however, in the gait cycle, midstance may be the point most susceptible to a ML perturbation, causing a fall or corrective stepping (Hof et al, 2010). Heel strike was defined as the instant in which the heel marker reached its local stride to stride minimum (Fellin et al, 2010).…”

Locomotor stability and adaptation during perturbed walking across the adult female lifespan

“…The gait perturbation was applied using a custom built brake-and-release system described previously (McCrum et al, 2014;Süptitz et al, 2013) which applies and removes 2.1kg of resistance to the leg via an ankle strap and Teflon cable, controlled via an electronically 5 driven magnet system. Resistance is turned on during the right leg stance phase and removed following right foot touchdown, so that the entire swing phase is affected.…”

“…Our method to assess gait stability on the treadmill has been described in previous studies (McCrum et al, 2014;Süptitz et al, 2012;Süptitz et al, 2013), and a detailed description is provided in the appendix (see Supplementary Material). Briefly, a full kinematic model was tracked using 26 markers and an eight camera (120 Hz) Vicon Nexus motion capture system (Vicon Motion Systems, Oxford, UK).…”