Perturbing stroke patients

Abstract

Abstract Pilot study Introduction: Falls are a primary cause of accidental deaths, serious injuries, dependency and society costs. The response to perturbations could identify how well persons are able to reject perturbations. The aim of the study was to compare four different medio-lateral swing perturbations in order to select the most appropriate perturbation type and intensity for further perturbations studies. Methods: Five healthy subjects aged between 18 and 40 were included. Baseline walking on an CAREN was measured, followed by four perturbation trials in which the similar perturbation was twelve times repeated. Subjects were exposed to two different perturbation types; contra-lateral and ipsi-lateral perturbations and two different perturbation intensities; 0.05m displacement in 1.77s and 0.035m displacement in 1.62s. The perturbation response was quantified using the gait sensitivity norm and observational analysis. Results: The lager intensity of 0.05 m showed an increased response to contra-lateral perturbations compared to the lower intensity 0.035m (p=0.02). Contra-lateral perturbations tend to result in a larger response compared to ipsi-lateral perturbations. Subjects showed opposite responses to contra- and ipsi-lateral perturbations. Following contra-lateral perturbations, subjects decreased MOS and step width in the fist two step following the perturbation and increased step length and step time. In response to ipsi-lateral perturbations, subjects increased their MOS and step width, but decreased step length and step time. Conclusion: The contra-lateral perturbation of 0.05m intensity and the described protocol were recommended for further studies in order to discriminate fall-prone subjects. Abstract Study with stroke survivors Introduction: Around 40% of stroke patients show residual walking disabilities that increase fall risk. Therefore, it is important to identify patient specific responses related to fall risk. The aim of this study was to determine whether the ability to recover from external perturbations on the walking surface could discriminate patients from healthy controls and discriminate fallers from non-fallers in the stroke patient group. In addition, relations were studied between clinical fall assessments and perturbation responses. Methods: 14 stroke patients and 15 healthy controls were included in the study. Baseline walking on a CAREN was measured, followed by a trail with ten contra-lateral perturbations with an 0.05m displacement in 1.77s. The trials were performed in fixed speed and self-paced walking. The perturbation response was quantified using the gait sensitivity norm and observational analysis. Group differences in perturbation response were tested between stroke and healthy subjects and within the stroke patient group between fallers and non-fallers. Clinical fall assessments were correlated to GSN outcomes. Results: Stroke patients showed a larger perturbation response based on the gait sensitivity norm compared to healthy controls (p = 0.04) in fixed speed walking. In self-paced walking, stroke patients showed a larger gait sensitivity norm response (corrected)(p=0.04) and a larger step time (=0.02) and MOS response (p=0.03). Stroke patients showed reduced step width response (p=0.03). No differences in perturbation responses were found between stroke patients with and without fall history. Positive correlations were found between the timed up and go (TUG) score and GSN outcomes (p=0.03, p=