Anticipatory and compensatory postural adjustments during standing in faller and non-faller multiple sclerosis patients and healthy subjects

Abstract

Background: While previous studies have investigated postural adjustment mechanisms in multiple sclerosis (MS) patients, no study has yet investigated the relationship between anticipatory and compensatory postural adjustments (APAs and CPAs) and falls. Methods: Seventeen MS fallers, 17 MS non-fallers and 15 healthy controls were exposed to a series of expected and unexpected backward pull perturbations applied at the trunk level. Electrical activity of 12 leg and trunk muscles as well as center of pressure (COP) displacements were recorded. Results: Most studied muscles initiated significantly later in MS fallers in comparison to non-fallers and healthy controls. Regarding the magnitudes of muscle activations, significantly lower magnitudes of muscle activities during the APAs were detected in MS fallers in comparison to controls. Moreover, in the unexpected condition of perturbation, significantly smaller CPA was seen in MS-fallers in comparison to healthy controls. Both groups of MS patients required more times to stabilize their COP following both types of perturbations in comparison to controls. Conclusion: The inability to produce efficient APAs and CPAs during perturbations may explain the high rates of postural instability and falls in MS patients. Significance: These results are important for the development of fall management protocols in patients with MS.