Investigating differences in dynamic stability and physiological impairments in persons with multiple sclerosis based on fall history

Abstract

Around 60% of persons with multiple sclerosis (MS) experience falls, however the cause of these falls is not well understood. The purpose of this study is to further our understanding of why persons with MS fall during gait. Falls most frequently occur during walking, and are most commonly attributed to loss of balance and tripping. While fall occurrence is high, not all persons with MS fall, suggesting that there may be underlying differences between fallers and non-fallers with MS. Only three studies to date have compared walking between persons with MS with a history of falls and persons with MS with no falls history, and these studies have only measured walking speed and spatiotemporal parameters. The first goal of this study is, therefore, to compare specific features of dynamic balance between persons with MS who have a history of falls, persons with MS who have no falls history, and healthy controls. Also, while persons with MS can develop many different physiological impairments, it is unknown which specific physiological impairments are altered in fallers with MS relative to non-fallers and are associated with gait instability. The second goal of this study is, therefore, to determine if physiological impairments are different between persons with MS with a history of falls and persons with MS with no fall history, and to examine the relationship between physiological impairments and dynamic balance in persons with MS. By understanding of why persons with MS fall, these results may lead to improved methods of predicting and preventing falls. Fifty-five persons with MS (27 recurrent fallers, 28 non-fallers) and twenty-seven healthy controls walked on a treadmill for 3 minutes at their self-selected pace. Physiological impairments (sensorimotor delays, spasticity, plantar cutaneous sensation, and the sensory, cerebellar, and pyramidal Expanded Disability Status Scale subscales) were examined in all persons with MS. Variability of trunk accelerations, margin of stability, minimum toe clearance during swing phase, and spatiotemporal parameters during the walking trial were compared between all three groups. Physiological impairments were compared between fallers and non-fallers with MS. The relationship between physiological impairments and dynamic balance in persons with MS was assessed using correlation coefficients. Compared to non-fallers and healthy controls, fallers with MS walked more cautiously, with decreased control of the center of mass, and with lower toe clearance during swing phase. Fallers also had more severe physiological impairments than non-fallers. Worse physiological impairment was associated with worse dynamic balance in persons with MS. The present work provides evidence that within a group of persons with MS, there are specific measurable differences in dynamic balance and physiological impairments that are influenced by falls history which likely help to explain why some individuals with MS fall. It was found that fallers with MS have poor control over their center of mass and lower toe clearances during swing phase relative to non-fallers and healthy controls, which seems to be compensated for by adapting to a slow cautious gait. As dynamic balance was associated with loss of sensory information, longer sensorimotor delays, and pyramidal motor impairments, instability appears to be multifactorial in persons with MS. Evaluating distinct dynamic balance and physiological impairments in persons with MS may provide useful indicators of disease progression and fall risk, lead to improved fall prevention strategies, and aid in evaluating an individual’s responsiveness to different interventions.