Determinants of falls on the novel standing-slip and motor learning on repeated standing-slips among people with multiple sclerosis

Background: Falls are common and detrimental in people with multiple sclerosis (PwMS). It is essential to identify fall risk factors to prevent PwMS from falling. Perturbation training has shown promise in reducing falls. However, whether all PwMS can learn fall-resistant skills from perturbation training remains unknown. This study identified the determinants leading PwMS to a fall on the first standing-slip and allowing them to adapt to repeated standing-slips. Methods: Twenty-six PwMS (median Patient-Determined Disability Steps [PDDS]: 1.50) experienced five unexpected treadmill standing-slips. Two sets of comparisons were conducted regarding demographics, gait speed, PDDS, knee strength, and cognition (assessed by the Blessed-Orientation Memory Concentration test): between fallers and non-fallers on the first slip and between responders (those who fell on the initial slip but did not on later slips) and non-responders (those who fell on all five slips). Results: There were 17 fallers and nine non-fallers on the first slip. Among 17 fallers, nine were classified as responders and eight as non-responders. Non-fallers showed lower PDDS, faster gait speeds, and stronger knee strengths than fallers. Responders were younger, less disabled, walked faster, and had slightly better cognitive function. Conclusion: Disability level, walking speed, and leg strength may be key fall determinants upon the novel standing-slip. Not all PwMS could quickly adapt to repeated standing-slips. The motor learning ability from perturbation training depends on age, disability level, gait speed, and cognition level. Our findings could provide valuable information for screening PwMS at high fall risk and implementing perturbation training for this population.