Assessing nonlinear gait characteristics in multiple sclerosis: Insights from a systematic review

Abstract Background Multiple sclerosis is a chronic neurodegenerative disease that often compromises gait, a key determinant of independence and quality of life. Nonlinear gait analysis may provide useful information about motor control alterations in people with multiple sclerosis, yet current evidence remains limited and fragmented. This systematic review synthesized research on nonlinear gait variables in this population, focusing on entropy, Lyapunov exponents, and detrended fluctuation analysis. Methods This systematic review followed PRISMA guidelines and included studies retrieved from PubMed and Web of Science. Eligible studies compared people with multiple sclerosis and healthy controls during treadmill or overground walking tests and reported nonlinear gait variability outcomes. Methodological quality was assessed using the JBI Checklist. Findings From 99 records initially identified, 10 studies met the inclusion criteria, comprising 430 patients and 212 healthy controls. Most studies examined the Lyapunov exponent; five of nine studies reported significant between-group differences, although only three showed higher values in people with multiple sclerosis. Fewer studies assessed entropy or detrended fluctuation analysis, and significant differences were less consistent. Interpretation Nonlinear gait metrics, particularly the Lyapunov exponent, may provide useful information about altered gait dynamics in people with multiple sclerosis, including minimally disabled patients. These metrics may be influenced by fatigue, motor control alterations, and methodological choices, although current evidence remains limited and heterogeneous. Future studies using transparent, pre-specified, and harmonised reporting approaches are needed to clarify their role in research and clinical contexts.