Evolution of autonomic nervous system abnormalities in multiple sclerosis: a 6-year follow-up

BACKGROUND: Due to the lack of long-term studies, this research aimed to explore the changes and predictors of autonomic dysfunction (AD) in people with multiple sclerosis (pwMS) over a 6-year period from disease onset. METHODS: Among the 121 pwMS cohort, 75 underwent autonomic function tests at baseline and year 6. Autonomic symptoms were assessed using the Composite Autonomic System Score-31 (COMPASS-31), while the results of autonomic tests were recorded using the Composite Autonomic Scoring Scale (CASS) at baseline and biennially over 6 years. Symptomatic dysautonomia was identified by a COMPASS-31 score greater than 7.913 and a CASS score greater than 0. RESULTS: No significant changes were noted in the COMPASS-31 and CASS scores from baseline to year 6. However, there was a significant decline in the cardiovagal index (p=0.001) and the sudomotor index (p=0.036 and p=0.001, respectively) at years 4 and 6, compared with baseline. The number of participants with symptomatic dysautonomia increased significantly from year 0 to 6 (14 (20.9%) vs 29 (39.2%), respectively; p=0.049). Multivariable logistic regression analysis revealed that experiencing a relapse during the 6 years increased the likelihood of symptomatic dysautonomia (Exp(B) 3.886, 95% CI 1.019 to 14.825, p=0.047). Conversely, transitioning to high-efficacy disease-modifying therapy (HET) reduced the probability of having a CASS score greater than 0 at year 6 (Exp(B) 0.221, 95% CI 0.067 to 0.734, p=0.014). CONCLUSIONS: Dysfunction of the cardiovagal and sudomotor systems progresses alongside disease duration in pwMS. The early initiation of HET may help mitigate the risk of developing AD.