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.