Prevalence of Autonomic Dysfunction in Patients with Multiple Sclerosis

BACKGROUND: Autonomic nervous system dysfunction is commonly seen in multiple sclerosis patients and should be explored in the routine evaluation. Composite Autonomic Symptom Score questionnaire was validated as a self-assessment instrument of autonomic symptoms. OBJECTIVES: Determine the frequency of autonomic symptoms in multiple sclerosis patients through a Portuguese version of Composite Autonomic Symptom Score; compare questionnaire results between patients and a control group; assess the feasibility of this questionnaire application in multiple sclerosis Portuguese patients. MATERIAL AND METHODS: This case-control study used a Portuguese translated version of Composite Autonomic Symptom Score to determine the frequency of autonomic symptoms in multiple sclerosis patients. RESULTS: One-hundred and three relapsing-remitting multiple sclerosis patients - median age 41 years, median disease duration 6 years, median EDSS score 1 - and 80 healthy subjects were included. Alterations in autonomic function were reported in 97.1% of the cases, with statistical significance in orthostatic intolerance and gastrointestinal domain scores. Nevertheless, the difference between multiple sclerosis patients (41.7%) without confounding factors that could interfere with autonomic dysfunction (i.e. comorbidities or medications) and controls showed no statistical significance. DISCUSSION: Our results may be related to the short disease duration, young age and lowdisability status of our patients unaffected by confounding factors. The questionnaire was not designed specifically for multiple sclerosis and it may not be as sensible to early autonomic symptoms as to more severe manifestations. CONCLUSIONS: Further studies are needed to achieve more robust results, validate this questionnaire and assess its application in multiple sclerosis patients in Portugal.