Cardiovascular autonomic dysfunction in multiple sclerosis: correlations with clinical, brainstem auditory evoked potential and magnetic resonance imaging

Multiple sclerosis [MS] is one of the most disabling neurological disorders, in which autonomic impairment is not rare. The aim of the current study was to assess the frequency of cardiovascular [CV] autonomic dysfunction in MS patients. We also related these autonomic abnormalities to the brainstem dysfunctions in those patients evidenced by brainstem auditor evoked potential [BAEP] and magnetic resonance imaging [MRI] studies. We studied 20 patients with clinically definite relapsing remitting MS and 20 sex and age matched healthy control. The patients were evaluated clinically using expanded disability status scale [EDSS]. Autonomic functions were evaluated with blood pressure response to both standing and static exercise [sympathetic], and 24-hour electrocardiographic [ECG] recording, time domain [parasympathetic]. Brainstem auditory evoked potential and MRI were performed to all patients. The MS patients included 11 [55%] males and nine [45%] females with a mean age of 29.8 +/- 8.4 years, whereas control group was composed of five [50%] males and five [50%] females with a mean age of 34.2 +/- 13.4 years. Regarding tests of CV autonomic functions, 13 [65%] patients had at least one abnormal test. The results showed statistically significant differences in all CV autonomic tests when comparing MS patients to controls. We found significant correlations between autonomic tests with duration of the disease. Significant correlations were detected between autonomic tests and brainstem lesions as well as periventricular parameters of MRI. BAEP findings were indicative of brainstem affection and there was a significant correlation between autonomic tests and I-V interpeak latency. These results suggest that a significant number of patients with MS show evidence of CV autonomic dysfunction, which is correlated with brainstem function