Non-invasive characterization of cardiovascular autonomic dysfunction in multiple sclerosis

Multiple Sclerosis (MS) is associated with autonomic nervous system damaged. Reported cardiovascular autonomic dysfunction (CAD) prevalence in MS varies between studies. As CAD lowers quality of life and may contribute to sudden death in MS, early CAD detection may assist in treatment and in risk identification. A comprehensive suite of cardiovascular autonomic tests was applied to 53 MS patients and results associated with clinical markers of MS severity. CAD was identified through analysis of continuous electrocardiogram and non-invasive finger blood pressure recording during 5-minutes supine rest, short-term deep breathing, Valsalva manoeuvre, orthostatic challenge and isometric exercise. There was greater prevalence of sympathetic (58%) than parasympathetic impairment (34%). Total brain and spine lesions was correlated with dampened sympathetic response in Valsalva manoeuvre and orthostatic challenge. Age corrected score for sympathetic control showed deterioration with longer disease duration and/or treatment delay>10 years. Comparison of a subset of MS patients (n=23) with age and gender-matched controls showed diminished baroreceptor reflex in MS and impaired sympathetic function using frequency domain systolic blood pressure variability analysis, techniques novel to MS investigations. Findings presented in this thesis demonstrate high prevalence of CAD in MS that can be evaluated using a combination of standard and more novel analysis techniques.