Oliver Tolson
Newcastle University, UK
Title: Exploring the association between fatigue and autonomic dysfunction in multiple sclerosis
Biography
Biography: Oliver Tolson
Abstract
Background: Fatigue is a common debilitating symptom of multiple sclerosis (MS) but its pathophysiology remains poorly understood. Recent studies in a variety of diseases have shown dysfunction of the cardiovascular autonomic nervous system correlates with fatigue severity. Objectives: To investigate the prevalence of fatigue and orthostatic intolerance in a representative MS cohort. To objectively assess fatigued secondary-progressive patients for cardiovascular autonomic dysfunction. Methods: Fatigue severity and orthostatic intolerance were measured using validated questionnaires in 144 patients (85.2% response). Subsequently, 11 fatigued secondary-progressive MS patients underwent objective assessment of resting heart rate variability (HRV) and blood pressure variability (BPV). Results: Fatigue was identified in 74.8% of MS patients, with fatigue severity significantly higher in secondary-progressive patients. Moderate orthostatic intolerance was identified in 54.3% of patients and correlated significantly with fatigue (r=0.49, p<0.0001). Objective assessment revealed significant reductions in low-frequency HRV and BPV in the fatigued secondary-progressive group versus controls. A substantial reduction was seen in low-frequency systolic BPV (33.6% versus 48.9%, p=0.03), an established marker of sympathetic vasomotor function. Furthermore reductions in this parameter correlated significantly with orthostatic symptoms (r=−0.87, p=0.0007) and fatigue severity (r=−0.66, p=0.03). Conclusions: Fatigue severity correlates significantly with increasing orthostatic intolerance. Additionally, fatigued secondary-progressive patients have objective evidence of sympathetic vasomotor dysfunction.