Ultrasound investigation of risk factors for extracranial vascular pathology in patients with multiple sclerosis

Abstract

Introduction: Cerebral hypoperfusion and impaired cerebral venous drainage are reported to be risk factors for multiple sclerosis (MS). Furthermore, lifestyle and biochemistry have significant effects on the brain and vascular system. This study investigates, with vascular ultrasound, the risk factors for extracranial vascular disease in patients with MS. Methods: Grey-scale imaging, Colour and Spectral Doppler analysis of the carotid arteries and internal jugular veins were performed on a cohort of 50 female participants (25 MS patients and 25 age-matched controls). The major neck vessels were sonographically interrogated to determine patency, carotid intima media thickness (cIMT), carotid artery cross-sectional diameters (CSD), internal jugular vein (IJV) cross-sectional area (CSA), stenosis, occlusions and abnormal blood flow patterns. Both cohorts underwent blood tests, genetic tests and a lifestyle assessment. The MS participants had a neurological assessment to determine MS disability status (Expanded Disability Status Scale, EDSS). Results: Statistically significant associations (p-value <0.05) were found between the extracranial vascular ultrasound variables and biochemical markers (s-iron, s-transferrin, %Tf saturation, ferritin, haemoglobin, vitamin B12, s-folate, homocysteine, CRP, 25-OH vitamin D, total cholesterol, HDL and triglycerides), lifestyle factors, genetic factors (HLA DRB1*1501 allele) and MS disability in both cohorts. The carotid artery blood flow parameters were negatively associated with MS disability, whereas the cIMT was positively associated with MS disability. Physical activity was positively associated with carotid artery blood flow velocities and passive smoking was found to have a negative association in the MS cohort of participants. Passive smokers also demonstrated a larger IJV CSA in comparison to non-smokers in both cohorts. In addition, drinking 1-13 units of alcohol/week was positively associated with carotid blood flow velocities in MS participants. Conclusion: Several significant positive and negative associations between extracranial vascular ultrasound variables and genetic, lifestyle, biochemical and vascular factors as well as MS disability were demonstrated in this study. The new MS findings that unfolded in this study include significant associations between: 1) the carotid vessel diameters and biochemical and lifestyle parameters as well as the presence of the HLA DRB1*1501 allele; 2) IJV CSA in MS and biochemical and lifestyle parameters, specifically passive smoking; 3) MS disability and carotid artery blood flow velocities; and 4) carotid artery blood flow parameters and biochemical markers. Further studies are therefore needed to establish the clinical relevance of these new findings.