Impaired Neurovisceral Integration of Cardiovascular Modulation Contributes to Multiple Sclerosis Morbidities

Stroke risk in multiple sclerosis: a critical appraisal of the literature

Observational studies suggest that the occurrence of stroke on multiple sclerosis (MS) patients is higher compared to the general population. MS is a heterogeneous disease that involves an interplay of genetic, environmental and immune factors. The occurrence of stroke is subject to a wide range of both modifiable and non-modifiable, short- and long-term risk factors. Both MS and stroke share common risk factors. The immune mechanisms that underlie stroke are similar to neurodegenerative diseases and are attributed to neuroinflammation. The inflammation in autoimmune diseases may, therefore, predispose to an increased risk for stroke or potentiate the effect of conventional stroke risk factors. There are, however, additional determinants that contribute to a higher risk and incidence of stroke in MS. Due to the challenges that are associated with their differential diagnosis, the objective is to present an overview of the factors that may contribute to increased susceptibility or occurrence of stroke in MSpatients by performing a review of the available to date literature. As both MS and stroke can individually detrimentally affect the quality of life of afflicted patients, the identification of factors that contribute to an increased risk for stroke in MS is crucial for the prompt implementation of preventative therapeutic measures to limit the additive burden that stroke imposes.

Understanding and managing autonomic dysfunction in persons with multiple sclerosis

INTRODUCTION

Multiple sclerosis (MS) is a chronic demyelinating immune mediated disease of the central nervous system. Autonomic dysfunction (AD) is frequently present in persons with MS (pwMS) and increases with disease duration and progression.

AREAS COVERED

Cardiovascular, genitourinary, and sudomotor autonomic dysfunction in pwMS are reviewed and managing of these disorders is addressed.

EXPERT OPINION

AD in pwMS can manifest with a myriad of symptoms including cardiovascular, urogenital, and sweating disorders. These symptoms can significantly impact the quality of life of pwMS with poor tolerance of upright position, difficulties in sexual function, and low endurance of physical activity especially in warm environments. Health professionals involved in care of pwMS should possess basic knowledge of the function of the autonomic nervous system and be informed of the way disorders of the autonomic function may manifest in pwMS in order to provide the proper care.

Cardiac Autonomic Modulation Is Different in Terms of Clinical Variant of Multiple Sclerosis

This study evaluates whether the cardiac autonomic response to head-up tilt test (HUTT) differs between patients with relapsing-remitting multiple sclerosis (RRMS) and those with progressive MS (PMS) as compared to healthy controls (HC). Baroreflex sensitivity, cardiac parameters, heart rate (HRV) and blood pressure variability (BPV) were compared between 28 RRMS, 21PMS and 25 HC during HUTT. At rest, PMS patients had higher values of the sympathovagal ratio, a low-frequency band HRV (LFnu-RRI) and lower values of parasympathetic parameters (HFnu-RRI, HF-RRI) compared to RRMS and HC. Resting values of cardiac parameters were significantly lower in RRMS compared to PMS patients. No intergroup differences were observed for post-tilt cardiac and autonomic parameters, except for delta HF-RRI with lower values in the PMS group. The MS variant corrected for age, sex and Expanded Disability Status Scale (EDSS) score was an independent predictor of changes in the sympathovagal ratio as measured by HRV. Furthermore, a higher overall EDDS score was related to a higher sympathovagal ratio, lower parasympathetic parameters at rest, and decrease post-tilt changes of the sympathovagal ratio of sBP BPV. Autonomic imbalance is markedly altered in the MS patient group compared to control changes were most pronounced in the progressive variant of MS disease. The MS variant appeared to have a potential influence on cardiac autonomic imbalance at rest.

Adrenergic hyperactivity: a missing link between multiple sclerosis and cardiovascular comorbidities?

The aim of the study is to investigate differences in non-standard adrenergic baroreflex sensitivity (BRS) indices in patients with different phenotypes of multiple sclerosis (pwMS) and healthy controls (HC). Retrospective analysis of types of systolic blood pressure (BP) curves during Valsalva maneuver (VM) [balanced (BAR), augmented (AAR) and suppressed (SAR) autonomic responses] and adrenergic baroreflex sensitivity (BRSa) measured with BRSa₁, α-BRSa and β-BRSa in patients with clinically isolated syndrome (CIS), relapsing remitting multiple sclerosis (RRMS), progressive multiple sclerosis (PMS) and HC. We also investigated correlations between BRSa_1, α-BRSa, β-BRSa and resting catecholamine levels. pwMS had higher α-BRSa compared to HC (p = 0.02). There was no difference in BRSa₁, s and β-BRSa between patients with CIS, RRMS and PMS. There was no association between pwMS and HC, and the type of sBP curve [χ2 = 4.332, p = 0.114]. pwMS and BAR or AAR had higher supine systolic and diastolic BP compared to pwMS and SAR. There was a significant correlation between α-BRSa and upright systolic BP (r_p =0.194, p = 0.017), α-BRSa and norepinephrine (r_s =0.228, p = 0.021), and BRSa₁ and epinephrine (r_s = 0.226, p = 0.040). pwMS and HC exhibit different alpha-adrenergic response to Valsalva maneuver. These results may explain the connection between MS and increased cardiovascular risk.

Autonomic symptom burden is an independent contributor to multiple sclerosis related fatigue

OBJECTIVES

To investigate a possible association between autonomic dysfunction and fatigue in people with multiple sclerosis.

METHODS

In 70 people with multiple sclerosis early in the disease course (51 females, mean age 33.8 ± 9.1), quantitative sudomotor axon reflex tests, cardiovascular reflex tests (heart rate and blood pressure responses to the Valsalva maneuver and heart rate response to deep breathing), and the tilt table test were performed. Participants completed the Composite Autonomic Symptom Score 31, the Modified Fatigue Impact Scale, and the Epworth Sleepiness Scale, as well as the Beck Depression Inventory. Cutoff scores of ≥ 38 or ≥ 45 on the Modified Fatigue Impact Scale were used to stratify patients into a fatigued subgroup (N = 17 or N = 9, respectively).

RESULTS

We found clear associations between fatigue and scores in subjective tests of the autonomic nervous system: fatigued patients scored significantly worse on Composite Autonomic Symptom Score 31, and there was a strong correlation between the Modified Fatigue Impact Scale and the Composite Autonomic Symptom Score 31 (r_s = 0.607, p < 0.001). On the other hand, we found only modest associations between fatigue and scores in objective tests of the autonomic nervous system: there was a clear trend for lower sweating outputs at all measured sites, which reached statistical significance for the distal leg and foot. We found weak correlations between the Modified Fatigue Impact Scale and the Valsalva ratio (r_s = - 0.306, p = 0.011), as well as between the Modified Fatigue Impact Scale and quantitative sudomotor axon reflex tests of the forearm, proximal, and distal lower leg (r_s = - 0.379, p = 0.003; r_s = - 0.356, p = 0.005; and r_s = - 0.345, p = 0.006, respectively). A multiple regression model showed that the Composite Autonomic Symptom Score 31, Beck Depression Inventory, and Epworth Sleepiness Scale were independent predictors of fatigue (p = 0.005, p = 0.019, and p = 0.010, respectively).

CONCLUSION

These results suggest that-even early in the course of the disease-people with multiple sclerosis suffer from objective and subjective impairments of the autonomic nervous system. The results also point to an association between autonomic nervous system impairment and multiple sclerosis related fatigue.

Cardiovascular conditions in persons with multiple sclerosis, neuromyelitis optica and transverse myelitis

BACKGROUND

Cardiovascular conditions are associated with poorer outcomes in multiple sclerosis (MS). Whether the burden of cardiovascular conditions differs between those with demyelinating disease and unaffected controls is not clear. The objective of this study is to investigate the burden and age of onset of cardiovascular conditions in a US population with MS, neuromyelitis optica spectrum disorder (NMOSD), or transverse myelitis (TM) to unaffected controls adjusting for likely confounders.

METHODS

Using a case-control study design, we compared the burden of self-reported diabetes mellitus type 2, heart disease, hyperlipidemia, and hypertension in cases with MS (N = 1,548), NMOSD (N = 306), and TM (N = 145) to controls (N = 677), adjusting for demographics, smoking history, obesity, family history of individual cardiovascular conditions, and presence of other cardiovascular conditions. The age of onset for individual cardiovascular conditions were also compared between cases and controls.

RESULTS

MS cases were 48% more likely to have ever had hypertension than controls (p = 0.01). The prevalence of other cardiovascular conditions did not differ across cases and controls. There were also no differences in the age of cardiovascular disease onset between cases and controls.

CONCLUSION

Cardiovascular conditions are as common in those with demyelinating diseases compared to unaffected individuals, with hypertension being more common among those with MS.