Article - Continuous monitoring with wearables in multiple sclerosis reveals an association of cardiac autonomic dysfunction with disease severity.

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Take home message

Cardiac autonomic dysfunction can be detected in patients with MS using wearable devices.
Dysfunction is linked to the severity and progression of the disease, with reduced circadian adaptation particularly during sleep in progressive MS.

Evidence category

D: Case-reports, evidence-based clinical findings

Summary review

Introduction

Multiple sclerosis (MS) is a disease characterised by autonomic dysfunction, including bladder and sexual dysfunction.
Using a novel method to measure Heart Rate Variability (HRV), the aim of the study was to understand and measure the impact of cardiac autonomic dysfunction on MS.

Methods

Participants were ≥ age 18, 55 with MS and 24 healthy individuals who did not have concomitant disease.
To understand subjective measures, two questionnaires were completed - the fatigue scale for motor and cognitive functions and the abbreviated Composite Autonomic Symptom Score.
Inflammation was defined as either radiological activity in the last year or clinical relapse.
A progressive disease state without relapse was defined as neurodegeneration.
Participants wore heart rate devices validated with a gold-standard electrocardiogram device for 2 weeks.
Using inter-beat-intervals, heart rate data was cleaned and analysed to assess trends in HRV and their relationship to MS severity.

Results

For inflammatory activity, measuring adaptation of the circadian rhythm compared to single segment measurements showed a significant difference (P=0.0490. SMD= -0.5466).
For progressive disease, compared to non-progressive disease, both single and adaptative measures were significantly different (P=010148, SMD=0.7994 and P=0.0016, SMD=1.1491 respectively).
A sleep window of 60–80% could be used to differentiate disability severity using the Expanded Disability Status Score (P=0.0389, SMD=0.6163). It also showed strong correlations with HRV (rS=-0.3775, P=0.0135).
The best proportional HRV differences between groups occurred during 60–100% of the day and 40–80% of sleep (P=0.0034, SMD=0.9333).

Conclusion

A novel method using continuous HRV measurement over at least seven days captures cardiac autonomic dysfunction reliably in MS, revealing reduced circadian adaptation, especially during sleep, in progressive MS and patients with high lesion volumes.
Progressive MS shows parasympathetic dysfunction.
Inflammatory MS presents impaired circadian adaptation, with higher nighttime sympathetic activity and reduced HRV variability.
These patterns are linked to disease severity and progression.

Clinical practice applications

Practitioners could consider using wearables to monitor HRV in their clients who have MS to understand how to best support their autonomic nervous system with individualised recommendations.
When working with MS patients’, nutritional protocols might benefit from supporting cardiovascular health and autonomic nervous function.

Considerations for future research

Additional studies could explore the role of autonomic nervous function in multiple sclerosis to see if it is possible to support disease progression with early intervention therapy.
Larger studies are required to repeat the results found in this study.
Further studies to understand the impact medication has on autonomic nervous function and if wearables can detect any potential affects would be beneficial.

Abstract

BACKGROUND

Dysfunction of the autonomic nervous system is common in multiple sclerosis patients, and probably present years before diagnosis, but its role in the disease is poorly understood.

OBJECTIVES

To study the autonomic nervous system in patients with multiple sclerosis using cardiac autonomic regulation measured with a wearable.

METHODS

In a two-week study, we present a method to standardize the measurement of heart rate variability using a wearable sensor that allows the investigation of circadian trends. Using this method, we investigate the relationship of cardiac autonomic dysfunction with clinical hallmarks and subjective burden of fatigue and autonomic symptoms.

RESULTS

In 55 patients with multiple sclerosis and 24 healthy age- and gender-matched controls, we assessed the cumulative circadian heart-rate variability trend of two weeks. The trend analysis revealed an effect of inflammation ( = 0.0490, SMD = -0.5466) and progressive neurodegeneration ( = 0.0016, SMD = 1.1491) on cardiac autonomic function. No association with subjective symptoms could be found.

CONCLUSIONS

Trend-based heart rate variability measured with a wearable provides the opportunity for unobtrusive long-term assessment of autonomic functions in patients with multiple sclerosis. It revealed a general dysregulation in patients with multiple sclerosis.