Case report: A multiple sclerosis patient with imaging features of glymphatic failure benefitted from CSF flow shunting

Glymphatic dysfunction in relapsing-remitting multiple sclerosis and its association with brain structural damage and cognitive impairment

OBJECTIVE

To explore the glymphatic dysfunction in relapsing-remitting multiple sclerosis (RRMS) and its potential associations with brain structural damage, clinical disability, and cognitive impairment (Co-I).

METHODS

The study involved 70 patients with RRMS and 44 healthy controls. Neurological and MRI assessments were performed, and cognitive performance was assessed via the Brief Repeatable Battery of Neuropsychological Tests (BRB-N). To assess the glymphatic function, we calculated the choroid plexus volume (CPV) and diffusion tensor imaging along perivascular spaces (DTI-ALPS) index. Multivariable linear regression analyses were used to examine correlations between glymphatic dysfunction and MRI-derived brain damage metrics. Additionally, we utilised random forest analysis to identify predictors of Co-I and assessed the mediating role of DTI-ALPS.

RESULTS

Patients with RRMS, particularly those with Co-I, exhibited a low DTI-ALPS index and large CPV. A lower DTI-ALPS index was associated with longer disease duration, greater disability, larger lesion volume (LV), mean diffusivity (MD), and CPV, as well as lower fractional anisotropy (FA) (all FDR-p < 0.05). Moreover, DTI-ALPS mediated 27.21 % and 43.75 % of CPV effects on information processing speed and visuospatial memory, respectively. Random forest analysis indicated that lower education (relative importance [RI] = 100 %), higher CPV (RI = 95.8 %), lower DTI-ALPS index (RI = 80.7 %), higher MD (RI = 61.3 %), lower FA (RI = 60.5 %), older age (RI = 54.6 %), and higher EDSS score (RI = 45.4 %) are predictors of Co-I.

CONCLUSION

The study implied that glymphatic dysfunction may contribute to brain structural damage, clinical disability, and cognitive impairment in RRMS, indicating that glymphatic dysfunction may play a key role in the pathogenesis of RRMS.

Cerebral small vessel disease and glymphatic system dysfunction in multiple sclerosis: A narrative review

As the multiple sclerosis (MS) population ages, the prevalence of vascular comorbidities increases, potentially accelerating disease progression and brain atrophy. Recent studies highlight the prevalence of cerebral small vessel disease (CSVD) in MS, suggesting a potential link between vascular comorbidities and accelerated disability. CSVD affects the brain's small vessels, often leading to identifiable markers on MRI such as enlarged perivascular spaces (EPVS). EPVS are increasingly recognized also in MS and have been associated with vascular comorbidities, lower percentage of MS-specific perivenular lesions, brain atrophy and aging. The exact sequence of event leading to MRI visible EPVS is yet to be determined, but an impaired perivascular brain fluid drainage appears a possible physiopathological explanation for EPVS in both CSVD and MS. In this context, a dysfunction of the brain fluid clearance system - also known as "glymphatic system" - appears associated in MS to aging, neuroinflammation, and vascular dysfunction. Advanced imaging techniques show an impaired glymphatic function in both MS and CSVD. Additionally, lifestyle factors such as physical exercise, diet, and sleep quality appear to influence glymphatic function, potentially revealing novel therapeutic strategies to mitigate microangiopathy and neuroinflammation in MS. This review underscores the potential role of glymphatic dysfunction in the complex and not-yet elucidated interplay between neuroinflammation and CSVD in MS.

The glymphatic system and multiple sclerosis: An evolving connection

Multiple sclerosis (MS) is a complex autoimmune disorder that affects the central nervous system, resulting in demyelination and an array of neurological manifestations. Recently, there has been significant scientific interest in the glymphatic system, which operates as a waste-clearance system for the brain. This article reviews the existing literature, and explores potential links between the glymphatic system and MS, shedding light on its evolving significance in the context of MS pathogenesis. The authors consider the pathophysiological implications of glymphatic dysfunction in MS, the impact of disrupted sleep on glymphatic function, and the bidirectional relationship between MS and sleep disturbances. By offering an understanding of the intricate interplay between the glymphatic system and MS, this review provides valuable insights which may lead to improved diagnostic techniques and more effective therapeutic interventions.

The glymphatic system: a new perspective on brain diseases

The glymphatic system is a brain-wide perivascular pathway driven by aquaporin-4 on the endfeet of astrocytes, which can deliver nutrients and active substances to the brain parenchyma through periarterial cerebrospinal fluid (CSF) influx pathway and remove metabolic wastes through perivenous clearance routes. This paper summarizes the composition, overall fluid flow, solute transport, related diseases, affecting factors, and preclinical research methods of the glymphatic system. In doing so, we aim to provide direction and reference for more relevant researchers in the future.