Brain microstructural and metabolic alterations detected in vivo at onset of the first demyelinating event

Brain, 2021 · DOI: 10.1093/brain/awab043 · Published: April 27, 2021

Simple Explanation

This study used advanced MRI techniques to look at the brains of people experiencing their first demyelinating event, which is often a sign of early multiple sclerosis. The researchers looked at the structure of brain cells and the amount of sodium in different brain areas, comparing patients to healthy individuals. The goal was to find subtle brain changes that aren't visible with standard MRI, potentially providing new insights into how multiple sclerosis develops.

Study Duration

Not specified

Participants

42 patients with clinically isolated syndrome or multiple sclerosis and 16 healthy controls

Evidence Level

Cross-sectional study

Key Findings

1
Patients showed increased axonal dispersion in normal-appearing white matter, especially in the corpus callosum, along with axonal degeneration and sodium accumulation.
2
Higher axonal dispersion in the corpus callosum was linked to worse walking performance, suggesting that changes in this area may contribute to disability in multiple sclerosis.
3
Increased sodium levels in the left frontal middle gyrus were associated with higher disability scores, indicating a link between metabolic changes and disease severity.

Research Summary

The study investigates microstructural and metabolic alterations in the brains of patients at the onset of their first neurological episode suggestive of demyelination using neurite orientation dispersion and density imaging (NODDI) and 23Na MRI. The results showed that patients had higher orientation dispersion index and total sodium concentration, and lower neurite density index in normal-appearing white matter, including the corpus callosum, compared with healthy controls. The study concludes that the combined use of NODDI and 23Na MRI can detect and provide insights, in vivo, into early multiple sclerosis pathology and clinical associations.

Practical Implications

Early Detection

Advanced MRI techniques can detect subtle brain changes in early MS, potentially allowing for earlier diagnosis and intervention.

Pathophysiological Insights

The study highlights the role of axonal dispersion, degeneration, and sodium accumulation in the development of disability in MS.

Therapeutic Targets

The corpus callosum and frontal middle gyrus could be potential targets for therapies aimed at preventing or slowing down disability progression in MS.

Study Limitations

1
The sample size was relatively small, and not all subjects completed both NODDI and 23Na MRI protocols.
2
The discussion of NODDI results is based on previous histological findings in animal models and observational studies.
3
The low 23Na sensitivity at 3 T means that we could derive only TSC, rather than intracellular and extracellular sodium concentrations.

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