Diffusely Abnormal White Matter, T₂ Burden of Disease, and Brain Volume in Relapsing-Remitting Multiple Sclerosis

Area of Science:

• Neurology
• Radiology
• Neuroimmunology

Background:

• Diffusely abnormal white matter (DAWM) represents a distinct magnetic resonance imaging (MRI) finding in multiple sclerosis (MS).
• DAWM is characterized by mild hyperintensity, differentiating it from typical MS lesions.
• Understanding DAWM's prevalence and progression is crucial for characterizing MS pathology.

Purpose of the Study:

• To determine the prevalence of DAWM in a large cohort of relapsing-remitting MS (RRMS) patients.
• To investigate the natural history and long-term changes in DAWM.
• To explore the relationship between DAWM and key MS disease markers.

Main Methods:

• Magnetic resonance imaging (MRI) was used to assess DAWM in 348 RRMS patients at baseline and long-term follow-up (7-8 years).
• Evaluated changes in T2 burden of disease (BOD), brain fractional ratio (BFR), and Expanded Disability Status Scale (EDSS).
• Correlated baseline DAWM status and changes with disease markers.

Main Results:

• DAWM was present in 25.3% of patients at baseline.
• DAWM remained stable in most patients (69.3%) at long-term follow-up; increases were rare (2.3%).
• DAWM was associated with a greater reduction in brain fractional ratio (brain atrophy) but did not predict EDSS or its progression.

Conclusions:

• DAWM is a common finding in RRMS, typically stable over time.
• DAWM predicts brain atrophy but not physical disability.
• Further research into DAWM's association with cognitive and visual-spatial function is warranted due to its location.