Cognitive impairment and structural brain damage in benign multiple sclerosis.

Area of Science:

• Neuroimaging
• Neurology
• Neuroscience

Background:

• Benign multiple sclerosis (BMS) typically presents with minimal locomotor disability but may involve subclinical cognitive impairment.
• Conventional MRI often misses subtle tissue damage, necessitating advanced techniques like Diffusion Tensor (DT) MRI.

Purpose of the Study:

• To investigate the extent of structural brain damage associated with cognitive dysfunction in BMS.
• To contribute to a more reliable definition of the BMS disease phenotype.

Main Methods:

• Conventional and DT MRI scans were performed on 62 BMS patients, 36 secondary progressive multiple sclerosis (SPMS) patients, and 19 healthy controls.
• Neuropsychological tests assessed memory, attention, and frontal lobe functions in BMS patients.
• Metrics included normalized brain volume (NBV), mean diffusivity (MD), and fractional anisotropy (FA) in normal-appearing white matter (NAWM) and gray matter (GM).

Main Results:

• 19% of BMS patients met criteria for cognitive impairment.
• BMS patients exhibited abnormal MD and FA values in both NAWM and GM.
• BMS patients with cognitive impairment showed no significant difference in MRI metrics compared to SPMS patients, unlike those without cognitive impairment.

Conclusions:

• Cognitive dysfunction in BMS correlates with severe structural brain damage, comparable to patients with more debilitating MS.
• The preservation of cognitive function should be an essential criterion for defining BMS.