Leukoencephalopathies involving U-fibres

U-fibres (subcortical arcuate fibres) sit right under the cortex. The disease involvement represents juxtacortical/subcortical process rather than “pure periventricular deep WM” disease.

Acquired

• Progressive multifocal leukoencephalopathy – classic asymmetric subcortical lesions with U-fibre involvement.
• Multiple sclerosis – juxtacortical plaques (touching cortex) are a core pattern.
• ADEM (and MOGAD-spectrum demyelination) – large “fluffy” cortical–subcortical lesions can hit U-fibres.
• Hypertensive encephalopathy – vasogenic oedema often posterior, frequently involves subcortical WM including U-fibres.

Genetic

• Canavan disease.