Corticoefferent pathways in pure lower motor neuron disease: a diffusion tensor imaging study.

Area of Science:

• Neuroimaging
• Neurology
• White Matter Diseases

Background:

• Diagnosing upper motor neuron (UMN) pathology in lower motor neuron disease (LMND) presents clinical challenges.
• Diffusion tensor imaging (DTI) offers in vivo insights into white matter integrity.

Purpose of the Study:

• To investigate white matter alterations in adult pure LMND using DTI.
• To compare fast and slow progressing LMND patients and explore tract-specific changes.

Main Methods:

• Whole-brain DTI and spatial statistics compared 37 LMND patients with 53 controls.
• Fractional anisotropy (FA) maps identified white matter structural differences.
• Fiber tracking analyzed tract-specific alterations based on ALS staging.

Main Results:

• LMND patients exhibited widespread FA reductions, predominantly in the corticospinal tract (CST).
• Fast progressing LMND showed greater CST involvement than slow progressors.
• Fast progressors also displayed alterations in ALS-related tracts beyond the CST.

Conclusions:

• Findings demonstrate corticoefferent fiber involvement in pure LMND, supporting its classification as a phenotypic variant of ALS.
• This suggests LMND patients should be managed similarly to ALS patients, including trial eligibility.