Corticospinal tract abnormalities and ventricular dilatation: A transdiagnostic comparative tractography study

Area of Science:

• Neuroimaging
• Neurodegeneration
• White Matter Diseases

Background:

• Corticospinal tract (CST) microstructural alterations are known in idiopathic normal pressure hydrocephalus (iNPH).
• The impact of ventricular dilatation on the CST in Progressive Supranuclear Palsy (PSP) remains unstudied.

Purpose of the Study:

• To investigate the CST diffusion profile in a large cohort of PSP patients.
• To assess the effect of ventricular dilatation on CST microstructural integrity in PSP.

Main Methods:

• Diffusion tensor imaging (DTI) metrics (FA, MD, AxD, RD) were calculated for CST regions in 87 PSP, 23 iNPH, and 26 control participants.
• Ventricular dilatation was quantified using Evans index (EI) and ventricular volume (VV).
• Statistical analyses (ANCOVA) examined group differences and correlations between CST metrics and ventricular dilatation measures.

Main Results:

• PSP patients with ventricular dilatation (PSP-vd) showed increased FA and AxD in CST regions compared to PSP patients without dilatation (PSP-wvd) and controls.
• iNPH patients exhibited the most pronounced CST alterations.
• A strong correlation was observed between CST diffusion metrics and EI or VV.

Conclusions:

• Microstructural CST changes are confirmed in iNPH.
• For the first time, similar CST alterations are demonstrated in PSP patients with ventricular dilatation (PSP-vd).
• Ventricular dilatation likely contributes to mechanical compression of the CST in PSP.