Altered DTI-ALPS index in Acute Pontine Stroke: Associations with Infarct Size and Cognition

Given that the pons is a critical hub for long-range white matter tracts (e.g., the corticospinal tract), its impact on remote hemispheric diffusion remains unexplored. We aimed to investigate the alteration of the diffusion tensor image analysis along the perivascular space (DTI-ALPS) index in patients with acute pontine stroke, and its association with infarct size and cognition.

We prospectively recruited 103 patients with acute unilateral pontine stroke (PS) and 60 healthy controls (HCs). All participants underwent DTI scanning. We compared DTI-ALPS index and related diffusion parameters between groups, and analyzed their correlations with the National Institutes of Health Stroke Scale (NIHSS), Montreal Cognitive Assessment (MoCA) and the ratio of infarct area to hemi-pontine area (R_PS).

Compared with HC, PS group showed significantly reduced DTI-ALPS indices in bilateral cerebral hemispheres (both P < 0.01). In patients, the DTI-ALPS index was negatively correlated with infarct burden (R_PS; ρ =  - 0.19, P = 0.048) and positively correlated with MoCA scores (ρ = 0.64, P < 0.001). R_PS was positively correlated with NIHSS scores (ρ = 0.36, P < 0.001) and negatively correlated with MoCA scores (ρ =  - 0.69, P < 0.001).

This study suggests that acute isolated pontine stroke is associated with impaired perivascular diffusion function in the remote cerebral hemispheres. The DTI-ALPS index is closely related to infarct burden and cognitive impairment, providing a novel perspective for investigating remote functional alterations in the supratentorial hemispheres induced by infratentorial pontine lesions.