Parasagittal dural space and arachnoid granulations morphology in pre-clinical and early clinical multiple sclerosis

There is limited knowledge on the post-glymphatic structures such as the parasagittal dural (PSD) space and the arachnoid granulations (AGs) in multiple sclerosis (MS).

To evaluate differences in volume and macromolecular content of PSD and AG between people with newly diagnosed MS (pwMS), clinically isolated syndrome (pwCIS), or radiologically isolated syndrome (pwRIS) and healthy controls (HCs) and their associations with clinical and radiological disease measures.

A total of 69 pwMS, pwCIS, pwRIS, and HCs underwent a 3.0 Tesla magnetic resonance imaging (MRI) including selective inversion recovery quantitative magnetization transfer imaging to compute the macromolecular-to-free water pool-size-ratio (PSR) and the free water relaxation rate (R_1f), T₂-weighted (T₂-w) volumetric isotropic turbo-spin-echo to segment the PSD and AG, T₂-w fluid-attenuated inversion recovery images to compute T₂-lesions burden, and a T₁-w sequence to quantify chronic black holes (cBHs) burden and brain parenchymal fraction.

After adjusting for age and sex, larger frontal (p = 0.006) and parietal (p = 0.047) PSD volumes along with larger parietal AG volumes (p = 0.033) were measured in patients compared to HCs. Parietal PSD volume correlated with cBH PSR (r = -0.430, p = 0.032).

Upon diagnosis, enlarged structures in the post-glymphatic system may be observed, indicating a need for further investigation of their role.