Choroid Plexus Enlargement Exacerbates White Matter Hyperintensity Growth through Glymphatic Impairment.

OBJECTIVE

Choroid plexus (CP) is a key regulator in cerebrospinal fluid production, but its contribution to glymphatic clearance function and association with white matter hyperintensity (WMH) remains unclear.

METHODS

This retrospective study included 2 prospective 3.0-T magnetic resonance imaging (MRI) cohorts. In cohort 1, patients with indications for lumbar puncture underwent 3-dimensional T1-weighted sequence (3D-T1) before and at 39 hours after intrathecal administration of contrast agent (glymphatic MRI). In cohort 2, patients with WMH were enrolled from the CIRCLE study and had a median follow-up time of 1.4 years. WMH and CP of the lateral ventricles were automatically segmented on T2 fluid-attenuated inversion recovery (FLAIR) and 3D-T1, respectively. CP volume was expressed as a ratio to intracranial volume. Glymphatic clearance was measured as signal percentage change from baseline to 39 hours at 8 brain locations based on glymphatic MRI in the first cohort, or as noninvasive diffusion tensor image analysis along the perivascular space (DTI-ALPS) index based on DTI in the second cohort.

RESULTS

In cohort 1, a total of 52 patients were included. Higher CP volume was correlated with slower glymphatic clearance rate in all brain locations. In cohort 2, a total of 197 patients were included. Baseline CP volume was positively associated with WMH volume and its growth. Furthermore, DTI-ALPS index partially mediated the association of CP with both WMH load and growth.

INTERPRETATIONS: Enlarged CP volume could be an indicator for larger growth of WMH, potentially involving impaired glymphatic clearance function. The exploration of CP may provide a novel perspective to clarify the mechanism of WMH pathogenesis, as well as other glymphatic-related disorders. ANN NEUROL 2023;94:182-195.