Enlarged choroid plexus in multiple sclerosis is associated with increased lesion load and atrophy in white matter but not gray matter atrophy

Background: Enlargement of the choroid plexus (CP) is reported to associate with inflammatory activity and contribute to brain atrophy in patients with multiple sclerosis (pwMS). However, a recent study in healthy volunteers (HVTs) has suggested that CP enlargement can be attributed to ventriculomegaly. Objectives: To clarify the pathological significance of the enlargement of CP in multiple sclerosis (MS). Methods: A total of 102 pwMS (89 with relapsing-remitting MS and 13 with secondary progressive MS) and 41 HVTs were cross-sectionally evaluated using brain volumetry. The CP volume was compared between disease groups and investigated for the relationships with other brain regional volumes. Results: CP volume was significantly larger in pwMS than in HVTs in the univariate analysis, but not in multivariable analysis. Meanwhile, the CP and lateral ventricle (LV) volumes were significantly correlated. CP enlargement was significantly associated with increased lesion load and cerebral white matter (WM) atrophy, even after adjusting for LV volume. In contrast, multivariable analyses revealed that LV enlargement, but not CP enlargement, was associated with total gray matter (GM) atrophy. Conclusion: CP enlargement was closely associated with LV enlargement. After adjusting for LV volume, CP enlargement in pwMS was associated with increased lesion load and WM atrophy but not GM atrophy.