Choroid plexus enlargement in Chinese multiple sclerosis is independent of oligoclonal band status and associated with thalamic atrophy: A 7T MRI study.

BACKGROUND

Choroid plexus (CP) enlargement and oligoclonal bands (OCBs) are recognized biomarkers in multiple sclerosis (MS), reflecting neuroinflammatory activity and intrathecal humoral immunity, respectively. However, their interrelationship remains unclear.

METHODS

In this cross-sectional study, 54 patients with relapsing-remitting MS and 40 healthy controls underwent 7T MRI. Normalized CP volume (nCPV) was manually segmented and compared between groups and across clinical subgroups. Correlations between nCPV, OCB status, brain volumetrics, paramagnetic rim lesions (PRLs), and disability (EDSS) were assessed using age- and sex-adjusted models.

RESULTS

CP volume was significantly enlarged in MS patients compared to controls (mean nCPV: 1.5 ± 0.3 vs. 1.3 ± 0.2 × 10⁻³; p = 0.001). However, no significant difference in nCPV was found between OCB-positive and OCB-negative patients (p = 0.346), nor across subgroups based on PRL presence, disease-modifying therapy, or disability level. nCPV was inversely correlated with normalized thalamic volume (ρ = -0.270, p = 0.049) and whole-brain volume (ρ = -0.297, p = 0.029), and showed a strong positive correlation with normalized T2 lesion volume (ρ = 0.697, p < 0.001). No significant correlations were found with EDSS or PRL count.

CONCLUSION

CP enlargement in MS is a notable imaging marker of neuroinflammation that is independent of OCB status and humoral immunity. Its association with increased T2 lesion burden and subsequent brain atrophy implicates a role in innate immune-mediated, rather than B-cell-driven, pathology.