Choroid Plexus Abnormalities in Autoimmune Encephalitis.

BACKGROUND: Recent evidence suggests that the choroid plexus (ChP) serves as a gateway for neuroinflammation. Autoimmune encephalitis (AE) features a high inflammatory burden, yet the role of ChP in AE remains unclear. This study compared choroid plexus volume (CPV) at symptom onset between AE patients and healthy controls (HCs), and evaluated its association with prognosis. METHODS: This single-center study included 151 AE patients with definite autoantibodies. ChP volume (CPV) was segmented from baseline 3D-T1 MRI and normalized. Baseline CPV was compared between AE and age- and sex-matched HCs, and its associations with 12-month functional outcomes (mRS) and progression to autoimmune encephalitis-associated epilepsy (AEAE) were assessed. A logistic regression model based on ChP radiomic features was developed to predict AEAE. Exploratory cerebrospinal fluid (CSF) proteomics and metabolomics were performed in a small subset to generate hypotheses on underlying pathways. RESULTS: Of 151 AE patients, 141 completed 12-month follow-up; 26 (18.4%) developed AEAE. AE patients had significantly larger CPV than controls (1.235 ± 0.274 vs. 1.035 ± 0.264, p < 0.001). Larger baseline CPV was significantly associated with AEAE and mRS (p < 0.05). A two-feature radiomic model (RunEntropy and original volume) predicted AEAE with AUCs of 0.766 (training) and 0.851 (test). Exploratory proteomics in a subset suggested CPV-correlated downregulation of glutamatergic synapse pathways and upregulation of PI3K-Akt/integrin pathways. CONCLUSIONS: Baseline CPV was greater in AE patients than in HCs, and larger baseline CPV was associated with progression to AEAE and poor one-year functional outcomes. ChP imaging may aid in early risk stratification for AE patients.