Permeability of the blood-CSF barrier in MOGAD: clinical correlation based on the 2023 diagnostic criteria

The pathogenesis of myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD) is associated with damage to the blood-cerebrospinal fluid (CSF) barrier (BCB), but a specific correlation remains unclear. We used the newly proposed diagnostic criteria in 2023 with the aim to evaluate the permeability of the BCB in MOGAD. We retrospectively analyzed data from 48 eligible patients with MOGAD. Serum and CSF samples were collected simultaneously prior to initiation of immunotherapies at admission. Elevated CSF/serum albumin quotient (QAlb) and indicators of intrathecal immunoglobulin G (IgG) synthesis were calculated as indicators of BCB damage. The relationship between the parameters and clinical features, disease severity, and prognosis were analyzed. Elevated QAlb levels were detected in 50% of patients, but only a small proportion of patients met the corresponding classifications of intrathecal IgG synthesis, namely IgG index &gt;0.7 (10.4%), IgG synthesis rate &gt;10 (6.2%), and local IgG synthesis rate &gt;0 (8.1%). Elevated QAlb was significantly more common in patients with myelitis than in those with optic neuritis (<i>p</i> = 0.049). It was identified as an independent predictor of moderate-severe disease at admission (modified Rankin Scale [mRS]/Expanded Disability Status Scale [EDSS] ≥ 4). Moreover, elevated QAlb emerged as an independent risk factor for a poor long-term prognosis (mRS/EDSS ≥3 at the last follow-up). BCB damage was common in MOGAD. Elevated QAlb could serve as a biomarker for evaluating disease severity at admission and predicting long-term prognosis.