Comprehensive factors influencing cerebrospinal fluid leukocytosis in myelin oligodendrocyte glycoprotein antibody-associated disease

More than half of patients with MOGAD exhibit cerebrospinal fluid (CSF) leukocytosis. Although it has been associated with greater disease severity and more intensive clinical management, this relationship may be confounded by other clinical and radiological factors, and its clinical relevance remains unclear. To identify the main factors contributing to CSF leukocytosis in MOGAD. One hundred patients were enrolled from a well-characterised longitudinal cohort of 248 patients with MOGAD. Patients with CSF leukocytosis were younger at attack ( p = 0.001 ) and more frequently had Expanded Disability Status Scale (EDSS) > 3 ( p = 0.012). They also exhibited more cerebral cortical encephalitis (CCE, p < 0.001) and mixed demyelinating events ( p = 0.003), higher median MOG-IgG titres ( p < 0.001) with more patients having titres ≥ 1:100 ( p = 0.004), elevated CSF total protein (TP) levels ( p = 0.005) with more patients above the normal range ( p = 0.017), and a higher frequency of longitudinally extensive transverse myelitis (LETM, p = 0.047). In univariable analysis, age at attack (OR 0.962, 95% CI 0.938–0.987, p = 0.003), EDSS score > 3 (OR 3.211, 95% CI 1.307–7.890, p = 0.011), CCE (OR 6.200, 95% CI 2.139–17.969, p < 0.001), mixed demyelinating events (OR 4.038, 95% CI 1.581–10.316, p = 0.004), MOG-IgG titre ≥ 1:100 (OR 5.167, 95% CI 1.693–15.764, p = 0.004), and LETM (OR 4.148, 95% CI 1.066–16.139, p = 0.040) were associated with CSF leukocytosis. After multivariable adjustment, only CCE (OR = 9.834, 95% CI: 1.119–86.402; p = 0.039) and MOG-IgG titre ≥ 1:100 (OR = 3.845, 95% CI: 1.002–14.761; p = 0.049) remained independently associated with CSF leukocytosis. Systemic/central inflammatory activity and lesion localisation, are the main factors associated with CSF leukocytosis in MOGAD. CSF findings should therefore be interpreted in the context of these factors rather than in isolation or as direct indicators of disease severity or treatment requirements.