Oligoclonal band count as a marker of MRI lesion burden and clinical profile in newly diagnosed multiple sclerosis.

BACKGROUND AND PURPOSE: Oligoclonal band (OCB) positivity is a well-established biomarker in multiple sclerosis (MS), yet the clinical and radiological relevance of OCB count remains unclear. Although magnetic resonance imaging (MRI) markers reflect disease burden, it is unknown whether OCB count parallels MRI-defined lesion distribution and early cognitive involvement. We investigated associations between OCB count and demographic, clinical, radiological, and cognitive features in newly diagnosed MS. METHODS: We evaluated 62 newly diagnosed MS patients and 59 controls. Cerebrospinal fluid OCB count was analyzed as a continuous variable. Associations with MRI features-lesion distribution (Mtotal), T1-hypointense and gadolinium-enhancing lesions, and spinal cord involvement-and cognitive performance (SDMT, BVMT-R, CVLT-II) were assessed using correlation, subgroup comparisons, and multivariable regression. RESULTS: Higher OCB counts were independently associated with IgG index (β = 5.25, p = 0.004) and wider lesion dissemination (Mtotal; β = 1.57, p = 0.025). Coexisting spinal cord and T1-hypointense lesions were associated with higher OCB counts and showed a moderate effect size (η² = 0.092, p = 0.027). Mtotal was independently associated with CVLT-II performance (β = -3.221, p = 0.046), and OCB count correlated negatively with CVLT-II scores (r = - 0.266, p = 0.036). CONCLUSION: In early, minimally disabled MS, higher OCB counts are associated with broader MRI lesion distribution and subtle impairment in verbal learning and memory. These findings suggest that OCB count reflects intrathecal immune activity that parallels MRI-defined lesion topography and may help identify patients with early radiological and cognitive vulnerability.