Exploring the Type 4 Cerebrospinal Fluid Oligoclonal Band Pattern: Clinical and Paraclinical Features with Diagnostic...

Type 4 ("mirror-pattern") oligoclonal bands (OCBs) are commonly viewed as systemic immune activation indicators, but their clinical significance in demyelinating disorders remains uncertain. This study assessed features of patients with type 4 OCB positivity and determined variables associated with multiple sclerosis (MS).

This multicenter retrospective study included 92 patients with type 4 OCB positivity detected during cerebrospinal fluid evaluation for suspected demyelinating disease. Patients were grouped as: MS, non-MS inflammatory disorders, and diagnostic evaluation ongoing (DEO). Demographic characteristics, relapse features, treatment response, Expanded Disability Status Scale (EDSS) scores, and magnetic resonance imaging (MRI) findings were analyzed. Logistic regression identified factors associated with MS diagnosis.

MS patients were younger and had higher relapse frequency than non-MS and DEO groups. Relapses with pyramidal and multisystem involvement were frequent in MS, while opticospinal attacks were more common in non-MS disorders. Periventricular and cortical/juxtacortical MRI lesions were associated with MS, whereas systemic autoimmune diseases occurred only in non-MS and DEO groups. Younger age and polysymptomatic presentation were independently associated with MS, whereas a higher relapse frequency and typical MS-related lesion distribution were associated with MS in the univariable analysis only.

Type 4 OCB positivity should not be viewed solely as a systemic immune activation marker. In patients with inflammatory demyelinating disease, the mirror pattern does not exclude MS and should be interpreted with clinical presentation and MRI findings. Its diagnostic relevance depends on patient age, relapse profile, and lesion distribution rather than OCB pattern alone. Type 4 OCB status may inform clinical reasoning but should not independently direct diagnostic decisions.