A 28-year-old woman has a single episode of unilateral optic neuritis. MRI shows two typical periventricular lesions. Cerebrospinal fluid analysis reveals oligoclonal bands present in the CSF but absent in the paired serum sample. This finding indicates:

• A Dissemination in time, allowing diagnosis of multiple sclerosis now
• B Intrathecal synthesis of IgG supporting dissemination in space ✓
• C Confirmation that the demyelination is aquaporin-4 mediated
• D Active blood-brain barrier breakdown requiring urgent steroids

Explanation

Oligoclonal bands restricted to CSF reflect intrathecal IgG synthesis and are found in over 85 percent of clinically definite multiple sclerosis cases. They support the diagnosis but do not by themselves establish dissemination in time, which requires new lesions on follow-up MRI or simultaneous enhancing and non-enhancing lesions. They are nonspecific and can occur in other inflammatory disorders, so they do not confirm an AQP4 mechanism.

Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.