A 35-year-old woman presents with a second demyelinating episode affecting the optic nerve and cervical spinal cord (transverse myelitis). MRI brain shows 4 T2/FLAIR lesions typical of demyelination. Criteria for MS diagnosis are now being applied. Which modification in the 2017 McDonald Criteria allows diagnosis of MS after a single clinical attack?
- A Presence of oligoclonal bands in CSF allows dissemination in time to be inferred ✓
- B Gadolinium enhancement alone on MRI is sufficient for DIT
- C Spinal cord lesions >3 vertebral segments fulfil McDonald criteria for DIT
- D Visual evoked potential abnormalities substitute for MRI criteria for DIS
Explanation
The 2017 McDonald Criteria introduced CSF-specific oligoclonal bands (OCBs) as a surrogate for dissemination in time (DIT). If a patient fulfils dissemination in space (DIS) criteria and has CSF OCBs but no imaging DIT, MS can still be diagnosed after a single clinical attack (clinically isolated syndrome). This modification was the most important change from the 2010 criteria. Gadolinium enhancement demonstrates active inflammation but specifically satisfies DIT only when combined with a non-enhancing T2 lesion. Long spinal cord lesions (>3 segments) are more suggestive of neuromyelitis optica spectrum disorder (NMOSD) than MS.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.