This review in Brain treats the 2024 McDonald criteria as an intervention in clinical behaviour rather than just a consensus document. The criteria add new ways to reach a multiple sclerosis diagnosis, including the optic nerve as a fifth location, the central vein sign and paramagnetic rim lesions on MRI.
The authors' concern is application outside expert centres, where MRI protocols, laboratory testing and specialist reading vary. More diagnostic options can mean more heterogeneous practice and a higher risk of misdiagnosis, which leads to inappropriate long-term disease-modifying treatment. They propose firmer definitions for acquiring and reading the new biomarkers.
This is expert opinion, not new data, but it names the most common harm in MS care: labelling non-specific white matter lesions as MS.
- Apply the McDonald criteria to patients with a typical clinical syndrome; the 2024 revision allows a diagnosis without symptoms only in narrowly defined radiologically isolated cases, best confirmed at an MS centre.
- Central vein sign and rim lesions need specific MRI sequences and experienced reading.
- Non-specific white matter lesions from migraine, small vessel disease or other causes are the common source of misdiagnosis.
- When unsure, refer to an MS centre before starting disease-modifying therapy.
Why it matters
Wider criteria diagnose MS earlier, and also make it easier to diagnose it wrongly.
Don't overread it
This is a review and opinion, not a study measuring misdiagnosis rates under the new criteria.
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