October 6, 2025 /
Sept 2025
The International Advisory Committee on Clinical Trials in Multiple Sclerosis (IACCTMS), co-sponsored by ECTRIMS and the National MS Society (U.S.), has released updated recommendations to the McDonald Diagnostic Criteria for multiple sclerosis (MS). These revisions were published today in The Lancet Neurology in a peer-reviewed article titled, “Diagnosis of multiple sclerosis: 2024 revisions of the McDonald criteria.” They mark the fifth update since the criteria were first introduced in 2001.
The McDonald Criteria are internationally recognised guidelines that help neurologists ensure accurate diagnosis of MS. They have significantly shortened the time from first symptoms to confirmed diagnosis and earlier treatment initiation, improving long-term outcomes for people with MS.
The 2024 revisions reflect the work of the Committee, comprised of 56 international experts from 16 countries across neurology, radiology, methodology, epidemiology, and patient advocacy. A formal consensus process was followed, requiring at least 80% agreement on proposed statements. Patient representatives also participated, ensuring the updated criteria reflect both scientific progress and lived experience.
Enhanced pathways to diagnosis use tests that are more accessible and less invasive, supporting adoption across diverse settings. Since 2001, updates to the criteria have reduced average time to diagnosis by ~75% (from ~4 years to ~1 year in recent studies), enabling earlier treatment. Revisions to diagnostic criteria do not affect existing MS diagnoses but help guide future diagnostic assessments.
“These revisions represent an important step forward for the field. By integrating novel biomarkers and rigorous consensus methodology, the updated criteria strengthen diagnostic accuracy and become more globally applicable. This balance between sensitivity and specificity is essential — and now ensures that people with MS can be identified earlier, equally across all ages, and that misdiagnosis is reduced.”
Professor Bruno Stankoff | ECTRIMS President
Key Updates in the 2024 Revisions
- Optic nerve added as a fifth topographical area of the central nervous system for demonstrating dissemination in space.
- Kappa free light chain (KFLC) accepted as an alternative to oligoclonal bands for demonstrating dissemination in time.
- Novel MRI biomarkers – including the central vein sign (CVS) and paramagnetic rim lesions (PRLs) – recognised as supportive evidence in certain diagnostic situations.
- Biological diagnosis: In select cases, individuals with typical MRI and additional findings may meet diagnostic criteria even before symptoms appear.
- Specialised criteria introduced for children, older adults, and individuals with vascular risk factors.
With this publication, supporting papers were also published:
- “2024 MAGNIMS-CMSC-NAIMS consensus recommendations on the use of MRI for the diagnosis of multiple sclerosis”
- “Recommendations on the use of optical coherence tomography and visual evoked potentials for fulfilling dissemination in space as part of the 2024 Revised McDonald Diagnostic Criteria for multiple sclerosis”
Additionally, a related paper published today in eBioMedicine, “Positive cerebrospinal fluid in the 2024 McDonald criteria for Multiple Sclerosis.”
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