Updates to McDonald Diagnostic Criteria for MS published

TORONTO, ON (September 18, 2025) - The McDonald criteria - a set of guidelines to help neurologists provide an accurate, timely multiple sclerosis diagnosis - was recently updated and published in The Lancet Neurology.

Some people who have symptoms of MS experience years of testing, frustration and confusion before receiving a diagnosis. These updates provide neurologists with additional ways to diagnose MS more quickly and accurately. An earlier diagnosis allows people to begin treatment sooner, significantly improving their health outcomes.  

“New advancements in MS research are helping to shorten the diagnostic timeline — reducing it from years to months in some cases," said Dr. Pamela Valentine, President and CEO of MS Canada. “We recognize that there is still work needed in having the most current McDonald criteria used consistently in MS diagnosis across Canada. MS Canada will advocate for adoption of the updated criteria, and for systems changes in every jurisdiction to facilitate earlier diagnosis and intervention for long-term benefits for people living with MS.” 

The process to diagnose MS continues to be revisited and enhanced to keep pace with advancing research and technology. For people with MS, the new criteria won’t affect an existing MS diagnosis. However, for those who may have to navigate the MS diagnostic journey, the continued improvement of these criteria could lead to an earlier diagnosis and faster access to treatments.

Updating how we diagnose MS

The updates to the diagnostic criteria reflect new understanding of how MS appears and progresses in individuals. 

  • The recommendations demonstrate the shift toward considering the biologic basis of MS at diagnosis.
  • The updated criteria include tests that target what is happening under the surface and the damage that is being caused by MS, in addition to the symptoms a person experiences.
  • The updated criteria also include mechanisms to prevent misdiagnosis.

This initiative is being led by the International Advisory Committee on Clinical Trials in Multiple Sclerosis, a global body sponsored by the National Multiple Sclerosis Society in the United States, and ECTRIMS (European Committee for Treatment and Research in Multiple Sclerosis). MS Canada is committed to working alongside global partners to ensure healthcare professionals have the tools and knowledge needed to quickly and accurately diagnose MS.  

 

References:

The peer-reviewed paper that designates the updated criteria, titled “Diagnosis of multiple sclerosis: 2024 revisions of the McDonald criteria” was published in Lancet Neurology on September 17, 2025.  

Supporting papers include:  

  • Imaging Guidelines: “2024 MAGNIMS-CMSC-NAIMS consensus recommendations on the use of MRI for the diagnosis of multiple sclerosis” (corresponding author: Frederik Barkhof)
  • Visual System: “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” (corresponding author: Shiv Saidha)
  • Cerebrospinal Fluid-based Diagnosis: “Positive cerebrospinal fluid in the 2024 McDonald criteria for Multiple Sclerosis” (published in eBioMedicine)  


About Multiple Sclerosis

Canada has one of the highest rates of multiple sclerosis (MS) in the world. On average, 12 Canadians are diagnosed every day. MS is a neurological disease of the central nervous system (brain, spinal cord). Most people are diagnosed with MS between the ages of 20 and 49. MS is a continuous disease process that progresses through different stages over time, and everyone experiences it differently as severity, symptoms and response to treatment can vary from one person to the next. The unpredictable, episodic yet progressive nature of MS makes it particularly challenging to maintain an adequate quality of life.   

About MS Canada

At MS Canada, we are inspired by the vision of a world free of multiple sclerosis. We focus on support, advocacy and research that will positively impact the lives of people living with, and affected by MS. For over 75 years, we have been a trusted connection for the MS community to valuable resources and programs needed on their unique MS journey. We advocate for policy change that removes barriers and improves the well-being of persons affected by MS in Canada. We invest in life-changing research that will advance treatment and care, enhance well-being, help to understand and halt disease progression, and ultimately prevent MS. 

For more information visit mscanada.ca   

For media inquiries: mediarelations@mscanada.ca

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