- The updated McDonald Diagnostic Criteria will allow clinicians to diagnose MS earlier, and with fewer symptoms.
- New tools like eye scans and new spinal fluid tests make diagnosis easier and more precise.
- These changes are based on the latest research and have been approved by global experts.
Living with MS can be challenging, especially when it takes a long time to get a diagnosis. In MS, time is brain. The longer it takes to confirm a diagnosis, the greater the risk of irreversible damage to the brain and spinal cord, leading to accumulating disability that can significantly affect a person’s quality of life. Delays also mean missing the opportunity to start treatment early, when it can be most effective.
The updated McDonald Diagnostic Criteria aims to change that, making it easier for clinicians to confirm MS and start treatment sooner. For many, receiving a diagnosis brings clarity and relief.
This is powerfully echoed by members of MS Australia’s Lived Experience Expert Panel.
As Sarah Flaim shared in the World MS Day ‘My Diagnosis” Report:
“And with the diagnosis came relief – an end to the disquieting uncertainty of ‘what is wrong with me?’ – and the promise of disease-modifying therapies to stall neurodegeneration.”
Laura Birchall reflected on the emotional toll of waiting:
“Waiting for a diagnosis had an enormous impact on me emotionally, my ability to focus and my ability to work.”
These updates are not just about clinical accuracy – they’re about helping people move forward with confidence, access treatment earlier, and feel supported in their MS journey.
What is the McDonald Diagnostic Criteria?
The McDonald Diagnostic Criteria are guidelines to help clinicians provide an accurate diagnosis of MS. They were first developed in 2001, have been updated several times to account for new information about the disease, and were last updated in 2017.
A committee made up of 56 international experts from 16 countries, with expertise in clinical management, radiology, methodology, epidemiology and patient perspectives, came together to review and update the 2017 McDonald Diagnostic Criteria. The committee is co-sponsored by the European Committee for Treatment and Research in MS (ECTRIMS) and the National MS Society (US).
The latest update was published online in Lancet Neurology and two supporting papers were published in the same issue – one on imaging guidelines and another on eye tests, which help clinicians spot signs of MS in the visual system more easily.
What has changed?
The 2025 updates include several improvements that make diagnosis faster, easier, and more accurate.
Recognising MS earlier through MRI findings
- Radiologically Isolated Syndrome (RIS) – MS-like damage seen on MRI scans, even without symptoms, can now be diagnosed as MS if other tests support it.
Easier diagnosis
- Clinicians no longer need to see signs of MS damage occurring over different dates (called dissemination in time).
- A single episode of symptoms may be enough for an MS diagnosis if other signs are present.
- The optic nerve is now included as a key area to check for MS-related damage.
- Optical Coherence Tomography (OCT), which is a simple eye scan, can help detect damage to the optic nerve.
- A new unified framework helps clinicians diagnose all types of MS, including primary progressive MS.
- A newer test that looks for certain proteins in spinal fluid (called kappa free light chains or kLFCs) can help confirm an MS diagnosis, sometimes without needing the older test for oligoclonal bands. This makes it easier and faster for some people to get diagnosed
More accurate diagnosis
- MRI scans remain the most important tool.
- New signs seen on MRI scans, like a small vein in the centre of a lesion (called central vein sign or CVS), or a dark rim around it (known as paramagnetic rim lesions or PRLs), can help clinicians feel more confident that what they’re seeing is MS and not something else.
- For people over 50 with other health risks (like vascular risk factors or headache disorders), extra checks like spinal cord scans and fluid tests are recommended to confirm a diagnosis.
- Additional laboratory tests should be used for confirming diagnosis in children and adolescents.
Why does this update matter?
Getting diagnosed with MS earlier means people can start treatment sooner, and that can make a big difference in long-term health and quality of life. The updated McDonald Diagnostic Criteria gives clinicians more tools and flexibility to confirm a diagnosis, even when symptoms are mild or unclear. This helps reduce delays and uncertainty, which can be stressful for individuals and families.
The changes also make it easier to diagnose MS in children and older adults, who may show different signs of the disease. By improving accuracy and reducing the chance of misdiagnosis, the new criteria support better care and more personalised treatment plans from the very beginning of someone’s MS journey.
What’s next?
Clinicians can begin using the updated McDonald Diagnostic Criteria right away, as they have now been peer-reviewed and published. To support this transition, the National MS Society and ECTRIMS are developing a range of educational resources. These resources are designed to help clinicians understand and apply the new criteria confidently and consistently, ensuring people with MS receive timely and accurate diagnoses.
A global effort
This update reflects a worldwide commitment to improving MS care. By making diagnosis faster and more accurate, people have more control of their MS journey, bringing us closer to a future where MS is better understood, treated, and eventually cured.
