Updated guidelines could make MS diagnosis quicker and easier

The McDonald criteria are a set of guidelines neurologists use to diagnose MS. They’re updated every few years to reflect our growing understanding of MS. 

Since the criteria were last updated in 2017, research has given us a better understanding of how MS shows up on MRI scans, new insights into biological markers and more evidence of how symptoms develop over time. 

Researchers have used these insights to update the criteria. The new criteria were first presented to the scientific community in 2024. Today they've been officially published. They aim to make diagnosis faster and more accurate, reduce the risk of misdiagnosis, and could help people with MS can access earlier treatment. 

What are the key changes to the McDonald criteria? 

The new criteria aim to use our understanding of the biology of MS to improve diagnosis. Some of the key changes include:

• In some cases, MS could now be diagnosed in people who have no symptoms but have signs of MS on an MRI. 
• Neurologists can now take a sign of MS (lesion) in the optic nerve into consideration when diagnosing MS. Previously, doctors would only look for lesions in the brain and spinal cord. But problems with vision can be a common symptom of MS.
• To make MS diagnosis more accurate, neurologists can now use extra details that show up on MRI scans. Two particular types of lesions can help them distinguish between MS and other conditions.
• There are new recommendations to help diagnose MS in children and people over 50.
• There are also recommendations for diagnosing people who already have other health conditions, including high blood pressure and diabetes. 

What do the McDonald updates mean?

If you have already been diagnosed with MS, the new criteria won’t change your diagnosis. They don’t mean there’s a problem with diagnoses made before now. They just mean that neurologists have additional guidance when making a diagnosis.

Professor Olga Ciccarelli was involved in updating the criteria. She says: “The 2024 McDonald criteria are the result of an international effort to bring precision and speed to MS diagnosis. They’ll help deliver faster, more accurate answers and fewer misdiagnoses, so people can move forward with the right care.” 

But despite these changes to make an MS diagnosis easier, it’s important to remember that the NHS is under significant strain. There're still long waiting lists for appointments and diagnostic tests. These updates are a great step forward, but many people may still face delays before getting the answers and treatment they need. We don’t yet know how the updates will affect this situation, but we’re working with stakeholders and our medical advisers to better understand the wider implications.  

What’s next?

Doctors can now use the updated McDonald criteria when diagnosing people with MS. And we’re continuing to fund more research to make diagnosing and monitoring MS more accurate and comfortable.

Now the update's been published, we're working with expert neurologists to update our guide to the McDonald criteria.