Behind the headlines: MS misdiagnosis
You might have read in the news about actress Christina Applegate being misdiagnosed with MS. If you’re living with an MS diagnosis, we know that this can be concerning to hear. We look behind the headlines at what the research says about MS misdiagnosis. And what this means for people with MS.
How is MS diagnosed?
MS is diagnosed by a specialist doctor called a neurologist. Neurologists follow the McDonald criteria to diagnose MS. These are a set of international guidelines. They’ve been updated several times since they were first introduced in 2001, as our understanding of MS grows and as tests get better.
There isn’t a single test that is used to diagnose MS. The McDonald criteria tell neurologists what evidence they need for a diagnosis of MS. Your doctor might gather this evidence from MRI scans, lumbar punctures, and neurological examination.
How common is MS misdiagnosis?
We don’t know for sure how common misdiagnosis is. There is no single figure. Research suggests it can vary from country to country and between hospitals.
A paper published in 2024 looked at data from lots of different studies. In these studies, misdiagnosis ranged from 5% to 41%. When researchers pooled this data together, it showed that an estimated 15% of cases of MS were misdiagnosed.
This shows that misdiagnosis isn’t uncommon. But it’s important to remember that the majority of people who have a diagnosis of MS do have MS.
Why does misdiagnosis happen?
MS is a complex condition and it can be difficult to diagnose. It's hard to pinpoint exactly when MS begins, and the early signs and symptoms are different for everyone. It is not uncommon for a diagnosis to take several months, and frustratingly it can take even longer.
There are a few reasons why misdiagnosis can happen:
- Other conditions cause damage to the brain that can look like MS on MRI scans. This includes cerebrovascular disorders (like stroke), migraine, and other conditions that cause myelin damage.
- Most people are diagnosed with MS between 20 and 40. It can be more difficult to diagnose people who are under 18 or over 50 as their symptoms can look different. And for older people, other age-related conditions can be mistaken for MS.
- Misdiagnosis can also be a result of lack of access to specialist neurologists and equipment. Some hospitals might not have access to newer, more sensitive MRI machines. And neurologists may need further training to support them to use updated diagnostic criteria.
How is research helping to reduce misdiagnosis?
The McDonald criteria are updated every few years to reflect our growing understanding of MS. They’ve been updated several times. Expert neurologists from around the world agree them together.
Updates to the criteria in 2024 include:
- Looking for a ‘central vein sign’ in lesions. This is where MS lesions show a vein in the middle.
- Cerebrospinal fluid (taken from a lumbar puncture) that contains a marker called ‘kappa free light chains’.
These can help distinguish between MS and other conditions. Research into these markers over the past decades has led to them being included in the new criteria.
And researchers are continuing their work to find ways to better identify, diagnose and monitor MS. For example, we’re funding a project by Professor Mitra Tavakoli in Exeter. She’s researching whether subtle changes in the eye can be used to identify early signs of MS. And distinguish between people with and without MS.
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