Clinically isolated syndrome (CIS)

CIS is diagnosed by a specialist doctor called a neurologist. They treat people with conditions of the brain, spinal cord and nerves. Some people who have CIS only get symptoms once, then never again. But some go on to develop MS. 

What is clinically isolated syndrome (CIS)?

In the name ‘clinically isolated syndrome’: 

• ‘clinically’ means you have symptoms that a doctor can notice. With CIS these are very like MS symptoms
• ‘isolated’ means these symptoms have only happened once
• a ‘syndrome’ is a collection of symptoms or signs that something’s not right in your body

You can be diagnosed with clinically isolated syndrome (CIS) if you’ve had a one-off attack of symptoms. If you later have a second attack of symptoms, you’re likely to then be diagnosed with MS. 

As testing gets better, fewer people are getting a diagnosis of CIS. They get diagnosed earlier with MS instead. But a lot of people with CIS never go on to get MS.

The causes of clinically isolated syndrome (CIS) 

Like MS, clinically isolated syndrome (CIS) happens when your immune system attacks nerves in your spinal cord or brain, including your optic nerve. This causes inflammation and nerve damage. The fatty covering around the nerves (myelin) gets stripped away. Without this protection messages travel less easily along nerves, causing symptoms.

We don’t know exactly why the immune system attacks like this. But in MS it’s thought to be a combination of your genes, lifestyle and something in your environment.

What are the symptoms of clinically isolated syndrome (CIS)?

The symptoms of clinically isolated syndrome (CIS) are like the ones people get with MS. Just like with MS, symptoms of CIS can affect almost any part of your body. They can range from being very mild to quite disabling.

Symptoms come on over a few days or weeks, then usually go away. To be classed as CIS symptoms, they must last for over 24 hours. They must be caused by inflammation damaging the myelin around nerves in your spinal cord or your brain. The brain also includes the optic nerve that connects your eyes to your brain. If you get a second attack of symptoms, it won’t be diagnosed as CIS. 

• The most common symptom of CIS is when inflammation in your spinal cord causes pain or strange feelings in your arms or legs, or makes them weak
• The next most common symptom is the eye condition optic neuritis

How is CIS diagnosed?

Only a neurologist can diagnose CIS. Neurologists are doctors who are specialists in the brain, spinal cord and nerves. 

There’s no one test for CIS. First a neurologist will check with blood tests for other possible causes for your symptoms, like an infection. 

They’ll test your reflexes, balance, how you move, your vision and other senses. 

You’ll have an MRI scan of your brain or spinal cord. If your eyes are affected, you can also have a test called optical coherence tomography (OCT) or one called a visual evoked potential (VEP) test.

MRI scans will show any areas of nerve damage in your brain or spinal cord. 

Usually an MRI scan shows damage that looks like the lesions we see with MS. But there might not always be lesions. 

A lumbar puncture will test the fluid from around your brain and spinal cord. It will look for signs of inflammation. 

A diagnosis of MS with only one attack

When there’s only one attack of symptoms, this is usually diagnosed as CIS. But sometimes it’s also possible to diagnose MS after just one attack of symptoms. So a diagnosis of CIS can soon become one of MS if further tests find more evidence that points towards MS.

You can be diagnosed with MS if you’ve had a one-off attack of symptoms, but you have MS-like lesions in at least two parts of your spinal cord or brain (including the optic nerve). But only if certain types of lesions show up on a specialist MRI scan. 

If you have lesions in just one part of your brain or spinal cord, then a lumbar puncture test must show signs of inflammation in the shape of:

• antibodies called ‘oligoclonal bands’ 

  or 

• high levels of something called ‘kappa free light chains’ (also a protein)

On top of oligoclonal bands or high levels of kappa free light chains, you must also have certain types of lesions on a specialist MRI scan. Your MRI scans must show lesions from attacks at different times.

If after a one-off attack your scans find lesions in four or five parts of your brain and spinal cord, then you’ll be diagnosed with MS. There’s no need for any more evidence.

Read more about diagnosing MS after one attack of symptoms or diagnosing CIS

What’s the difference between CIS and MS?

The main difference is usually to do with how many times you’ve had symptoms. With CIS, you’ve had one attack of symptoms. People with MS have usually had symptoms more than once. 

The symptoms of CIS and MS can be the same, and some treatments are used for both. 

Does CIS mean I have MS, or will get it later?

CIS is a one-off event. But CIS can be an early stage of MS for many people. If the symptoms happen again, this is likely to lead to a diagnosis of MS. And even if you haven’t had more symptoms, some test results might show evidence of MS. But for a lot of people their CIS won’t lead to MS. 

With a diagnosis of CIS your neurologist should plan regular reviews with you to check it's not become MS. They should talk over with you when these happen, for example, once a year. 

When you get your CIS diagnosis, you should be given information about it. They should tell you who to contact for advice if your existing symptoms change or you get new ones.

What are the chances of CIS becoming MS?

If your MRI scans show certain types of lesions common with MS, your chances of developing MS in the future are higher. Around 60% to up to 85% of people with these lesions get MS in the years to come. If you have few or no lesions on your scans, then your risk of MS is much lower, at about 20%.

You’re also at higher risk of going from CIS to MS if you have:

• a bigger number of lesions on your MRI scans
• any lesions on your spine
• low levels of vitamin D
• symptoms in different parts of your body

You’re also more likely to go from CIS to MS if you’re:

• younger
• female
• from an ethnic background that’s not white
• a smoker (not smoking might lower your risk of CIS leading to MS). 

Your risk of getting MS is much lower if scans show few or no lesions. It’s also lower if you get a negative result from a lumbar puncture that checks the fluid around your spinal cord. The test is negative if it finds no oligoclonal bands or your levels of kappa free light chains aren’t high.

If you’re at high risk of going from CIS to MS, a disease modifying therapy (DMT) can delay this.

MS treatments for CIS

Steroids

With CIS most people get over their one-off attack of symptoms on their own, with no need for treatment. A short course of steroids can help if the attack is especially bad, like if your eyesight is affected. Steroids dampen down the inflammation that happens when your immune system attacks your nerves. 

Steroids speed up your recovery by a couple of weeks. Whether you take them or not, your long-term recovery will be just as good. Steroids also don’t seem to make a difference to whether you develop MS in the longer term.

Disease modifying therapies (DMTs)

After you’ve had CIS, you’re likely to get a diagnosis of MS if something similar happens again. To delay this, you can take a disease modifying therapy (DMT). You’ll be offered this only if your scans show you’re at a higher risk of getting MS. And you must keep taking it long term.

If after further tests your CIS diagnosis is changed to one of MS, you’ll be offered the same DMTs that are available for relapsing MS.