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How is MS diagnosed

MS is diagnosed by your neurologist. They will use a specific checklist to diagnose MS, known as the McDonald criteria. They'll carry out a number of tests to run through the criteria, which could include blood tests and MRI.

Although it can be frightening to go through medical tests, your health professionals should reassure you and make it as easy for you as possible.

Tests to diagnose MS

  • Neurological examination

    Your neurologist will ask you lots of questions about your health problems and symptoms, now and in the past. This will help them get a better picture of you and identify any other problems that could explain your symptoms.

    They'll also give you a physical examination to check for changes or weaknesses in your eye movements, leg or hand coordination, balance, sensation, speech or reflexes. While your neurologist may strongly suspect MS at this stage, they won't be able to give you a diagnosis until other test results confirm MS.

  • Magnetic resonance imaging (MRI)

    An MRI scanner uses a strong magnetic field to create a detailed image of inside your brain and spinal cord. It's very accurate and can pinpoint the exact location and size of any inflammation, damage or scarring (lesions). MRI scans confirm a diagnosis in over 90 per cent of people with MS.

    To get the image of your brain and spinal cord you'll be asked to lie down and enter a small tunnel in the centre of the MRI scanner. The process can take between 10 and 60 minutes and is painless, though some people can feel a little claustrophobic in the scanner. Read 7 things to know about MRI and MS.

  • Evoked potentials tests

    This painless test measures the time it takes for your brain to receive messages from your eyes, ears and skin.

    Your health professional will put small electrodes on your head. These check how your brain reacts to sounds you hear in headphones, patterns you see on a screen or sensations you feel on your skin. Messages to and from your brain will be slower if MS has damaged the myelin covering around some of your nerves.

  • Lumbar puncture or spinal tap

    Your health professional will give you a local anaesthetic. Then they'll insert a needle in your lower back, into the space around your spinal cord and take a small sample of your spinal fluid to test for signs of MS. People with MS often have antibodies in this fluid which show your immune system is active in your brain and spinal cord. People who don't have MS wouldn't normally have these.

    You might get headaches following a lumbar puncture. Your medical team will talk to you about how to manage them. Lumbar punctures are used less now that MRI scans are more common.

  • Blood tests and tests for other conditions

    Your health professional might also want to rule out conditions that are similar to MS by running some other tests. These could include blood tests to check for particular antibodies, and inner ear tests to check your balance.

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