The diagnosis of multiple sclerosis is a clinical judgement made by a neurologist.
As none of the symptoms of MS unique to the condition, diagnosis means a range of other possible explanations have to be ruled out. The process usually involves several tests. There is no one test that will, on its own, show that someone has MS. This means that it can sometimes take some time to reach a diagnosis of multiple sclerosis.
How multiple sclerosis is diagnosed?
The neurologist is looking for signs of scarring in your brain or spinal cord (the central nervous system). For a diagnosis of MS there needs to be two or more areas of scarring. These need to have happened at different points in time. Although MRI scans can sometimes show enough evidence to make a diagnosis, it is still unusual to diagnose MS from just a single episode of symptoms.
The most commonly used guidance for making a diagnosis of MS is called the McDonald criteria.
A number of tests are used to look for information to support a diagnosis.
Medical or clinical history
To find out if symptoms have occurred at different times, the neurologist will ask about your previous symptoms and health. Sometimes symptoms, such as numbness or double vision, which may have happened several years earlier and might have been treated without thought of MS at the time, can prove significant.
There are a number of simple tests that a neurologist can carry out that can suggest, or rule out, MS as a cause of symptoms. These include checks on movement, coordination, vision, balance, reflexes and other functions of the senses. These tests not only suggests whether you might have MS, but can also indicate where in the central nervous system damage has taken place.
Blood may be taken for testing. There is as yet no blood test that can show whether you have MS or not. However, the blood test may suggest that another condition may be the cause of your symptoms.
Although the medical history and neurological examinations might suggest a diagnosis of MS, the process usually involves one or more tests to look for evidence of MS within your body.
Magnetic resonance imaging (MRI)
MRI creates images of cross sections of the body. The scars caused by MS show up as white patches, giving a picture of the effects of MS on the brain and spinal cord.
An evoked potentials test measures the speed of messages along nerves. Very small delays can indicate that there is damage to the nerve pathway.
Last updated: November 2017
Last reviewed: April 2016
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