MS diagnosis: The full guide

Your neurologist will ask about your health history and any symptoms you’ve experienced, such as changes in vision, numbness, weakness, or balance problems.

This involves a physical examination to check how well your nervous system is working. It may include testing your reflexes, muscle strength, coordination and balance.

Magnetic resonance imaging (MRI) is the main tool used to support an MS diagnosis. MRI scans can show areas of inflammation or damage in the brain, spinal cord or optic nerve. These areas are often called lesions.

In some cases, a small sample of spinal fluid is taken to look for signs of immune system activity linked to MS. This can help support a diagnosis.

Blood tests are usually done to rule out other conditions that can cause similar symptoms to MS.

These tests are used less often than in the past, but you may still be offered one. Small electrodes measure how quickly signals travel along certain nerves. Slower signals can suggest damage to the protective myelin covering around nerves.

This is known as ‘Dissemination in space (DIS)’. Your healthcare team will look for evidence of MS-related changes in more than one part of the central nervous system (the brain, spinal cord or optic nerve).

This is know as ‘Dissemination in time (DIT)’. Your team will look for evidence that MS activity has happened at different points in time. In some situations, results from spinal fluid tests can support a diagnosis without waiting for another clinical episode.

MRI scans may show patterns typical of MS, such as lesions in characteristic locations. Some specialist centres may also use advanced MRI features, though these are not available everywhere.

A lumbar puncture may be used to look for specific patterns in spinal fluid that support an MS diagnosis.

There is no single test for MS, and many MS symptoms – such as fatigue, pain or low mood – can also occur in other conditions. Doctors use a combination of tests to rule out other causes and build confidence in the diagnosis.

Yes, in some cases. The updated McDonald criteria allow a diagnosis after a single episode if MRI scans or other test results provide clear evidence.

Some people are told they have clinically isolated syndrome (CIS), meaning a first episode of neurological symptoms that may or may not develop into MS. Your doctor may arrange follow-up scans over time.

MRI scans are a key tool for monitoring MS. In this video, Dr Jonathan White explains how MRI scans are used to assess disease activity and progression in relapsing-remitting MS.

Most people with MS live into old age, and MS is not a terminal condition. On average, life expectancy may be slightly lower than for people without MS, but the difference is usually only a few years and has reduced over time. Individual outcomes vary and are influenced by overall health, lifestyle and access to good medical care.