How is MS diagnosed?
Due to its complexity and variety of symptoms, MS is not easy to diagnose. There is no single diagnostic test and other conditions with similar symptoms may need to be ruled out before a final diagnosis can be made. Specific diagnostic criteria have been developed to assist healthcare professionals with making a diagnosis.
A neurologist should always be involved in the diagnosis of MS. Traditionally, it was only possible to confirm MS when there had been at least two occurrences of MS symptoms, each involving different areas of the central nervous system. However, it is now possible to determine if a person has MS after they have had only one occurrence of neurological symptoms, so long as there is evidence of new lesions on an MRI scan at least one month later.
The following are the most commonly used tests and procedures:
Diagnostic tests
The neurologist will ask lots of questions about past symptoms and problems, which may help explain current symptoms. They will then do a physical examination to check for abnormalities in nerve pathways involved in movement, reflexes, sensation or vision. This involves looking for changes in vision, eye movements, coordination of legs or hands, balance, sensation, speech or reflexes, as well as any signs of weakness. Although the neurologist may strongly suspect MS at this stage, a diagnosis may not be possible until there have been further investigations. The whole picture – symptoms, signs and test results – would need to meet the criteria for diagnosing MS.
The MRI scanner is a large piece of equipment that uses strong magnetic fields to create a detailed image of the brain and spinal cord. It is very accurate and can pinpoint the exact location and size of myelin damage. To get an image of their brain and spinal cord, a person lies in the tunnel-like centre of the MRI scanner. The process takes between 10 and 30 minutes and is painless. MRI scans show changes in the central nervous system in over 95 per cent of people with MS.
This involves testing the time it takes the brain to receive messages. Small electrodes are placed on the head to monitor how brain waves respond to what is seen or heard. If myelin damage has occurred, messages and responses will be slower or weaker. This procedure is also painless.
Sometimes called a spinal tap, this is carried out under local anaesthetic and involves a needle being inserted into the space around the spinal cord in the lower back (a procedure similar to an epidural injection). A small sample of the fluid that flows around the brain and spinal cord is taken and tested. Most people with MS have abnormal proteins in this fluid, showing that the immune system has been at work in the central nervous system. A lumbar puncture is not carried out as often as it used to be and tends only to be used where a diagnosis of MS has not been confirmed by other tests. People commonly report headaches following a lumbar puncture and a neurologist can advise on how best to manage this side effect.
To rule out conditions that mimic MS, other tests may also be carried out, such as blood tests and inner ear tests to check balance.
Diagnostic Criteria
Although the criteria say it is possible to clinically diagnose MS without any tests, they recommend that investigations are carried out so test results can provide further evidence of MS.Diagnosis of relapsing remitting MS rests on:
- two relapses, separated by more than 30 days OR
- one relapse and an MRI scan three months later that shows new lesions
- had relapses in the past
- shown a steady increase in disability for at least six months, whether or not they continue to have relapses
Primary progressive MS is diagnosed if there have been no previous relapses and if there is:
- a progression of disability over at least a year
- an MRI scan that shows lesions consistent with MS
- evidence of MS detected by examining the spinal fluid collected during a lumbar puncture (this is the only situation where a lumbar puncture is needed to diagnose MS).
Results
After assessment, you will be given one of the following diagnoses:- You have MS
- You have possible MS. This may happen if your tests are not clear. For example, your symptoms and spinal fluid test suggest MS, but there are no lesions visible on the MRI scan.
- You do not have MS
