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Here is a quick guide to the most commonly used diagnostic tests, what is involved and how much they can tell you. The doctor or neurologist may want you to undertake all of these examinations before making a clinical diagnosis.
Medical History
The doctor will ask you for a detailed medical history which will include your past record of signs and symptoms as well as the current status of your health.
When the type of symptoms you have experienced, possibly over a long period of time, are examined their pattern may suggest MS. However, a full physical examination and medical tests will be needed to confirm the diagnosis.
Neurological Examination
A neurological examination looks at how well your nervous system is working. The neurologist is testing for abnormalities in the nerve pathways that take messages from the brain to the other parts of your body. They will look for changes in eye movements, limb co-ordination, weakness, balance, sensation, speech, and reflexes.
This examination may also uncover symptoms that suggest MS, but cannot be used to determine what is causing any problems that may exist. Other possible conditions that produce similar symptoms to MS must be eliminated.
Testing of Visual, Auditory and Somatosensory Evoked Potentials.
In spite of their complicated sounding name, the point of these tests is straightforward. They are used to measure the speed at which messages from the brain pass along the nerves.
The speed of messages passing through the nervous system is measured by placing small electrodes on the head, which monitor brain waves in response to visual and auditory (hearing) or sensory stimuli. The most useful of the three tests is the visual evoked potential although nowadays, with increased use of MRI, the evoked potential test are required less often.
These tests are not invasive or painful and therefore do not require a stay in hospital.
The time it takes for nerves to pass on messages from the brain is an indicator of the condition of the nervous system and is used to help determine whether demyelination has occurred.
Magnetic Resonance Imaging (MRI)
The MRI scanner is a more recent diagnostic test and takes very detailed pictures of ‘slices’ of the brain and spinal cord, showing any existing areas of sclerosis (lesions or plaques).
During an MRI scan the person being tested lies absolutely still on a table that moves inside a large tube which is part of the machine that contains the magnet. The person conducting the test sits in a separate room monitoring the equipment receiving the images; however they can also see the person being tested, usually through a large window.
There is no pain involved in MRI, but many people find it quite an unusual experience, and it can be both claustrophobic and noisy. Any discomfort can be alleviated by a mild sedative. Sometimes an injection is given in to a vein of a contrast agent containing gadolinium as this can show up new areas of inflammation and may help to make the diagnosis.
It is worth remembering that the person conducting the test is not usually able to give you any direct feedback and the images from the scan will be sent to your doctor for analysis.
Whilst this is the only test in which the lesions of Multiple Sclerosis can be seen, it cannot be regarded as conclusive. The scanner may not pick up all lesions, particularly in the early stages of the disease, and some other conditions can produce identical changes in the nervous system.
The MRI clearly shows the size, quantity and distribution of lesions and together with supporting evidence from medical history and neurological examination, is very significant indicator toward confirming the diagnosis of MS. It is abnormal in over 95% with a definite clinical diagnosis. The MRI is a very useful tool in clinical trials in assessing the value of new therapies, due to its ability to demonstrate changes in the disease’s activity.
Lumbar Puncture
There are several tests that can be carried out on cerebrospinal fluid (the fluid which flows around the brain and spinal cord), but usually with MS the patterns formed by proteins are examined.
The fluid is taken from the spinal cord by inserting a needle into the lower back. A local anaesthetic is given to numb the skin, and therefore whilst it is uncomfortable it is not usually painful.
This test requires the person to lay flat for a number of hours after the test, and headaches due to dehydration are a noted side effect; this can be alleviated by drinking fluids immediately after the procedure, to help the body rapidly replace the cerebrospinal fluid it has lost. Some people may require an overnight stay in hospital and a subsequent short period of recuperation.
The proteins in the spinal fluid of the majority of people (90%) with established MS form a particular pattern when an electrical current is passed through them, and so this procedure can potentially confirm an MS diagnosis. However, the cerebrospinal fluid proteins of people with early or mild MS do not always show the same pattern, so again may not be conclusive. It is often used when MRI results have been inconclusive. |
