Diagnosis of MS

MS is not easy to diagnose. There is no single conclusive test for MS. Other conditions may need to be ruled out.

A GP should always refer a patient to a neurologist to make or confirm the diagnosis. The neurologist will not usually diagnose MS until there have been at least two occurrences of symptoms involving different areas of the central nervous system, at least a month apart and each lasting for at least 24 hours. This means that there is always a delay between the appearance of the first symptom and a diagnosis of MS.

A clinical diagnosis, made by a doctor after seeing you for various MS-type symptoms over a period of time, needs to be backed up by tests. It may be necessary to have several different tests to identify MS. The following are the most commonly used tests for MS.

Neurological Examination

This tests for abnormalities in nerve pathways involved in movement or sensation. The neurologist looks for changes in eye movements, co-ordination of legs or hand, balance, sensation, speech or reflexes, as well as any signs of weakness.

Evoked Potentials

Evoked potentials test the time it takes for the brain to receive and interpret messages. This is a non-invasive and painless test. Small electrodes are placed on the head to monitor brain waves responding to what you see or hear. In a healthy person, responses are virtually instantaneous. If myelin damage has occurred, messages may take longer to get through.

MRI Scan

The MRI (Magnetic Resonance Imaging) scanner is used in most areas of the country to diagnose MS. Linked to a computer, it takes detailed pictures of the brain and spinal cord. It is very accurate and can pinpoint the exact location and size of plaques. Over 90 per cent of people with MS have plaques that show up on MRI scans, but some people's scans show no myelin damage.

Lumbar Puncture

This test has been used to diagnose MS for many years. A needle is inserted into the lower back, under local anaesthetic, and a small sample of cerebrospinal fluid (which flows around the brain and spinal cord) is taken from the spinal cord. This fluid is tested for abnormalities in protein patterns.

Other Tests

Conditions that mimic MS can be ruled out by using MRI or other tests. These include CAT (Computer Axial Tomography) scans, which give a cross-sectional image of the brain; tests to reveal certain antibodies in the blood; and inner ear tests to check balance.