Investigations in Multiple Sclerosis

No single test is diagnostic of multiple sclerosis, but laboratory tests can help doctors distinguish multiple sclerosis from other disorders that produce similar symptoms such as motor neurone disease, arthritis of the neck and other inflammatory or vascular disorders of the brain and spinal cord.

The diagnosis relies on the combination of clinical findings and the results of diagnostic tests comprising Magnetic Resonance Imaging (MRI) scanning with or without spinal fluid analysis and evoked potential electrophysiological testing.

Examination of cerebral spinal fluid following a lumbar puncture may show a higher white blood cell count and protein level than normal. Most importantly, the concentration of antibodies in cerebral spinal fluid may be high, and a specific pattern of antibodies is detected in up to 90% of people with multiple sclerosis. The presence of these ‘oligoclonal bands’ in the spinal fluid but not in the blood is highly specific for MS.

Magnetic resonance imaging, (MRI) is the best imaging procedure for detecting areas of demyelination (plaques) in the brain and spinal cord and is routinely used to confirm the diagnosis.

However, MRI changes are not well correlated with outcome, especially if a standardised approach is not used. Thus MRI is not a useful way to follow how patients are doing, and this is a common misconception.

A procedure involving evoked responses (a measure of the delay in the electrical response to a sensory stimulation) may be performed. For example for visual evoked responses flashing lights are used to activate certain areas of the brain. In people with MS the response of the optic nerves to the stimulus may be slow because signal conduction along the affected nerve fibres is impaired. Evoked responses to sounds and sensation can also be performed.

In April, 2001, an international panel revised the diagnostic criteria for multiple sclerosis. These new criteria have become known as the McDonald criteria after their lead author and make use of both clinical presentation and additional data including those due to advances in MRI imaging techniques that allow identification of plaques.

Amended April 2008