MS Answers

Diagnosis and Types of MS
Answered on: 11/7/2011

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Q :

Does the number of lesions on your MRI correlate to your symptoms and level of disability?

A :

On an MRI done after a first clinical relapse (e.g. optic neuritis, spinal cord relapse), the presence of areas of abnormality on brain MRI consistent with demyelination greatly increases the chance that an individual will go on to develop definite MS within the next 5 to 10 years.

This “baseline” MRI also has modest predictive value for the risk of developing early disability. The number of lesions seen on one’s first MRI, and the number of new lesions that develop on MRI over the first five years of disease, are modestly correlated with the risk of becoming more severely disabled at 10 to 15 years from diagnosis.

In someone with established MS however, the severity of MRI abnormalities does not always correlate with the severity of clinical disability. Some people will have a small number of lesions in critical pathways (for instance, involving the motor pathways in the spinal cord) that will cause significant disability, while others will have a large number of lesions in more clinically silent areas of the brain and have little apparent disability. There may be a better correlation between the number and size of brain lesions and cognitive symptoms than physical disability, but even that relationship is not always consistent.

There are new MRI techniques being developed which measure axonal and neuronal loss/damage in MS, rather than just areas of demyelination. It is believed that these new measures will likely be more strongly correlated with clinical disability than the current techniques.

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DISCLAIMER: Please be aware that this information does not necessarily represent the opinion of the MS Society of Canada, and is not intended as medical advice. For specific advice and opinion, always consult a physician.