Demyelination: Meaning in a Radiology Report

Also written as: demyelinating lesions, demyelinating plaques, demyelinating disease

Demyelination is damage to myelin, the protective coating around nerve fibers. On MRI it can show up as bright spots called lesions or plaques.

What it means

Myelin is a fatty coating that wraps nerve fibers, like insulation on a wire, and helps signals travel quickly. Where it is damaged, the tissue holds more water and looks bright on T2 and FLAIR MRI images. Multiple sclerosis is the best-known cause. Other inflammatory conditions, some infections and a lack of vitamin B12 can also damage myelin.

When it matters

Not every bright white matter spot is demyelination: small vessel change and migraine cause similar spots. Radiologists look at shape, size and location. Spots beside the fluid chambers, just under the brain surface, in the brainstem or in the spinal cord are typical of multiple sclerosis. Spots that brighten after contrast suggest active inflammation. No scan alone makes the diagnosis. A neurologist combines MRI with symptoms, an examination and sometimes a spinal fluid test.

Questions to ask your doctor

Do the spots look typical of multiple sclerosis, or could they be something else?
Did any of the lesions enhance with contrast?
Do I need a spine MRI or a referral to a neurologist?

General information, not medical advice. What a finding means for you depends on your symptoms, your history and the images themselves, so talk your results through with a doctor.