Multiple sclerosis is a demyelinating disease of the central nervous system that is often marked by changes in the brain. Using magnetic resonance imaging (MRI), these changes can appear as lesions, “black holes," or brain atrophy.
What are lesions?
In MS, the fatty, protective covering that surrounds nerves, called myelin, becomes damaged due to inflammation in the central nervous system. The result of this inflammatory damage is demyelination. Lesions are the hardened areas (scars) or plaques where myelin has been damaged. Multiple sclerosis literally means "many scars."
Where inflammation damages the blood-brain barrier, lesions can develop. This inflammation and active lesions appear on MRI scans as white spots when gadolinium, a contrast agent, is injected into a vein beforehand. Lesions can also affect the spinal cord or optic nerves.
What are black holes?
When so much of the protective myelin has been damaged that nerves die, the resulting lesions appear as dark spots on MRI scan. These dark spots are often referred to as “black holes.” Although the body can work hard to repair myelin, once the nerves have died they do not grow back. The damage is permanent.
Read this post in its entirety:
Brain Atrophy, Pseudoatrophy, and Multiple Sclerosis