Demyelinating Plaque
Demyelinating plaques are areas of damage to the myelin sheath—the protective coating around nerve fibers in the brain and spinal cord. These lesions disrupt the transmission of electrical signals along nerves, leading to various neurological symptoms. They are most commonly associated with multiple sclerosis (MS), but can also occur in other demyelinating diseases. Detection of these plaques through MRI imaging is crucial for diagnosis and monitoring of disease progression.
What is it?
Demyelinating plaques are focal areas of damage where the myelin sheath—the insulating layer that surrounds nerve fibers—has been destroyed or damaged. Myelin is essential for the rapid and efficient transmission of electrical impulses along nerves. When it is damaged, nerve signals slow down or become blocked entirely, leading to the diverse neurological symptoms associated with demyelinating diseases.
These plaques appear as white or bright spots on MRI scans and can vary in size, number, and location. They most commonly occur in the white matter of the brain, particularly around the ventricles (fluid-filled spaces), in the brainstem, cerebellum, and spinal cord. The plaques represent areas where inflammation has occurred, often triggered by an autoimmune response where the body’s immune system mistakenly attacks its own myelin. Over time, new plaques may form while older ones may partially heal, though scarring (sclerosis) often remains.
Important to Know
While demyelinating plaques are most strongly associated with multiple sclerosis, they can also occur in other conditions such as acute disseminated encephalomyelitis (ADEM), neuromyelitis optica spectrum disorder (NMOSD), and progressive multifocal leukoencephalopathy (PML). The pattern, location, and timing of plaque development help distinguish between these conditions. MRI remains the gold standard for detecting demyelinating plaques, particularly when using contrast agents that highlight areas of active inflammation. Early detection and diagnosis are crucial because disease-modifying therapies can significantly slow disease progression and reduce the formation of new plaques, helping preserve neurological function and quality of life.