What Does a Brain Look Like With MS Lesions?

Multiple sclerosis (MS) affects the central nervous system, causing a loss of the white fatty myelin sheath that covers nerve fibers. This phenomenon is called demyelination. Inflammation is also present. The patient’s own immune system appears to cause the condition.

Symptoms

• Symptoms include weakness, blurred vision and abnormal sensations. The symptoms can fluctuate or recur.

Lesions

• The plaques, or scars, constitute the characteristic MS lesions; they are multiple and can form anywhere in the central nervous system white matter, which explains the variability of the symptoms. These lesions are visualized by radiological methods and histopathologic examination of post-mortem brain or biopsy tissue.

Brain Imaging

• Magnetic resonance imaging (MRI) is the best imaging test for diagnosing and monitoring MS. This method gives high-resolution images of cross-sections of the brain. The plaques typically appear as bright, ovoid-shaped lesions, mainly in the white matter. Gadolinium, a contrast agent, is injected into the bloodstream to help distinguish areas of recent demyelination and active inflammation from areas of long-standing damage.

Brain Biopsy

• Examination of an MS brain biopsy with a microscope is rarely required for diagnosis. When performed, it most likely shows early lesions, in which the integrity of the nerve fibers is relatively preserved. Myelin loss and infiltration by immune cells can still be seen. White blood cells and fluid accumulate around blood vessels.

Brain Autopsy

• At autopsy, long-lasting lesions are more evident. Gradual, cumulative damage leads to significant loss of white matter and a reduction in total brain volume. Macroscopically, on a brain section, lesions present as gray-tan or pink firm areas, hence the term “sclerosis in plaques.” They can be ovoid or wedge-shaped and their size varies. Under the microscope, patches of myelin destruction are noted, with loss of axons and some inflammatory reaction. Changes in astrocytes, a type of glial cell, contribute to generating the scar-like lesions. Remyelination (repair) areas can be seen.