MS primarily targets which tissue?

• A. CNS white matter
• B. Peripheral nerves
• C. Gray matter only
• D. Brainstem

Answer: (A)

MS is an autoimmune inflammatory disease that primarily damages the myelin sheaths of axons in the central nervous system. The tissue most affected is CNS white matter, where myelin sheaths around long-range axons are destroyed by immune attacks on oligodendrocytes. This loss of myelin disrupts rapid saltatory conduction, leading to the variety of neurological symptoms seen in MS, such as visual disturbances, weakness, and sensory changes. Peripheral nerves aren’t the main target because their myelin is produced by Schwann cells in the peripheral nervous system, which MS typically spares. Gray matter can be involved in MS, especially as the disease progresses, but the defining and most consistent pathology is demyelination of CNS white matter.