Multiple Sclerosis

Understanding the Myelin Sheath

To understand MS, it helps to know how nerve cells work. The axon is the long part of a nerve cell that carries signals from the cell body to other cells. Myelin is a fatty layer that covers and protects these axons, much like insulation on an electrical wire.

• Function: Myelin allows electrical impulses to transmit quickly and efficiently along the nerve cells.
• The Attack: In MS, T cells (a type of white blood cell) cross the blood-brain barrier and attack the myelin.
• Inflammation: This attack causes inflammation and destroys the myelin and the cells that produce it (oligodendrocytes).
• Disruption: When myelin is damaged, the nerve signals slow down, become distorted, or stop altogether.

The Formation of Plaques

When the inflammation goes down, the body tries to fix the damage. Often, this leads to scar tissue forming, called lesions or plaques.

• Locations: These plaques can form anywhere in the CNS, including the brainstem, cerebellum, and spinal cord.
• Sclerosis: The accumulation of this scar tissue is what gives the disease its name.
• Axonal Loss: Over time, the nerve fiber itself may be damaged or destroyed, leading to permanent neurological deficits.