Demyelinating diseases are a heterogeneous group of neurological conditions. Their common feature is damage to the myelin sheath, a protective layer surrounding the axons of neurons. Myelin is formed by oligodendrocytes in the central nervous system and Schwann cells in the peripheral nervous system.
Myelin performs an important function. By encapsulating nerve fibers (like the insulating lining around electrical wires), it ensures rapid transmission of neural impulses. Therefore, in demyelinating diseases, nerve conduction is considerably slowed and in some cases completely blocked.
The most common demyelinating disease is Multiple Sclerosis. Other, less common diseases in this group, are the following: