Demyelination occurs where there’s damage to the myelin. Myline is the protective coating of nerve cells. When this happens, neurological problems can occur.
Demyelination can result from various medical conditions, most common of which is multiple sclerosis (MS). 
This article gives an overview on Demyelinating disorder. Its causes, possible symptoms, and treatment options.
What Are Demyelinating Diseases?
Many of the nerves in the nervous system have a coating, or sheath, of myelin, which is a fatty white substance. The work of myelin sheath is to protect nerve fibers and enable electrical impulses to pass along nerve cells quickly and efficiently.
How well impulses travel determines how smoothly and quickly a person can perform everyday movements. When there’s an issue with the myelin sheath, it can result in complications with the nervous system.
Some conditions result in damage to the myelin sheath, which can cause problems in the brain, the eyes, the spinal cord, and other parts of the body. Doctors call these conditions demyelinating diseases.