Achronic, progressive disorder, is the most common condition in which demyelination of nerve fibers in the brain, spinal cord, and optic nerves can occur.

Demyelination disease is a chronic, progressive condition where demyelination of nerve fibers located in the brain, spinal cord as well as the optic nerves. When there is a damage in the myelin sheath, the nerve impulses become slow or sometimes even stops that then causes neurological problems. The most known example of this is Multiple Sclerosis.