Demyelinating disorders are the disorders where the myelin sheath is damaged. Myelin sheath is an insulating layer present on the nerve cells, and is made up of fatty substances and proteins. The function of the myelin sheath is to provide smooth transmission of nerve impulses throughout the immune system. Several disorders, such as multiple sclerosis, damage the myelin sheath. Once the myelin sheath is damaged, a scar forms in that area, and the nerve impulses cannot transmit through these scars.