An Overview of Chronic Inflammatory Demyelinating Disease: Multiple Sclerosis BACKGROUND The central nervous system (CNS) includes gray matter, which contains the cell bodies of neurons, and white matter, which contains the nerve axons. Most nerve axons are concentrically wrapped in a lipid-rich biological membrane, known as the myelin sheath. In the central nervous system, myelin is produced by oligodendrocytes. a type of glial cell. (Pfeiffer et al., 1993). These electrically insulating multilamellar membranes significantly increase electrical resistance, to prevent leakage of electrical current from axons, as well as decrease electrical capacitance to reduce the ability of axons to store electrical energy (Shivane & Chakrabarty, 2007). Therefore, the myelin sheath allows for high-speed passatelliary conduction of nerve impulses. Demyelination is a group of diseases characterized by the destruction of the normal myelin sheath, with relative preservation of the axons. Degeneration of the myelin sheath could be the result of a disease that directly damages the myelin sheath or a disease that damages oligodendrocytes (Love, 2006). Ultimately, demyelination leads to impairment of the normal conduction of electrical impulses in the affected nerves. MULTIPLE SCLEROSIS Multiple sclerosis (MS) is the most common inflammatory demyelinating disease of the central nervous system. It is a chronic neurological disease that normally affects young people and is a major cause of disability. The pathological feature of this chronic disease is the formation of demyelinated plaques with reactive glial scar tissue, which are distributed focally or diffusely throughout the brain and spinal cord (Lucchinetti et al...... half of the article ... ..ns induced by effector CD8 T cells recognizing an antigen sequestered on oligodendrocytes, The Journal of Immunology, 181(3), 1617-1621.Saxena, A., Martin-Blondel, G., Mars, LT, & Liblau , RS. (2011). Role of CD8 T cell subsets in the pathogenesis of multiple sclerosis, FEBS, 585(23), 3758-3763. 193-202. Simpson, S., Blizzard, L., Otahal, P., Van der Mei, I., & Taylor, B. (2011) Latitude is significantly associated with the prevalence of multiple sclerosis: a meta-analysis Journal of Neurology, Neurosurgery & Psychiatry, 82(10), 1132-1141.Thompson, A.J., Polman, C.H., Miller, D.H., McDonald, W.I., Brochet, B., Montalban, X.F.M., & De Sa, J. (1997) . Primary progressive multiple sclerosis. Brain, 120(6), 1085-1096.