Multiple Sclerosis: A Brief Overview of the Illness

Abstract

Multiple Sclerosis (MS) is a disease of the human central nervous system (CNS), of the brain, spinal cord and optic nerves, in which nerve tissue is damaged and destroyed. Conventionally the principal element of this destruction is the erosion of the myelin sheath surrounding nerve fibres or axons, by immune cells that have crossed the blood-brain barrier to enter the CNS. Here these cells mistakenly identify myelin as alien tissue and attack it causing lesions of acute inflammation. These lesions leave behind hardened scars or plaques, areas of sclerosis that from their nineteenth-century pathological analysis became the eponymous characteristic of this disease. In these lesions the mass of immune cells squeezed into a small space and the damaged myelin interfere with signals trying to travel along the underlying nerve fibres. Such messages may be partially blocked, slowed down, diverted into other nerve fibres or in the most severe cases stopped altogether. Thus, the control by the brain of the bodily parts to which the affected nerves are connected can be impaired to a lesser or greater degree. This is the familiar, common understanding of the proximate cause of MS symptoms by most commentators. It is ‘a demyelinating disorder’. The very essence of the disease therefore is to do with the integrity of myelin surrounding nerve fibres (Rose et al. 2000, 2; Wade and Green 2001, 6; MS Society 2010a, 3).