Multiple Sclerosis (MS) is an inflammatory neurological disease affecting the central nervous system which results in loss of myelin, the insulating material around nerves, a process called demyelination. The lesions in MS are scarred, thickened areas, giving rise to the term sclerosis in this disease. MS is an active disease with continual formation of lesions and a steady worsening clinical situation involving increasing disability. Patients who have the commonest form of MS have relapsing (worsening) and remitting (recovering) disease with about five to ten new neurological lesions every year and one or two clinical worsenings.
MRI scanning has allowed an important increase in the ability to confirm MS as a diagnosis as the lesions in the central nervous system show up in the scans. No triggering factor or agent for this disease has yet been found, although it is known to be better during pregnancy and worse in the period following birth of the child. MS may be brought on by a number of different factors but only a quarter of MS onsets can be linked to any kind of infection at the time.
There are several different forms of multiple sclerosis which have differing patterns and severities of disease. MS is more common in Caucasian populations and the incidence increases with increasing latitude, in other words how far to the north the individual lives. Genetic inheritance may be important in the risk of getting MS but the environment plays a role somewhere as it is known that moving to a higher risk area before the age of 15 years means you suffer the increased risk of the new area.
In the world overall it is estimated that the number of people suffering from multiple sclerosis is 2.5 million. MS causes significant disability and due to its age profile these are often people with families and work. MS does not cause death directly but is thought to shorten life by about 5 to 7 years due to the likelihood of getting repeated infections secondary to immobility and urinary complications. Northern Europeans are the most commonly affected group, with women suffering 1.6 to 2.1 times as much as men. Hormonal factors are again thought to be important as women outnumber men three to one under fifteen years of age or over fifty.
Male patients are more likely to get the primary progressive form of the disease while females are more likely to get the relapsing form. Attacks of the disease manifest themselves in newly developed central nervous system symptoms, symptoms which vary in part of the body affected and are spread over a variable time. Typical examples can be a sudden weakness of one or more of the limbs, double vision from involvement of the optic nerve and loss of sensations in variable areas. There can also be a steady worsening in both the physical and mental abilities without obvious attacks.
If someone has an acute attack and then improves afterwards they are said to have the relapsing and remitting form of multiple sclerosis. However, most people in this group will at some time enter a phase of steady worsening known as secondary progressive disease. The primary progressive form exhibits continuing increase in disability without any remissions, often progressing rapidly to complete paralysis. This type of MS is more disabling and less responsive to therapy than the other forms. If patients do not recover their disability inbetween relapses they can be classified as having relapsing and progressive MS.
The symptoms of MS tend to cover a wide range of abilities in any individual patients but there can be a concentration of symptoms involving the visual, mental functioning or balance and coordination systems. It is thought that at some point in the disease MS sufferers reach a point where the disease worsens more continuously with an indication of neurodegeneration rather than just inflammation. However, one of the characteristics of MS is that patients can present with almost any combination of symptoms or with severe changes in one particular neurological system. Severe loss of mental ability may be evident without much evidence of central nervous system lesions.
Author: Jonathan Blood-Smyth