What is multiple sclerosis?

About MS

Around each nerve fibre - the pathways along which messages and instructions are passed between different parts of the brain and the rest of the body - is an insulating wrapping of fatty membrane called myelin. In multiple sclerosis (MS) the myelin is broken down in patches throughout the central nervous system and the damaged patches become scarred (this is where the name comes from - sclerosis meaning scars and multiple obviously means many). Without the myelin coating, nerve messages cannot travel normally and they can become garbled or lost so that the instructions sent by the nervous system to different parts of the body are disrupted.

Who has it?

It is thought that between 85 and 100 thousand people in the UK - about 1 in 600 - have been diagnosed. MS affects more women than men with symptoms usually becoming apparent in young adults even though a firm diagnosis might not be made for many years. It is rare for children to be diagnosed.

What causes it?

No one knows - despite vast amounts of research which is still going on. Various factors may trigger an inborn susceptibility to MS. Such factors may cause inappropriate activity of the immune system - the body's defence mechanism - causing the destruction of myelin. Factors associated with MS may be more likely to occur in Northern Europe, Canada, the Northern States of the USA, New Zealand and Tasmania since these are the places where the incidence of MS is highest. MS is not contagious - you cannot catch it from someone.

What problems does it cause?

As with most chronic illnesses, the problems are both physical and emotional. The severity and incidence of symptoms vary enormously from person to person and even from hour to hour.

Physical symptoms can include any of the following:- tingling sensations, loss or distortion of the sense of touch, double or blurred vision, temporary blindness, fatigue and dizziness, loss of co-ordination of movement leading to some staggering, clumsiness (spilling and dropping things), slurred speech and an inability to perform fine movements - e.g. doing up buttons, tying shoe laces etc. Legs or arms may suddenly go into spasm which is often painful, and walking may become very difficult when sticks or a wheelchair may be necessary. Incontinence can be a problem. Symptoms can become more pronounced when the MS is active and may lessen or disappear again when the MS is quiet. In some people, symptoms fluctuate when the person is tired, upset or anxious.

Emotional difficulties arise from the uncertainties associated with MS as the unpredictability of the disease means that no one knows when or how it is going to strike.

MS shows up differently in each person. Some people are only mildly affected throughout their lives. A few people deteriorate rapidly from the beginning and may die early. Most people with MS experience something in between these two extremes.

Benign MS

This type starts with a small number of mild attacks followed by complete recovery. It does not worsen over time and there is no permanent disability. The first symptoms usually affect sensation or sight. People are only classified as having benign MS when they have little sign of disability 10 to 15 years after the first onset of symptoms. However, disability may occasionally develop after many years in which the disease has been inactive. Around 20 per cent of people with MS have the benign form.

Relapsing-remitting MS

For most people MS starts as the relapsing-remitting type. This means they have relapses (a flare-up of symptoms), followed by remissions (periods of recovery). Relpases (also known as attacks or exacerbations) tend to be unpredictable and their causes are unclear. They can last for hours, days, weeks or months, and vary from mild to severe. During a relapse new symptoms may occur, or previous symptoms may return. At their worst, acute relapses may need hospital treatment. Remissions can last any length of time - even years. No one knows exactly what makes MS go into remission. Even during remissions there may still be plaques visible on MRI scans. In the early stages of relapsing-remitting MS, symptoms usually disappear during remissions. However, after several attacks there may be some residual damage to myelin, resulting in the person being slightly more affected than before the relapse. Around 25 per cent of people with MS have the relapsing-remitting form.

Secondary progressive MS

Many people who start out with relapsing-remitting MS later develop a form known as secondary progressive. This means that disability does not go away after a relapse and progressively worsens between attacks, or that the cycle of attack followed by remission is replaced by a steady progression of disability. Around 40 per cent of people with MS develop the secondary progressive form, usually about 15 to 20 years after the initial onset of MS.

Primary progressive MS

Some people with MS never have distinct relapses and remissions. From the start they experience steadily worsening symptoms and progressive disability. This may level off at any time or may continue to get worse. Around 15 per cent of people with MS have the primary progressive form of the disease, which is also known as chronic progression.