Multiple Sclerosis is a long term disease that affects the central nervous system (CNS). The CNS consists of the brain, spinal cord, and the optic nerves.
The nerve fibres of the CNS are surrounded and protected by a fatty tissue called myelin, which helps nerve fibres conduct electrical impulses around the body. Myelin not only protects nerve fibres, it also makes their job possible, so when either myelin or the nerve fibre is destroyed or damaged, the ability of the nerves to conduct electrical impulses to and from the brain is disrupted.
In MS, myelin is lost in multiple areas, leaving scar tissue called sclerosis, which is where the disease gets its name. These damaged areas are also known as plaques or lesions. Sometimes the nerve fibre itself is damaged or broken. This damage to myelin and/or the nerve fibres produces the various symptoms of MS.
Recent evidence suggests that some people may have a genetic predisposition to develop MS, but whether they develop the disease is dependent on them being exposed to a certain trigger, e.g. physical/mental stress or injury. Symptoms vary depending on which part of the CNS is affected.
It is estimated that at least 100,000 people in the UK have MS, but this may underestimate the extent of the disease. It normally manifests itself in people between the ages of 20-40, although with modem technology, MRI scanners, it is now possible to detect MS at a much earlier age.
Types of MS
There are four recognised patterns of MS, each with its own characteristics.
Someone with a small number of relapses followed by a complete recovery may be described as having benign MS. It is only possible to make a diagnosis of benign MS once someone has experienced little or no disability for a period of 10 to 15 years. However, a relapse may occasionally occur after many years in which the MS has been inactive.
Relapsing Remitting MS
Most people are diagnosed with relapsing remitting MS. This is when relapses (a flare-up of symptoms) are followed by remissions (periods of recovery). Relapses are unpredictable. They can last for days, weeks or months and vary from mild to severe. During a relapse there will either be new symptoms, or a recurrence or worsening of previous symptoms. Any changed or new symptoms must last for at least 24 hours to be described as a relapse. During remission, symptoms can disappear completely, although sometimes people make only a partial recovery.
Primary Progressive MS
Primary progressive MS affects about 10 to 15 per cent of people diagnosed with MS. It has this name because from the first (primary) symptoms it is progressive. Symptoms gradually get worse over time, rather than appearing as sudden attacks (relapses).In primary progressive MS, early symptoms are often subtle problems with walking, which develop – often slowly – over time.
Secondary Progressive MS
Most people who have relapsing remitting MS eventually develop secondary progressive MS. This type of MS is identified when someone’s condition becomes steadily worse and their disability progresses for a period of six months or more, whether or not they continue to have relapses.