Multiple sclerosis

Multiple sclerosis (MS) is the most common nervous system disorder affecting young adults. In this condition, nerves in the brain and spinal cord are progressively damaged, causing a wide range of symptoms that affect sensation, movement, body functions, and balance. Specific symptoms may relate to the particular areas that are damaged and vary in severity between individuals. For example, damage to the optic nerve may cause blurred vision. If nerve fibres in the spinal cord are affected, it may cause weakness and heaviness in the legs or arms. Damage to nerves in the brain stem, the area of the brain that connects to the spinal cord, may affect balance.

In many people with MS, symptoms occur intermittently and there may be long periods of remission. However, some people have chronic (long-term) symptoms that gradually get worse.

In the UK, about 85,000 people are affected by MS. People who have a close relative with MS are more likely to develop the disorder. The condition is much more common in the northern hemisphere, which suggests that environmental factors also play a part. MS is more common in females and the disorder is more likely develop between early adulthood and middle age.

What are the causes?

MS is an autoimmune disorder, in which the body’s immune system attacks its own tissue, in this case those of the nervous system. Many nerves in the brain and spinal cord are covered by a protective insulating sheath of material called myelin. In MS, small areas of myelin are damaged, leaving holes in the sheath, a process known as demyelination. Once the myelin sheath has been damaged, impulses cannot be conducted normally along nerves to and from the brain and spinal cord. At first, the damage may be limited to only one nerve, but myelin covering other nerves may become damaged over time. Eventually, damaged parches of myelin insulation are replaced by scar tissue.

It is thought that MS may be triggered by external factors such as a viral infection during childhood in genetically susceptible individuals.

What are the types?

There are two types of MS. In the most common, known as relapsing remitting MS, symptoms last for days or weeks and then clear up for months or even years. However, some symptoms may eventually persist between the attacks. About 3 in 10 people with MS have a type known as chronic-progressive MS, in which there is a gradual worsening of symptoms with no remission.

A person with relapsing-remitting MS may go on to develop chronic-progressive MS.

What are the symptoms?


Symptoms may occur singly in the initial stages and in combination as the disorder progresses. They may include:

- Blurred vision.
- Numbness or tingling in any part of the body.
- Tiredness, which may be persistent.
- Weakness and a feeling of heaviness in the legs or arms.
- Problems with coordination and balance, such as an unsteady gait.

Stress and heat sometimes make symptoms worse. About half of the people who have MS find it hard to concentrate and experience memory lapses. Depression is common. Later in the course of the disease, some people with muscle weakness develop painful muscle spasms. Spinal cord damage can lead to urinary incontinence, and men may have increasing difficulty in achieving an erection. Eventually, damage to myelin covering nerves in the spinal cord may cause partial paralysis, and an affected person may need a wheelchair.

How is it diagnosed?

There is no single test to diagnose MS, and, because symptoms are so wide-ranging, a diagnosis is only made once other possible causes of the symptoms have been excluded. Your doctor will take your medical history and carry out a physical examination. If you are having visual problems, such as blurred vision, you may be referred to an ophthalmologist, who will assess the optic nerve, which is commonly affected in the early stages of the disorder. Your doctor may arrange for tests to find out how quickly your brain receives messages when particular nerves are stimulated. The most common test measures damage to the visual pathways. You will probably also have an imaging test of the brain, such as MRI, to see if there are areas of demyelination.

Your doctor may arrange for a lumbar puncture, a procedure in which a small amount of the fluid that surrounds the spinal cord is removed for microscopic analysis. Abnormalities in this fluid may confirm the diagnosis.

What is the treatment?

There is no cure for MS, but if you have relapsing-remitting MS, interferon beta may help to lengthen remission periods and shorten the length of attacks. Your doctor may also prescribe corticosteroids to shorten the duration of a relapse. However, at present, there is no specific treatment to halt the progression of chronic-progressive MS.

Many of the more common symptoms that occur in all types of MS can be relieved by drugs. For example, your doctor may treat muscle spasms with a drug that relaxes muscles. Similarly, incontinence can often be improved by drugs. Problems in getting an erection may be helped by a drugs treatment such as sildenafil. If you have mobility problems, your doctor may arrange for you to have physiotherapy. Occupational therapy may make day-to-day activities easier.

What can I do?

If you are diagnosed with MS, you and your family will need time and possibly counseling to come to terms with the disorder. You should minimize stress in your life and avoid exposure to high temperatures if hear tends to make your symptoms worse. Regular, gentle exercise, such as swimming, will help to keep your muscle strong without the risk of overstraining them.

The progression of MS is extremely variable, but people who are older when the disease first develops tend to fare less well. About 7 in 10 people with MS have active lives with long periods of remission between relapses. However, some people, particularly those with chronic-progressive MS, become increasingly disabled. Half of all people with MS are still leading active lives 10 years after diagnosis, and the average lifespan from diagnosis is 25-30 years.


VISUAL EVOKED RESPONSES

A visual evoked response test measure the function of the optic nerve, the nerve that transmits messages from the eye to the brain. The test is most often used to in the diagnosis of multiple sclerosis and can detect abnormalities even if visual symptoms are not apparent. The test records brain activity in response to a visual stimulus to find out the speed at which messages from the eye reach the brain. The test takes 20-30 minutes.