A progressive disease of nerves in the brain and spinal cord causing weakness and problems with sensation and vision
- Usually develops between the ages of 20 and 40
- More common in females
- Sometimes runs in families
- Stress and heat may aggravate symptoms
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 100,000 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 to 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 tissues, in this case those of the central 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 patches 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 main types of MS: relapsing–remitting and progressive MS. In relapsing–remitting MS, the most common type, symptoms typically last for days or weeks (relapse) and then clear up for months or even years (remission). In a few cases of relapsing–remitting MS, the symptoms are very mild and may not cause significant disability even after as long as 20 years; this type is known as benign relapsing–remitting MS. However, whatever the type of relapsing–remitting MS, eventually some symptoms may persist between attacks.
About 1 in 10 people with MS have a type known as primary progressive MS, in which there is a gradual worsening of the symptoms from the start, with no remissions. Many people who initially have relapsing–remitting MS go on to develop secondary progressive MS, in which there is a progressive increase in symptoms with few, if any, remissions.
What are the symptoms?
The type, severity, and progression of symptoms vary considerably from person to person. In the initial stages, symptoms may occur singly, then, as the disease progresses, in combination. They may include:
Blurred vision, usually affecting only one eye.
Numbness or tingling in any part of the body.
Fatigue, which may be persistent.
Problems with coordination and balance, such as an unsteady gait.
Stress and heat sometimes make symptoms worse. Depression is common. 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 (see Erectile dysfunction). 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 a diagnosis is only made once other possible causes of the symptoms have been excluded. Your doctor will take your medical history and examine you. If you have visual problems, you may be referred to an ophthalmologist, who will assess the optic nerve, which is commonly affected in the early stages of the disorder (see Optic neuritis). 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 (see Visual evoked responses). You may also have a brain scan, such as an MRI scan, to look for demyelination.
Your doctor may arrange for a lumbar puncture, in which a sample of the fluid around the spinal cord is removed for 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, disease-modifying drugs such as interferon beta (see Interferon drugs), glatiramer, or natalizumab, may help to lengthen remission periods and shorten attacks. Your doctor may also prescribe corticosteroid drugs to shorten the duration of a relapse. At present, there is no treatment to halt the progression of 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 muscle relaxant and incontinence can often be improved by drugs (see Drugs that affect bladder control). Problems in getting an erection may be helped by a drug such as sildenafil. If you have mobility problems, your doctor may arrange for you to have physiotherapy, and occupational therapy may make day-to-day activities easier.
Many people with MS believe that cannabis relieves symptoms such as muscle stiffness and pain, and there is experimental evidence to support that belief. However, cannabis has no approved medicinal use, cannot be prescribed by doctors, and its use is illegal.
What can I do?
If you are diagnosed with MS, you and your family will need time and possibly counselling to come to terms with the disorder. You should minimize stress in your life and avoid exposure to high temperatures if heat makes your symptoms worse. Regular, gentle exercise will help to keep your muscles strong without overstraining them. Many hospitals have a specialist MS nurse, who can provide support and information.
What is the prognosis?
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 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.
From the 2010 revision of the Complete Home Medical Guide © Dorling Kindersley Limited.
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