Multiple sclerosis is a complex condition that affects the nervous system.
Symptoms range widely. In milder cases, there may be numbness in the limbs. Severe cases may involve paralysis or vision loss.
It is not possible to predict how multiple sclerosis (MS) will progress in any individual.
Over 400,000 people in the United States (U.S.) have MS, and around 10,000 new cases are diagnosed each year.
It is two to three times more common in women than in men, and diagnosis usually occurs between the ages of 20 and 50 years.
Here are some key points about multiple sclerosis. More detail is in the main article.
- Multiple sclerosis affects the central nervous system.
- Diagnosis usually happens between the ages of 20 and 50 years.
- It is impossible to predict how the disease will progress.
- Mild symptoms include tingling and numbness, but severe cases can involve vision loss and paralysis.
- There is no cure, but treatment can relieve symptoms and help the person manage their daily living.
What is MS?
MS affects the central nervous system (CNS), but exactly why is happens is unclear.
In the CNS, nerve fibers are surrounded by a myelin sheath, which protects them. Myelin also helps the nerves conduct electrical signals quickly and efficiently. In MS, the myelin sheath disappears in multiple areas, leaving a scar, or sclerosis.
Multiple sclerosis means "scar tissue in multiple areas."
The areas where there is no myelin or a lack of myelin are called plaques or lesions. As the lesions get worse, nerve fibers can break or become damaged. As a result, the electrical impulses from the brain do not flow smoothly to the target nerve.
When there is no myelin, the fibers cannot conduct the electrical impulses at all. The messages from the brain to the muscles cannot be transmitted.
Types of MS
There are four types of MS:
Clinically isolated syndrome (CIS): This is a single, first episode, with symptoms lasting at least 24 hours.
Relapse-remitting MS (RRMS): This is the most common form, affecting around 85 percent of people with MS and involving attacks of new or increasing symptoms.
Primary progressive MS (PPMS): Symptoms worsen progressively, without early relapses or remissions. Around 15 percent of cases are PPMS.
Secondary progressive MS (SPMS): After initial episodes or relapse and remission, the disease progresses steadily.
MS affects the CNS, which controls all the actions in the body. When nerve fibers that carry messages to and from the brain are damaged, symptoms may occur in any part of the body.
For some patients, symptoms are so mild that they do not notice anything until later in the course of the disease. Others may be aware of their symptoms in the early stages.
The overall symptoms of MS are:
- muscle weakness
- visual disturbances
- difficulties with co-ordination and balance
- numbness and tingling, as in "pins-and-needles"
- problems with thinking and memory
Effects of MS
These can lead to:
Bladder problems: There may be difficulty emptying the bladder completely, frequent urination, and urge incontinence.
Bowel problems: Constipation can lead to fecal impaction, and this can lead to bowel incontinence.
Fatigue: This affects up to 90 percent of patients, and it can undermine their ability to function at work or at home.
Dizziness and vertigo: These are common problems, along with difficulties with balance.
Sexual dysfunction: A loss of interest in sex is common in both males and females.
Spasticity and muscle spasms: Damaged nerve fibers in the spinal cord and brain can cause painful muscle spasms. Muscles might get stiff and be resistant to movement, known as spasticity.
Tremor: There may be involuntary quivering movements.
Vision problems: There may be double vision or blurring vision, a partial or total loss of vision, or red-green color distortion. This usually affects one eye at a time. Inflammation of the optic nerve can result in pain when the eye moves.
Gait and mobility changes: MS can change the way people walk, because of muscle weakness and problems with balance, dizziness, and fatigue.
Emotional changes and depression: Demyelination and nerve-fiber damage in the brain can trigger emotional changes, apart from the challenges of adjusting to the diagnosis of MS, an unpredictable, disabling disorder. Research has linked MS with a 50 percent chance of depression.
Less common symptoms include:
- hearing loss
- respiratory or breathing problems
- speech disorders
- swallowing problems
In the later stages, there may also be changes in perception and thinking and heat sensitivity.
Multiple sclerosis is an unpredictable disease, and it affects people in different ways. For some, it starts with a subtle sensation, and months or years could pass without noticing progression. For others, symptoms worsen rapidly, within weeks or months.
Causes and risk factors
The exact cause of MS is unknown, but it is thought to be an autoimmune disorder. This means that the immune system attacks the myelin as if it were an undesirable foreign body, just as it might attack a virus or bacteria.
Risk factors include:
- Age: A diagnosis is more likely between the ages of 20 and 50 years
- Sex: More women develop MS than men
- Ethnicity: It is more common among people of European descent
- Genetic factors: Susceptibility can be passed down in the genes
Rates of MS are higher in people who live further away from the equator, suggesting that exposure to sunlight may impact MS risk.
Other possible factors that have been linked to MS, but are not confirmed by research, include:
- Exposure to a toxic substance: This could be a heavy metal or solvent.
- Infections: Viruses, such as Epstein-Barr, or mononucleosis, and varicella zoster, may be triggers.
- Salt: In 2013, a study suggested that too much salt in the diet may trigger an autoimmune reaction.
Previous theories have included exposure to canine distemper, physical trauma, or aspartame, an artificial sweetener, but there is no evidence to support these.
It is unlikely there is a single trigger for MS, but it is probably triggered by multiple factors.
The doctor will carry out a physical examination, ask about symptoms, and consider the patient's medical history. No single test can confirm a diagnosis, so several strategies are needed when deciding whether a patient meets the criteria for a diagnosis.
There will be a neurologic exam, imaging scans, a test to measure the electrical activity of the brain, a spinal fluid analysis, and possibly other tests. These can help rule out other possible causes of the symptoms.
There is no cure for MS, so treatment focuses on suppressing the autoimmune response and managing symptoms.
Several disease-modifying drugs are approved for the relapsing forms of MS.
Corticosteroids: Are the most commonly prescribed drugs for MS. They reduce inflammation and suppress the immune system. They mostly treat an acute flare-up of symptoms in certain types of MS.
Interferon Beta 1a or 1b: These may slow down the progression of symptoms, but they must be used with care, as they can cause liver damage.
One study of data for 868 patients concluded that Interferon Beta was not helpful in preventing disability in the long term.
Copaxone (Glatiramer): This aims to stop the immune system from attacking myelin. It is injected once a day. Flushing and shortness of breath may occur after receiving the injection.
Tysabri (Natalizumab): This is used for patients who either cannot tolerate other treatments or have not benefitted from them. It increases the risk of developing multifocal leukoencephalopathy, a fatal brain infection.
Mitoxantrone (Novantrone): This immunosuppressant is normally used only in the later stages. It can damage the heart, but if symptoms are worsening rapidly, it can help slow down the progression of disability.
Aubagio (teriflunomide): This is a once-daily tablet for adults with relapsing forms of MS.
Rehabilitation aims to help patients improve or maintain their ability to perform effectively at home and at work.
Programs generally include:
Physical therapy: This aims to provide people with the skills to maintain and restore maximum movement and functional ability.
Occupational therapy: The therapeutic use of work, self-care, and play activities to increase development and prevent disability.
Speech and swallowing therapy: A speech and language therapist will carry out special training.
Cognitive rehabilitation: This helps people manage specific problems in thinking and perception.
Vocational rehabilitation: This helps people with disabilities make career plans, learn job skills, get and keep a job.
Plasmapheresis involves withdrawing blood from the patient, removing the plasma, and replacing it with new plasma.The blood is then transfused back into the patient.
This process removes the antibodies in the blood that are attacking parts of the patient's body, but whether it can help patients with MS is unclear. Studies have produced mixed results.
Vitamin D and Omega-3 supplements
Researchers have found a link between vitamin D deficiency and MS, but they are still investigating whether vitamin D supplements might help in treatment. Patients should not use supplements without first consulting their doctor.
It has been suggested that omega-3 fatty acid supplements may help patients with MS, but scientists in Norway concluded that they do not.
Hyperbaric oxygen therapy
It has been suggested that hyperbaric oxygen therapy (HBOT) may help people with MS, but this is unproven.
The progression of MS is different for each person, so it is hard to predict what will happen.
However, the lifespan of a person with multiple sclerosis is usually about the same as for a person without MS.
In rare cases, the symptoms can be fatal.