What is multiple sclerosis?
Multiple sclerosis (MS) is a chronic and disabling disease of the central nervous system that affects the brain, spinal cord, and optic nerves. This disease often begins in young adults between the ages of 20 and 40 years and rarely appears before the age of 10 or after the age of 60.
There are two types of multiple sclerosis, called relapsing-remitting MS (RRMS) and secondary progressive MS (SPMS). The former type involves flare-ups followed by periods of remission; this pattern can continue for months or years, but eventually RRMS leads to the latter type of MS.
History of multiple sclerosis:
The first signs of MS were noted back in 1868 by Jean-Martin Charcot, a French neurologist. At that time, Charcot was working with a patient who had tremors on one side of his body and weakness in his limbs.
Fast forward to 2010, when researchers discovered that MS is an autoimmune disease that affects a person's nerve cells and myelin. Myelin is a fatty material found in cells called oligodendrocytes and forms an insulating layer around nerve cells allowing electrical signals to pass quickly. With MS, however, immune cells attack and damage myelin in parts of your brain, spinal cord and optic nerves.
It wasn't until 2010 that a team of researchers at Johns Hopkins University School of Medicine discovered how myelin damage occurs in MS patients. The scientists found that immune cells called T-cells were responsible for attacking and destroying myelin. More specifically, they identified an enzyme called cathepsin-B that was required for T-cells to attack myelin.
However, not all T-cells in an MS patient's body are bad. A 2013 study published in The Lancet showed that a type of immune cell called regulatory T-cells actually protects against myelin damage. These cells go around looking for other potentially harmful T-cells and stop them from causing damage to your myelin sheath. If you don't have enough regulatory T-cells, your risk for MS increases.
More recent research has uncovered a few more intriguing pieces to multiple sclerosis's puzzle. Last year, scientists discovered a gene that appears to have an effect on whether or not you develop MS.
In fact, researchers found that people with one version of a gene called MDR1 are about three times more likely to develop MS than those who carry another variant. Also in 2016, scientists identified another potential contributor to multiple sclerosis development - exposure to house dust mites.
Causes:
MS is an autoimmune disease, which means that your immune system mistakenly attacks healthy cells in your body. In people with MS, immune cells attack a fatty substance called myelin, which protects nerve fibers in your brain and spinal cord.
The loss of myelin disrupts communication between your brain and other parts of your body, causing many of MS's symptoms. Scientists aren't sure what causes multiple sclerosis (MS) or why it targets some people but not others.
Although researchers have yet to fully understand what causes MS, they've uncovered a number of risk factors that can make you more likely to develop MS. These include a family history of MS or another autoimmune disease, living farther from the equator and having had a viral infection such as Epstein-Barr virus or cytomegalovirus.
Research has shown that being female and getting older are also factors that may increase your risk for MS. In fact, two-thirds of people with MS are women, most typically in their 20s and 30s.
The number of new cases diagnosed each year is equal among men and women, however, suggesting that women's increased lifetime risk for developing MS more than makes up for any gender differences in incidence rates.
Additionally, your risk for MS may be higher if you have certain genetic variations. Several genes are thought to play a role in determining who develops MS, including HLA-DRB1 and HLA-DQB1.
Environmental factors may also play a role in MS. One study found that people who lived farther from the equator, where sunlight is less intense year-round, were more likely to develop MS than those who lived closer to it. The researchers hypothesized that people living at higher latitudes may have reduced levels of vitamin D, which helps keep your immune system healthy and plays a role in how your body absorbs calcium.
People who have multiple sclerosis are also more likely to have been infected with Epstein-Barr virus or cytomegalovirus, two types of herpes viruses. Experts aren't sure if these infections actually cause MS or if they only increase your risk for developing it.
If you have MS, you may wonder if your lifestyle choices play a role in causing or worsening symptoms. Smoking and drinking alcohol can worsen multiple sclerosis symptoms, but it's not clear whether these habits can directly cause MS.
To help control your symptoms, eat a healthy diet that is low in saturated fat and high in fruits, vegetables and whole grains. Exercise regularly to keep your muscles strong. If you experience bladder problems or trouble urinating, ask your doctor about pelvic floor exercises to strengthen these muscles. These may help with bladder control issues as well as sexual dysfunction caused by MS, such as difficulty reaching orgasm during sex (delayed ejaculation).
Symptoms:
MS is one of a group of conditions called demyelinating diseases. You might recognize that last word - demyelination - as a fancy word for damage to or stripping away of myelin, a layer that coats and protects nerve fibers in your brain and spinal cord. In people with MS, demyelination happens when immune cells attack and destroy parts of the myelin sheath.
The symptoms vary depending on where and how much myelin is lost, which areas of your brain or spinal cord are involved, and whether it's acute or chronic. How long you've had MS also affects what your symptoms will be - for example, people who are newly diagnosed are more likely to have a severe course than those who've had MS for many years.
In its mildest form, MS is similar to getting a bad cold. You might experience muscle weakness and numbness, tingling or pins-and-needles sensations, fatigue, pain or loss of coordination. But sometimes even these signs and symptoms can be difficult to distinguish from more common conditions like an inner ear infection or a pinched nerve.
More severe forms are much easier to recognize; over time people with MS may lose their ability to walk, use their arms and hands, see normally and speak clearly.
Vision problems are also common, such as:
- Blurred vision
- Prolonged double vision; and
- Partial or complete loss of vision, often with pain during eye movement (usually in one eye at a time)
Multiple sclerosis symptoms may also include:
- Fatigue
- Dizziness
- Slurred speech
- Problems with sexual, bowel and bladder function
- Tingling or pain in parts of the body
Diagnosis:
If you're concerned that you or someone you know might have MS, your doctor can diagnose it by reviewing your medical history and conducting a physical exam.
The disease can also be confirmed with a variety of tests, including MRIs and spinal taps. The tests aren't perfect, however, so other conditions may sometimes be confused with MS, especially early on.
As a result, some people are misdiagnosed and go undiagnosed for years.
Treatments:
There are a variety of treatments for MS, but none is guaranteed to stop or reverse progression. One common approach is to begin with an immunomodulatory drug that attempts to halt or slow down disease progression, followed by either an injectable agent that slows attacks or some form of disease-modifying therapy (DMT).
Doctors may also prescribe oral medications such as corticosteroids and glatiramer acetate for acute relapses and early stages. These treatments can be used alone or in combination.
Other types of DMTs, such as natalizumab (Tysabri), may also be used, but due to potentially severe side effects that can occur in less than 1% of patients - which include progressive multifocal leukoencephalopathy (PML) - these are typically reserved for more severe cases. Some newer medications, such as fingolimod and teriflunomide, have been FDA-approved recently.
Another type of DMT, dimethyl fumarate (Tecfidera), was approved in September 2013. The disease-modifying therapies are designed to slow or stop MS from worsening.
Some medications used for treatment may come with side effects, including nerve pain and drowsiness - as well as less common side effects such as joint pain, tremors, depression and weight loss. These side effects can be addressed with other medications and symptoms can also be managed to some extent.
Another newer treatment is ocrelizumab, an antibody drug that targets B cells, which play a role in creating inflammation and exacerbating MS symptoms. Ocrelizumab showed promising results for slowing disease progression in phase 3 clinical trials. An FDA panel recommended its approval in February 2017; it was approved later that month.
The outlook for people with MS can vary, depending on whether they're experiencing relapses or progressive disease. Some people with MS may only experience mild symptoms, while others might be confined to a wheelchair by severe, continuous disability.
Between attacks, most people with relapsing-remitting MS have no problems functioning in everyday life and have minimal disabilities that can often be managed through treatment.
The outlook for people with progressive MS is more dire. As opposed to relapsing-remitting MS, which shows disease activity by discrete attacks that eventually subside, progressive MS causes a steady decline in ability and function.
With each relapse, symptoms become increasingly worse, often progressing until walking becomes difficult or impossible. People with primary-progressive MS rarely see a remission from their symptoms after an attack ends and don't experience any periods of improvement.
Conclusion
Multiple sclerosis (MS) is a long-term disease that affects your brain and spinal cord. It disrupts your communication between these two areas, which can make it hard for you to move, feel or think. MS usually strikes people in their 20s and 30s but it's different for everyone. You may have mild symptoms or have many attacks throughout your life that become worse over time.
The median survival time for people diagnosed with MS is 20 years. However, only about 10% of those who develop MS will die from it. The remaining 90% may die from other diseases that are unrelated to MS. These statistics show how hard it is to predict when a person with MS will pass away. There is no cure for multiple sclerosis yet, but there are treatments available that help people manage their symptoms and live long, healthy lives.
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