What is Multiple Sclerosis?
Multiple sclerosis (MS) involves an immune-mediated process in which an abnormal response of the body’s immune system is directed against the central nervous system (CNS), which is made up of the brain, spinal cord and optic nerves. The exact antigen — or target that the immune cells are sensitized to attack — remains unknown, which is why MS is considered by many experts to be “immune-mediated” rather than “autoimmune.”
Within the CNS, the immune system attacks myelin — the fatty substance that surrounds and insulates the nerve fibers — as well as the nerve fibers themselves.
The damaged myelin forms scar tissue (sclerosis), which gives the disease its name.
When any part of the myelin sheath or nerve fiber is damaged or destroyed, nerve impulses traveling to and from the brain and spinal cord are distorted or interrupted, producing a wide variety of symptoms.
The disease is thought to be triggered in a genetically susceptible individual by a combination of one or more environmental factors.
People with MS typically experience one of four disease courses, which can be mild, moderate or severe.
Causes of MS
While the cause (etiology) of MS is still not known, scientists believe that the interaction of several different factors may be involved. To answer this important question, studies are ongoing in the areas of immunology (the science of the body’s immune system), epidemiology (the study of patterns of disease in the population) and genetics. Scientists are also studying infectious agents that may play a role. Understanding what causes MS will speed the process of finding more effective ways to treat it and — ultimately — cure it, or even prevent it from occurring in the first place.
Factors
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Immune-Mediated Response
In MS, an abnormal immune-mediated response attacks the myelin coating around nerve fibers in the central nervous system, as well as the nerve fibers themselves. In recent years, researchers have been able to identify which immune cells are mounting the attack, some of the factors that cause them to attack, and some of the sites (receptors) on the attacking cells that appear to be attracted to the myelin to begin the destructive process. Ongoing efforts to learn more about the immune-mediated process in MS — what sets it in motion, how it works, and how to slow or stop it — are bringing us closer to understanding the cause of MS.
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MS is known to occur more frequently in areas that are farther from the equator. Epidemiologists — scientists who study disease patterns — are looking at variations in geography, demographics (age, gender and ethnic background), genetics, infectious causes and migration patterns in an effort to understand why.
Studies have shown that people born in an area with a high risk of MS who then move — or migrate — to an area with a lower risk before the age of 15 assume the risk of their new area. Such data suggest that exposure to some environmental agent before puberty may predispose a person to develop MS later on.
Growing evidence suggests that vitamin D plays an important role. People who live closer to the equator are exposed to greater amounts of sunlight year-round. As a result, they tend to have higher levels of naturally-produced vitamin D, which is thought to support immune function and may help protect against immune-mediated diseases like MS. The possible relationship between MS and sunlight exposure is currently being looked at in a Society-funded epidemiological study in Australia.
The evidence is also growing that smoking plays an important role in MS. Studies have shown that smoking increases a person’s risk of developing MS and is associated with more severe disease and more rapid disease progression. Fortunately, the evidence also suggests that stopping smoking — whether before or after the onset of MS — is associated with a slower progression of disability.
MS “clusters” — the perception that very high numbers of cases of MS have occurred in a specific time period or location — may provide clues to environmental or genetic risk for the disease. So far, cluster studies in MS have not produced clear evidence for the existence of any causative or triggering factor or factors in MS.
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Since initial exposure to numerous viruses, bacteria and other microbes occurs during childhood, and since viruses are well-recognized as causes of demyelination and inflammation, it is possible that a virus or other infectious agent is the triggering factor in MS. More than a dozen viruses and bacteria — including measles, canine distemper, human herpes virus-6, Epstein-Barr, and Chlamydia pneumonia — have been or are being investigated to determine if they are involved in the development of MS, but none have been definitively proven to trigger MS.
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While MS is not hereditary, having a first-degree relative such as a parent or sibling with MS does significantly increase an individual’s risk of developing the disease. Studies have shown that there is a higher prevalence of certain genes in populations with higher rates of MS. Common genetic factors have also been found in some families where there is more than one person with MS. Some researchers theorize that MS develops because a person is born with a genetic predisposition to react to some environmental agent that, upon exposure, triggers an immune-mediated response. Sophisticated new techniques for identifying genes are helping to answer questions about the role of genes in the development of MS.
(Resource: National Multiple Sclerosis Society)
Who does MS affect?
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2.3 million worldwide
Every week about 200 people are diagnosed with Multiple Sclerosis.
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Ages 20-50 diagnosed
Most people with MS are diagnosed between the ages of 20 and 50.
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67% of women diagnosed
2:3 ratio of women diagnosed to with the disease to men.
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African Americans
26% of African-American families have a history of Multiple Sclerosis.
The Four Types of MS
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CIS is a first episode of neurologic symptoms caused by inflammation and demyelination in the central nervous system. The episode, which by definition must last for at least 24 hours, is characteristic of multiple sclerosis but does not yet meet the criteria for a diagnosis of MS because people who experience a CIS may or may not go on to develop MS.
When CIS is accompanied by lesions on a brain MRI (magnetic resonance imaging) that are similar to those seen in MS, the person has a high likelihood of a second episode of neurologic symptoms and diagnosis of relapsing-remitting MS. When CIS is not accompanied by MS-like lesions on a brain MRI, the person has a much lower likelihood of developing MS.
The 2017 diagnostic criteria for MS make it possible to diagnose MS in a person with CIS who also has specific findings on brain MRI that provide evidence of an earlier episode of damage in a different location and indicate active inflammation in a region other than the one causing the current symptoms. As MRI technology improves, the diagnosis of MS will be made more quickly and easily. In the meantime, individuals with CIS who are considered at high risk for developing MS may now be treated with a disease-modifying therapy that has been approved by the U.S. Food and Drug Administration (FDA) for that purpose. Early treatment of CIS has been shown to delay onset of MS.
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RRMS – the most common disease course – is characterized by clearly defined attacks of new or increasing neurologic symptoms. These attacks – also called relapses or exacerbations – are followed by periods of partial or complete recovery (remissions). During remissions, all symptoms may disappear, or some symptoms may continue and become permanent. However, there is no apparent progression of the disease during the periods of remission. At different points in time, RRMS can be further characterized as either active (with relapses and/or evidence of new MRI activity) or not active, as well as worsening (a confirmed increase in disability over a specified period of time following a relapse) or not worsening.
Approximately 85 percent of people with MS are initially diagnosed with RRMS.
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PPMS is characterized by worsening neurologic function (accumulation of disability) from the onset of symptoms, without early relapses or remissions. PPMS can be further characterized at different points in time as either active (with an occasional relapse and/or evidence of new MRI activity) or not active, as well as with progression (evidence of disease worsening on an objective measure of change over time, with or without relapse or new MRI activity) or without progression.
Approximately 15 percent of people with MS are diagnosed with PPMS.
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SPMS follows an initial relapsing-remitting course. Most people who are diagnosed with RRMS will eventually transition to a secondary progressive course in which there is a progressive worsening of neurologic function (accumulation of disability) over time. SPMS can be further characterized at different points in time as either active (with relapses and/or evidence of new MRI activity) or not active, as well as with progression (evidence of disease worsening on an objective measure of change over time, with or without relapses) or without progression.
The Effects
MS symptoms are variable and unpredictable. No two people have exactly the same symptoms, and each person’s symptoms can change or fluctuate over time. One person might experience only one or two of the possible symptoms while another person experiences many more.
Common symptoms
Fatigue
Walking (Gait) Difficulties
Numbness or Tingling
Spasticity
Weakness
Vision Problems
Dizziness and Vertigo
Bladder Problems
Sexual Problems
Bowel Problems
Pain
Cognitive Changes
Emotional Changes
Depression
African-Americans with MS
Studies show:
A 2012 study of military personnel published in Military Medicine reported 46 percent more cases of MS in blacks than in non-Hispanic whites.
A 2013 study found that blacks had a 47 percent increased risk of MS compared with whites. The study, which was published in Neurology, also found that among blacks, women had triple the risk of MS compared with men. This mirrors the increased risk of MS among women of northern European ancestry.
A follow-up study found that about 26 percent of blacks have a family history of MS, a rate similar to that of whites.
Diagnosing MS
Overview
Several strategies are used to determine if a person meets the long-established criteria for a diagnosis of MS, and to rule out other possible causes of whatever symptoms the person is experiencing. These strategies include a careful medical history, a neurologic exam and various tests.
Criteria for a diagnosis of MS:
Find evidence of damage in at least two separate areas of the central nervous system (CNS), which includes the brain, spinal cord and optic nerves, and
Find evidence that the damage occurred at different points in time, and
Rule out all other possible diagnoses
Tools for making a diagnosis.
The physician performs a variety of tests to evaluate mental, emotional and language functions, movement and coordination, balance, vision, and the other four senses. In many instances, the person’s medical history and neurologic exam provide enough evidence to meet the diagnostic criteria.
While there is no definitive blood test for MS, blood tests can rule out other conditions that cause symptoms similar to those of MS, including Lyme disease, a group of diseases known as collagen-vascular diseases, certain rare hereditary disorders, and AIDS. Other tests (listed below) are used to confirm the MS diagnosis or provide additional evidence if it’s necessary.
Magnetic Resonance Imaging (MRI)
Cerebrospinal Fluid (CSF)
Evoked Potentials (EP)
FAQs
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Multiple sclerosis is a chronic, unpredictable disease of the central nervous system (CNS), which is made up of the brain, spinal cord and optic nerves. It is thought to be an immune-mediated disorder, in which the immune system incorrectly attacks healthy tissue in the CNS.
MS can cause many symptoms, including blurred vision, loss of balance, poor coordination, slurred speech, tremors, numbness, extreme fatigue, problems with memory and concentration, paralysis, and blindness and more. These problems may come and go or persist and worsen over time. Most people are diagnosed between the ages of 20 and 50, although individuals as young as 2 and as old as 75 have developed it.
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Anyone may develop MS but there are some patterns. More than two to three times as many women as men develop MS and this gender difference has been increasing over the past 50 years. Studies suggest that genetic risk factors increase the risk of developing MS, but there is no evidence that MS is directly inherited. Environmental factors, such as low Vitamin D and cigarette smoking have also been shown to increase the risk of MS. MS occurs in most ethnic groups, including African-Americans, Asians and Hispanics/Latinos, but is most common in Caucasians of northern European ancestry.
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Because MS causes damage in the CNS, nearly any function can be adversely affected. However, the most common symptoms are overwhelming fatigue, visual disturbances, altered sensation and difficulties with mobility.
Symptoms of MS are unpredictable, and vary in type and severity from one person to another and in the same person over time. Symptoms may disappear or remit completely or they may persist and may worsen over time.
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MS symptoms occur when the immune-system produces inflammation within the CNS. The inflammatory attack damages myelin, (the protective insulation surrounding nerve fibers), oligodendrocytes (cells that make CNS myelin) and sometimes the underlying nerve fiber. The damage caused by inflammation can produce symptoms that resolve over weeks to months or symptoms that are permanent.
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No. Moreover, the majority of people with MS do not become severely disabled. Two-thirds of people who have MS remain able to walk, though many will need an aid, such as a cane or crutches, and some will use a scooter or wheelchair because of fatigue, weakness, balance problems, or to assist with conserving energy.
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Life expectancy for people with MS has increased over time. We believe this is due to treatment breakthroughs, improved healthcare and life style changes. Recent research however, indicates that people with MS may live an average of about seven years less than the general population because of disease complications or other medical conditions. Many of these complications are preventable or manageable. Attention to overall health and wellness can help reduce the risk of other medical conditions, such as heart disease and stroke, that can contribute to a shortened life expectancy. In some rare instances, there are cases of MS that progress rapidly from disease onset and can be fatal.
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No. MS is not contagious or directly inherited. Studies do indicate that genetic factors and certain environmental factors may make certain individuals more susceptible to the disease.
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Not yet. There are now FDA-approved medications that have been shown to “modify” the course of MS by reducing the number of relapses and delaying progression of disability to some degree. In addition, many therapeutic and technological advances are helping people manage symptoms. Advances in treating and understanding MS are made every year, and progress in research to find a cure is very encouraging.
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The National Multiple Sclerosis Society recommends that a person consider treatment with one of the FDA-approved “disease-modifying” drugs as soon as possible following a definite diagnosis of MS with active or relapsing disease. These medications help to reduce inflammation in the CNS, reduce the frequency and severity of MS attacks and the numbers of lesions in the CNS, and may slow the progression of disability.
In addition to these medications that address the disease process, there are many medications and other strategies to manage MS symptoms such as spasticity, pain, bladder problems, fatigue, sexual dysfunction, weakness, and cognitive problems. People should consult a knowledgeable MS care provider to develop a comprehensive plan to manage their MS.
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Diagnosing MS can be a challenging process. In early MS, symptoms may be non-specific and suggestive of several disorders of the nervous system. Early symptoms that come and go may be ignored. While no single laboratory test is yet available to prove or rule out MS, magnetic resonance imaging (MRI) is a great help in reaching a definitive diagnosis. Diagnostic criteria that incorporate MRI findings have been developed and revised by experts in the field and have helped providers make an accurate and timely diagnosis.