What is Multiple Sclerosis?
Multiple sclerosis is a disease that causes an immune-mediated process that leads to an abnormal response by the body’s immune system that eventually damages the CNS – or central nervous system. This damages central nervous system (CNS) tissues in which the immune system attacks the myelin, the substance that surrounds and insulates nerves fibers causing slow loss of mylein that leads to nerve damage. As the exact antigen or target of the immune-mediated attack is not known, many experts prefer to label multiple sclerosis as “immune-mediated instead of an “autoimmune disease.”
In order to properly understand what actually happens to someone with MS, we must first discuss the ways in which these body parts work in a person living without MS. The neurons are structures composed of a cell body as well as an axon – the part of the cell body that carries messages from place to place. These neurons are incredibly important to our body – they allow us to see, think, hear, feel, speak, eliminate and move. The axons, the part of the nervous system that carries messages around the body is coated with myelin, sort of like a barrier around an electrical wire, are comprised of proteins and a lipid rich substance. This myelin sheath insulates and protects the axon to help increase the speed of nerve transmissions.
While myelin is present in the both the central nervous system (CNS) and peripheral nervous system (PNS), only the central nervous system is affected by MS. CNS myelin is created by cells called oligodendrocytes. while the PNS myelin is produced by Schwann cells. The two types of myelin are chemically different, but both do the same function – to increase efficient transmission of a nerve impulse along the axo.pids (fatty substances) and proteins. Like the coating around an electrical wire, myelin insulates and protects the axon, while increasing the speed of nerve transmission
Myelin is present in the central nervous system (CNS) and peripheral nervous system (PNS); however only the central nervous system is affected by MS. CNS myelin is produced by special cells called oligodendrocytes. PNS myelin is produced by Schwann cells. The two types of myelin are chemically different, but they both perform the same function — to promote efficient transmission of a nerve impulse along the axon. Damage to the myelin sheath is caused by inflammation and can occur anywhere in the central nervous system, including the brain and spinal cord. The optic nerves are also frequently affected.Multiple sclerosis is a chronic disease that affects the nervous system. It is often difficult to diagnose because symptoms frequently come and go, and can also mimic other diseases.
MS affects more women than men, and patients are usually diagnosed between the ages of 20 and 50, although MS can occur in young children, teenagers, and older adults.
What Is Abnormal Immune System Response in MS?
- Damages/destroys myelin and oligodendrocytes
- Causes damage to the underlying nerve fiber
- Produces damaged areas (lesions or scars) along the nerve, which can be detected on magnetic resonance imaging (MRI)
- Slows or halts nerve conduction – producing the neurologic signs and symptoms of MS
What is known is that when the myelin sheath surrounding a nerve cell is damaged by inflammation, scar tissue forms (a process called sclerosis), resulting in the slowing down or stopping of the impulses that travel along the nerve cell. This means that the impulses cannot travel effectively across the nerve cells, the affected area cannot function correctly, and the symptoms of MS appear.
What Are The Types of Multiple Sclerosis?
Just like any other disease, multiple sclerosis affects each person differently. The following are the most common types of MS:
CIS is the first episode of neurologic symptoms caused by inflammation and demyelination in the central nervous system. By definition, this episode must last for at least 24 hours and is very characteristic of multiple sclerosis, however it doesn’t yet meet the criteria for a proper diagnosis of MS. People who experience a CIS may or may not develop MS.
The episode usually has no associated fever or infection and is followed by a complete or partial recovery. CIS can be either monofocal or multifocal:
- Monofocal episode: A person experiences a single neurologic sign or symptom – such as an attack of optic neuritis – caused by a single lesion.
- Multifocal episode: The person experiences more than one sign or symptom – such an attack of optic neuritis accompanied by numbness or tingling in the legs – caused by lesions in more than one place.
People who experience Clinically-Isolated Syndrome may or may not go on to develop MS. While diagnosing the healthcare provider faces two challenges: first, determining whether the person is experiencing damage in the CNS; and second, to determine the chance that a person experiencing this type event will go onto develop MS.
- Higher risk for developing MS: When CIS is accompanied by magnetic resonance imaging (MRI)-detected brain lesions similar to those seen in MS, the person has a 60 to 80 percent chance of a second neurologic event and diagnosis of MS within several years.
- Lower risk for developing MS: When CIS is not accompanied by MRI-detected brain lesions, the person has about a 20 percent chance of developing MS over the same period of time.
People with CIS who are at high risk for developing MS may now be treated with a disease-modifying therapy 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.
Relapsing-Remitting MS (RRMS)
RRMS is the most common disease course of MS (Approximately 85 percent of people with MS are initially diagnosed with RRMS) that is characterized by clearly-defined attacks of new or increasing neurologic symptoms (attacks can take the form of worsening of old symptoms or appearance of new symptoms depending upon which areas of the nervous system are affected). These attacks (also known as relapses and exacerbations) are generally followed by partial or complete recovery (called “remissions”).
Following a relapse, the new symptoms may disappear without causing any increase in level of disability, or the new symptoms may partially disappear, resulting in an increase in disability. New lesions on MRI often occur as part of a relapse. However, new MRI lesions indicating MS activity may also occur without symptoms of which the person is aware.
During remissions, all or some symptoms may disappear while others become permanent. There are no obvious progressions of MS during periods of remissions.
At other times, RRMS is classified as:
- Active – relapses and evidence of new MRI activity
- Not active
- Worsening – diagnosed increase in disability over a period of time following a relapse.
- Not Worsening.
Symptoms of RRMS: People with progressive forms of MS are more likely to experience gradually worsening problems with walking and mobility, in addition to other symptoms they may have.
- Episodic bouts of fatigue
- Vision problems
- Spasticity or stiffness
- Bowel and bladder problems
- Problems with cognition (including learning, memory, and information, or information processing).
- Active (with relapses and/or evidence of new MRI activity) or not active
- With progression (evidence of disease worsening on an objective measure of change over time, with or without relapses) or without progression
In SPMS, people may or may not continue to experience relapses; the disease gradually changes from the inflammatory process seen in RRMS to a more steadily progressive phase characterized by nerve damage or loss.
Diagnosis of Secondary-Progressive MS:
A variety of strategies, including a careful history of the changes in a person’s symptoms, the neurologic examination, and repeat magnetic resonance imaging (MRI) scans, help determine whether the transition to SPMS has occurred.
PPMS is characterized by worsening neurologic function (accumulation of disability) from the onset of symptoms, without early relapses or remissions. Approximately 15 percent of people with MS are diagnosed with PPMS.
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.
What Cause Multiple Sclerosis?
As of today, the cause of MS is not known. Scientists believe MS is triggered by a combination of factors. To identify the cause, research is ongoing in areas of immunology (the study of the body’s immune system), epidemiology (the study of disease patterns in large groups of people) and genetics (understanding the genes that may not be functioning correctly in people who develop MS). 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.
Potential Immunologic Factors of MS:
In recent years, researchers have identified immune cells that target the CNS in people with MS, some of the factors that cause them to respond abnormally, and the process of the immune system response. Ongoing efforts to learn more about the immune-mediated process in MS — what sets it in motion, and how to slow or stop it — will bring us closer to understanding the cause of MS.Although the cause of MS is not known, more is being learned about environmental factors that contribute to the risk of developing MS. There is no single risk factor that provokes MS, but several factors are believed to contribute to the overall risk.
Geographic Factors of MS:
Multiple sclerosis occurs more often in areas farther from the equator. Scientists who study disease patterns in large groups of people trying to understand why and are looking at changes in geography, demographics (age, gender, and ethnic background), genetics, infectious causes, and migration patterns. Some 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 may an important role in MS. Low vitamin D levels in the blood have been identified as a risk factor in the development of MS. Some researchers believe that increased exposure to the sun (a natural form of Vitamin D) – such as experienced by people in areas closer to the equator, may support immune function and help protect us from MS and other diseases similar to MS.
Researchers have begun to suspect that smoking plays an important role in the development of multiple sclerosis. Studies show that smoking increases a person’s risk of developing MS and is associated with more severe disease and more rapid disease progression. This evidence also suggests that stopping smoking — before or after the onset of MS — is associated with a slower progression of MS disability.
Childhood obesity, notably in girls, puts children at an increased the risk for developing MS. Other studies show that obesity in early adulthood may also contribute to an increased of developing MS. Also, obesity may contribute to inflammation and more MS activity in those already diagnosed with MS.
Symptoms of Multiple Sclerosis:
Patients with MS experience a variety of symptoms with a wide range of severity, depending upon which area of the central nervous system is affected and the course of their particular disease. More than one area can be affected at a time. No two patients’ symptoms are exactly alike.
The most common symptoms of MS include:
Bladder Problems: Bladder dysfunction, occurring in at least 80% of people with MS, can often be managed quite successfully with medications, fluid management, and intermittent self-catheterization.
Bowel Problems: Constipation is a particular concern among people with MS, as is loss of control of the bowels. Bowel issues can typically be managed through diet, adequate fluid intake, physical activity, and medication.
Cognitive Changes: a range of high-level brain functions are affected in more than 50% of people with MS, including the ability to process incoming information, learn, remember new information, organize, problem-solve, focus attention, and accurately perceive the environment.
Depression: Studies have suggested that major depressive disorder – the most severe type of depression – is one of the most common symptoms of MS. It is more common among people with MS than it is in the general population or in people who have many other chronic, disabling conditions.
Dizziness and Vertigo: People with MS may feel off balance or lightheaded, or -less often – have the sensation that they or their surroundings are spinning (vertigo).
Emotional Changes: Can be a reaction to the stresses of living with MS as well as the result of neurologic and immune changes. Significant depression, mood swings, irritability, and episodes of uncontrollable laughing and crying pose significant challenges for people with MS and their families
Fatigue: occurs in about 80% of people with MS and can significantly interfere with the ability to function at home and work. In fact, fatigue may be the most prominent symptom in a person who otherwise has minimal activity limitations.
Numbness or Tingling: Numbness of the face, body, or extremities (arms and legs) is often the first symptom experienced by those eventually diagnosed as having MS.
Pain: Pain syndromes are common in MS. In one study, 55% of people with MS had “clinically significant pain” at some time, and almost half had chronic pain.
Sexual Problems: are very common in the general population including people with MS. Sexual responses can be affected by damage in the central nervous system, as well by symptoms such as fatigue and spasticity, and by psychological factors.
Spasticity: Refers to feelings of stiffness and a wide range of involuntary muscle spasms. These spasms can occur in any limb, but it is much more common in the legs.
Walking (Gait) Difficulties: Related to several factors including weakness, spasticity, loss of balance, sensory deficit and fatigue, walking and gait challenges can sometimes be helped by physical therapy, assistive therapy, and medications.
Weakness; Weakness in MS, which results from de-conditioning of unused muscles or damage to nerves that stimulate muscles. Weakness may be managed with rehabilitation strategies and the use of mobility aids and other assistive devices.
Vision Problems: The first symptom of MS for many people. Onset of blurred vision, poor contrast or color vision, and pain on eye movement can be frightening and should be evaluated promptly.
Breathing Problems: Respiration problems occur in people whose chest muscles have been severely weakened by damage to the nerves that control those muscles.
Headache Although headache is not a common symptom of MS, some reports suggest that people with MS have an increased incidence of certain types of headache.
Hearing Loss About 6% of people who have MS complain of impaired hearing. In very rare cases, hearing loss has been reported as the first symptom of the disease.and swallowing
Itching: is one of the family of abnormal sensations — such as “pins and needles” and burning, stabbing or tearing pains — which may be experienced by people with MS.
Speech Problems: Speech problems, including slurring and loss of volume occur in approximately 25-40% of people with MS, particularly later in the disease course and during periods of extreme fatigue. Stuttering is occasionally reported as well.
Swallowing Problems Swallowing problems result from damage to the nerves controlling the many small muscles in the mouth and throat.
Tremor: Tremor, or uncontrollable shaking, can occur in various parts of the body because of damaged areas along the complex nerve pathways that are responsible for coordination of movements.
Seizures: Seizures, the result of abnormal electrical discharges in an injured or scarred area of the brain, have been estimated to occur in 2-5% people with MS, compared to the estimated 3% of the general population.
The primary symptoms described on this page are the direct result of damage to the myelin and nerve fibers in the central nervous system (CNS), the secondary symptoms are complications that can arise as a result of these primary symptoms. For example:
- Bladder dysfunction can cause repeated urinary tract infections.
- Inactivity can result in loss of muscle tone and disuse weakness (not related to demyelination), poor postural alignment and trunk control, decreased bone density (and resulting increased risk of fracture), and shallow, inefficient breathing
- Immobility can lead to pressure sores.
While secondary symptoms can be treated, the optimal goal is to avoid them by treating the primary symptoms.
Tertiary symptoms are the “trickle down” effects of the disease on your life. These symptoms include social, vocational, and psychological complications. For example, if you are no longer able to drive or walk, you may not be able to hold down your usual job. The stress and strain of dealing with MS often alters social networks and sometimes fractures relationships. Problems with bladder control, tremor or swallowing may cause people to withdraw from social interactions and become isolated.
Diagnosis of Multiple Sclerosis:
Diagnosing MS is often difficult because symptoms can mimic other diseases. In addition, there are no tests specifically designed to detect MS. Healthcare professionals typically rule out other diseases first and then use a combination of medical history, neurological exams, blood tests, MRIs, visual evoked potential tests, and cerebrospinal fluid analysis to determine if a patient has MS
A patient is considered to have MS if all of the following criteria are met:
- The patient has damage in at least two separate areas of the central nervous system (brain, spinal cord and optic nerves) AND
- The damage has occurred at least one month apart AND
- All other possible diagnoses have been ruled out.
Treatment for Multiple Sclerosis:
Multiple Sclerosis International Foundation (MSIF) is a worldwide foundation that connects patients and professionals.
The MS International Federation is a unique global network of MS organizations, people affected by MS, volunteers and staff from around the world. Our movement is made up of 48 MS organisations with links to many others.
Educational Resources and Fact Sheets:
National Institute of Neurological Disorders and Stroke – Multiple Sclerosis provides information and educational information about multiple sclerosis.