The cause is unknown but may involve an attack by the immune system against the body’s own tissues (autoimmune reaction).
In most people with multiple sclerosis, periods of relatively good health alternate with episodes of worsening symptoms, but over time, multiple sclerosis gradually worsens.
People may have vision problems and abnormal sensations, and movements may be weak and clumsy.
Usually, doctors diagnose multiple sclerosis based on symptoms and results of a physical examination and magnetic resonance imaging.
Treatment includes corticosteroids, medications that help keep the immune system from attacking the myelin sheath, and medications to relieve symptoms.
Life span is unaffected unless the disorder is very severe.
The term “multiple sclerosis” refers to the many areas of scarring (sclerosis) that result from destruction of the tissues that wrap around nerves (myelin sheath) in the brain and spinal cord. This destruction is called demyelination Overview of Demyelinating Disorders Most nerve fibers inside and outside the brain are wrapped with many layers of tissue composed of a fat (lipoprotein) called myelin. These layers form the myelin sheath. Much like the insulation... read more . Sometimes the nerve fibers that send messages (axons) are also damaged. Over time, the brain may shrink in size because axons are destroyed.
World wide, about 2.8 million people have multiple sclerosis, and about 107,000 people are diagnosed with multiple sclerosis each year.
Most commonly, multiple sclerosis begins between the ages of 20 and 40, but it can begin anytime between ages 15 and 60 years. It is somewhat more common among women. Multiple sclerosis is uncommon among children.
Most people with multiple sclerosis have periods of relatively good health (remissions) alternating with periods of worsening symptoms (flare-ups or relapses). Relapses can be mild or debilitating. Recovery during remission is good but often incomplete. Thus, multiple sclerosis worsens slowly over time.
Causes of Multiple Sclerosis
The cause of multiple sclerosis is unknown, but a likely explanation is that people are exposed early in life to a virus (possibly a herpesvirus or retrovirus) or some unknown substance that somehow triggers the immune system to attack the body’s own tissues (autoimmune reaction Autoimmune Disorders An autoimmune disorder is a malfunction of the body's immune system that causes the body to attack its own tissues. What triggers an autoimmune disorder is not known. Symptoms vary depending... read more ). The autoimmune reaction results in inflammation, which damages the myelin sheath and the underlying nerve fiber.
Genes seem to have a role in multiple sclerosis. For example, having a parent or sibling (brother or sister) with multiple sclerosis increases the risk of acquiring the disease several-fold. Also, multiple sclerosis is more likely to develop in people with certain genetic markers on the surface of their cells. Normally, these markers (called human leukocyte antigens Recognition ) help the body to distinguish self from nonself and thus know which substances to attack.
Environment also has a role in multiple sclerosis. Where people spend the first 15 years of life affects their chance of developing multiple sclerosis. It occurs as follows:
In about 1 of about 2,000 people who grow up in a temperate climate
In only 1 of about 10,000 people who grow up in a tropical climate
Much less commonly in people who grow up near the equator
These differences may be related to vitamin D levels. When the skin is exposed to sunlight, the body forms vitamin D. Thus, people who grow up in temperate climates may have a lower vitamin D level. People with a low level of vitamin D are more likely to develop multiple sclerosis. Also, in people who have the disorder and a low vitamin D level, symptoms appear to occur more frequently and are worse. But how vitamin D may protect against the disorder is unknown.
Where people live later in life—regardless of the climate—does not change their chances of developing multiple sclerosis.
Prior infection with Epstein-Barr virus Infectious Mononucleosis Epstein-Barr virus causes a number of diseases, including infectious mononucleosis. The virus is spread through kissing. Symptoms vary, but the most common are extreme fatigue, fever, sore throat... read more 
(which causes mononucleosis) appears to increase the risk of developing multiple sclerosis.
Cigarette smoking also appears to increase the chances of developing multiple sclerosis. The reason is unknown.
Symptoms of Multiple Sclerosis
Symptoms of multiple sclerosis vary greatly, from person to person and from time to time in one person, depending on which nerve fibers are demyelinated:
If nerve fibers that carry sensory information become demyelinated, problems with sensations (sensory symptoms) result.
If nerve fibers that carry signals to muscles become demyelinated, problems with movement (motor symptoms) result.
Patterns of multiple sclerosis
Multiple sclerosis may progress and regress unpredictably. However, there are several typical patterns of symptoms:
Relapsing-remitting pattern: Relapses (when symptoms worsen) alternate with remissions (when symptoms lessen or do not worsen). Remissions may last months or years. Relapses can occur spontaneously or can be triggered by an infection such as influenza.
Primary progressive pattern: The disease progresses gradually with no remissions or obvious relapses, although there may be temporary plateaus during which the disease does not progress.
Secondary progressive pattern: This pattern begins with relapses alternating with remissions (the relapsing-remission pattern), followed by gradual progression of the disease.
Progressive relapsing pattern: The disease progresses gradually, but progression is interrupted by sudden relapses. This pattern is rare.
On average, without treatment, people have about one relapse every 2 years, but frequency varies greatly.
Early symptoms of multiple sclerosis
Vague symptoms of demyelination in the brain sometimes begin long before the disorder is diagnosed. The most common early symptoms are the following:
Tingling, numbness, pain, burning, and itching in the arms, legs, trunk, or face and sometimes a reduced sense of touch
Loss of strength or dexterity in a leg or hand, which may become stiff
Problems with vision
Vision may become dim or blurred. Mainly, people lose the ability to see when looking straight ahead (central vision). Peripheral (side) vision is less affected. People with multiples sclerosis may also have the following vision problems:
Internuclear ophthalmoplegia Internuclear Ophthalmoplegia Internuclear ophthalmoplegia is impairment of horizontal eye movements caused by damage to certain connections between nerve centers in the brain stem (the lower part of the brain). In internuclear... read more : The nerve fibers that coordinate the eyes when they move horizontally (look from side to side) are damaged. One eye cannot turn inward, causing double vision when looking toward the side opposite the affected eye. The unaffected eye may move involuntarily, moving rapidly and repetitively in one direction, then slowly drifting back (a symptom called nystagmus).
Optic neuritis Optic Neuritis Optic neuritis is inflammation of the optic nerve. Multiple sclerosis is the most common cause. Loss of vision may develop, and there may be pain with eye movement. Magnetic resonance imaging... read more (inflammation of the optic nerve): Vision may be partially lost in one eye, and pain occurs when the eye is moved.
Walking and balance may be affected. Dizziness and vertigo Dizziness and Vertigo Dizziness is an inexact term people often use to describe various related sensations, including Faintness (feeling about to pass out) Light-headedness Dysequilibrium (feeling off balance or... read more are common, as is fatigue.
Excess heat—for example, warm weather, a hot bath or shower, or a fever—may temporarily make symptoms worse.
When the back part of the spinal cord in the neck is affected, bending the neck forward may cause an electrical shock or a tingling sensation that shoots down the back, down both legs, down one arm, or down one side of the body (a response called Lhermitte sign). Usually, the sensation lasts only a moment and disappears when the neck is straightened. Often, it is felt as long as the neck remains bent forward.
Later symptoms of multiple sclerosis
As multiple sclerosis progresses, movements may become shaky, irregular, and ineffective. People may become partially or completely paralyzed. Weak muscles may contract involuntarily (called spasticity), sometimes causing painful cramps. Muscle weakness and spasticity may interfere with walking, eventually making it impossible, even with a walker or another assistive device. Some people are confined to a wheelchair. People who cannot walk may develop osteoporosis Osteoporosis (decreased bone density).
Speech may become slow, slurred, and hesitant.
People with multiple sclerosis may become unable to control emotional responses and may laugh or cry inappropriately. Depression is common, and thinking may be mildly impaired.
Multiple sclerosis often affects the nerves that control urination or bowel movements. As a result, most people with multiple sclerosis have problems controlling their bladder Urinary Incontinence in Adults Urinary incontinence is involuntary loss of urine. Incontinence can occur in both men and women at any age, but it is more common among women and older people, affecting about 30% of older women... read more 
, such as the following:
Frequent and strong urges to urinate
Involuntary passage of urine (urinary incontinence)
Difficulty starting to urinate
Retained urine can be a breeding ground for bacteria, making urinary tract infections more likely to develop.
People may also be constipated Constipation in Adults Constipation is difficult or infrequent bowel movements, hard stool, or a feeling that the rectum is not totally empty after a bowel movement (incomplete evacuation). (See also Constipation... read more or, occasionally, pass stool involuntarily (fecal incontinence Fecal Incontinence Fecal incontinence is the loss of control over bowel movements. Fecal incontinence can occur briefly during bouts of diarrhea or when hard stool becomes lodged in the rectum ( fecal impaction)... read more ).
Rarely, late in the disorder, dementia Dementia Dementia is a slow, progressive decline in mental function including memory, thinking, judgment, and the ability to learn. Typically, symptoms include memory loss, problems using language and... read more develops.
If relapses become more frequent, people become increasingly disabled, sometimes permanently.
Diagnosis of Multiple Sclerosis
A doctor's evaluation
Magnetic resonance imaging
Sometimes additional tests
Because symptoms vary widely, doctors may not recognize the disorder in its early stages. Doctors suspect multiple sclerosis in younger people who suddenly develop blurred vision Vision, Blurred Blurred vision is the most common vision symptom. When doctors talk about blurred vision, they typically mean a decrease in sharpness or clarity that has developed gradually. Sudden, complete... read more 
, double vision Vision, Double Double vision is seeing two images of one object. Double vision may occur when only one eye is open (monocular diplopia) or, more commonly, when both eyes are open (binocular diplopia). Binocular... read more , or movement problems Overview of Movement Disorders Every body movement, from raising a hand to smiling, involves a complex interaction between the central nervous system (brain and spinal cord), nerves, and muscles. Damage to or malfunction... read more and abnormal sensations in various unrelated parts of the body. Fluctuating symptoms and a pattern of relapses and remissions support the diagnosis. People should clearly describe all of the symptoms they have had to their doctor, particularly if the symptoms are not present when they visit their doctor.
When doctors suspect multiple sclerosis, they thoroughly evaluate the nervous system (neurologic examination Neurologic Examination When a neurologic disorder is suspected, doctors usually evaluate all of the body systems during the physical examination, but they focus on the nervous system. Examination of the nervous system—the... read more ) during a physical examination. They examine the back of the eye (retina) with an ophthalmoscope What Is an Ophthalmoscope? 
. The optic disk (the spot where the optic nerve joins the retina) may be unusually pale, indicating damage to the optic nerve.
Magnetic resonance imaging Magnetic Resonance Imaging (MRI) In magnetic resonance imaging (MRI), a strong magnetic field and very high frequency radio waves are used to produce highly detailed images. MRI does not use x-rays and is usually very safe... read more 
(MRI) is the best imaging test for detecting multiple sclerosis. It usually detects areas of demyelination in the brain and spinal cord. However, MRI cannot determine whether the demyelination has been there for a long time and is stable or it is very recent and still progressing. Nor can MRI determine whether immediate treatment is required. So doctors may inject gadolinium (a paramagnetic contrast agent) into the bloodstream and do MRI again. Gadolinium helps distinguish areas of recent demyelination from areas of long-standing demyelination. This information helps doctors plan treatment.
Sometimes demyelination is detected when MRI is done for another reason, before multiple sclerosis causes any symptoms.
Additional testing
A diagnosis of multiple sclerosis may be clear based on current symptoms, a history of relapses and remissions, the physical examination, and MRI. If not, other tests are done to obtain additional information:
Spinal tap Spinal Tap Diagnostic procedures may be needed to confirm a diagnosis suggested by the medical history and neurologic examination. Electroencephalography (EEG) is a simple, painless procedure in which... read more
(lumbar puncture): A sample of cerebrospinal fluid is removed and analyzed. The protein content of the fluid may be higher than normal. The concentration of antibodies may be high, and a specific pattern of antibodies (called oligoclonal banding) is detected in most people with multiple sclerosis.Evoked responses Evoked Responses Diagnostic procedures may be needed to confirm a diagnosis suggested by the medical history and neurologic examination. Electroencephalography (EEG) is a simple, painless procedure in which... read more
: For this test, sensory stimuli, such as flashing lights, are used to activate certain areas of the brain, and the brain’s electrical responses are recorded. In people with multiple sclerosis, the brain’s response to stimuli may be slow because the demyelinated nerve fibers cannot conduct nerve signals normally. This test can also detect slight damage to the optic nerve that is not causing symptoms.
Other tests can help doctors distinguish multiple sclerosis from disorders that cause similar symptoms, such as AIDS Acquired immunodeficiency syndrome (AIDS) Human immunodeficiency virus (HIV) infection is a viral infection that progressively destroys certain white blood cells and is treated with antiretroviral medications. If untreated, it can cause... read more 
, tropical spastic paraparesis HTLV-1–Associated Myelopathy/Tropical Spastic Paraparesis (HAM/TSP) HTLV-1–associated myelopathy/tropical spastic paraparesis is a slowly progressive disorder of the spinal cord caused by the human T-lymphotropic virus 1 (HTLV-1). The virus is spread through... read more , vasculitis Overview of Vasculitis Vasculitic disorders are caused by inflammation of the blood vessels (vasculitis). Vasculitis can be triggered by certain infections or drugs or can occur for unknown reasons. People may have... read more 
, arthritis of the neck, Guillain-Barré syndrome Guillain-Barré Syndrome (GBS) Guillain-Barré syndrome is a form of polyneuropathy causing muscle weakness, which usually worsens over a few days to weeks, then slowly improves or returns to normal on its own. With treatment... read more , hereditary ataxias Friedreich ataxia Coordination disorders often result from malfunction of the cerebellum, the part of the brain that coordinates voluntary movements and controls balance. The cerebellum malfunctions, causing... read more , lupus Systemic Lupus Erythematosus (SLE) Systemic lupus erythematosus is a chronic autoimmune inflammatory connective tissue disorder that can involve joints, kidneys, skin, mucous membranes, and blood vessel walls. Problems in the... read more 
, Lyme disease Lyme Disease Lyme disease is a tick-transmitted infection caused by Borrelia species, primarily by Borrelia burgdorferi and sometimes by Borrelia mayonii in the United States. These... read more 
, rupture of a spinal disk Herniated Disk A herniated disk occurs when the tough covering of a disk in the spine tears or ruptures. The soft, jelly-like interior of the disk may then bulge out (herniate) through the covering. Aging... read more 
, syphilis Syphilis Syphilis is a sexually transmitted infection caused by the bacteria Treponema pallidum. It can occur in three stages of symptoms, separated by periods of apparent good health. Syphilis... read more 
, and a cyst in the spinal cord (syringomyelia Syrinx of the Spinal Cord or Brain Stem A syrinx is a fluid-filled cavity that develops in the spinal cord (called syringomyelia), in the brain stem (called syringobulbia), or in both. Syrinxes may be present at birth or develop later... read more ). For example, blood tests may be done to rule out Lyme disease, syphilis, AIDS, tropical spastic paraparesis, and lupus, and imaging tests can help rule out arthritis of the neck, rupture of a spinal disk, and syringomyelia.
Blood tests to measure an antibody specific for neuromyelitis optica Neuromyelitis Optica Spectrum Disorder (NMOSD) Neuromyelitis optica spectrum disorder affects mainly the nerves in the eyes and spinal cord, causing patches of myelin (the substance that covers most nerve fibers) and the nerve fibers under... read more spectrum disorder may be done to differentiate that disorder from multiple sclerosis.
Treatment of Multiple Sclerosis
Corticosteroids
Medications that help keep the immune system from attacking myelin sheaths
Measures to control symptoms
No treatment for multiple sclerosis is uniformly effective.
Corticosteroids
For an acute attack, corticosteroids are most commonly used. They probably work by suppressing the immune system. They are given for short periods to relieve immediate symptoms (such as loss of vision, strength, or coordination) if the symptoms interfere with functioning. For example, prednisone may be taken by mouth, or methylprednisolone may be given intravenously. Although corticosteroids may shorten relapses and slow the progression of multiple sclerosis, they do not stop its progression.
Corticosteroids are rarely used for a long time because they can have many side effects, such as increased susceptibility to infection, diabetes, weight gain, fatigue, osteoporosis, and ulcers. Corticosteroids are started and stopped as needed.
Medications to help control the immune system
Medications that help keep the immune system from attacking myelin sheaths are usually also used. These medications help reduce the number of future relapses. They include the following:
Interferon-beta injections reduce the frequency of relapses and may help delay disability.
Glatiramer acetate injections may have similar benefits for people with early mild multiple sclerosis.
Natalizumab is a monoclonal antibody Monoclonal Antibodies Immunotherapy is the use of drugs that mimic or modify components of the immune system (such as tumor antigens and immune checkpoints—see also Overview of the Immune System) to fight disease... read more given intravenously as an infusion once a month. It is more effective than other medications in reducing the number of relapses and preventing further damage in the brain. However, natalizumab may increase the risk of a rare, fatal infection of the brain and spinal cord (progressive multifocal leukoencephalopathy Progressive Multifocal Leukoencephalopathy (PML) Progressive multifocal leukoencephalopathy is a rare infection of the brain that is caused by the JC (John Cunningham) virus. People with a weakened immune system are most likely to get the... read more ).
Fingolimod, ozanimod, ponesimod, siponimod, teriflunomide, cladribine, dimethyl fumarate, monomethyl fumarate, and diroximel fumarate may be used to treat multiple sclerosis that occurs in relapsing patterns. These medications can be taken by mouth. Fingolimod, dimethyl fumarate, monomethyl fumarate, and diroximel fumarate also increase the risk of progressive multifocal leukoencephalopathy, although the risk is much less than with natalizumab.
Ocrelizumab is a monoclonal antibody used to treat multiple sclerosis that occurs in relapsing or primary progressive patterns. It is given as an infusion into a vein every 6 months. It can cause infusion reactions, which may include a rash, itching, difficulty breathing, swelling of the throat, dizziness, low blood pressure, and a fast heart rate.
Alemtuzumab (used to treat leukemia), also a monoclonal antibody, is effective in treating multiple sclerosis that occurs in relapsing patterns (relapsing-remitting pattern and progressive relapsing pattern). It is given intravenously. However, it increases the risk of serious autoimmune disorders and certain cancers. Consequently, alemtuzumab is usually used only when treatment with two or more other medications has been ineffective.
Ofatumumab is used to treat relapsing forms of multiple sclerosis and multiple sclerosis that is actively progressing. It is injected under the skin (subcutaneously). People with multiple sclerosis can be taught to administer it themselves.
Ublituximab is also used to treat relapsing forms of multiple sclerosis and multiple sclerosis that is actively progressing. It is given intravenously. Ublituximab increases a person's susceptibility to infections (such as urinary tract infections, upper respiratory infections, and herpesvirus infections) Herpesvirus Infections because it suppresses the immune system.
Mitoxantrone, a chemotherapy medication, can reduce the frequency of relapses and slow the progression of the disorder. It is used only when other medications do not work and is typically given for only up to 2 years because it can eventually lead to heart damage.
Immune globulin, given intravenously once a month, occasionally helps when other medications have been ineffective. Immune globulin consists of antibodies obtained from the blood of people with a normal immune system.
Medications that increase the risk of progressive multifocal leukoencephalopathy (natalizumab, fingolimod, and dimethyl fumarate) are used only by specially trained doctors. Also, people who take them must be checked periodically for signs of progressive multifocal leukoencephalopathy. Blood tests for the JC virus, which causes progressive multifocal leukoencephalopathy, are done periodically. If a person taking natalizumab develops progressive multifocal leukoencephalopathy, plasma exchange can be done to remove the medication quickly.
Other treatments
Plasma exchange Plateletpheresis (platelet donation) In addition to normal blood donation and transfusion, special procedures are sometimes used. In plateletpheresis, a donor gives only platelets rather than whole blood. Whole blood is drawn from... read more is recommended by some experts for severe relapses not controlled by corticosteroids. However, the benefits of plasma exchange have not been established. For this treatment, blood is withdrawn, abnormal antibodies are removed from it, and the blood is returned to the person.
Stem cell transplantation Stem Cell Transplantation Stem cell transplantation is the removal of stem cells (undifferentiated cells) from a healthy person and their injection into someone who has a serious blood disorder. (See also Overview of... read more , done at centers that specialize in stem cell transplantation, may be somewhat useful for severe, difficult-to-treat disease.
Symptom control
Other medications can be used to relieve or control specific symptoms of multiple sclerosis:
Muscle spasms: The muscle relaxants baclofen or tizanidine
Problems with walking: Dalfampridine, taken by mouth, to improve walking
Pain due to abnormalities in nerves: Antiseizure medications (such as gabapentin, pregabalin, or carbamazepine) or sometimes tricyclic antidepressants (such as amitriptyline)
Tremors: Clonazepam or gabapentin or in severe cases, referral to a specialist who is experienced in injecting botulinum toxin (a bacterial toxin used to paralyze muscles or to treat wrinkles)
Fatigue: Amantadine (used to treat Parkinson disease) or, less often, medications used to treat excessive sleepiness (such as modafinil, armodafinil, or amphetamine)
Depression: Antidepressants such as sertraline or amitriptyline, counseling, or both
Urinary incontinence: Oxybutynin, tamsulosin, or another incontinence medication Treatment Urinary incontinence is involuntary loss of urine. Incontinence can occur in both men and women at any age, but it is more common among women and older people, affecting about 30% of older women... read more
, depending on the type of incontinenceConstipation: Stool softeners or laxatives taken regularly
People with urine retention can learn to catheterize themselves and thus empty their bladder.
General measures
People with multiple sclerosis can often maintain an active lifestyle, although they may tire easily and may not be able to keep up with a demanding schedule. Encouragement and reassurance help.
Regular exercise such as riding a stationary bicycle, walking, swimming, or stretching reduces spasticity and helps maintain cardiovascular, muscular, and psychologic health.
Physical therapy can help with maintaining balance, the ability to walk, and range of motion and can help reduce spasticity and weakness. People should walk on their own for as long as possible. Doing so improves their quality of life and helps prevent depression.
Avoiding high temperatures—for example, by not taking hot baths or showers—can help because heat can worsen symptoms. People who smoke should stop.
Because people who have low levels of vitamin D tend to have more severe multiple sclerosis and because taking vitamin D may reduce the risk of developing osteoporosis Osteoporosis Osteoporosis is a condition in which a decrease in the density of bones weakens the bones, making breaks (fractures) likely. Aging, estrogen deficiency, low vitamin D or calcium intake, and... read more 
, doctors usually recommend that people take vitamin D supplements. Whether vitamin D supplements can help slow the progression of multiple sclerosis is being studied.
People who become weak and unable to move easily may develop pressure sores Prevention Pressure sores are areas of skin damage resulting from a lack of blood flow due to prolonged pressure. Pressure sores often result from pressure combined with pulling on the skin, friction,... read more 
, so they and their caregivers must take extra care to prevent the sores.
If people are disabled, occupational, physical, and speech therapists can help with rehabilitation. They can help people learn to function despite disabilities caused by multiple sclerosis. Social workers can recommend and help arrange for needed services and equipment.
Prognosis for Multiple Sclerosis
What effects multiple sclerosis has and how quickly it progresses vary greatly and unpredictably. Remissions can last months up to 10 years or more. However, some people, such as men who develop the disorder during middle age and who have frequent attacks, may become rapidly incapacitated. Nonetheless, about 75% of people who have multiple sclerosis never need a wheelchair, and for about 40%, normal activities are not disrupted.
Smoking cigarettes may make the disease progress faster.
Unless multiple sclerosis is very severe, life span is usually unaffected.
More Information
The following English-language resources may be useful. Please note that THE MANUAL is not responsible for the content of these resources.
Multiple Sclerosis Association of America (MSAA): This web site provides general information about multiple sclerosis (including symptoms, diagnosis, and treatment), about prescription management, and about living with the disorder (including links to other people who have it, blogs, and an app that helps with managing multiple sclerosis).
National Multiple Sclerosis Society: This web site provides general information about multiple sclerosis (including symptoms, diagnosis, and treatment), tips (for diet, exercise, and mental health), and resources and support links.
