Multiple sclerosis (MS) is a chronic disease of the central nervous system (CNS), which includes the brain and the spinal cord. MS can be treated, but there is no cure. Symptoms vary among people with MS, but motor and cognitive problems are among the most common.
MS is an autoimmune disease in which the protective fat (myelin) that covers nerve fibers is eroded away, largely by inflammation. This process is called demyelination. Demyelination interrupts communication within the CNS, leading to the symptoms of MS.
Most people with MS eventually develop some degree of disability. Although symptoms of MS can significantly affect one’s quality of life, the disease is rarely fatal.
An estimated 1 million people in the United States and more than 2.8 million worldwide are living with MS. MS has a strong geographic pattern: The farther a region is from the equator, the more prevalent the condition is in that region.
Females are about three times as likely as men to develop MS: Research from 2017 found that 74 percent of people in the U.S. with the condition are female and 26 percent are male.
According to the National Multiple Sclerosis Society, “Research has demonstrated that MS occurs in most ethnic groups, including African Americans, Asians, and Hispanics/Latinos, but is most common among Caucasians of northern European ancestry.”
MS is most commonly diagnosed between the ages of 20 and 50, but it is sometimes diagnosed in children and older adults.
There are different types of MS, each with its own typical disease course. The most common form of the disease is relapsing-remitting multiple sclerosis (RRMS): About 70 percent to 80 percent of people who are newly diagnosed with MS have this type.
RRMS has a clear pattern of relapses (also called flare-ups or exacerbations) and remissions. During remission, people with RRMS may recover fully or partially and exhibit no symptoms. During relapses, people experience a flare of disease activity and more intense symptoms.
About 10 percent of people with MS have primary progressive MS (PPMS). In PPMS, the disease generally progresses without clear relapses or periods of remission. Instead, symptoms gradually worsen over time.
People initially diagnosed with RRMS may experience a pattern of progressive worsening of neurologic function and increased disability. In these cases, the disease may be reclassified as secondary progressive MS (SPMS). People with SPMS may continue to experience disease flares associated with inflammation as with RRMS, or flares may give way to a more steadily progressive course.
Rare types of MS include pediatric MS, a type of MS diagnosed in people under 18. It accounts for 3 percent to 5 percent of MS diagnoses. Tumefactive MS is another rare form of MS with signs and symptoms similar to those caused by brain tumors. Less than 1 percent of all MS cases are diagnosed as tumefactive MS.
MS causes damage to the CNS, severely affecting neurological function and resulting in a wide array of symptoms. Common symptoms of MS include:
Anyone experiencing debilitating symptoms on a regular basis should communicate with their health care provider to explore a possible diagnosis of MS or other underlying cause.
Following a physical exam and medical history assessment, a doctor will perform several tests to diagnose MS. They will also need to rule out conditions that may cause similar symptoms — including other demyelinating diseases or a brain tumor.
The doctor will perform a neurological exam to examine you for signs of nerve damage. This provides an objective assessment of signs and symptoms that may suggest MS or another condition.
MRI uses a strong magnetic field and radio waves to show the location, extent, and number of lesions on the brain, spinal cord, and optic nerves. MRI can also reveal “silent” damage to the CNS that is not causing symptoms.
An evoked potential test is sometimes conducted as part of the diagnosis process for MS. This test measures electrical activity in the brain in response to specific stimuli. During an evoked potential test, a medical professional will check for areas where electrical conduction is slower due to demyelination. The test can help confirm MS by revealing the extent and location of lesions that are otherwise difficult to detect.
A lumbar puncture — also called a spinal tap — is used to analyze the cerebrospinal fluid, the fluid that protects the CNS. During a lumbar puncture, you will be asked to lie on your side with your knees pulled up to your chest to create space between vertebrae. A medical professional will insert a hollow needle between two vertebrae in the lower back and draw out a small amount of cerebrospinal fluid from the spinal canal. High levels of certain proteins in the fluid can be an indicator of MS.
There are more than a dozen disease-modifying therapies (DMTs) approved by the U.S. Food and Drug Administration (FDA) to treat MS. Other drugs are targeted toward managing MS symptoms.
DMTs help to slow the progression of MS. They work by suppressing elements of the immune system, thereby reducing the autoimmune response. Most people with MS take DMTs on a long-term basis.
There are several classes of DMTs that each work in a different way. They are also administered in different ways and on different schedules. Some are taken orally every day, some are injected under the skin several times a month, and some are infused intravenously at a clinic at longer intervals.
DMTs approved to treat MS include:
Doctors may prescribe additional medications like corticosteroids, to control flare-ups. Corticosteroids, also called steroids, simulate the effects of the hormone cortisol, thereby suppressing immune activity and relieving inflammation. Standard corticosteroid treatment options for relapses include drugs such as methylprednisolone (Solu-Medrol) and the closely related drug Acthar Gel.
Many medications used to help manage disease symptoms are antidepressants, including:
These therapies may be prescribed to alleviate depression, fatigue, or neuropathic pain.
Plasmapheresis, also called therapeutic plasma exchange, is a technique that removes, filters, and replaces the blood plasma of a person undergoing treatment. Plasmapheresis may be used to treat symptoms of MS, especially for people who cannot tolerate high doses of steroids.
Although the average life expectancy for a person with MS is around seven years less than that of the general population, people with the condition generally live a long time. However, disease symptoms can significantly affect a person’s quality of life. MS may cause walking difficulties or vision problems. Some people may also develop cognitive impairment, affecting memory and thinking. Research is ongoing to better understand the causes of MS, possible preventive measures, and how to effectively treat the condition.
Multiple Sclerosis Condition Guide