Overview

What is multiple sclerosis? An expert explains

Learn more from neurologist Oliver Tobin, M.B., B.Ch., B.A.O., Ph.D.

I'm Dr. Oliver Tobin, a neurologist specializing in multiple sclerosis at Mayo Clinic. In this video, we'll be covering the basics of multiple sclerosis. What is it? Who gets it? The symptoms, diagnosis, and treatment. Whether you're looking for answers about your own health or that of someone you love, we're here to provide you with the best information available. Multiple sclerosis is a disorder in which the body's immune system attacks the protective covering of the nerve cells in the brain, optic nerve and spinal cord, called the myelin sheath. And this sheath is often compared to the insulation on an electrical wire. When that covering is damaged, it exposes the actual nerve fiber, which can slow or block the signals being transmitted within it. The nerve fibers themselves might also be damaged. The body can repair damage to the myelin sheath, but it's not perfect. The resulting damage leaves lesions or scars, and this is where the name comes from: multiple sclerosis, multiple scars. Now everyone loses brain cells and spinal cord cells as they get older. But if part of the brain or spinal cord has been damaged by MS, the nerve cells in that area will die off faster than the areas around it that are normal. This happens very slowly, usually over decades and typically shows up as gradual walking difficulty happening over several years. When you read about multiple sclerosis, you may hear about different types -- the most frequent being relapsing-remitting multiple sclerosis. And this is characterized by attacks, or relapses.

We don't know what causes MS, but there are certain factors that may increase the risk or trigger its onset. So while MS can occur at any age, it mostly makes its first appearance in people between the ages of 20 and 40. Low levels of vitamin D and low exposure to sunlight, which enables our body to make vitamin D, are associated with an increased risk of developing MS. As people who have MS who have low vitamin D tend to have more severe disease. So people who are overweight are more likely to develop MS and people who have MS and are overweight tend to have more severe disease and a faster onset of progression. People who have MS and who smoke tend to have more relapses, worse progressive disease, and worse cognitive symptoms. Women are up to three times as likely as men to have relapsing-remitting MS. The risk for MS in the general population is about 0.5%. If a parent or sibling has MS, your risk is about twice that or about 1%. Certain infections are also important. A variety of viruses have been linked to MS, including Epstein-Barr virus, which causes mono. Northern and southern latitudes have a higher prevalence, including Canada, the northern US, New Zealand, southeastern Australia, and Europe. White people, especially of northern European descent, are at the highest risk. People of Asian, African, and Native American ancestry have the lowest risk. A slightly increased risk is seen if a patient already has autoimmune thyroid disease, pernicious anemia, psoriasis, type 1 diabetes, or inflammatory bowel disease.

Symptoms of a relapse usually come on over 24 to 48 hours, last for a few days to a few weeks and then improve in the region of 80 to a 100 percent. Those symptoms include loss of vision in an eye, loss of power in an arm or leg or a rising sense of numbness in the legs. Other common symptoms associated with MS include spasms, fatigue, depression, incontinence issues, sexual dysfunction, and walking difficulties.

There's currently no single test to make a diagnosis of MS. However, there are four key features which help to secure the diagnosis. Firstly, are there typical symptoms of multiple sclerosis? Again, those are loss of vision in an eye, loss of power in an arm or leg, or sensory disturbance in an arm or leg lasting for more than 24 hours. Secondly, do you have any physical examination findings consistent with MS? Next, is the MRI of your brain or spine consistent with MS? Now here it's important to note that 95 percent of people over the age of 40 have an abnormal brain MRI, just the same as many of us have wrinkles on our skin. Lastly, are the results of the spinal fluid analysis consistent with MS? Your doctor may recommend blood tests to check for other diseases that share the same symptoms. They may also recommend an OCT test or optical coherence tomography. This is a short scan of the thickness of the layers at the back of your eye.

So the best thing to do when living with MS is to find a trusted interdisciplinary medical team that can help you monitor and manage your health. Having a multidisciplinary team is essential for addressing the individual symptoms that you're experiencing. If you have an MS attack or relapse, your doctor may prescribe you corticosteroids to reduce or improve your symptoms. And if your attack symptoms do not respond to steroids, another option is plasmapheresis or plasma exchange, which is a treatment similar to dialysis. About 50 percent of people who do not respond to steroids have a significant improvement with a short course of plasma exchange. There are over 20 medications currently approved for prevention of MS attacks and prevention of new MRI lesions.

As learning to function with MS can be challenging, there are medical experts ready to work with you to help you manage it, so you can still live a full life. Consulting with a physiatrist, physical or occupational therapist can help you deal with physical difficulties. Physical activity is strongly recommended for all people with MS. Mental health is also an important consideration. So keeping up personal connections with friends and family and trying to stay involved with your hobbies is important. But also be kind to yourself and realistic about what you're up for. This can change from day to day, so it's okay to give yourself permission if something seems like too much or if you need to cancel plans. You may also find support groups helpful to connect with people who understand what you are going through and discuss your feelings and concerns with a doctor or a counselor. Meanwhile, scientists are hard at work, expanding our understanding of this disease and developing new treatments and medications which are ever more effective. If you want to learn more, watch more of our videos or visit mayoclinic.org. We wish you well.

Multiple sclerosis is a disease that causes breakdown of the protective covering of nerves. Multiple sclerosis can cause numbness, weakness, trouble walking, vision changes and other symptoms. It's also known as MS.

In MS, the immune system attacks the protective sheath that covers nerve fibers, known as myelin. This interrupts communication between the brain and the rest of the body. Eventually, the disease can cause permanent damage of the nerve fibers.

Symptoms of MS depend on the person, the location of damage in the nervous system and how bad the damage is to the nerve fibers. Some people lose the ability to walk on their own or move at all. Others may have long periods between attacks without any new symptoms, called remission. The course of the disease varies depending on the type of MS.

There's no cure for multiple sclerosis. However, there are treatments to help speed the recovery from attacks, modify the course of the disease and manage symptoms.

Types

Some conditions are classified as stages, but multiple sclerosis is classified as types. MS types depend on the progression of symptoms and frequency of relapses. Types of MS include:

Relapsing-remitting MS

Most people with multiple sclerosis have the relapsing-remitting type. They experience periods of new symptoms or relapses that develop over days or weeks and usually improve partially or completely. These relapses are followed by quiet periods of disease remission that can last months or even years.

Secondary-progressive MS

At least 20% to 40% of people with relapsing-remitting multiple sclerosis can eventually develop a steady progression of symptoms. This progression may come with or without periods of remission and happens within 10 to 40 years of disease onset. This is known as secondary-progressive MS.

The worsening of symptoms usually includes trouble with mobility and walking. The rate of disease progression varies greatly among people with secondary-progressive MS.

Primary-progressive MS

Some people with multiple sclerosis experience a gradual onset and steady progression of signs and symptoms without any relapses. This type of MS is known as primary-progressive MS.

Clinically isolated syndrome

Clinically isolated syndrome refers to the first episode of a condition that affects the myelin. After further testing, clinically isolated syndrome may be diagnosed as MS or a different condition.

Radiologically isolated syndrome

Radiologically isolated syndrome refers to findings on MRIs of the brain and spinal cord that look like MS in someone without classic symptoms of MS.

Symptoms

Multiple sclerosis symptoms vary depending on the person. Symptoms may change over the course of the disease depending on which nerve fibers are affected.

Common symptoms include:

  • Numbness or tingling.
  • Electric-shock sensations that happen with certain neck movements, especially bending the neck forward. This sensation is called Lhermitte sign.
  • Lack of coordination.
  • Trouble with walking or not being able to walk at all.
  • Weakness.
  • Partial or complete loss of vision, usually in one eye at a time. Vision loss often happens with pain during eye movement.
  • Double vision.
  • Blurry vision.
  • Dizziness and a false sense that you or your surroundings are moving, known as vertigo.
  • Trouble with sexual, bowel and bladder function.
  • Fatigue.
  • Slurred speech.
  • Troubles with memory, thinking and understanding information.
  • Mood changes.

Small increases in body temperature can temporarily worsen symptoms of MS. These aren't considered true disease relapses but pseudorelapses.

When to see a doctor

Make an appointment with your doctor or other healthcare professional if you have any symptoms that worry you.

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Causes

The cause of multiple sclerosis is not known. It's considered an immune-mediated disease in which the body's immune system attacks its own tissues. In MS, the immune system attacks and destroys the fatty substance that coats and protects nerve fibers in the brain and spinal cord. This fatty substance is called myelin.

Myelin can be compared to the insulation coating on electrical wires. When the protective myelin is damaged and the nerve fiber is exposed, the messages traveling along that nerve fiber may be slowed or blocked.

It isn't clear why MS develops in some people and not others. A combination of genetics and environmental factors may increase the risk of MS.

Risk factors

Factors that increase the risk of multiple sclerosis include:

  • Age. MS can happen at any age. However, onset most commonly happens between 20 and 40 years of age.
  • Sex. Women are 2 to 3 times more likely than men to have relapsing-remitting MS.
  • Family history. If one of your parents or siblings has had MS, you are at higher risk of developing the disease.
  • Certain infections. A variety of viruses have been linked to MS, including Epstein-Barr. Epstein-Barr is the virus that causes infectious mononucleosis.
  • Race. People with white skin, particularly those of Northern European descent, have the highest risk of developing MS. People of Asian, African or Native American descent have the lowest risk. A recent study suggests that the number of Black and Hispanic young adults with multiple sclerosis may be greater than previously thought.
  • Climate. MS is far more common in places with temperate climates. These include Canada, the northern United States, New Zealand, southeastern Australia and Europe.
  • Vitamin D. Having low levels of vitamin D and low exposure to sunlight is linked to a greater risk of MS. Your birth month also may affect the chances of developing MS. This has to do with levels of sun exposure when a mother is pregnant.
  • Obesity. People who are obese or were obese in childhood have an increased risk of multiple sclerosis.
  • Certain autoimmune diseases. You have a slightly higher risk of developing MS if you have other autoimmune conditions. These may include thyroid disease, pernicious anemia, psoriasis, type 1 diabetes or inflammatory bowel disease.
  • Smoking. People who smoke have a higher risk of relapsing-remitting MS than people who don't smoke.
  • Gut microbiome. People with MS may have a different gut microbiome than people who don't have MS. More research is needed to understand this connection.

Complications

Complications of multiple sclerosis may include:

  • Mood changes, such as depression, anxiety or mood swings.
  • Muscle stiffness or spasms.
  • Seizures, though they are very rare.
  • Severe weakness or paralysis, typically in the arms or legs.
  • Trouble with bladder, bowel or sexual function.
  • Trouble with thinking and memory.
Nov. 01, 2024
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