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.