No one has identified an exact cause for the autoimmune condition known as multiple sclerosis (MS). But we do know the condition disrupts the ability to move and even see. With MS, the body’s immune system mistakenly targets the protective covering of your nerve fibers, called myelin. Myelin allows your nerve fibers to facilitate communication between your brain and the rest of your body. The damage to myelin interrupts the signals your nerves send back and forth to control various functions. As a result, you might experience some tingling, weakness, or numbness in your legs or on the limbs on one side of your body. You might experience double or blurred vision. Your muscles might get stiff, and you may have trouble walking. Many people experience a cycle: their MS symptoms flare up for a while before they slide into a period of remission. But others may find their MS symptoms progress without any relief from remission, short or long term. It’s useful to learn more about how MS can and often does progress over time. Understanding the Different Types of MS MS isn’t just one condition. There are actually four main types of multiple sclerosis: Relapsing-remitting multiple sclerosis (RRMS): This is the most common type of MS, characterized by acute attacks, followed by periods of remission. Secondary progressive multiple sclerosis (SPMS): Most people with relapsing-remitting multiple sclerosis eventually develop this form, in which symptoms begin steadily worsening over time, instead of continuing the cycle of attack followed by remission. Primary progressive multiple sclerosis (PPMS): About 10% of people with MS have this type. This form of MS starts and continues to progress, without ever going into periods of remission. Progressive-relapsing multiple sclerosis (PRMS): This form is very rare, accounting for only about 5% of cases, according to the National Multiple Sclerosis Society. People with PRMS experience a progressive worsening of their symptoms from the very beginning, as well as relapses, but their symptoms don’t ever go into remission. Understanding your specific MS diagnosis is critical for understanding what you can anticipate, with regard to progression of the disease. Talk to your doctor if you have specific questions about your particular diagnosis, since the most appropriate medications and management strategies vary. Learning the Difference Between a Relapse and Progression If you’re in the majority of people with MS, you have relapsing-remitting MS. So you’re already familiar with the pattern of this particular type of the disease. You’ve experienced the cycle of inflammatory attack, or relapse, followed by a period of remission. Some people have relatively mild cases, while others experience more severe symptoms that require treatment to hasten their recovery. What does a typical relapse look like? It can vary, based on how severe your disease is and where the damage to your nerve cells occurs. You may experience a flare-up of any number of symptoms, from weakness to intense fatigue to lack of coordination. You may have trouble seeing, and your balance may be affected. A relapse might last about 24 hours or more before it abates. Then a remission, or period of recovery, follows. The remission can be short-lived or lengthy. Your symptoms can disappear entirely, or they might only partially resolve. By contrast, your MS would get steadily worse if you were experiencing progression of your disease. Your symptoms would be constant and the myelin protecting your nerve fibers would become more and more damaged. Recognizing Progression When It Develops Most people with relapsing-remitting MS do eventually develop secondary-progressive MS, usually between 10 and 25 years after diagnosis. In fact, some doctors consider it to be the second phase of relapsing-remitting MS. Although it’s very common for RRMS to progress into SPMS, it can be a little challenging to determine if your MS is transitioning to a progressive form. Your doctor may still want to run some tests, including taking Magnetic Resonance Imaging (MRI) of your brain and spinal cord, to gather more information and make a diagnosis. The main characteristic of secondary-progressive MS is a steady worsening of the disease. You might still experience some relapses, but you might not. In fact, some people with secondary-progressive MS report fewer relapses and some don’t experience any inflammatory relapses. Some experts believe that’s because the nerve fibers that were damaged earlier in the course of the disease have begun to disappear. Those remissions might start to fade away, too, or you’ll notice that they’re not complete remissions anymore. You might still experience symptoms during those times. Even if you have some periods where the disease seems relatively stable to you, MS continues to get worse over time. The speed of this progression, however, is variable, too. During progression, you may notice certain symptoms worsen or occur more often. Common examples include: Increased fatigue More vision problems Increased numbness or tingling Stiff or spastic muscles Decreased lack of coordination Trouble with your memory Bladder problems, such as an increased urge to urinate or trouble emptying your bladder or holding your urine. Once your doctor has determined that your MS is progressing, you can discuss the best treatment options for you. There’s no cure, but there are ways to manage your symptoms and help you live your life as fully as possible. You might take certain medications to address relapses if you continue to experience them, and your doctor might also recommend occupational therapy or physical therapy. Finding the right combination may take some time as you adjust to a different approach toward managing your MS.