Multiple sclerosis (MS) is a chronic illness involving your central nervous system (CNS). The immune system attacks myelin, which is the protective layer around nerve fibers.
This causes inflammation and scar tissue, or lesions. This can make it hard for your brain to send signals to the rest of your body. See illustrations that show the physiological changes associated with MS.
People with MS experience a wide range of symptoms. Due to the nature of the disease, symptoms can vary widely from person to person. They can also change in severity from year to year, month to month, and even day to day.
Two of the most common symptoms are fatigue and difficulty walking.