This page includes answers to some of the most common questions people ask me regarding multiple sclerosis.What is multiple sclerosis?What causes multiple sclerosis?How do you diagnose multiple sclerosis?How bad is multiple sclerosis?Are there different types of multiple sclerosis?Should I exercise if I have multiple sclerosis?Will a special diet help?Will having children make MS worse?Will my children have multiple sclerosis?What is multiple sclerosis? MS is a disease which affects the brain and the spinal cord. It mostly affects myelin or white matter. Myelin is the insulation on the nerve cells. If you remove or damage myelin, the nerve cells can't send signals to each other. This causes symptoms such as weakness, vision problems, numbness, or poor coordination. The usual course of MS is relapsing-remitting. During a relapse, MS symptoms get worse fairly rapidly over a few days and stay bad for a few weeks. This is typically followed by a remission with partial or complete improvement of the symptoms. Usually there is a long stable period of monthsor years between relapses. MS can also be progressive, with symptoms getting slowly and steadily worse without sudden changes.What causes multiple sclerosis? We don't know for sure. The leading theory now is that it is an autoimmune disease. The immune system, which is supposed to fight infections, for some reason starts to attack myelin instead. There is a lot of evidence for this, and most of the treatments for MS are aimed at the immune system. Other ideas are that MS is the result of a chronic infection or some defect in the myelin which causes it to be unstable and break down.How do you diagnose multiple sclerosis? MS is diagnosed mainly based on the symptoms and signs. To make a definite diagnosis, there should be at least two relapses or steady progression for 6 months. There is no single laboratory test that can make or exclude the diagnosis of MS, but several tests are helpful. MRI scans of the brain and spinal cord almost always show white matter lesions in MS. Examination of the spinal fluid is also useful. People with MS typically have acertain type of protein called "oligoclonal bands" in their spinal fluid. Blood tests are helpful to exclude some other diseases which can look like MS.How bad is multiple sclerosis? MS varies a lot in severity. Some people will have few relapses or symptoms, while others develop significant disability. The average relapse frequency is about one every three years, and most people develop some disability over time. MS does not usually affect how long people live.Are there different types of multiple sclerosis? We divide MS up according to the pattern of the symptoms over time. Most people start with relapses followed by remissions, and are called relapsing-remitting. People who start with progressive symptoms without relapse are called primary progressive. People who start with relapses and then develop progressive symptoms, usually after 15 to 20 years, are called secondary progressive.Should I exercise if I have multiple sclerosis? Several studies have shown that an exercise program is helpful for people with MS. I don't think that exercise affects the long-term course of MS, but it does help people to maximize their function. Regular exercise is also good for general overall health reasons.Will a special diet help? There are only a few known effects of diet or nutrition on MS. Low Vitamin D levels increase risk for MS. Taking a multi-vitamin containing Vitamin D is reasonable. Vitamin D is toxic in large doses, so don't take more than the recommended amount of 50 micrograms or 2000 IU per day. Vitamin B12 deficiency can cause neurologic symptoms, and I often check B12 levels in someone with new onset of neurologic symptoms. Some people advocate taking supplements of polyunsaturated fatty acids such as fish oil or evening primrose oil. This affects both the activity of the immune system and the structure of myelin. The evidence that this helps is modest. A very low fat diet may also be helpful, but is not very appealing, and most people have trouble staying on it.Will having children make MS worse? Overall, pregnancy has little effect on the course of MS. Symptoms are less active during pregnancy, particularly the last trimester, and more active for a short while after delivery.Will my children have multiple sclerosis? If you have MS, then the risk of MS in a child (or any other first-degree relative such as mother, father, brother, or sister) is about 3 to 4%, or 1 in 25.