| Multiple sclerosis (MS) is a progressive, lifelong chronic disease of the central nervous system. It is the most common cause of neurologic disability in young adults. In MS, local areas of the fatty substance (myelin) that surrounds and insulates nerve cell fibers in the brain and spinal cord are destroyed. This demyelination can cause slowed or blocked nerve impulse conduction and occurs in random patches (plaques) at any site where "white matter" (nerves encased in myelin) occurs. New evidence suggests that nerve fiber loss may provide an explanation for some of the neurologic deficits experienced by many persons with MS.
MS is characterized by recurrent exacerbations (attacks, flares, relapses), during which time symptoms worsen or new symptoms appear. Exacerbations will last from days to weeks, and are caused by a new area of inflammation or new plaque formation in the central nervous system. These episodes may be minimized through anti-inflammatory or plasmapheresis treatment. Temporary exacerbations lasting approximately 24 hours are known as "pseudoexacerbations," and are typically triggered by stress, fever, urinary tract infections, or hot weather.
Although the exact cause of MS is unknown, many believe it to be a condition in which the body's defense system reacts against its own tissue (autoimmune disease). Such attacks may be linked to unknown environmental triggers such as viruses. There seems to be a genetic factor as well, as first-degree relatives (children or siblings) of those with MS have a 3% to 5% chance of getting the disease (Scott).Risk: Since MS is 5 times more common in temperate zones (such as the northern US, Canada, and Europe) than in the tropics, environment may also play a part. Living the first 15 years or more in a high-risk area seems to increase the risk, suggesting that environmental factors acquired during this early period of life may be responsible for a susceptible person later developing the disease. There may be a protective effect of vitamin D intake, as those taking multivitamins containing vitamin D have a 40% lower risk of MS (Munger).
MS generally occurs in persons between 15 and 45 years of age; the average age at diagnosis is 25 years in women, and 28 years in men (Scott).
Women outnumber men at a ratio of 2:1; this ratio is more balanced among those who develop symptoms at a later age. Whites are afflicted more than twice as often as other races. It is more common in whites of northern European descent. MS is essentially unknown among Eskimos, Gypsies, and Bantus, and rare among Native North and South Americans and Asian people. Incidence and Prevalence: MS is the most common chronic neurological disease causing disability, with more than 1.5 million people affected worldwide (Neuhaus). In high-risk areas, and for white Americans, the prevalence is about 1 per 1000 people; blacks have a prevalence of 0.33 per 1000, and Japanese Americans have a prevalence of 0.25 per 1000 (Wilson). There are approximately 350,000 to 450,000 individuals with MS in the US (Frohman), and 25,000 new cases are diagnosed each year (Lazoff). Prevalence in northern Europe and Japan is 2 per 1000, although in Scotland prevalence is 2.5 per 1000 (Wilson). The remaining population has a prevalence of 1 per 1,000,000 (Lazoff). |