Muscular sclerosis is the former term for multiple sclerosis, or MS. Multiple sclerosis is characterized by demyelination of the axon, the region of a neuron that transmits nerve impulse. As a nerve impulse travels down the axon, myelin propagates the signal by increasing impulse speed. Therefore, the degradation of myelin results in a slower or absent nerve impulse. This may cause sensory or motor difficulties. The causes for multiple sclerosis vary, but all are directly related to demyelination.
Immunologic
According to the National Multiple Sclerosis Society, multiple sclerosis can be caused by an autoimmune response. This process involves the degradation of myelin around the neuron's axon. The exact antigen has not been identified, but immune cells involved in the assault are known. Immune cells have significant lytic abilities, causing the target to break apart. These cells are attracted to the myelin sheath. However, the trigger for this process, the mechanism and a solution are not yet known.
Environmental
Geography has an affect on MS. The National Multiple Sclerosis Society stated that MS prevalence is higher in locations farther from the equator. Although geographical dynamics may be a factor, migration pattern data suggests an environmental agent. Some believe that the environmental agent is sunlight. Vitamin D is synthesized by the body from sunlight, and vitamin D helps absorb calcium into the body. Since high levels of vitamin D are associated with improved immune function, areas with more sunlight may protect residents from autoimmune causes of MS. The association between vitamin D and demyelination is not fully understood.
Infectious
Several bacteria, viruses and other infectious antigens are known to cause demyelination. Viral and bacterial vectors, such as human herpes virus, Epstein-Barr, canine distemper, measles and Chlamydia pneumonia, are key infectious agents being studied, according to the National Multiple Sclerosis Society, although as of 2010 data has not definitively associated any of these vectors to MS. However, multiple sclerosis is not contagious, and only people with a genetic predisposition may have a viral cause for MS.
Genetic
People who have a family history of MS are at risk. Having a close relative multiplies the risk factor seven times that of the general population. However, the National Multiple Sclerosis Society states that MS is not necessarily hereditary. The current understanding of the genetic cause of MS is that a person may carry a predisposing gene, but environmental factors activate the gene.
