To date, no research has provided a definitive reason for this varying distribution. MS is not considered a fatal, contagious or directly hereditary illness, although a susceptibility to MS may be inherited. Prevalence in families of persons with MS runs somewhat higher than in the general population. Several investigations are underway into this question. MS is often characterized by a pattern of exacerbations and remissions.
Some people experience only very mild symptoms with difficult, but non-disabling symptoms.
More common are severe attacks followed by periods of recovery. Still others progress to a serious stage in which they may need a wheelchair. Symptoms include fatigue, which can be overwhelming though a person may appear well. In addition, loss of coordination, muscle weakness, spasticity, numbness, slurred speech, and visual difficulties often occur. Most acute symptoms, but least occurring, may be paralysis, muscle cramps, bladder or bowel problems and sexual dysfunction.