Patients may then remain symptom-free for weeks, months, or even years. The periods of disease activity are called exacerbations or relapses and the periods without symptoms are called remissions - thus the term relapsing remitting multiple sclerosis. Later, about a third of these individuals will develop disease that will gradually worsen over time without, in most cases, discernable relapses and remissions. This type of MS is called secondary progressive MS . This is referred to as primary progressive MS .
Nerve impulses move quickly by jumping from node to node.
When portions of the myelin sheath are destroyed, the message must travel via the axon which is less efficient. MS is a disorder that usually affects young adults, typically beginning between the ages of 15 and 50. It affects women more often than men and people of European descent more often than individuals of African or Asian ancestry. Multiple sclerosis occurs more frequently in temperate zones than in areas near the Equator. People with family members diagnosed with MS are at slightly higher risk for developing the disease.