MS cases vary from patient to patient
Multiple sclerosis (MS) is thought to be an autoimmune disease that affects the central nervous system (CNS). Surrounding and protecting the nerve fibers of the CNS is a fatty tissue called myelin, which helps nerve fibers conduct electrical impulses.
In MS, myelin is lost in multiple areas, leaving scar tissue called sclerosis. These damaged areas are also known as plaques or lesions. Sometimes the nerve fiber itself is damaged or broken.
Myelin not only protects nerve fibers, but also makes their job possible. When myelin or the nerve fiber is destroyed or damaged, the ability of the nerves to conduct electrical impulses to and from the brain is disrupted, and this produces the various symptoms of MS.
People with MS can expect one of four clinical courses of disease, each of which might be mild, moderate, or severe.
Relapsing-Remitting Characteristics: People with this type of MS experience clearly defined flare-ups (also called relapses, attacks, or exacerbations). These are episodes of acute worsening of neurologic function. They are followed by partial or complete recovery periods (remissions) free of disease progression. Frequency: Most common form of MS at time of initial diagnosis. Approximately 85%.Primary-Progressive Characteristics: People with this type of MS experience a slow but nearly continuous worsening of their disease from the onset, with no distinct relapses or remissions. However, there are variations in rates of progression over time, occasional plateaus, and temporary minor improvements.Frequency: Relatively rare. Approximately 10%.
Secondary-Progressive Characteristics: People with this type of MS experience an initial period of relapsing-remitting MS, followed by a steadily worsening disease course with or without occasional flare-ups, minor recoveries (remissions), or plateaus. Frequency: 50% of people with relapsing-remitting MS developed this form of the disease within 10 years of their initial diagnosis, before introduction of "disease-modifying" drugs. Long-term data are not yet available to demonstrate if this is significantly delayed by treatment.
Progressive-Relapsing Characteristics: People with this type of MS experience a steadily worsening disease from the onset but also have clear acute relapses (attacks or exacerbations), with or without recovery. In contrast to relapsing-remitting MS, the periods between relapses are characterized by continuing disease progression. Frequency: Relatively rare. Approximately 5%.
1. National Multiple Sclerosis Society, What is Multiple Sclerosis. www.nmss.org.