Multiple Sclerosis (cont.)

Medical Author:
Medical Editor:
Medical Editor:

What causes multiple sclerosis?

The cause of multiple sclerosis is still unknown. In the last 20 years, researchers have focused on disorders of the immune system and genetics for explanations. The immune system is the body's defender against foreign invaders and is highly organized and regulated. If triggered by an aggressor or foreign object, the immune system mounts a defensive action which identifies and attacks the invader and then withdraws. This process depends upon rapid communication among the immune cells and the production of cells that can destroy the intruder. In multiple sclerosis, researchers suspect that a foreign agent such as a virus alters the immune system so that the immune system perceives myelin as an intruder and attacks it. The attack by the immune system on the tissues that it is supposed to protect is called autoimmunity, and multiple sclerosis is believed to be a disease of autoimmunity. While some of the myelin may be repaired after the assault, some of the nerves are stripped of their myelin covering (become demyelinated). Scarring also occurs, and material is deposited into the scars and forms plaques.

Is multiple sclerosis inherited?

Although its role is unclear, genetics may play a role in multiple sclerosis. European gypsies, Eskimos, and African Bantu essentially do not develop multiple sclerosis, while Native Indians of North and South America, Japanese, and other Asian groups have a low incidence. The general population has less than a 1% chance of developing multiple sclerosis. The chance increases in families where a first-degree relative has the disease. Thus, a brother, sister, parent, or child of a person with multiple sclerosis stands a 1% to 3% chance of developing multiple sclerosis. Similarly, an identical twin runs a nearly 30% chance of acquiring multiple sclerosis whereas a non-identical twin has only a 4% chance if the other twin has the disease. These statistics suggest that genetic factors play a major role in multiple sclerosis. However, other data suggest that environmental factors also play an important role. The environmental factors most commonly implicated and for which evidence seems to be mounting include lack of sun exposure with subsequent low levels of vitamin D, Epstein Barr virus (EBV) infection, and smoking, but their relative contributions to disease susceptibility and severity remain controversial.

What are the types of multiple sclerosis?

There are different clinical manifestations of multiple sclerosis. During an attack, a person experiences a sudden deterioration in normal physical abilities that may range from mild to severe. This attack, sometimes referred to as an exacerbation of multiple sclerosis, typically lasts more than 24 hours and generally more than a few weeks (rarely more than 4 weeks).

Most individuals begin with relapsing-remitting (RR) MS, the most common type. In this type, they experience a series of attacks followed by complete or partial disappearance of the symptoms (remission) until another attack occurs (relapse). It may be weeks to decades between relapses.

In primary-progressive (PP) MS, there is a continuous, gradual decline in a person's physical abilities from the outset rather than relapses. About some individuals begin with PP-MS.

Those beginning with RR-MS can then enter a phase where relapses are rare but more disability accumulates, and are said to have secondary-progressive (SP) MS. About half of RR-MS individuals will develop SP-MS within 10 years. Over several decades, most RR-MS persons will experience progression to SP-MS. Progressive-relapsing (PR) MS is a type of multiple sclerosis characterized by a steady decline in abilities accompanied by sporadic attacks. There are cases of multiple sclerosis that are mild and can be recognized only retrospectively after many years and also rare cases of extremely rapid progression of multiple sclerosis symptoms (sometimes fatal) known as malignant or fulminant (Marburg variant) multiple sclerosis.

Medically Reviewed by a Doctor on 8/1/2014

Patient Comments

Viewers share their comments

Multiple Sclerosis - Symptoms Question: The symptoms of multiple sclerosis can vary greatly from patient to patient. What were your symptoms at the onset of your disease?
Multiple Sclerosis - Treatments Question: How do you manage your multiple sclerosis?
Multiple Sclerosis - Diagnosis Question: How many doctors did you go to before you received a multiple sclerosis diagnosis?
Multiple Sclerosis - Causes Question: Were you, a friend, or relative diagnosed with MS? What do you think the cause might be?
Multiple Sclerosis - Type Question: What type of multiple sclerosis do you have? How do you cope with the symptoms and your condition?

STAY INFORMED

Get the Latest health and medical information delivered direct to your inbox!