Multiple sclerosis (MS) is a disease in which the nerves of the central nervous system (brain and spinal cord) degenerate. Myelin, which provides a covering or insulation for nerves, improves the conduction of impulses along the nerves and also is important for maintaining the health of the nerves. In multiple sclerosis, inflammation causes the myelin to disappear.
Consequently, the electrical impulses that travel along the nerves decelerate, that is, become slower. In addition, the nerves themselves are damaged. As more and more nerves are affected, a person experiences a progressive interference with functions that are controlled by the nervous system such as vision, speech, walking, writing, and memory.
About 350,000 people in the U.S. have multiple sclerosis. Usually, a person is diagnosed with multiple sclerosis between 20 and 50 years of age, but multiple sclerosis has been diagnosed in children and in the elderly. Multiple sclerosis is twice as likely to occur in Caucasians as in any other group. Women are twice as likely as men to be affected by multiple sclerosis earlier in life.
Symptoms of multiple sclerosis may be single or multiple and may range from mild to severe in intensity and short to long in duration. Complete or partial remission from symptoms occurs early in about 70% of individuals with multiple sclerosis.
Visual disturbances may be the first symptoms of multiple sclerosis, but they usually subside. A person may notice a patch of blurred vision, red-to-orange or red-to-gray distortions (color desaturation), or monocular visual loss (loss of vision in one eye). Visual symptoms due to optic nerve inflammation (optic neuritis) in multiple sclerosis usually are accompanied or preceded by eye pain.
Limb weakness with or without difficulties with coordination and balance may occur early.
Muscle spasms, fatigue, numbness, and prickling pain are common symptoms.
There may be a loss of sensation, speech impediment (typically a problem articulating words), tremors, or dizziness.
Fifty-percent of people experience mental changes such as:
- decreased concentration,
- attention deficits,
- some degree of memory loss,
- inability to perform sequential tasks,
- impairment in judgment.
Other symptoms may include:
- manic depression,
- an uncontrollable urge to laugh and weep.
As the disease worsens, individuals may experience sexual dysfunction or reduced bowel and bladder control. Heat appears to intensify multiple sclerosis symptoms for about 60% of those with the disease. Pregnancyseems to reduce the number of attacks, especially during the third trimester.
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 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.
There are many issues for the patient and physician to consider in treating multiple sclerosis.
Goals may include:
- improving the speed of recovery from attacks (treatment with steroid drugs);
- reducing the number of attacks or the number of MRI lesions;
- attempting to slow progression of the disease (treatment with disease modifying drugs or DMDs).
An additional goal is relief from complications due to the loss of function of affected organs (treatment with drugs aimed at specific symptoms).
Most neurologists will consider treatment with DMDs once the diagnosis of relapsing remitting multiple sclerosis is established. Many will begin treatment at the time of the first multiple sclerosis attack, since clinical trials have suggested that patients in whom treatment is delayed may not benefit as much as patients who are treated early.
It is important for patients to talk to their doctor before deciding to go on therapy since DMDs differ in their uses (for example, one DMD may be used for slowing progressing disability but not for treatment of the first attack of MS; another DMD may be used for reducing relapses but not for slowing progressing disability). Finally, utilizing support groups or counseling may be helpful for patients and their families whose lives may be affected directly by multiple sclerosis.
Once goals have been set, initial therapy may include medications to manage attacks, symptoms, or both. An understanding of the potential side effects of drugs is critical for the patient because sometimes side effects alone deter patients from drug therapy.
Patients may choose to avoid drugs altogether or choose an alternative drug that may offer relief with fewer side effects. A continuous dialogue between the patient and physician about the medications is important in determining the needs for treatment.
Drugs known to affect the immune system have become the primary focus for managing multiple sclerosis. Initially, corticosteroids, such as prednisone (Deltasone, Liquid Pred, Deltasone, Orasone, Prednicen-M) ormethylprednisolone (Medrol, Depo-Medrol), were widely used.
However, since their effect on the immune system is non-specific (general) and they may use may cause numerous side effects, corticosteroids now tend to be used to manage only severe multiple sclerosis attacks (that is, attacks leading to physical disability or causing pain).