Multiple sclerosis
Multiple sclerosis
Classification & external resources
Multiple sclerosis (abbreviated MS, formerly known as disseminated sclerosis or encephalomyelitis disseminata) is a chronic, inflammatory, demyelinating disease that affects the central nervous system (CNS). Disease onset usually occurs in young adults, is more common in women and the disease has a prevalence that ranges between 2 and 150 per 100,000 depending on the country or specific population.[1] MS was first described in 1868 by Jean-Martin Charcot.
MS affects the neurons in the areas of the brain and spinal cord known as the white matter. These cells carry signals in between the grey matter areas, where the processing is done, and between these and the rest of the body. More specifically, MS destroys oligodendrocytes which are the cells responsible for creating and maintaining a fatty layer, known as the myelin sheath, which helps the neurons carry electrical signals. MS results in a thinning or complete loss of myelin and, less frequently, the cutting (transection) of the neuron's extensions or axons. When the myelin is lost, the neurons can no longer effectively conduct their electrical signals. The name multiple sclerosis refers to the scars (scleroses - better known as plaques or lesions) in the white matter. Loss of myelin in these lesions causes some of the symptoms that may vary widely depending upon which signals are interrupted. However, more advanced forms of imaging are now showing that much of the damage happens outside these regions. A consequence of this course of action is that almost any neurological symptom can accompany the disease.
Multiple sclerosis may take several forms, with new symptoms occurring either in discrete attacks (relapsing forms) or slowly accumulating over time (progressive forms). Most people are first diagnosed with relapsing-remitting MS but develop secondary-progressive MS (SPMS) after a number of years. Between attacks, symptoms may resolve completely, but permanent neurological problems often persist, especially as the disease advances.
Although much is known about the mechanisms involved in the disease process, the cause remains elusive. The theory with the most adherents is that it results from attacks to the nervous system by the body's own immune system. Some believe it is a metabolically dependent disease while others think that it might be caused by a virus such as Epstein-Barr. Still other people believe that its virtual absence from the tropics points to a deficiency of vitamin D during childhood.[citation needed]
The disease currently does not have a cure, but several therapies have proven helpful. The aims of treatment are returning function after an attack, preventing new attacks, and preventing disability. As with any treatment, medications have several adverse effects, and many therapies are still under investigation. At the same time different alternative treatments are pursued by many patients, despite the paucity of supporting scientific study.
The prognosis, or expected course of the disease, for a person depends on the subtype of the disease; the characteristics of the individual, the initial symptoms; and the degree of disability the person experiences as time advances. However life expectancy of patients is nearly the same as that of the unaffected population and in many cases a normal life is possible
Treatment
If your attacks are mild or infrequent, your doctor may advise a wait-and-see approach, with counseling and observation.
Medications for relapsing MS
If you have a relapsing form of the disease, your doctor may recommend treatment with disease-modifying medications early in the course of disease. You can't take these medications if you're pregnant or may become pregnant. These medications for multiple sclerosis treatment include:
Beta interferons. Interferon beta-1b (Betaseron) and interferon beta-1a (Avonex, Rebif) are genetically engineered copies of proteins that occur naturally in your body. They help fight viral infection and regulate your immune system.
If you use Betaseron, you inject yourself under your skin (subcutaneously) every other day. If you use Rebif, you inject yourself subcutaneously three times a week. You self-inject Avonex into your muscle (intramuscularly) once a week. These medications reduce but don't eliminate flare-ups of multiple sclerosis. It's uncertain which of their many actions lead to a reduction in disease activity and what their long-term benefits are. Beta interferons aren't used in combination with one another; only one of these medications is used at a time.
The Food and Drug Administration (FDA) has approved beta interferons only for people with relapsing forms of MS who can still walk. Beta interferons don't reverse damage and haven't been proved to significantly alter long-term development of permanent disability. Some people develop antibodies to beta interferons, which may make them less effective. Other people can't tolerate the side effects, which may include symptoms similar to those of the flu (influenza).
Doctors generally recommend beta interferons for people who have more than one attack of MS a year and for those who don't recover well from flare-ups. The treatment may also be used for people who have a significant buildup of new lesions as seen on an MRI scan, even when there may not be major new symptoms of disease activity.
The FDA has approved the use of several beta interferons for people who've experienced a single attack that suggests multiple sclerosis, and who may be at risk of future attacks and developing definite MS. Risk of MS may also be suggested when an MRI scan of the brain shows lesions that predict a high risk of conversion to definite MS. Controversy exists as to whether these people should take these expensive and often inconvenient drugs for indefinite periods, especially because some people do well both in the short term and long term without therapy. Some doctors prefer to observe people at high risk with follow-up examinations and MRI scans to document any ongoing inflammatory disease activity before recommending long-term therapies such as beta interferon.
Glatiramer (Copaxone). This medication is an alternative to beta interferons if you have relapsing remitting MS. Doctors believe that glatiramer works by blocking your immune system's attack on myelin. You must inject glatiramer subcutaneously once daily. Side effects may include flushing and shortness of breath after injection.
Natalizumab (Tysabri). This drug is administered intravenously once a month. It works by blocking the attachment of immune cells to brain blood vessels — a necessary step for immune cells to cross into the brain — thus reducing the immune cells' inflammatory action on brain nerve cells.
During clinical trials, this drug was shown to significantly reduce the frequency of attacks in people with relapsing MS. After receiving FDA approval, however, the drug was withdrawn from the market because of reports from three people who developed a rare, often fatal, brain disorder called progressive multifocal leukoencephalopathy.
In 2006, after reconsideration of the drug's benefits for people with multiple sclerosis, the FDA agreed to allow the drug to be marketed again under specific conditions. Chief among these conditions is the requirement that doctors, pharmacists and patients be involved in a special distribution program known as TOUCH in order to prescribe, dispense or receive the drug. Because of the drug's risks, it's generally recommended only for people whose condition hasn't responded to other forms of MS therapy. Furthermore, there has been no study direct comparing natalizumab to existing treatments to prove whether it's superior to existing treatments.
Other medications. Mitoxantrone (Novantrone) is a chemotherapy drug used for many cancers. This drug is also FDA-approved for treatment of aggressive forms of relapsing remitting MS, as well as certain forms of progressive MS. It's given intravenously, typically every three months.
Mitoxantrone may cause serious side effects, such as heart damage, after long-term use, so it's typically not used for longer than two to three years. And it's typically reserved for people with severe attacks or rapidly advancing disease who don't respond to other treatments. Close monitoring is critical for anyone on this medication.
Some doctors are also prescribing other chemotherapy drugs, such as cyclophosphamide (Cytoxan), for people with severe, rapidly progressing MS. However, these medications aren't FDA-approved for treatment of MS.
Medications for progressive MS
Some medications may relieve symptoms of progressive MS. They include:
Corticosteroids. Doctors most often prescribe short courses of oral or intravenous corticosteroids to reduce inflammation in nerve tissue and to shorten the duration of flare-ups. Prolonged use of these medications, however, may cause side effects, such as osteoporosis and high blood pressure (hypertension), and the benefit of long-term therapy in multiple sclerosis isn't established.
Muscle relaxants. Baclofen (Lioresal) and tizanidine (Zanaflex) are oral treatments for muscle spasticity. If you have multiple sclerosis, you may experience muscle stiffening or spasms, particularly in your legs, which can be painful and uncontrollable. This typically occurs in people with persisting or progressive weakness of their legs. Baclofen may temporarily increase weakness in your legs. Tizanidine controls muscle spasms without causing your legs to feel weak, but can be associated with drowsiness or a dry mouth.
Medications to reduce fatigue. To help combat fatigue, your doctor may prescribe an antidepressant medication, the antiviral drug amantadine (Symmetrel) or a medication for narcolepsy called modafinil (Provigil). All drugs prescribed for this purpose appear to work because of their stimulant properties. One study has showed that aspirin treatment may be effective in controlling MS-related fatigue; further research is planned to address the benefits of aspirin on fatigue.
Other medications. Many medications are used for the muscle stiffness, depression, pain and bladder control problems associated with multiple sclerosis. Drugs for arthritis and medications that suppress the immune system may slow MS in some cases.
MS treatments other than medications
In addition to medications, these treatments also may be helpful:
Physical and occupational therapy. A physical or occupational therapist can teach you strengthening exercises and show you how to use devices that can ease the performance of daily tasks. Therapists are usually supervised by doctors (physiatrists) who advise and coordinate the therapy that you might receive. Therapists can assist you in finding optimal mobility assistance devices such as canes, wheelchairs and motorized scooters. These devices and exercises can help preserve your independence.
Counseling. Individual or group therapy may help you cope with multiple sclerosis and relieve emotional stress. Your family members or caregivers also may benefit from seeing a counselor.
Plasma exchange (plasmapheresis). Plasma exchange may help restore neurological function in people with sudden severe attacks of MS-related disability who don't respond to high doses of steroid treatment. This procedure involves removing some of your blood and mechanically separating the blood cells from the fluid (plasma). Your blood cells then are mixed with a replacement solution, typically albumin, or a synthetic fluid with properties like plasma. The solution with your blood is then returned to your body.
Replacing your plasma may dilute the activity of the destructive factors in your immune system, including antibodies that attack myelin, and help you to recover. Plasma exchange has no proven benefit beyond three months from the onset of the neurological symptoms.