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Multiple Sclerosis

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Synonyms of Multiple Sclerosis

Disorder Subdivisions

General Discussion

Multiple sclerosis is a chronic neuroimmunologic (both the nervous system and the immunological system are involved) disorder of the central nervous system involving the brain, spinal cord and optic nerves. By means of a mechanism not clearly understood, the protective fatty, insulating substance called myelin sheath that covers the nerve is destroyed. The inflammatory attacks that produce the characteristic scarring (plaques or patches) of the myelin sheath occurs randomly, vary in intensity, and at multiple sites. The course of the disease may advance, relapse, remit, or stabilize. The randomness of the location of plaques or patches affects the nerve's ability to transmit information (neurotransmission) and causes a wide range of neurological symptoms, which may vary from person to person.

Recently it has been learned that the nerve fibers themselves, (axons), in addition to the myelin sheaths, are affected by the neuroimmunologic attacks. Damage to the nerve cells may be irreversible. As a result, clinicians recommend early intervention with one of the disease-modifying agents (see below).

Symptoms

The symptoms of multiple sclerosis may vary greatly. Some people may have visual impairment (including blind spots), double vision (diplopia), or involuntary rhythmic movements of the eyes (nystagmus). People with multiple sclerosis may also experience impairment of speech, numbness or tingling sensation in the limbs and difficulty walking. Dysfunction of the bladder and bowel may also be present. Multiple sclerosis is rarely fatal; the average life expectancy is 93 percent of that of the general population. In some cases however, constraints on mobility make it necessary to use a cane, or crutches, or other aids. In a small number of cases, the disease accelerates and may result in life-threatening complications.

In order to illustrate by how much symptoms of MS may vary, the National Multiple Sclerosis Society (NMSS) cites a study of 697 persons with MS who experienced the following symptoms in addition to pain, depression and other emotional changes:

Fatigue-----------------------------88%
Ambulation problems---------87%
Bowel/Bladder problems----65%
Visual Disturbances-----------58%
Cognitive problems------------44%
Tremor------------------------------41%
Difficulty moving arms---------41%

Causes

The exact cause of multiple sclerosis is not known. Nevertheless, most clinical investigators agree that MS may be the result of an abnormal autoimmune response to some infection or environmental trigger in a genetically susceptible person. Immunologic, genetic, and environmental factors are thought to play some role in causing the disorder.

Many researchers suggest that the disorder may represent an abnormal immune reaction directed against the body's own tissues (autoimmune disorder). In autoimmune disorders, the body's natural defenses (e.g., antibodies, lymphocytes) against substances that are perceived as foreign (antigens) inappropriately begin to attack healthy tissues, for unknown reasons. According to many researchers, the autoimmune process may be triggered by exposure to particular environmental agents (e.g., certain bacteria or viruses) in individuals with a genetic susceptibility for MS. Research is concentrating on immune therapies designed to moderate the autoimmune attack without harming normal immune cells.

Some researchers believe that one or more different viruses may play some role in triggering the disease process in individuals with MS. For example, laboratory studies of blood serum and cerebrospinal fluid (CSF) in those with the disorder have demonstrated increased number of antibodies against certain viruses, such as herpes simplex, measles, chickenpox (varicella), Epstein-Barr, influenza-C, and rubella. However, no specific virus has been isolated consistently among individuals with MS.

Other researchers suggest that a common bacterium may contribute to the development of MS. In one study, the cerebrospinal fluid from all 37 individuals with MS (relapsing-remitting or progressive MS) showed the presence of the bacterium that causes "walking pneumonia" (Chlamydia pneumoniae). In contrast, the study's control group (i.e., individuals with neurologic diseases other than MS) the bacterium was present in only a small number of cases and few of the control subjects had developed antibodies against the microorganism. The researchers cautioned that additional investigation is necessary to determine whether the bacterium actually triggers the disease process in certain susceptible individuals or whether those with the disease are more prone to infection with C. pneumoniae.

Evidence also suggests that individuals with MS may have a genetic susceptibility for the disorder that may be determined by the "cumulative" interaction of several genes (polygenic inheritance); in addition, there may be different genetic abnormalities or mechanisms that result in susceptibility to the disease (heterogeneity). Researchers have implicated several different genes that may be associated with MS. These include certain closely linked genes (major histocompatibility complex [MHC]) that regulate production of the major histocompatibility antigens, a group of proteins that play a role in the immune system. Researchers suggest that the presence of certain genetically determined histocompatibility antigens may play some role in predisposing individuals to MS.

Two large studies reported in the New England Journal of Medicine (February 2001) failed to show any evidence of a link between vaccination and multiple sclerosis.

Affected Populations

In 1998, 10,060 new cases of definite or possible multiple sclerosis were identified in the United States, raising the prevalence rate to 278,000. Some researchers estimate the number will rise to 315,300 by the year 2008. Twice as many females as males are affected. The disorder may appear at any age, although the diagnosis is most often made between 20 and 50 years of age.

Over the past decade it has become common for clinical researchers to classify MS into several types. These types were originally proposed to improve experimental design but are used often at this time as a guide to treatment options. MS is classified as:

Relapsing Remitting MS (RRMS)
This form of MS is characterized by clearly defined acute attacks with full recovery or modest residual deficit upon recovery. Between attacks, the severity of the disease is stable. About 70-75% of initial diagnoses of MS are later classified as RRMS.

Secondary-Progressive MS (SPMS)
SPMS usually begins as RRMS. SPMS is characterized by progressive disability at a variable rate that may be accompanied by relapses, minor remissions, and plateaus. Of the people with an initial diagnosis of RRMS, 50% or more will develop SPMS within 10 years and 90% within 25 years.

Primary Progressive MS (PPMS)
From onset, PPMS shows steady rates of progression of disability or occasional plateaus and/or minor remissions. PPMS makes up about 15% of all MS diagnoses.

Progressive-Relapsing MS (PRMS)
PRMS is the least common form of the disorder, occurring in only about 6-10% of initial diagnoses. It is characterized by steady progression of disabilities interrupted by clearly defined acute relapses and followed by total or only partial recovery.

Multiple sclerosis is more common in Caucasian Americans than in Americans of African or Asian heritage. In a few ethnic societies (Inuits, Bantus and American Indians), multiple sclerosis is rare or absent. This may hint at a genetic link to this disorder. Multiple sclerosis seems to occur more often in the moderate regions (temperate climates).

Related Disorders

Symptoms of the following disorders can be similar to those of multiple sclerosis. Comparisons may be useful for a differential diagnosis:

Amyotrophic lateral sclerosis (ALS) is a disease of the motor neurons that send signals to the skeletal muscles. It generally affects both the upper and the lower muscle groups and results in the progressive weakness and wasting away of the muscles involved. There are several varieties of Amyotrophic Lateral Sclerosis. The early symptoms may include slight muscular weakness, clumsy hand movements and difficulty performing fine motor tasks. Weakness in the legs may result in clumsiness and tripping, and a slowing of speech may also be present. Other symptoms may include muscle stiffness and coughing. (For more information on this disorder, choose "Amyotrophic Lateral Sclerosis" as your search term in the Rare Disease Database.)

Charcot-Marie-Tooth Disease (also known as CMT disease) is a hereditary neurological disorder characterized by muscle weakness and atrophy, primarily in the muscles of the legs. Symptoms of Type I Charcot-Marie-Tooth disease usually begin in middle childhood or teenage years with a deformity of the foot characterized by a high arch and hyperextension of the toes (gampsodactyl or claw-foot). This produces a "stork leg" deformity. With time, Charcot-Marie-Tooth disease spreads to the upper extremities and produces a "stocking-glove" pattern of diminished sensitivity. There is a decrease in the sensitivity to vibration, pain and temperature. (For more information on this disorder, choose "Charcot-Marie-Tooth Disease " as your search term in the Rare Disease Database.)

Dejerine-Sottas disease is a rare progressive hereditary disorder that causes the enlargement of the peripheral nerves and the loss of myelin. This results in a burning or tingling sensation in the limbs, generalized muscle weakness and the loss of coordination in the hands and forearms. Weakness in the back of the legs eventually spreads to the front of the legs resulting in difficulty and pain when walking. Mild vision problems may also be present. (For more information on this disorder, choose "Dejerine-Sottas Disease" as your search term in the Rare Disease Database.)

Friedreich's ataxia is a progressive hereditary disorder that affects the neuromuscular system. It is generally diagnosed in childhood or adolescence. There are slow degenerative changes of the spinal cord and the brain that affect speech and motor coordination. These changes may produce an unsteady walk or numbness and weakness in the arms and legs. The legs generally become progressively weaker resulting in a staggering, lurching walk or trembling when standing still. (For more information on this disorder, choose "Friedreich's Ataxia" as your search term on the Rare Disorder Database.)

Guillain-Barre syndrome (acute idiopathicpolyneuritis) is a rare rapidly progressive polyneuropathy. Although the exact cause is not known, a gastrointestinal virus or respiratory infection precedes the onset of the syndrome in almost half the cases. The myelin sheath that covers the nerves is damaged and results in muscle weakness. The symptoms may include a burning or tingling sensation in the feet followed by weakness of the legs. Eventually the torso, upper limbs and face may be affected. (For more information on this disorder, choose "Guillain-Barre Syndrome" as your search term in the Rare Disease Database.)

Chronic inflammatory demyelinating polyneuropathy (CIDP) is a rare disorder in which there is swelling of the nerve roots and the destruction of the covering (myelin sheath) over the nerves. This causes weakness, paralysis and impairment of motor function especially in the limbs. Symptoms may include burning, numbness or tingling of the hands and feet or the arms and legs. Reflexes may be weakened or absent, and the muscles of the face may become weak. Other symptoms may include difficulty in walking and respiratory problems. (For more information on this disorder, choose "Chronic Inflammatory Demyelinating Polyneuropathy" as your search term on the Rare Disease Database.)

Leukodystrophy is the name given to a group of very rare, progressive, metabolic, genetic diseases that affect the brain, spinal cord and often the peripheral nerves. Each of the leukodystrophies will affect one of the chemicals that make up the myelin sheath that covers the nerve fibers or it may affect the white matter of the brain. Most of the leukodystrophies are present at birth but some may appear more slowly over time and even into adulthood. Leukodystrophy causes the patient to have problems with movement, vision, hearing, feeling and thinking. This can result in difficulty walking, stiffness, a "floppy" feeling in the muscles, paralysis or convulsions. (For more information on these disorders, choose "Leukodystrophy" as your search term on the Rare Disease Database.)

Standard Therapies

Although multiple sclerosis (MS) has no known prevention or cure, there are treatments available to manage symptoms, alter the course of the disease, and help with exacerbations (relapses or flare-ups). Standard pain medications are not effective for pain in MS, which is of two types: spasmodic and neurogenic pain. Antispasmodics are used to treat spasmodic pain and neurogenic pain is usually treated by anticonvulsants and/or antidepressants. Trigeminal neuralgia is treated with anti-convulsants such as Tegretol and Dilantin. Recurrent attacks and relapses (exacerbations) are commonly treated with corticosteroids to reduce the inflammation in the central nervous system that damages the myelin and slows or blocks the transmission of nerve impulses. These drugs do not slow down or stop the progression of this disorder. Physical therapy and exercise programs (especially aquatic or water therapy) are of value in most patients.

Disease-modifying medications help to reduce the frequency and severity of attacks, reduce the accumulation of damaged or active disease areas (lesions) in the brain and spinal cord, and appear to slow down the progression of disability. It is believed that these drugs are most effective when started early, before the disease progresses further. The following are disease-modifying drugs that have been approved by the FDA:

Betaseron (interferon beta-1b), by Bayer HealthCare Pharmaceuticals, Inc., was approved by the FDA in 1993 for use in ambulatory MS patients to reduce the frequency of episodes of relapsing symptoms. This drug is made from one of the naturally occurring interferons, which is a type of protein. It is taken as a subcutaneous (under the skin) injection every other day. Patients and others can get additional product information by calling BETAPLUS at 800-788-1467.

Avonex (interferon beta 1-a), manufactured by Biogen, Inc., was approved by the FDA in 1996 for the treatment of relapsing-remitting forms of multiple sclerosis, and may reduce the frequency of attacks. Avonex is taken once a week as an intramuscular (into the muscle) injection. For more information about Avonex, contact 800-456-2255.

Copaxone (glatiramer acetate), manufactured by Teva Pharmaceuticals Industries, Ltd., was approved by the FDA in 1996 to reduce the number of clinical exacerbations in relapsing-remitting multiple sclerosis. It has also been approved for patients who have MRI features that are consistent with MS and are experiencing a first clinical episode. Copaxone is a synthetic protein that simulates a protein component of myelin that insulates nerve fibers in the brain and spinal cord. It is delivered as a daily subcutaneous injection. To learn more about Copaxone, contact Teva's Shared Solutions Program at 800-877-8100.

Novantrone (mitoxantrone) manufactured by EMD Serono, Inc., was approved by the FDA in 2000 for reducing frequency of relapses and/or neurologic disability in patients with several forms of advanced or chronic multiple sclerosis. Novantrone had earlier been approved for treating certain types of cancer. This was the first case in which an anticancer drug was approved for treatment of MS. Novatrone belongs to a group of medicines called antineoplastics, which suppresses the activity of T-cells, B-cells, and macrophages that are believed to lead the attack on the myelin sheath. Novantrone is taken four times a year by an IV infusion in a medical facility.

Some patients treated with Novantrone may develop heart problems that can be very serious. The risk of heart disease increases with cumulative doses. For this reason, the professional labeling and patient information recommend that physicians closely monitor their patients receiving Novantrone. For more information about Novatrone, call 888-275-7376.

Rebif (interferon beta 1-a), manufactured by EMD Serono, Inc. was approved by the FDA in 2002 for MS patients with relapsing forms to reduce the frequency of exacerbations and to delay the occurrence of physical disability. Rebif is given as a subcutaneous injection three times a week. For more information about Rebif, contact MS LifeLines at 877-447-3243.

Tysabri (natalizumab), manufactured by Bioden Idec and Elan Pharmaceuticals, Inc., was
approved by the FDA in 2006 for the treatment of relapsing forms of multiple sclerosis
to lessen the amount of clinical exacerbations and progression of physical disability.
Tysabri is not meant to be used in combination with another disease modifying therapy.
Tysabri was originally approved by the FDA in 2004. However, the drug was later
withdrawn from the market after three patients developed progressive multifocal
leukoencephalopathy (PML), a serious and rare viral infection of the brain. Two of the
cases were fatal. In 2006, FDA again approved an application for resumed marketing
of Tysabri, with special restrictions. It is only available through a program known as
TOUCH. For information, call 800-456-2255.

Extavia (interferon beta-1b), by Novartis Pharmaceuticals Corporation, was approved by the FDA in 2009 to reduce the number of flare-ups in relapsing forms of MS. It has also been approved for patients who are experiencing a first clinical episode and have MRI features that are consistent with that of multiple sclerosis. Extavia is taken every other day as a subcutaneous injection. For more information about Extavia, call Extavia Go Program at 866-398-2842.

Gilenya (fingolimod), manufactured by Novartis Pharmaceuticals Corporation, was approved by the FDA in 2010 for adults with relapsing types of multiple sclerosis to reduce the frequency of flare-ups and delay the accumulation of physical disability. Gilenya is a sphingosine 1-phosphate receptor module. This medication is believed to act by retaining lymphocytes, a type of white blood cell, in the lymph nodes. This helps reduce inflammatory damage to nerve cells by preventing lymphocytes from crossing the blood-brain barrier into the central nervous system. Gilenya is a capsule taken orally once a day. For more information about Gilenya, call 800-445-3692.

The drug Baclofen, infused through a surgically implanted pump, is manufactured by Medtronic and used for treatment of severe spasticity associated with multiple sclerosis. It is thought that infusion of the drug directly into the spinal space, rather than oral administration, may relieve spasticity and may improve muscle tone for longer periods of time. For more information, call 800-328-0810

Investigational Therapies

Information on current clinical trials is posted on the Internet at www.clinicaltrials.gov. All studies receiving U.S. government funding, and some supported by private industry, are posted on this government website.

For information about clinical trials being conducted at the NIH Clinical Center in Bethesda, MD, contact the NIH Patient Recruitment Office:

Tollfree: (800) 411-1222
TTY: (866) 411-1010
Email: prpl@cc.nih.gov

For information about clinical trials sponsored by private sources, contact:
www.centerwatch.com

Organizations related to Multiple Sclerosis

References

TEXTBOOKS
Hauser SL, et al. Multiple sclerosis and other demyelinating diseases. In: Fauci AS, et al., eds. Harrison's Principles of Internal Medicine. 14th ed. New York, NY; McGraw-Hill Companies; 1998:2409-2419.

Silberberg DH. The demyelinating diseases. In: Wyngaarden JB, et al., eds. Cecil Textbook of Medicine. 19th ed. Philadelphia, PA; W.B. Saunders Company; 1990:2196-2200.

JOURNAL ARTICLES
Confavreux C, et al. Vaccinations and the risk of relapse in multiple sclerosis. N Engl J Med. 2001;344:319-26.

Ascherio A, et al. Hepatitis B vaccination and the risk of multiple sclerosis. N Engl J Med. 2001;344:327-32.

Weinstein A, et al. Neuropsychologic status in multiple sclerosis after treatment with glatiramer. Arch Neurol. 1999;56:319-324.

Tselis AC, et al. Multiple sclerosis: therapeutic update. Arch Neurol. 1999;56:277-280.

Jansen M, et al. Interferon response heterogeneity: activation of a pro-inflammatory response by interferon alpha and beta. A possible basis for diverse responses to interferon beta in MS. J Leukoc Biol. 1999;65:439-443.

Kastrukoff LF, et al. Natural killer cells in relapsing-remitting MS: effect of treatment with interferon beta-1b. Neurology. 1999;52:351-359.

Sriram S, et al. Chlamydia pneumoniae infection of the central nervous system in multiple sclerosis. Ann Neurol. 1999;46:6-14. Comment in: Ann Neurol. 1999;46:4-5.

Achiron A, et al. Intravenous immunoglobulin treatment in multiple sclerosis: effect on relapses. Neurology. 1998;50:398-402.

Cross AH, et al. Antibodies to beta-interferons in multiple sclerosis: can we neutralize the controversy? Neurology. 1998;50:1206-1208.

Rothwell PM, et al. Doctors and patients don't agree: cross sectional study of patients' and doctors' perceptions and assessments of disability in multiple sclerosis. BMJ. 1997;314:1580-1583.

Samkoff LM, et al. Amelioration of refractory dysesthetic limb pain in multiple sclerosis by gabapentin. Neurology. 1997;49:304-305.

Rudick RA, et al. Management of multiple sclerosis. New Eng J Med. 1997;337:1604-1611.

Millefiorini E, et al. Randomized placebo-controlled trial of mitoxantrone in relapsing-remitting multiple sclerosis: 24-month clinical and MRI outcome. J Neurol. 1997; 244:153-159.

Sadovnick AD. Depression and multiple sclerosis. Neurology. 1996;46:628-632.

Gonsette RE. Mitoxantrone immunotherapy in multiple sclerosis. Mult Scler. 1996;1:329-332.

Lublin FD, et al. Defining the clinical course of multiple sclerosis: results of an international survey. Neurology. 1996;46:907-911.

Cella DF, et al. Validation of the functional assessment of multiple sclerosis quality of life instrument. Neurology. 1996;47:129-139.

Bever CT, et al. Treatment with oral 3,4 diaminopyridine improves leg strength in multiple sclerosis patients: results of a randomized, double-blind, placebo-controlled, crossover trial. Neurology. 1996;47:1457-1462.

De Castro S, et al. Noninvasive assessment of mitoxantrone cardiotoxicity in relapsing remitting multiple sclerosis. J Clin Pharmacol. 1995;35:627-632.

Kidwell EP, et al. Treatment of multiple sclerosis with hyperbaric oxygen. Results of a national registry. Arch Neurol. 1991;48:195-199.

Ehrlich GD, et al. High dose oral baclofen: experience in patients with multiple sclerosis. Neurology. 1991;41:335-343.

Hinderer SR. The supraspinal anxiolytic effect of baclofen for spasticity. Am J Med Rehabil. 1990;69:254-258.

Penn RD, et al. Intrathecal baclofen for severe spasticity. New Eng J Med. 1989;320:1517-1521.

INTERNET
Online Mendelian Inheritance in Man (OMIM). The Johns Hopkins University. Multiple Sclerosis, Susceptibility to; MS. Entry No: 126200. Last Edited February 13, 2012. Available at: http://www.ncbi.nlm.nih.gov/omim/. Accessed February 27, 2012.

Multiple Sclerosis. National Multiple Sclerosis Society. http://www.nationalmssociety.org/about-multiple-sclerosis/what-we-know-about-ms/treatments/index.aspx. Accessed April 2, 2012.

Report last updated: 2012/03/29 00:00:00 GMT+0