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What Is Multiple Sclerosis?
Multiple sclerosis (MS) is a disease in which the nerves of the central nervous system (CNS) degenerate. The CNS is made up of the brain and spinal cord. They process information from our environment and control voluntary muscle movements to allow the body to do certain things. This neural system works efficiently, unless there is a disease process affecting the pathways in the spinal cord and brain. Multiple sclerosis is one of the diseases that can affect these pathways and results in the destruction of myelin, a covering or insulation for nerves, that improves the conduction of impulses along the nerves and also is important for maintaining the health of the nerves. The demyelination (also known as plaques) disrupts the transmission of information in the CNS and leads to the symptoms seen in multiple sclerosis.
Who Can Get Multiple Sclerosis?
Globally, the median estimated prevalence of multiple sclerosis is 30 per 100,000 of population. 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.
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, suspecting 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. Definitive proof of this viral theory is still lacking. However, the attack by the body's immune system on the neural tissues that it is supposed to protect is based on reasonable evidence. This attack is termed autoimmunity, thus making multiple sclerosis an autoimmune disease.
When Multiple Sclerosis Attacks
In multiple sclerosis, an agent such as a virus or foreign antigen, in theory, may alter or interact with the immune system so that the immune system perceives myelin as an intruder and attacks it. Inflammation occurs and causes myelin to disappear. Consequently, the electrical impulses that travel along the nerves decelerate, that is, become slower. In addition, the nerves themselves are damaged. 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. 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.
Is Multiple Sclerosis Inherited?
Although its role is unclear, genetics may play a role in multiple sclerosis. 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.
What Are the Types of Multiple Sclerosis?
In some ways, each person with multiple sclerosis lives with a different illness. Although nerve damage is always involved, the pattern is unique for each individual who has MS.
Although individual experiences with MS vary widely, doctors and researchers have identified several major types of MS. The categories are important because they help predict disease severity — and response to treatment. We'll discuss each of these categories presented on the following slides.
Relapsing-Remitting (RR) MS
About 65%-80% of individuals begin with relapsing-remitting MS (RR-MS). This is the most common type of MS and is characterized by unpredictable acute attacks, called "exacerbations," with worsening of symptoms followed by full, partial, or no recovery of some function. These series of attacks are followed by complete or partial disappearance of the symptoms (remission) until another attack occurs (relapse). It may be weeks to decades between relapses.
Primary-Progressive (PP) MS
Primary-progressive MS (PP-MS) is a type of MS characterized by a gradual but steady progression of disability, without any obvious relapses and remissions. This form of disease occurs in just 15% of all people with MS, but it is the most common type of MS in people who develop the disease after the age of 40.
Secondary-Progressive (SP) MS
Secondary-progressive MS (SP-MS) initially begins with a relapsing-remitting course, but later evolves into progressive disease. The progressive part of the disease may begin shortly after the onset of MS, or it may occur years or decades later. About 50% 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
Progressive-relapsing MS (PR-MS) is the least common form of the disease and is characterized by a steady progression in disability with acute attacks that may or may not be followed by some recovery. People with progressive relapsing MS initially appear to have primary progressive MS.
What Are the Symptoms of Multiple Sclerosis?
Symptoms of multiple sclerosis may be single or multiple and may range from mild to severe in intensity and short to long in duration. These include:
- Limb weakness, loss of coordination and balance
- Muscle spasms, fatigue, numbness, prickling pain
- Loss of sensation, speech impediment, tremors, or dizziness
- Bladder and bowel dysfunction
- Mental changes (decreased concentration, attention deficit, memory loss)
- Uncontrollable laughter and weeping
- Visual disturbances (blurred vision, color distortions, loss of vision in one eye, eye pain)
How Is Multiple Sclerosis Diagnosed?
Due to the broad range and subtleties of symptoms, multiple sclerosis may not be diagnosed for months to years after the onset of symptoms. Physicians, particularly neurologists, take detailed histories and perform complete physical and neurological examinations.
- Electrophysiological test
- Cerebrospinal fluid exam (spinal tap, lumbar puncture)
Collectively, these three tests help the physician in confirming the diagnosis of multiple sclerosis. For a definite diagnosis of multiple sclerosis, dissemination in time (at least two separate symptomatic events or changes on MRI over time) and in anatomical space (at least two separate locations within the central nervous system, which can be demonstrated by MRI or neurological exam) is usually required. Most physicians consult a neurologist to help obtain the definitive diagnosis of multiple sclerosis.
How Is Multiple Sclerosis Diagnosed?
On the left is a brain MRI of a 35-year-old man with relapsing remitting multiple sclerosis that reveals multiple lesions with high T2 signal intensity and one large white matter lesion. The right image shows the cervical spinal cord of a 27-year-old woman representing a multiple sclerosis demyelination and plaque (see arrow).
How Is Multiple Sclerosis Treated?
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; or
- 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).
Multiple Sclerosis Treatment
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, Orasone, Prednicen-M) or methylprednisolone (Medrol, Depo-Medrol), were widely used. However, since their effect on the immune system is non-specific (general) and they 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).
Multiple Sclerosis Treatment Medications
Since 1993, medications that alter the immune system, particularly interferons, have been used to manage multiple sclerosis.
Interferons for relapsing multiple sclerosis:
Other medications approved for relapsing multiple sclerosis:
- Glatiramer acetate (Copaxone)
- Natalizumab (Tysabri®)
- Mitoxantrone (Novantrone®)
- Fingolimod (Gilenya®)
How Are the Physical Manifestations of MS Treated?
There are numerous medications that are used to manage complications associated with multiple sclerosis. The following table (continued on the next slide) lists common complications, examples of drug and non-drug therapies, and comments about complications and/or management.
Physical Manifestations of MS Treated (continued)
Additional complications, examples of drug and non-drug therapies, and comments about complications and/or management are presented on this slide.
What Are the Future Directions for Managing Multiple Sclerosis?
There is a great deal of ongoing research in multiple sclerosis, and there continues to be a focus on the immune system in investigational therapies. In addition, scientists are trying to develop techniques that allow brain cells to generate new myelin or that prevent the death of nerves. Other promising approaches include the use of precursor (neuronal stem or progenitor) cells that could be implanted into the brain or spinal cord to repopulate areas of missing cells. Future therapy may involve methods designed to improve impulses traveling over the damaged nerves. Scientists also are exploring the effects of diet and other environmental factors on multiple sclerosis.
Multiple Sclerosis At A Glance
- Multiple sclerosis (MS) is a disease which progressively injures the nerves of the brain and spinal cord.
- Injury to the nerves in multiple sclerosis may be reflected by alterations of virtually any sensory or motor (muscular) function in the body.
- The cause of multiple sclerosis is unknown, but it has become widely accepted that genetic, immunological, and environmental factors play a role.
- The selection of drug treatment/therapy should be made after the patient with multiple sclerosis has been properly informed of drug efficacy, particular FDA-approved uses, administration routes, risks of adverse events, and methods to enhance tolerability and compliance.
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