Biology 103
2001 Second Web Report
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Multiple sclerosis (MS) is a chronic, unpredictable and incurable disease that randomly attacks the central nervous system (CNS), namely the brain and spinal cord. The CNS is a complex network of nerves that transmit and receive messages from one part of the body to another. Each nerve in the system is covered with a fatty substance called myelin. In a healthy central nervous system, this myelin serves as insulation and protection for each nerve, and it aids in the transmission of signals from the brain (1). MS symptoms begin to appear when this myelin becomes inflamed or begins to deteriorate. When myelin is destroyed, it is replaced with hard clusters of sclerotic tissue, known as plaques, and these will be scattered throughout the CNS (2). Once myelin has been replaced with the plaques the signals being sent through the CNS become altered and sometimes stopped, preventing body functions from occurring. Myelin can be restored and rebuilt, but this process does not occur fast enough to negate the rapid deterioration. Given the complexity and size of the CNS, as well as the pace of the deterioration of myelin, causes and symptoms of MS vary widely in both type and severity.

There is no one single cause for the disease, and though some studies have found some genetic factors that make some people more susceptible to MS, no study has found it to be directly inherited. The disease has been found to be more common in Caucasian and the female to male ratio is more than 2 to 1 (3). The course of the disease varies for each person, and the symptoms that one may experience can fluctuate from day to day, month to month, or even year to year (4). Though there is no definitive way as of yet to determine how an individual's condition will progress, the disease has been classified into four main types to better ascertain what can be expected through the course of the disease.

The four basic types of MS are: Relapsing-remitting, Primary progressive, Secondary progressive, and Progressive relapsing (1). Relapsing-remitting, the least severe form, is characterized by acute attacks, known as exacerbations, which are often followed by full recovery; with this form, the disease does not worsen between episodes. With a Primary progressive form, there is a gradual but steady progression, making it difficult to discern relapses or remissions. The Secondary progressive form begins as relapsing-remitting but over time exacerbations can be quantified at a variable rate. The final type of MS, Progressive relapsing, is the most severe because it has a steady progression of disability, in which exacerbations are not always followed by recovery. As a result of the various types of MS and because there are several other disorders that mimic MS, a doctor must be critical when diagnosing the disease.

There is no single diagnostic test that definitively answer the question: do I have MS? Because of conditions like brain infection and inflammation of blood vessels, which mimic MS, doctors have established a set of criteria to accurately diagnose the disease. The accepted criteria include: an onset occurring between 10 and 60 years of age, signs indicating plaques in the CNS, evidence of CNS disease after a neurological exam, an MRI scan that shows plaques, and a course that follows a pattern of either multiple exacerbations in a short amount of time or signs of a progressive deterioration over the course of several months (5). A magnetic response imaging (MRI) can show scar tissue deep within the brain or spinal cord, and though there may be other causes for this scar tissue, when the findings are coupled with the other criteria, these other causes can be ruled out. A spinal tap, which extracts cerebrospinal fluid, can also be used to detect MS because it looks for abnormal cells and bacteria in the protein and glucose rich fluid (6). Once a patient has been diagnosed with MS, doctors are better able to detect the common symptoms of the disease.

Symptoms of MS begin to occur when the myelin breaks down, leaving the nerve unprotected and unable to correctly function. Because this deterioration can occur in any part of the CNS, symptoms experienced are relative to the area affected. In general, demyelination of nerves that work with muscles results in problems with movement, for example, loss of balance and lack of coordination. While the demyelination of nerves that are responsible for sensory information leads to disturbances in sensation, for example, numbness, tingling, and blurred vision (3). As the disease progresses, other symptoms include heat sensitivity and possibly paralysis. As more symptoms occur, doctors are able to classify their patients' symptoms into three categories.

The three categories of symptoms are: Primary, Secondary, and Tertiary. Primary symptoms are the direct result of demyelination, including tremors, bladder dysfunction, numbness, and loss of balance. Secondary symptoms are the result of primary symptoms, for example, paralysis can lead to bed sores and bladder dysfunction can lead to urinary tract infections. Tertiary symptoms are the psychological, social, and vocational ramifications from the other two, for example, depression. The uncertainty of a diagnosis and the unpredictability of MS can cause prolonged stress which leads to frustration, anger, despair, and depression. Many of these symptoms are treatable with medication and various other therapies that will serve to lessen the degree of discomfort in patients.

The current treatments and therapies designed for the Primary symptoms, though not able to cure MS, help manage symptoms like exacerbations and control disease progression (7). By attacking some of the more debilitating symptoms, these treatments stand to prevent unnecessary complications and minimize disability. Until recently, there were no medications that could promise to slow the progression of MS, and since 1993, the Food and Drug Administration has approved three medications that promise to do just this (8). These medications have been shown to lessen the frequency and severity of exacerbations, reduce plaque development, and thus slow the progression of the disease. Because the ultimate consequence of the disease is that cells from the immune system enter the brain or spinal cord and damage the myelin, one other medication that is given to MS sufferers is the anticancer drug, Cytoxan, which works by suppressing the immune system. Cytoxan keeps patients' white blood cells from attacking the CNS, consequently reducing exacerbations. Side effects of using this drug include increased weakness, fatigue, and a decreased white blood count which leads to higher susceptibility to infection (9). With effective medications and other treatments, sufferers of MS can better take control of their lives and health; and with modern medicine and technology, they can live 90-95% of the normal life span (2).

Multiple sclerosis is a devastating disease because people live with its unpredictable physical and emotional effects for the rest of their lives. Emotional impacts of this disease, like depression and stress, should also be examined further because of their ability to mimic early MS symptoms and aggravate the disease over the years. Though the medical world is making great strides to attain further understanding of the causes and treatments for MS, the complexity of the CNS and myriad symptoms and forms of the disease present challenges and questions that can only be solved and answered through more extensive research.

WWW Sources

2)Frequently asked questions about MS,

3)Types of Symptoms,

4)MS Symptoms,

5)How is MS Diagnosed,

6)Spinal Tap Information,

7)Treatments for MS,

8)Medications for MS,

9)Cytoxan Information,

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