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Transcript
1 Multiple Sclerosis A. Introduction MS is thought to be an auto-immune disease that affects the central nervous system (CNS). The CNS consists of the brain, spinal cord, and the optic nerves. Surrounding and protecting the nerve fibers of the CNS is a fatty tissue called myelin, which helps nerve fibers conduct electrical impulses. Multiple sclerosis was first recognized as a disorder in the late nineteenth century, but it wasn’t until the nineteen sixties that researchers began to understand some of the disease processes that cause symptoms and long-term disability in multiple sclerosis. These processes seemed to involve inflammation and the loss of myelin, a protective covering around nerve fibers. The first standard guidelines for the diagnosis of multiple sclerosis and a disability rating scale were also established in the nineteen sixties, setting the stage for controlled research to test new therapies. In the late sixties, the first controlled clinical trials for multiple sclerosis therapy showed that treatment with adrenocorticotropic hormone speeded recovery from an attack. While this therapy helped to reduce inflammation during the acute symptoms of an attack, it did not slow the progression of multiple sclerosis. Multiple Sclerosis (MS) is an autoimmune disease, whereby the body destroys its own myelin (protective coating surrounding the nerves in the central nervous system). Because the myelin is damaged, messages moving along the nerve are transmitted more slowly or not at all. Areas of damaged myelin can be viewed through Magnetic Resonance Imaging (MRI) scanning and are known as plaques. These plaques, or sites of damage, can cause MS symptoms. At this time, it is not known what causes MS. It is known that MS affects approximately one in one thousand people, usually in early adulthood. There are two main classifications of the disease: progressive and relapsing remitting. Within the first classification there are two more differentiations, primary progressive and secondary progressive. HHROESELARE – AHOUTMAN BELGIUM 8/05/2017 version 1 2 B. Prevalence of Multiple sclerosis MS is predominately a disease of temperate latitudes and of the western hemisphere. Principally, it is a disease prevalent in Europe, North America, Australia and New Zealand. Although MS is found in Japan, China and some other temperate, eastern countries, it is very much rarer than it is in the West. Regions north of 40 degrees latitude have a markedly higher incidence than those souths of this divide. Within Europe, Scandinavia, The British Isles, the Low Countries and Germany have very high rates. Canada, northern USA and New Zealand have an equivalently high prevalence. Within these areas, certain localities such as the border areas of Scotland (203 per 100,000), Crowsnest Pass in Alberta, Canada (217 per 100,000), the northern-most province of Sweden (253 per 100,000) and others have been found to have extremely high incidences of the disease. Unequal distribution of multiple sclerosis around the world. HHROESELARE – AHOUTMAN BELGIUM 8/05/2017 version 1 3 Worldwide prevalence of MS Primary Progressive MS (PPMS) is characterized by a slow and continuous deterioration from the beginning, while Secondary Progressive MS (SPMS) becomes progressive following a course of attacks and recoveries. Within the second classification there are also two differentiations, benign and relapsing remitting. People with benign MS suffer the least amount of disability and seem to recover fully from their attacks, while people with relapsing remitting MS (RRMS) do not recover as well from attacks but do enjoy remissions. The percentage of people suffering from these types of MS at any one time breaks down to 10 per cent benign MS, 40 per cent RRMS, 10 per cent PPMS, and 40 per cent SPMS (M.S. Freedman, personal communication, November 21, 2002). HHROESELARE – AHOUTMAN BELGIUM 8/05/2017 version 1 4 C. The Nerve Function The CNS nerves are made up of single neurons that are responsible for carrying messages from the brain. Each neuron is made up of a nucleus, dendrites, axon, cell body and a covering called the myelin sheath. The nervous system contains millions of nerve cells, called neurons. Neurons are highly specialised to transmit messages from one part of the body to another. All neurons have a cell body and one or more fibres. These fibres vary in length from microscopic to over 1 metre. There are two different kinds of nerve fibres: fibres that carry information towards the cell body, called dendrites, and fibres that carry information away from it, called axons. Nerves are tight bundles of nerve fibres. The neurons can be divided into three types: Sensory neurons, which pass information about stimuli such as light, heat or chemicals from both inside and outside the body to the central nervous system Motor neurons, which pass instructions from the central nervous system to other parts of the body, such as muscles or glands Association neurons, which connect the sensory and motor neurons HHROESELARE – AHOUTMAN BELGIUM 8/05/2017 version 1 5 The neurons carry messages in the form of electrical signals called nerve impulses. To create a nerve impulse, the neurons have to be excited. Stimuli such as light, sound or pressure all excite your neurons, but in most cases, chemicals released by other neurons will trigger a nerve impulse. Although, millions of neurons that are densely packed within the nervous system, they never actually touch. So when a nerve impulse reaches the end of one neuron, a neurotransmitter* chemical is released. It diffuses from this neuron across a junction and excites the next neuron. (Neurotransmitter = Chemicals released by one neuron to excite a neighbouring one e.g. Acetylcholine, Noradrenalin, Dopamine, Endorphin, Serotonin, GABA, GLUTAMATE… ) Cranial Nerves HHROESELARE – AHOUTMAN BELGIUM 8/05/2017 version 1 6 The Nerve System The CNS (the brain, spinal cord and optic nerves) is made up of several different components: The gray matter contains the cell bodies of the nerves. The white matter contains nerve fibers coated with myelin. The supporting cells form a supporting network. HHROESELARE – AHOUTMAN BELGIUM 8/05/2017 version 1 7 THE PERIPHERAL NERVOUS SYSTEM (PNS) nerve cells perform two major functions: Sensory neurons collect information about the body's internal and external environment and convey it to the CNS. Motor neurons carry instructions from the CNS to the glands and muscles. The Spinal chord HHROESELARE – AHOUTMAN BELGIUM 8/05/2017 version 1 8 HHROESELARE – AHOUTMAN BELGIUM 8/05/2017 version 1 9 - Myelin The myelin sheath protects the nerve (axon) from damage. In MS, the bodies own defences (t-cells) attack the myelin, the substance that protects the nerve fibers of the brain, optic nerves, and spinal cord. Myelin not only protects nerve fibers, but makes their job possible. When myelin or the nerve fiber is destroyed or damaged, the ability of the nerves to conduct electrical impulses to and from the brain is disrupted, and this produces the various symptoms of MS. Myelin is also a substance rich in protein and lipids (fatty substances) that forms layers around the nerve fibers and acts as insulation. The nerve can be likened to an electrical cable; the axon, or nerve fiber that transmits the nerve impulse is like the wire, and the myelin sheath is like the insulation around the wire. Myelin is present in both the central nervous system (CNS) and the peripheral nervous system (PNS), but it is only the destruction of CNS myelin that produces the symptoms of MS. HHROESELARE – AHOUTMAN BELGIUM 8/05/2017 version 1 10 In MS, myelin is lost in multiple areas, leaving scar tissue called sclerosis. These damaged areas are also known as plaques or lesions. Sometimes the nerve fiber itself is damaged or broken. D. What Causes Multiple Sclerosis? Many different causes have been proposed and investigated but as yet the cause of multiple sclerosis remains elusive. There are however, some leading contenders by way of theories although none can fully explain how multiple sclerosis develops and some theories actually seem to fly in the face of others! A pathogen as the cause of multiple sclerosis has been the leading theory since multiple sclerosis was first documented. Considering the number of diseases which are caused by pathogens, it is easy to see why this theory has been foremost. Although there is some research, such as that on Epstein Barr and the Herpes virus, which shows some statistical correlation, no virus or other pathogen has ever been isolated as the cause of multiple sclerosis. The role of genetics as the cause of multiple sclerosis has not been established, however, there is strong evidence that there is a genetic component to the disease. What this means is that the genes the patient have inherited may play a role in making him/her more susceptible to developing multiple sclerosis. They do not, however, mean that it will definitely develop the disease. HHROESELARE – AHOUTMAN BELGIUM 8/05/2017 version 1 11 Some people with MS develop few symptoms, but for others the disease and society’s interactions with them lead to problems affecting all aspects of their lives. The disease often has an impact upon the family. Many people with MS need to make extensive use of primary and secondary health care, and social services. Because MS is twice as common in women as men, its been suggested that hormonal factors predispose women to develop MS. This theory hasn't been confirmed. Women however do not have more severe MS than men. No one has been able to prove conclusively that there significantly more women than men with MS. Although most researchers conclude there are more women than men suffering from autoimmune diseases. The researchers found that symptoms of MS in pregnant women were reduced during the second and third trimesters — a time when a woman's body contains high levels of estrogens. A research study on scleroderma an autoimmune disease that affects three times more woman than men suggests one hypothesis to explain this discrepancy. Stray cells from foetuses are transferred into a woman's body during pregnancy and can remain for decades. The transfers go both ways, cells from the mother's body enter the developing foetus. Most women have cells from their mother and their children. It is speculated that when these cell relate in precisely the wrong way it increases the risk of autoimmune disease. A study of Barrhead Alberta (Switzerland) and surrounding area with an MS rate of 196/100,000 population has an equal number of women to men with MS (In Switzerland 73% of MS cases are women). Women are almost twice as likely to develop MS as men; it is difficult to prove that more women than men have MS. Women go to doctors more than men. Men tend to ignore the symptoms whereas women do not. Most researchers believe that women face a much higher risk of developing autoimmune diseases such as MS and Lupus. They speculate it may be linked to hormones that may modulate susceptibility. HHROESELARE – AHOUTMAN BELGIUM 8/05/2017 version 1 12 E. Diagnoses of MS: A multiple sclerosis diagnosis usually begins with a complete neurological examination and a discussion of the full medical history with the healthcare provider. He or she will need an overall view of the health, including the symptoms and when they started. However, it may still be difficult, if not impossible, to confirm the presence of multiple sclerosis without using certain procedures. Many healthcare providers use magnetic resonance imaging (MRI) to help diagnose MS at an early stage by providing a detailed picture of the brain. Early diagnosis means that treatment can begin right away, rather than waiting for continued relapses to confirm diagnosis. Other tests for multiple sclerosis may include: Evoked potential tests, which measure how a person’s nervous system responds to certain stimulation Spinal tap, which checks spinal fluid for signs of multiple sclerosis F. Symptoms of MS: Numbness or tingling in the legs, arms, face, or extremities Impaired vision in one or both eyes, including: o Blurred vision o Double vision o Loss of vision o Changes in colour perception o Pain around the affected eye Fatigue Dizziness Muscle stiffness and spasms Muscle weakness Poor coordination or falling Trouble walking or maintaining balance Paralysis in one or more limbs HHROESELARE – AHOUTMAN BELGIUM 8/05/2017 version 1 13 Bladder problems including: o Urgency o Hesitancy o Incomplete emptying o Incontinence Bowel problems, including constipation or, less commonly, incontinence Sexual dysfunction Slurred speech Difficulty swallowing Forgetfulness, memory loss, or confusion Trouble concentrating or solving problems Depression Other psychiatric disorders Euphoria or inappropriate emotional responses Factors that may trigger or worsen symptoms include: Internal or external heat, including: o Hot weather o Hot baths or showers o Fever Overexertion Infection G. Treatment of MS Currently, there is no cure for MS, but there are treatments for the conditions associated with MS. Early multiple sclerosis diagnosis is very important because the healthcare provider may want to begin MS treatment at that time, rather than wait until the disease may have progressed. There are two ways to treat MS. One is to treat MS symptoms. The other is to treat the underlying disease to reduce the number of flare-ups and slow the progression of physical disability. Choosing the right multiple sclerosis treatment is an important step toward taking control of the multiple sclerosis. Modern medicine has failed to find an effective treatment for the overall condition although various drugs give short-term relief of different symptoms. HHROESELARE – AHOUTMAN BELGIUM 8/05/2017 version 1 14 Valium or similar tranquilizers are used to treat muscle spasms but can have the associated side effect of addiction, and doses often have to be increased sharply over time. MS patients who use Cannabis report a soothing of the painful muscle spasms and improved muscle coordination. Some are able to walk unaided when they were previously unable to do so. It also helps blurred vision, tremors, loss of bladder control, insomnia and depression. During symptomatic attacks, patients may be hospitalized and are typically given high doses of intravenous corticosteroids, such as methylprednisolone, to end the attack sooner and leave fewer lasting deficits. For relapsing-remitting MS, there are 5 FDA approved drugs available for treatment. There are interferons: Interferon beta-1a (Avonex) or beta-1b (Betaferon). A fourth medication is glatiramer acetate (Copaxone), a mixture of polypeptides which may protect important myelin proteins by substituting itself as the target of immune system attack. The final medication, mitoxantrone is effective but is limited by cardiac toxicity. Most people with multiple sclerosis eventually become involved with the rehabilitation process, the goals of which are to restore functions that are essential to Activities of Daily Living (ADL). While different rehabilitation therapies may focus on only one specific function, most comprehensive rehabilitation programs provide assistance, instruction, or advice for nearly all of a patient's needs. Rehabilitation programs may be managed in an inpatient or an outpatient setting, or in the individual's home. HHROESELARE – AHOUTMAN BELGIUM 8/05/2017 version 1 15 Conclusion Multiple sclerosis as an autoimmune disease (which means that the body's immune system mistakenly attacks itself, targeting the cells, tissues, and organs) is probably the most widely accepted theory among the scientific community at the present time. MS is a chronic, long-term condition that affects the central nervous system, which includes the brain and spinal cord. Making the diagnosis of MS as quickly and accurately as possible is important because: People who are living with frightening and uncomfortable symptoms want and need to know the reason that they feel this way. This can help them begin to adjust to their diagnosis and relieves them of worries about other diseases such as cancer. Since we now know that permanent damage can occur even in the earliest stages of multiple sclerosis, it is important to confirm the diagnosis so that MS treatment can begin as early as possible. MS is an autoimmune disease; it is thought that the immune system either mistakenly attacks the myelin believing it to be 'foreign substance', or, that the immune system attacks some other, unknown tissue or organism and the myelin gets damaged in the process. MS is an inflammatory demyelinating condition of the central nervous system (CNS) that is generally considered to be autoimmune in nature. White matter tracts are affected, including those of the cerebral hemispheres, infratentorium, and spinal cord. MS lesions, known as plaques, may form in CNS white matter in any location; thus, clinical presentations may be diverse. Continuing lesion formation in MS often leads to physical disability and, sometimes, to cognitive decline. Scientists now believe that multiple sclerosis results from an abnormal response to an infection or an environmental factor. Numerous studies show that genetics may play a role in the development of multiple sclerosis, but are not the sole cause of the disease.The course of illness is different for each person. Even when there are no symptoms, there is progression of damage to the central nervous system over time. Multiple sclerosis may affect 2.4 million people worldwide… HHROESELARE – AHOUTMAN BELGIUM 8/05/2017 version 1 16 HHROESELARE – AHOUTMAN BELGIUM 8/05/2017 version 1