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Multiple sclerosis (MS), also known as disseminated sclerosis or encephalomyelitis disseminata, is a demyelinating disease in which the insulating covers of nerve cells in the brain and spinal cord are damaged. This damage disrupts the ability of parts of the nervous system to communicate, resulting in a wide range of signs and symptoms,〔 including physical, mental,〔 and sometimes psychiatric problems. MS takes several forms, with new symptoms either occurring in isolated attacks (relapsing forms) or building up over time (progressive forms).〔 Between attacks, symptoms may disappear completely; however, permanent neurological problems often occur, especially as the disease advances.〔 While the cause is not clear, the underlying mechanism is thought to be either destruction by the immune system or failure of the myelin-producing cells. Proposed causes for this include genetics and environmental factors such as infections.〔〔 MS is usually diagnosed based on the presenting signs and symptoms and the results of supporting medical tests. There is no known cure for multiple sclerosis. Treatments attempt to improve function after an attack and prevent new attacks.〔 Medications used to treat MS, while modestly effective, can have adverse effects and be poorly tolerated. Many people pursue alternative treatments, despite a lack of evidence. The long-term outcome is difficult to predict, with good outcomes more often seen in women, those who develop the disease early in life, those with a relapsing course, and those who initially experienced few attacks.〔 Life expectancy is on average 5 to 10 years lower than that of an unaffected population.〔 Multiple sclerosis is the most common autoimmune disorder affecting the central nervous system. As of 2008, between 2 and 2.5 million people are affected globally with rates varying widely in different regions of the world and among different populations.〔 In 2013, 20,000 people died from MS, up from 12,000 in 1990. The disease usually begins between the ages of 20 and 50 and is twice as common in women as in men.〔 The name ''multiple sclerosis'' refers to scars (sclerae—better known as plaques or lesions) in particular in the white matter of the brain and spinal cord.〔 MS was first described in 1868 by Jean-Martin Charcot.〔 A number of new treatments and diagnostic methods are under development. ==Signs and symptoms== (詳細はautonomic, visual, motor, and sensory problems being the most common.〔 The specific symptoms are determined by the locations of the lesions within the nervous system, and may include loss of sensitivity or changes in sensation such as tingling, pins and needles or numbness, muscle weakness, very pronounced reflexes, muscle spasms, or difficulty in moving; difficulties with coordination and balance (ataxia); problems with speech or swallowing, visual problems (nystagmus, optic neuritis or double vision), feeling tired, acute or chronic pain, and bladder and bowel difficulties, among others.〔 Difficulties thinking and emotional problems such as depression or unstable mood are also common.〔 Uhthoff's phenomenon, a worsening of symptoms due to exposure to higher than usual temperatures, and Lhermitte's sign, an electrical sensation that runs down the back when bending the neck, are particularly characteristic of MS.〔 The main measure of disability and severity is the expanded disability status scale (EDSS), with other measures such as the multiple sclerosis functional composite being increasingly used in research. The condition begins in 85% of cases as a clinically isolated syndrome over a number of days with 45% having motor or sensory problems, 20% having optic neuritis, and 10% having symptoms related to brainstem dysfunction, while the remaining 25% have more than one of the previous difficulties.〔 The course of symptoms occurs in two main patterns initially: either as episodes of sudden worsening that last a few days to months (called relapses, exacerbations, bouts, attacks, or flare-ups) followed by improvement (85% of cases) or as a gradual worsening over time without periods of recovery (10-15% of cases).〔 A combination of these two patterns may also occur or people may start in a relapsing and remitting course that then becomes progressive later on.〔 Relapses are usually not predictable, occurring without warning.〔 Exacerbations rarely occur more frequently than twice per year.〔 Some relapses, however, are preceded by common triggers and they occur more frequently during spring and summer. Similarly, viral infections such as the common cold, influenza, or gastroenteritis increase their risk.〔 Stress may also trigger an attack. Women with MS who become pregnant experience fewer relapses; however, during the first months after delivery the risk increases.〔 Overall, pregnancy does not seem to influence long-term disability.〔 Many events have not been found to affect relapse rates including vaccination, breast feeding,〔 physical trauma, and Uhthoff's phenomenon.〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「multiple sclerosis」の詳細全文を読む スポンサード リンク
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