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Multiple system atrophy (MSA) is a degenerative neurological disorder. MSA is associated with the degeneration of nerve cells in specific areas of the brain. This cell degeneration causes problems with movement, balance, and autonomic functions of the body such as bladder control or blood-pressure regulation. The cause of MSA is unclear and no specific risk factors have been identified, although research indicates that a prion form of the alpha-synuclein protein may be the cause of the disease. Approximately 55% of MSA cases occur in men, with typical age of onset in the late 50s to early 60s. MSA often presents with some of the same symptoms as Parkinson's disease. However, those with MSA generally show minimal if any response to the dopamine medications used for Parkinson's disease. MSA is distinct from the more common syndrome multisystem proteinopathy. It should also not be confused with the two terms multiple organ dysfunction syndrome or multiple organ system dysfunction syndrome, which are the more modern and accurate terms for multiple organ failure or multiple organ system failure, which is an often-fatal complication of septic shock (due to severe sepsis, a systemic infection that has spread to the bloodstream) or other very severe illnesses or injuries. ==Classification== Many terms have historically been used to refer to this disorder, based on the predominant systems presented. These include olivopontocerebellar atrophy (OPCA), Shy–Drager syndrome (SDS), and striatonigral degeneration (SND), which were once considered to be separate disorders. These terms and their distinctions have been dropped in recent (1996 onwards) medical usage and replaced with MSA and its subtypes, but are helpful to understanding the older literature about this disease: The current terminology and diagnostic criteria for the disease were established at a 2007 conference of experts on the disease and set forth in the "Second consensus statement on the diagnosis of multiple system atrophy." The Second Consensus Statement defines two categories of MSA, based on the predominant symptoms of the disease at the time of evaluation. These are: * MSA with predominant parkinsonism (MSA-P) MSA-P is defined as MSA where extrapyramidal features predominate. The term striatonigral degeneration, parkinsonian variant, is sometimes used for this category of MSA. * MSA with cerebellar features (MSA-C). MSA-C is defined as MSA where cerebellar ataxia predominates. It is sometimes termed sporadic olivopontocerebellar atrophy. 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 system atrophy」の詳細全文を読む スポンサード リンク
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