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Central pontine myelinolysis (CPM), also known as Osmotic demyelination syndrome or Central pontine demyelination, is a neurological disease caused by severe damage of the myelin sheath of nerve cells in the brainstem, more precisely in the area termed the ''pons'', predominately of iatrogenic etiology. It is characterized by acute paralysis, dysphagia (difficulty swallowing), and dysarthria (difficulty speaking), and other neurological symptoms. It can also occur outside the pons. The term "osmotic demyelination syndrome" is similar to "central pontine myelinolysis", but also includes areas outside the pons. Central pontine myelinolysis presents most commonly as a complication of treatment of patients with profound, life-threatening hyponatremia (low sodium). It occurs as a consequence of a rapid rise in serum tonicity following treatment in individuals with chronic, severe hyponatremia who have made intracellular adaptations to the prevailing hypotonicity. Hyponatremia should be corrected at a rate of no more than 8-12 mmol/L of sodium per day to prevent central pontine myelinolysis.〔 Although less common, it may also present in patients with a history of chronic alcoholism or other conditions related to decreased liver function. In these cases, the condition is often unrelated to correction of sodium or electrolyte imbalance. ==Pathophysiology== The currently accepted theory states that the brain cells adjust their osmolarities by changing levels of certain osmolytes like inositol, betaine, and glutamine in response to varying serum osmolality. In the context of chronic low plasma sodium (hyponatremia), the brain compensates by decreasing the levels of these osmolytes within the cells, so that they can remain relatively isotonic with their surroundings and not absorb too much fluid. The reverse is true in hypernatremia, in which the cells increase their intracellular osmolytes so as not to lose too much fluid to the extracellular space. With correction of the hyponatremia with intravenous fluids, the extracellular tonicity increases, followed by an increase in intracellular tonicity. When the correction is too rapid, not enough time is allowed for the brain's cells to adjust to the new tonicity, namely by increasing the intracellular osmoles mentioned earlier. If the serum sodium levels rise too rapidly, the increased extracellular tonicity will continue to drive water out of the brain's cells. This can lead to cellular dysfunction and the condition of central pontine myelinolysis, where the myelin sheath surrounding the nerve axons becomes damaged in the part of the brain called the pons., 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「Central pontine myelinolysis」の詳細全文を読む スポンサード リンク
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