A demyelinating condition affecting the PONS and characterized clinically by an acute progressive QUADRIPLEGIA; DYSARTHRIA; DYSPHAGIA; and alterations of consciousness. Pathologic features include prominent demyelination in the central PONS with sparing of axons and neurons. This condition is usually associated with systemic disorders such as HYPONATREMIA; chronic ALCOHOLISM; LIVER FAILURE; severe BURNS; malignant NEOPLASMS; hemorrhagic PANCREATITIS; HEMODIALYSIS; and SEPSIS. The rapid medical correction of hyponatremia has been cited as a cause of this condition. (From Adams et al., Principles of Neurology, 6th ed, pp1125-6)