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)