Optic nerves and subcortical white matter are demyelinated. Patients present with visual changes, mental confusion, severe vomiting, severe acidosis, and an unexplainable anion gap. CPM is associated with a clinical syndrome of declining mental status, quadriparesis and cranial nerve abnormalities. Recovery is rare. Excessively rapid correction of hyponatremia is thought to lead to an osmotic instability in the pons with marked edema and secondary demyelination.
Macrophages containing digested myelin are a prominent pathologic feature.
Superior vermis is most often affected with loss of Purkinje cells and resultant ataxia. May be a folic acid problem.