[A case of central pontine myelinolysis and extrapontine myelinolysis during rapid correction of hypernatremia].

A 69-year-old woman was admitted because of severe dehydration due to anorexia. Consciousness disturbance was found to be due to severe abnormalities of serum electrolyte balance, but recovered quickly by correcting the hyperosmolality. While the initial serum sodium value of 186 mEq/L was corrected to 139 mEq/L in 5 days, locked-in syndrome, bilateral hand tremor and tetraparesis appeared. Brain magnetic resonance imaging (MRI) revealed symmetrically high signal intensity areas on T2-weighted images and low signal intensity areas on T1-weighted images in central part of pons and bilateral middle cerebellar peduncles. One and a half month later, these neurologic symptoms were improved and the MRI abnormalities also disappeared. Auditory brain stem responses which showed prolongations of III to V wave peak to peak latency at the onset returned to normal. It is noted in this case that central pontine myelinolysis (CPM) and extrapontine myelipolysis (EPM) appeared during the period of rapid correction of hypernatremia. Although it is known CPM and EPM are caused by hypernatremia or the rapid correction of hyponatremia, there has been reported only one case of CPM and EPM after rapid correction of hypernatremia. According to the hypothesis of Norenberg, rapid rise in serum sodium may cause CPM and EPM, but if CPM and EPM are caused by the rapid correction of hypernatremia in this case, CPM and EPM may be caused by another pathogenesis of the disorder.