Behavioural changes due to pontine and extrapontine myelinolysis

To report a case of central and extrapontine myelinolysis with unusual behavioural manifestations that developed after slow (not more than 0.5 mmol sodium per litre per hour) correction of hyponatraemia.

A 51-year-old Caucasian woman with hyponatraemia caused by psychogenic polydipsia experienced a delayed onset of behavioural changes with some ataxia, but no pyramidal signs, after correction of the hyponatraemia.

The hyponatraemia was corrected with a combination of hypertonic saline and fluid restriction at the currently recommended rate of not more than 0.5 mmol of sodium per litre per hour.

Central and extrapontine myelinolysis may develop after slow correction of hyponatraemia. Behavioural manifestations may be the most prominent clinical feature.