Osmotic demyelination syndrome (ODS) is a well-known disorder caused by rapid correction of
serum sodium. Many conditions including hormonal abnormality are associated with this syndrome. The
authors describe two cases of preoperative sellar region tumor associated with hypopituitarism and
secondary adrenal insufficiency. These two patients had hyponatremia. Neurological manifestations in both
of them were generalized dystonia. Magnetic resonance imaging (MRI) revealed a characteristic extrapontine
myelinolysis (EPM). The first case was a 35-year-old man with craniopharyngioma who developed
generalized dystonia after rapid correction of hyponatremia. The second case was a 24-year-old man with
gonadotroph pituitary adenoma who developed generalized dystonia, dysarthria, and dysphagia in the
course of hyponatremia. Hormonal changes will cause fluctuation in hyponatremia and correction of
hyponatremia, even if the recommended rate may be hazardous and will promote ODS. Patients with sellar
region tumors are at risk of developing ODS and correction of hyponatremia in these cases should be closely
monitored.

Keywords: Extrapontine myelinolysis, Sellar region tumor, Generalized dystonia, Hypopituitarism, Adrenal
insufficiency