Survival with serum sodium level of 180 mEq/L: permanent disorientation to place and time.

A 41-year-old woman who had undergone transfrontal craniotomy for a pituitary tumor 4 months before presentation was admitted with confusion and orientation only to self. She had a fever of 40 degrees C. Serum sodium and chloride levels on admission were 180 and 139 mEq/L, respectively. Measured serum osmolality was 380 mOsmol/L with a urine osmolality of 360 mOsmol/L. Magnetic resonance imaging revealed a 1.5-cm mass in the sella turcica, which was nonfunctioning on endocrine evaluation. The "bright spot" of a normal posterior pituitary was absent. Central diabetes insipidus was confirmed by a 300% increase in urine osmolality with desmopressin. The patient survived her severe hypernatremia, which has 70% mortality with a serum sodium level of 160 mEq/L or above. However, she developed permanent (6 months) disorientation to time and place even when hypernatremia was corrected, which has not been described previously.