Dural sinus thrombosis with severe hypernatremia developing in a patient on long-term lithium therapy

Dural sinus thrombosis has not been described in a patient with hypernatremia resulting from lithium-induced nephrogenic diabetes insipidus. A 63-year-old man on chronic lithium therapy for schizoaffective disorder was transferred to the Emergency Department with dehydration and signs of central nervous system dysfunction after a 3-week isolation in a room in a psychiatric hospital due to exacerbation of psychiatric disorder, during which he refused to eat. Laboratory examination revealed hypertonic hypernatremia (osmolality, 359 mOsm/kg and Na, 171 mEq/L) and hyposthenuria (specific gravity, 1.010 and osmolality, 249 mOsm/kg), with normal serum endogenous vasopressin concentration (2.3 pg/mL). The serum lithium concentration was within the therapeutic range (0.94 mEq/L). Cranial computed tomography demonstrated subarachnoid hemorrhage and suggested dural sinus thrombosis. Although treatment with indomethacin (25 mg parenterally at 8-hour intervals) was somewhat effective in restoring renal concentrating capacity, he died of massive hemorrhagic infarction on the sixth hospital day, probably secondary to dural sinus thrombosis. The clinical diagnosis was confirmed by postmortem examination. Physicians should be alert for the possibility of dural sinus thrombosis as a complication of hypernatremia resulting from lithium-induced nephrogenic diabetes insipidus.