[Neuroleptic malignant syndrome associated with the syndrome of inappropriate secretion of antidiuretic hormone].

We reported a case of neuroleptic malignant syndrome (NMS) associated with the syndrome of inappropriate secretion of antidiuretic hormone (SIADH). A 71-year-old woman, who had been diagnosed as hypertension and multiple cerebral infarction, was given sulpiride 150 mg daily for depressive state. Three days after started sulpiride, she developed fever, sweating, difficulty of movement and was admitted to the hospital. The white blood cell count rose to 16,300/mm3 and serum creatine kinase (CK) to 3,063 IU/L. Two days later CK rose to 20,050 IU/L regardless of stopping the drug, so she was transferred to our hospital for further investigation. On admission, it was the 6th day from the onset, she was mute and akinetic accompanied by muscle pain and rigidity in extremities. Serum CK was 1,831 IU/L, Na 122 mEq/L, osmolality 244 mOsm/kg, plasma antidiuretic hormone (ADH) level 6.5 pg/ml and urine Na was 101 mEq/L, osmolality 467 mOsm/kg. Renal and adrenal functions, plasma renin activity were normal. From the history, course and these data, diagnosis of NMS associated with SIADH was made. Intravenous sodium (130-200 mEq/day) and fluids (1,000-1,200 ml/day) were carefully infused. She became active, muscle pain disappeared and rigidity, akinesia decreased. CK, serum Na and osmolality gradually improved to normal. About the transient increase in ADH secretion, we considered that hypothalamic disturbance in NMS might induce leakage of stored ADH from neuroendocrine neurons in it.