[A patient with meningeal carcinomatosis accompanied by a small pituitary metastatic lesion from gastric cancer who developed cerebral salt wasting syndrome].

A 68-year-old man with disturbed consciousness had repeatedly developed light-headedness and dizziness since the summer of 1996 and was admitted to a hospital for detailed examinations on October 8, 1996. On admission, he weighed 49 kg and showed subclinical hypothyroidism with low T3 syndrome. The adrenal function and serum electrolytes were normal. Since the stool samples were positive for occult blood, gastroscopy was performed. Examination of the biopsy specimens demonstrated gastric cancer. On October 21, blood examination showed hyponatremia (127 mEq/l). On October 22, marked disturbance of consciousness developed. On October 24, the serum Na level further decreased to 116 mEq/l. On November 8, he was referred to our hospital. On admission, his skin and tongue showed marked dehydration, and severe disturbance of consciousness and neck stiffness were observed. The central venous pressure was 4 cmH2O. In the cerebrospinal fluid, atypical cells were observed, and a diagnosis of meningeal carcinomatosis was made. Syndrome of inappropriate secretion of antidiuretic hormone (SIADH) was excluded because of marked dehydration, a normal blood ADH level, and because plasma osmotic pressure was greater than urinary osmotic pressure. Considering the possibility of cerebral salt wasting syndrome (CSWS) or hypoadrenocorticism, Na supplementation and drip infusion of prednisolone (20 mg/day) were performed. The serum Na has normalized (140.1 mEq/l), and his consciousness improved. He died of aggravation of the general condition on December 16. Pathological examination demonstrated a small metastatic lesion in the infundibular part of the pituitary gland and a small metastatic lesion in the parenchyma of the bilateral adrenal glands. However, since neither hypotension nor hypoglycemia was observed before treatment, and the blood cortisol level and the serum K level were normal, hypoadrenocorticism was excluded. Hypoaldosteronism was also excluded because of a normal serum K level. CSWS has been reported to be caused by head trauma, subarachnoid hemorrhage, or trans-sphenoidal pituitary operation. This patient is a rare case of CSWS developed in the presence of meningeal carcinomatosis accompanied by a small pituitary metastatic lesion from gastric cancer. The aged with decreased ability to retain water and sodium in the body are more susceptible to CSWS than the young. In the aged with central hyponatremia, the possibility of CSWS should be considered, and early diagnosis and treatment are necessary.