[Cerebral salt wasting syndrome secondary to head injury: a case report].

A case of cerebral salt wasting syndrome secondary to head injury is reported here. A 4-year-old boy was admitted to our hospital with head injury. Neurological examination revealed no abnormal findings other than consciousness disturbance. Plain skull X-ray demonstrated a linear fracture of the bilateral parietal bones, and CT scan demonstrated subarachnoid hemorrhage of the tentorium of the cerebellum. He gradually improved, but on the 6th day deterioration of consciousness developed. At that time CT scan demonstrated no abnormal findings. Biochemical analysis showed hyponatremia (116mEq/L) with increased natriuresis. Although a high dose of NaCl was supplied, serum sodium levels did not normalize. So we suspected that SIADH might be causing the hyponatremia, and water restriction was started. He lost 1 kg in body weight over 3 days, but serum sodium levels remained low (118mEq/L) with increased natriuresis. We found that the hyponatremia was caused by cerebral salt wasting syndrome, so we treated the patient with fludrocortisone acetate. Consciousness disturbance improved two days after the medication with fludrocortisone acetate, and serum sodium levels became normal (137mEq/L) on the 27th day. The administration of fludrocortisone acetate was able to be stopped two months after admission, and then the patient was discharged without any neurological deficits. We discussed in detail the diagnosis and the treatment of cerebral salt wasting syndrome.