Cerebral salt wasting syndrome after calvarial remodeling in craniosynostosis

Hyponatremia and increased urine output after calvarial remodeling have been noted in pediatric patients with craniosynostosis. If not treated properly, patients develop hypoosmotic conditions that can lead to cerebral edema, increased intracranial pressure, and collapsed circulation. Postoperative hyponatremia after central nervous system surgery is considered as the syndrome of inappropriate antidiuretic hormone (SIADH) secretion. Recently, however, cerebral salt wasting syndrome (CSWS) instead of SIADH has been reported frequently. CSWS is associated with a decreased serum sodium level, increased urinary sodium level, increased urine output, decreased ECF volume, increased atrial natriuretic peptide (ANP) level, and increased brain natriuretic peptide (BNP) level. We experienced nine patients with craniosynostosis who underwent calvarial remodeling. By postoperative day 1, the ANP and BNP levels increased by 3-6 folds compared with the preoperative levels. They returned to the normal levels by postoperative day 5. The ADH level was within the normal range even after operation. The urinary sodium level increased in all patients by postoperative day 1 and 3. But the serum sodium level, and serum and urine osmolarity were normal due to appropriate replacement of sodium and fluid. After calvarial remodeling, the potential development of CSWS should be considered and distinguished from SIADH. The patients with CSWS require normal saline resuscitation and should prophylactically receive normal saline.