ABNORMALITIES OF WATER METABOLISM AFTER SURGERY FOR OPTIC CHIASMATIC ASTROCYTOMAS IN CHILDREN/

A major concern during the early postoperative period after surgical r esection of optic chiasmatic gliomas is the derangement of sodium and water metabolism which may add to the morbidity of the procedure. The purpose of this study was to characterize the abnormalities of water a nd sodium metabolism in children with optic chiasmatic gliomas treated surgically at British Columbia's Children's Hospital and to identify therapeutic modalities which might prevent or ameliorate the developme nt of these complications, A retrospective chart review of children wi th optic/chiasmatic gliomas undergoing operations on the tumor was per formed and the pre- and postoperative radiographs reviewed by an indep endent neuroradiologist, There were 11 patients who underwent 13 opera tions for either resection (n = 9) or biopsy (n = 4) of their optic ch iasm tumor, The extent of resection in patients undergoing more than s imple biopsy ranged from 83 to 99%, and all patients with resection ha d exophytic tumor extending into the hypothalamus. Postoperative syndr ome of inappropriate antidiuretic hormone secretion (SIADH) and/or dia betes insipidus occurred after 8 of the 9 tumor resections and was ass ociated with significant morbidity, No disturbance of water metabolism occurred after biopsy only. In patients with SIADH, the urinary sodiu m level rose markedly 6-12 h prior to the development of hyponatremia, and it was concluded that this was a valuable predictor of impending hyponatremia, Replacement of urine output was noted to be the most rel iable way to avoid rapid fluctuations in serum sodium and to avoid the morbidity of diabetes insipidus or SIADH and is recommended in the po stsurgical patients who cannot regulate fluid intake.