Cerebrospinal fluid overdrainage as a potential overlooked cause of SIAD-induced hyponatremia? A case report

Hyponatremia is a common and serious electrolyte imbalance observed in neurocritical care, often complicating severe neurological conditions. The underlying hormonal mechanism of hyponatremia in neurosurgical patients frequently involves Syndrome of Inappropriate Antidiuresis (SIAD) and Cerebral Salt Wasting Syndrome (CSWS). While many causes of hyponatremia in such patients are well understood, less attention has been given to instances arising from cerebrospinal fluid (CSF) overdrainage following ventriculoperitoneal (VP) shunt placements. This report highlights a 47-year-old male with Crouzon syndrome and obstructive hydrocephalus who underwent right Frazier's point VP shunt placement under general anesthesia. The patient developed profound hyponatremia at 115 mmol/L, accompanied by altered sensorium during his postoperative stay. Initial treatments, including hypertonic saline and fludrocortisone, only modestly corrected serum sodium levels, failing to improve his Further imaging indicated overdrainage, for which shunt ligation was performed. Shunt ligation resulted in remarkable improvement in both the patient's sensorium and serum sodium concentrations. This case highlights that CSF overdrainage may be an uncommon cause of hyponatremia in neurosurgical patients.