Hyponatremia Following Endoscopic Third Ventriculostomy in an Adolescent with an Aqueductal Web: A Case Report.

Background and Clinical Significance: Endoscopic third ventriculostomy (ETV) is a well-established cerebrospinal fluid (CSF) diversion technique for treating obstructive hydrocephalus. Here, the complication of post-ETV hyponatremia is rare. Separately, aqueductal web as a cause of obstructive hydrocephalus is also an uncommon occurrence. We present an unusual case of an adolescent who presented with late symptoms of obstructive hydrocephalus secondary to an aqueductal web and developed a delayed onset of post-operative hyponatremia after a successful ETV procedure. Pertinent aspects of the case are discussed in corroboration with the recent literature. Case Presentation: A previously well 14 year old presented with symptoms of raised intracranial pressure. Neuroimaging demonstrated progressively enlarging ventricles associated with an aqueductal web. She underwent an uneventful ETV and was discharged home. However, she was readmitted for symptomatic hyponatremia that was investigated and most likely attributed to Syndrome of Inappropriate Antidiuretic Hormone Secretion (SIADH). She was managed with fluid restriction with good clinical improvement. Conclusions: We herein report a case of delayed onset of obstructive hydrocephalus secondary to an aqueductal web, treatment challenges faced and the patient's unexpected occurrence of hyponatremia after a technically successful ETV. This emphasizes that clinicians need to be mindful of this potential post-operative complication and the ability to discern subtle symptoms in a patient whose clinical signs may not be straightforward.