Abstract
BACKGROUND: Endoscopic third ventriculostomy (ETV) is an effective procedure for the treatment of triventriculomegaly associated with aqueductal stenosis. However, some patients can develop severe and symptomatic intracranial pressure (ICP) elevations in the immediate postoperative period that can be monitored and treated with external ventricular drain (EVD) placement and controlled cerebrospinal fluid (CSF) diversion until the ICP normalizes and symptoms resolve. OBSERVATIONS: The authors describe the case of a 39-year-old male who underwent ETV and intraoperative EVD placement for obstructive hydrocephalus associated with aqueductal stenosis. The patient was noted to have sustained ICP elevations in the immediate perioperative period but ultimately experienced a successful clinical outcome without requiring a ventriculoperitoneal shunt. LESSONS: Significant sustained ICP elevations in the immediate postoperative period following ETV can occur and may indicate a prolonged adjustment period. These elevations can be tolerated if the patient's symptoms and ICP are well controlled, with temporary external CSF diversion if the patient becomes symptomatic, as the ICP will likely normalize with a reassuring clinical outcome. https://thejns.org/doi/10.3171/CASE24478.