Subdural Hygroma Following Endoscopic Third Ventriculostomy: Understanding the Pathophysiology

Endoscopic third ventriculostomy (ETV) has overtaken the use of a ventriculoperitoneal shunt for the treatment of congenital hydrocephalus. Although ETV is relatively safe, several postoperative complications have been reported. One of the least described and understood complications is subdural hygroma following third ventriculostomy.

In this series, we retrospectively analyzed patients who were managed for postventriculostomy subdural hygroma and analyzed the possible factors responsible for this condition.

A total of 248 patients who underwent ETV between 2014 and 2016 were included in this study. Twelve patients (4.8%) had developed subdural hygroma, including 6 patients with bilateral hygroma, 2 with contralateral hygroma, and 4 with ipsilateral subdural hygroma. Only 4 patients (1.6%) were symptomatic, with complains of pseudomeningocele, persistent vomiting, or headache. Significant mass effect was present in 2 patients with unilateral subdural hygroma, which improved after placement of a subduroperitoneal shunt. In 1 patient, the subdural hygroma decreased with persistent ventriculomegaly and improved after ventriculoperitoneal shunt implantation. One patient with posttraumatic hydrocephalus who had a bilateral subdural hygroma following ETV improved with conservative management. At a 12-month follow-up, all patients remained asymptomatic.

Post-ETV subdural hygroma may result from poor absorption of cerebrospinal fluid (CSF) in the subarachnoid space, dysfunction of the stoma with persistence of the ventriculosubdural fistula, or altered CSF cytology, such as hemorrhage. Most of these patients remain asymptomatic and improve with time. Symptomatic patients should be properly evaluated for the cause of the formation of subdural hygroma, which will guide the appropriate interventions.