ETV for fourth ventricle outlet obstruction (FVOO) in the long-term period following pediatric posterior fossa tumor resection.

PURPOSE: Hydrocephalus following posterior fossa tumors (PFT) resection occurs in about 25% of children. Post-resection hydrocephalus etiology is multifactorial. Despite several studies comparing endoscopic third ventriculostomy (ETV) vs. ventriculoperitoneal shunts (VPS), there is no specific focus on the timing of CSF diversion options. We present our experience performing ETV following PFT resection beyond the immediate postoperative period, either as a primary or secondary CSF procedure, and highlight the role of fourth ventricle outlet obstruction (FVOO) as a cause of late hydrocephalus.

METHODS

Following IRB approval, data was retrospectively collected and included patients who underwent PFT resections between 2001 and 2024 at our center.

RESULTS

One hundred ninety children fulfilled the inclusion criteria. Forty-one (21%) required CSF surgery. Thirty-one underwent VPS and 10 an ETV as their primary CSF diversion method. For all ETV patients, the aqueduct was open and thus was assumed to have FVOO. The median time to 1st CSF procedure was 24 days for the entire group, 12 days for those who received a VPS, and 144 days for those who underwent an ETV. 12/31 VPS and 3/10 ETV failed and required a secondary procedure. Six of seven secondary ETV (5 following VPS and 1 following an ETV failure) were successful, and one was lost to follow-up.

CONCLUSION

In children who develop late hydrocephalus following PFT resection, the anatomical point of obstruction is usually the outlet of the fourth ventricle (FVOO). Therefore, this group responds well to ETV as a primary or secondary treatment (following shunt malfunction).