# Initial Endoscopic Ventricular Failure to Relieve Hydrocephalus in Patients With Obstructing Brain Tumors Predicts a Histone 3K27M Mutation

## TL;DR

This study finds that patients with brain tumors linked to a specific mutation often fail to respond to a common hydrocephalus treatment, suggesting a need for alternative approaches.

## Contribution

The study identifies a link between H3K27M mutation and failure of endoscopic ventriculostomy in managing hydrocephalus.

## Key findings

- ETV failure was significantly higher in patients with H3K27M mutations compared to wild-type tumors.
- Ventriculoperitoneal shunt (VPS) was more successful in managing hydrocephalus in H3K27M patients.
- Hydrocephalus-free survival varied significantly among treatment groups.

## Abstract

Background

Diffuse midline gliomas (DMG) are a subset of malignant gliomas that could be linked to an H3K27M mutation. Hydrocephalus may be the initial presenting condition because of its frequent pontine location. This study evaluated the outcomes of tumor resection, endoscopic third ventriculostomy (ETV), and ventriculoperitoneal shunt (VPS) placement in DMG patients compared to wild-type (WT) tumors in treating hydrocephalus.

Materials and methods

We identified newly diagnosed pediatric and adult patients with midline tumors over an eight-year period (September 14, 2016-July 1, 2024).

Results

Out of a total of 74 patients, 20 (27.0%) patients were diagnosed with an H3K27M mutation, and 24 (32.4%) presented with hydrocephalus. Patients with a DMG H3K27M mutant (15 patients) were statistically more likely to be diagnosed with hydrocephalus compared to those with a WT midline glioma (9 patients) (p<0.001). Of the 24 patients with hydrocephalus, 8 (34.8%) underwent a VPS placement, 5 (22.7%) had tumor resection, 5 (21.7%) underwent an ETV, and 4 (17.4%) had both a VPS and ETV. A significant difference in hydrocephalus-free survival was observed among the treatment groups (p=0.0013). ETV failure was significantly higher in H3K27M patients while VPS was more successful in managing hydrocephalus.

Conclusions

As H3K27M mutation analysis is not available rapidly when patients initially present with midline gliomas, neurosurgeons use their best clinical judgment regarding the management of hydrocephalus. VPS demonstrated superior outcomes compared to ETV in controlling hydrocephalus among patients with a DMG H3K27M mutation in the present study; therefore, neurosurgical teams should have increased vigilance following ETV in this population.