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

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.