Retrospective analysis of the clinical and radiological features of 94 consecutive DIPGs patients to investigate the factors determining the development of hydrocephalus and its impact on clinical status and survival

Endoscopic transventricular biopsy in brainstem diffuse midline glioma: how I do it

BACKGROUND

Brainstem diffuse midline gliomas represent infiltrative and rare pediatric tumors with a dismal prognosis. Surgical biopsy is emerging as a valid technique to define diagnosis and molecular markers for future targeted therapies.

METHOD

We describe the key steps of an endoscopic trans-ventricular biopsy of a brainstem diffuse midline glioma and associated ventriculomegaly. The relevant surgical anatomy along with an illustrative video is described.

CONCLUSION

The endoscopic third ventriculostomy combined with a punch biopsy of a brainstem diffuse midline glioma associated with ventriculomegaly represent a feasible and low-risk procedure to simultaneously treat incipient hydrocephalus and molecular diagnosis for future treatment and research.

Leptomeningeal disease and tumor dissemination in a murine diffuse intrinsic pontine glioma model: implications for the study of the tumor-cerebrospinal fluid-ependymal microenvironment

Background

Leptomeningeal disease and hydrocephalus are present in up to 30% of patients with diffuse intrinsic pontine glioma (DIPG), however there are no animal models of cerebrospinal fluid (CSF) dissemination. As the tumor-CSF-ependymal microenvironment may play an important role in tumor pathogenesis, we identified characteristics of the Nestin-tumor virus A (Nestin-Tva) genetically engineered mouse model that make it ideal to study the interaction of tumor cells with the CSF and its associated pathways with implications for the development of treatment approaches to address CSF dissemination in DIPG.

Methods

A Nestin-Tva model of DIPG utilizing the 3 most common DIPG genetic alterations (H3.3K27M, PDGF-B, and p53) was used for this study. All mice underwent MR imaging and a subset underwent histopathologic analysis with H&E and immunostaining.

Results

Tumor dissemination within the CSF pathways (ventricles, leptomeninges) from the subependyma was present in 76% (25/33) of mice, with invasion of the choroid plexus, disruption of the ciliated ependyma and regional subependymal fluid accumulation. Ventricular enlargement consistent with hydrocephalus was present in 94% (31/33). Ventricle volume correlated with region-specific transependymal CSF flow (periventricular T2 signal), localized anterior to the lateral ventricles.

Conclusions

This is the first study to report CSF pathway tumor dissemination associated with subependymal tumor in an animal model of DIPG and is representative of CSF dissemination seen clinically. Understanding the CSF-tumor-ependymal microenvironment has significant implications for treatment of DIPG through targeting mechanisms of tumor spread within the CSF pathways.

Ventricular size determination and management of ventriculomegaly and hydrocephalus in patients with diffuse intrinsic pontine glioma: an institutional experience

OBJECTIVE

There is no consensus on the optimal clinical management of ventriculomegaly and hydrocephalus in patients with diffuse intrinsic pontine glioma (DIPG). To date, the impact on survival in patients with ventriculomegaly and CSF diversion for hydrocephalus in this population remains to be elucidated. Herein, the authors describe their institutional experience.

METHODS

Patients diagnosed with DIPG and treated with up-front radiation therapy (RT) at The Hospital for Sick Children between 2000 and 2019 were identified. Images at diagnosis and progression were used to determine the frontal/occipital horn ratio (FOR) as a method to measure ventricular size. Patients with ventriculomegaly (FOR ≥ 0.36) were stratified according to the presence of symptoms and categorized as follows: 1) asymptomatic ventriculomegaly and 2) symptomatic hydrocephalus. For patients with ventriculomegaly who did not require CSF diversion, post-RT imaging was also evaluated to assess changes in the FOR after RT. Proportional hazards analyses were used to identify clinical and treatment factors correlated with survival. The Kaplan-Meier method was used to perform survival estimates, and the log-rank method was used to identify survival differences between groups.

RESULTS

Eighty-two patients met the inclusion criteria. At diagnosis, 28% (n = 23) of patients presented with ventriculomegaly, including 8 patients who had symptomatic hydrocephalus and underwent CSF diversion. A ventriculoperitoneal shunt was placed in the majority of patients (6/8). Fifteen asymptomatic patients were managed without CSF diversion. Six patients had resolution of ventriculomegaly after RT. Of 66 patients with imaging at the time of progression, 36 (55%) had ventriculomegaly, and 9 of them required CSF diversion. The presence of ventriculomegaly at diagnosis did not correlate with survival on univariate analysis. However, patients with symptomatic hydrocephalus at the time of progression who underwent CSF diversion had a survival advantage (p = 0.0340) when compared to patients with ventriculomegaly managed with conservative approaches.

CONCLUSIONS

Although ventriculomegaly can be present in up to 55% of patients with DIPG, the majority of patients present with asymptomatic ventriculomegaly and do not require surgical interventions. In some cases ventriculomegaly improved after medical management with steroids and RT. CSF diversion for hydrocephalus at the time of diagnosis does not impact survival. In contrast, our results suggest a survival advantage in patients who undergo CSF diversion for hydrocephalus at the time of progression, albeit that advantage is likely to be confounded by biological and individual patient factors. Further research in this area is needed to understand the best timing and type of interventions in this population.

Ventricular Cerebrospinal Fluid Sampling in Pediatric Diffuse Midline Glioma Patients: Institutional Experience and Review of the Literature

Purpose: Increasing evidence suggests that circulating biomarkers may serve diagnostic and longitudinal monitoring purposes in pediatric neuro-oncology. Mutant tumor DNA is detectable in the cerebrospinal fluid (CSF) of pediatric diffuse midline glioma (DMG) patients and quantity can reflect disease burden. CSF sampling ("liquid biopsy") via a CSF access device could therefore play a role in DMG management. Therefore, we set to evaluate the incidence of hydrocephalus (HCP) in DMG patients, and to characterize ventricular reservoir placement and access practices. Methods: A single institution retrospective review of DMG patients ≤21-years-old was performed (1984-2019). MEDLINE searches for reports of ventricular reservoir or shunt placement in DMG, and reservoir access for intraventricular chemotherapy (IVC) were performed. Results: At our institution, 62.6% of DMG patients (67/108) required intervention for HCP: 19.4% provided transient CSF access (ETV alone n = 3, EVD n = 8, unspecified n = 2), and 80.6% permanent CSF access (ETV + reservoir n = 13, shunt n = 41). Further, 22/34 patients with initially transient CSF devices required conversion to a permanent device. Five devices were revised for malfunction, one for infection. Seventeen articles cited HCP in 22 to 100% of DMG patients. IVC administration was described in 632 patients (seven articles), with 42 infectious and 63 non-infectious complications. Conclusions: Management of HCP is often necessary in children with DMG. Given the low rate of clinical risk associated with VAD placement and access, and the potential utility of longitudinal disease monitoring via CSF analysis, VAD placement could be considered in future clinical trials to guide DMG treatment.