Tumors of the Pons

The intersect of neurosurgery with diffuse intrinsic pontine glioma

An invited article highlighting diffuse intrinsic pontine glioma (DIPG) to celebrate the 75th Anniversary of the Journal of Neurosurgery, a journal known to define surgical nuance and enterprise, is paradoxical since DIPG has long been relegated to surgical abandonment. More recently, however, the neurosurgeon is emerging as a critical stakeholder given our role in tissue sampling, collaborative scientific research, and therapeutic drug delivery. The foundation for this revival lies in an expanding reliance on tissue accession for understanding tumor biology, available funding to fuel research, and strides with interventional drug delivery.

The incidence of brainstem primitive neuroectodermal tumors of childhood based on SEER data

PURPOSE

Incidence of BS primitive neuroectodermal tumors (BS-PNET) in children is not reported to date. Our main objectives were to estimate the incidence and report the outcome of BS-PNET in children.

METHODS

Data were collected using the Surveillance Epidemiology and End Results cancer registry.

RESULTS

From 1973 to 2013, we identified 83 pediatric patients (aged 0-21 years). Patients were divided into two age groups (0-3 years and 4-21 years). Median overall survival was 53 months. Patients in the older age group had a significant survival advantage (P < 0.001), as did those who received three modalities of therapy (surgery, chemotherapy, and radiation therapy) (P < 0.001) and patients with gross or subtotal tumor resection (P < 0.001).

CONCLUSIONS

This study presents the first estimate of incidence and the largest cohort of pediatric BS-PNETs to date. A high index of suspicion of BS-PNET in similar cases is crucial for diagnosis, treatment, and outcome.

Nimotuzumab in pediatric glioma

High-grade gliomas and diffuse brainstem gliomas carry a very poor prognosis despite current therapies, and account together for the largest number of deaths in children with brain tumors. Many of these tumors have been found to overexpress the EGF receptor (EGFR). Nimotuzumab (h-R3) is a humanized monoclonal antibody against the EGFR, and consequently inhibits tyrosine kinase activation. In vitro and in vivo studies have supported the antiproliferative, antiangiogenic, pro-apoptotic and radiosensitizing activities of nimotuzumab. Emerging trials suggest a promising role for nimotuzumab as a therapeutic agent in patients with high-grade gliomas. This review attempts to provide a context for the evolving interest and evidence for nimotuzumab in pediatric glioma.

Difficult diagnosis of brainstem glioblastoma multiforme in a woman: a case report and review of the literature

INTRODUCTION

Brainstem gliomas are rare in adults. They most commonly occur in the pons and are most likely to be high-grade lesions. The diagnosis of a high-grade brainstem glioma is usually reached due to the presentation of rapidly progressing brainstem, cranial nerve and cerebellar symptoms. These symptoms do, however, overlap with a variety of other central nervous system disorders. Magnetic resonance imaging is the radiographic modality of choice, but can still be misleading.

CASE PRESENTATION

A 48-year-old Caucasian woman presented with headache and vomiting followed by cerebellar signs and confusion. Magnetic resonance imaging findings were suggestive of a demyelinating process, but the patient failed to respond to therapy. Her condition rapidly progressed and she died. At autopsy, a high-grade invasive pontine tumor was identified. Histological evaluation revealed glioblastoma multiforme.

CONCLUSION

While pontine gliomas are rare in adults, those that do occur tend to be high-grade and rapidly progressive. Progression of symptoms from non-specific findings of headache and vomiting to rapid neurological deterioration, as occurred in our patient, is common in glioblastoma multiforme. While radiographic findings are often suggestive of the underlying pathology, this case represents the possibility of glioblastoma multiforme presenting as a deceptively benign appearing lesion.

Image-guided convection-enhanced delivery of gemcitabine to the brainstem

Object

To determine if the potent antiglioma chemotherapeutic agent gemcitabine could be delivered to the brainstem safely at therapeutic doses while monitoring its distribution using a surrogate magnetic resonance (MR) imaging tracer, the authors used convection-enhanced delivery to perfuse the primate brainstem with gemcitabine and Gd–diethylenetriamine pentaacetic acid (DTPA).

Methods

Six primates underwent convective brainstem perfusion with gemcitabine (0.4 mg/ml; two animals), Gd-DTPA (5 mM; two animals), or a coinfusion of gemcitabine (0.4 mg/ml) and Gd-DTPA (5 mM; two animals), and were killed 28 days afterward. These primates were observed over time clinically (six animals), and with MR imaging (five animals), quantitative autoradiography (one animal), and histological analysis (all animals). In an additional primate, 3H-gemcitabine and Gd-DTPA were coinfused and the animal was killed immediately afterward.

In the primates there was no histological evidence of infusate-related tissue toxicity. Magnetic resonance images obtained during infusate delivery demonstrated that the anatomical region infused with Gd-DTPA was clearly distinguishable from surrounding noninfused tissue. Quantitative autoradiography confirmed that Gd-DTPA tracked the distribution of 3H-gemcitabine and closely approximated its volume of distribution (mean volume of distribution difference 13.5%).

Conclusions

Gemcitabine can be delivered safely and effectively to the primate brainstem at therapeutic concentrations and at volumes that are higher than those considered clinically relevant. Moreover, MR imaging can be used to track the distribution of gemcitabine by adding Gd-DTPA to the infusate. This delivery paradigm should allow for direct therapeutic application of gemcitabine to brainstem gliomas while monitoring its distribution to ensure effective tumor coverage and to maximize safety.

Brainstem tumors: where are we today?

Brainstem tumors comprise 10-20% of all pediatric central nervous system tumors. The management of these tumors has evolved dramatically in the past century. Once considered uniformly fatal, it is now known that brainstem tumors have distinguishing characteristics and do not behave identically. The focality and location of the lesion is determined from the clinical history, presentation, and associated imaging. Based on these findings, it is possible to predict the behavior of the tumor and choose an appropriate intervention. Focal lesions have a good prognosis and are treated operatively while diffuse lesions have a poor prognosis and are managed medically. This article reviews the current classification of brainstem tumors, current management options and future directions for the treatment of these rare tumors.

Real-time, image-guided, convection-enhanced delivery of interleukin 13 bound to pseudomonas exotoxin

PURPOSE

To determine if the tumor-targeted cytotoxin interleukin 13 bound to Pseudomonas exotoxin (IL13-PE) could be delivered to the brainstem safely at therapeutic doses while monitoring its distribution in real-time using a surrogate magnetic resonance imaging tracer, we used convection-enhanced delivery to perfuse rat and primate brainstems with IL13-PE and gadolinium-bound albumin (Gd-albumin).

EXPERIMENTAL DESIGN

Thirty rats underwent convective brainstem perfusion of IL13-PE (0.25, 0.5, or 10 microg/mL) or vehicle. Twelve primates underwent convective brainstem perfusion of either IL13-PE (0.25, 0.5, or 10 microg/mL; n = 8), co-infusion of 125I-IL13-PE and Gd-albumin (n = 2), or co-infusion of IL13-PE (0.5 microg/mL) and Gd-albumin (n = 2). The animals were permitted to survive for up to 28 days before sacrifice and histologic assessment.

RESULTS

Rats showed no evidence of toxicity at all doses. Primates showed no toxicity at 0.25 or 0.5 microg/mL but showed clinical and histologic toxicity at 10 microg/mL. Quantitative autoradiography confirmed that Gd-albumin precisely tracked IL13-PE anatomic distribution and accurately showed the volume of distribution.

CONCLUSIONS

IL13-PE can be delivered safely and effectively to the primate brainstem at therapeutic concentrations and over clinically relevant volumes using convection-enhanced delivery. Moreover, the distribution of IL13-PE can be accurately tracked by co-infusion of Gd-albumin using real-time magnetic resonance imaging.

Primary intrinsic brainstem oligodendroglioma in an adult. Case report and review of the literature

Primary intrinsic oligodendrogliomas of the brainstem are exceedingly unusual. The authors report the case of an intraaxial brainstem oligodendroglioma in an adult. In an extensive review of oligodendrogliomas, only six (0.4%) of 1593 cases recorded could be identified as intrinsic brainstem tumors. Five of these cases were found in children. This report documents a 25-year-old woman with a pontomedullary oligodendroglioma. An analysis of the world literature on this tumor type finds that posterior fossa oligodendrogliomas present at an earlier age and appear to be more aggressive biologically than their supratentorial counterparts. The overall prognosis for patients harboring an intrinsic brainstem oligodendroglioma remains unclear, with significant variability between patients.

Computerized tomography-guided stereotactic surgery for brainstem masses: a risk-benefit analysis in 71 patients

The benefits of the use of computerized tomography (CT)-guided stereotactic surgical techniques for the management of intrinsic brainstem masses diagnosed from clinical evaluation and imaging studies were evaluated vis-à-vis the risks involved in 71 consecutive patients. Seventy-two procedures were performed. The masses were diffuse, involving two or three contiguous brainstem segments, in 60 patients and focal in 11 patients. On the CT scans, 25 patients had hypodense nonenhancing masses, two had isodense nonenhancing masses, 19 had ring-enhancing masses, and 25 had heterogeneously enhancing masses. A positive biopsy was obtained in 68 of 69 patients (98.5%) undergoing a biopsy procedure. In nine patients (12.6%) with suspected malignant masses a benign pathology was diagnosed (four tuberculomas, two epidermoid cysts, one pyogenic abscess, one epidermal cyst, and one case of encephalitis). Additionally, fluid from cystic masses could be aspirated in eight cases, providing benefit in six (four patients had benign lesions and two had neoplastic lesions). Thereby, a total of 13 patients (18.3%) were deemed to have benefited from the surgery (two patients were included in both categories). Patients with focal masses and ring-enhancing masses had the highest proportion of benign lesions (60% and 36.8%, respectively) and therefore derived the most benefit from histological verification. There was no procedure-related mortality. One patient (1.4%) suffered permanent morbidity and four others (5.6%) had transient worsening attributable to the procedure. The authors conclude that CT-guided stereotactic surgery of the brainstem is safe and reliable. Histological verification of all enhancing (especially ring-enhancing) and focal brainstem masses should be undertaken to identify patients with benign nonneoplastic lesions. Selected patients with diffuse hypodense nonenhancing masses with atypical clinical or imaging features may also benefit from stereotactic biopsy. Even in these patients the lack of enhancement on a contrast-enhanced magnetic resonance image, rather than the diffuse location of the tumor alone, should form the basis for diagnosing a malignant glioma. The main value of stereotactic surgery lies in the identification of benign masses in a significant proportion of patients with intrinsic brainstem masses and in providing a rapid and safe method for evacuation of the contents of cystic masses.