Surgical management of brain-stem tumors in children: results and statistical analysis of 75 cases

A multimodal imaging-based classification for pediatric diffuse intrinsic pontine gliomas

OBJECT

Pediatric diffuse intrinsic pontine glioma (DIPG) is a radiologically heterogeneous disease entity, here we aim to establish a multimodal imaging-based radiological classification and evaluate the outcome of different treatment strategies under this classification frame.

METHODS

This retrospective study included 103 children diagnosed with DIPGs between January 2015 and August 2018 in Beijing Tiantan Hospital (Beijing, China). Multimodal radiological characteristics, including conventional magnetic resonance imaging (MRI), diffuse tensor imaging/diffuse tensor tractography (DTI/DTT), and positron emission tomography (PET) were reviewed to construct the classification. The outcome of different treatment strategies was compared in each DIPG subgroup using Kaplan-Meier method (log-rank test) to determine the optimal treatment for specific DIPGs.

RESULTS

Four radiological DIPG types were identified: Type A ("homocentric", n=13), Type B ("ventral", n=41), Type C ("eccentric", n=37), and Type D ("dorsal", n=12). Their treatment modalities were grouped as observation (43.7%), cytoreductive surgery (CRS) plus radiotherapy (RT) (24.3%), RT alone (11.7%), and CRS alone (20.4%). CRS+RT mainly fell into type C (29.7%), followed by type B1 (21.9%) and type D (50%). Overall, CRS+RT exhibited a potential survival advantage compared to RT alone, which was more pronounced in specific type, but this did not reach statistical significance, due to limited sample size and unbalanced distribution.

CONCLUSION

We proposed a multimodality imaging-based radiological classification for pediatric DIPG, which was useful for selecting optimal treatment strategies, especially for identifying candidates who may benefit from CRS plus RT. This classification opened a window into image-guided integrated treatment for pediatric DIPG.

Role of neuronavigation in the surgical management of brainstem gliomas

Objective

NeuroNavigation (NN) is a widely used intraoperative imaging guidance technique in neurosurgical operations; however, its value in brainstem glioma (BSG) surgery is inadequately reported and lacks objective proof. This study aims to investigate the applicational value of NN in BSG surgery.

Method

A retrospective analysis was performed on 155 patients with brainstem gliomas who received craniotomy from May 2019 to January 2022 at Beijing Tiantan Hospital. Eighty-four (54.2%) patients received surgery with NN. Preoperative and postoperative cranial nerve dysfunctions, muscle strength, and Karnofsky (KPS) were evaluated. Patients' radiological features, tumor volume, and extent of resection (EOR) were obtained from conventional MRI data. Patients' follow-up data were also collected. Comparative analyses on these variables were made between the NN group and the non-NN group.

Result

The usage of NN is independently related to a higher EOR in diffuse intrinsic pontine glioma (DIPG) (p=0.005) and non-DIPG group (p<0.001). It was observed that fewer patients in the NN group suffered from deterioration of KPS (p=0.032) and cranial nerve function (p=0.017) in non-DIPG group, and deterioration of muscle strength (p=0.040) and cranial nerve function (p=0.038) in DIPG group. Moreover, the usage of NN is an independent protective factor for the deterioration of KPS (p=0.04) and cranial nerve function (p=0.026) in non-DIPG patients and the deterioration of muscle strength (p=0.009) in DIPG patients. Furthermore, higher EOR subgroups were found to be independently related to better prognoses in DIPG patients (p=0.008).

Conclusion

NN has significant value in BSG surgery. With the assistance of NN, BSG surgery achieved higher EOR without deteriorating patients' functions. In addition, DIPG patients may benefit from the appropriate increase of EOR.

Management and outcome of pediatric brainstem and cerebellar peduncular low-grade gliomas: a retrospective analysis of 62 cases

PURPOSE

This study was designed to present our experience and recommendations regarding the management of pediatric brainstem and peduncular low-grade gliomas (LGGs).

METHODS

Retrospective analysis was performed for pathologically proven brainstem or cerebellar peduncular LGGs in patients admitted between 2014 and 2019. These lesions were classified into the dorsal exophytic, focal brainstem, cervicomedullary, lower peduncular, and upper peduncular groups, and this classification was the basis for the surgical approach for the lesions.

RESULTS

Sixty-two pediatric patients were included, and their distribution among the aforementioned groups were as follows: 12, 12, 3, 16, and 19 cases in the dorsal exophytic, focal brainstem, cervicomedullary, upper peduncular, and lower peduncular groups, respectively. Stereotactic biopsy was performed for all cases in the focal brainstem group, whereas other groups underwent open excision. Gross total resection (GTR) was achieved in 20 cases (40%), near-total resection (NTR) was achieved in 17 cases (34%), and subtotal resection (STR) was achieved in 13 cases (26%). The extent of GTR and NTR for the upper peduncular, lower peduncular, dorsal exophytic, and cervicomedullary groups were 81.2%, 68.4%,75%, and 66.6%, respectively. Then, 32 cases received chemotherapy. The 3- and 5-year progression-free survival rates were 95% (95% confidence interval (CI) 89.5-100%) and 90.3% (95% CI 79.9-100%), respectively. A significant difference in the 3-year progression-free survival rate was observed between the GTR and NTR groups (p = 0.06; 100% vs. 88.2% (95% CI 72.9-100%)).

CONCLUSION

Surgery plays a definitive curative role in grossly resected cases. Additionally, the role of surgical debulking should be considered, even if GTR is impossible. Meanwhile, chemotherapy showed a beneficial role in patients with focal brainstem lesions and progressive lesions, those with STR, and some patients with NTR.

Pediatric midline H3K27M-mutant tumor with disseminated leptomeningeal disease and glioneuronal features: case report and literature review

BACKGROUND

H3K27M-mutant midline lesions were recently reclassified by the World Health Organization (WHO) as "diffuse midline glioma" (DMG) based entirely on their molecular signature. DMG is one of the most common and most lethal pediatric brain tumors; terminal progression is typically caused by local midbrain or brainstem progression, or secondary leptomeningeal dissemination. H3K27M mutations have also been infrequently associated with a histologically and prognostically diverse set of lesions, particularly spinal masses with early leptomeningeal spread.

CASE PRESENTATION

A 15-year-old girl after 1 week of symptoms was found to have a T2/FLAIR-hyperintense and contrast-enhancing thalamic mass accompanied by leptomeningeal enhancement along the entire neuraxis. Initial infectious workup was negative, and intracranial biopsy was inconclusive. Spinal arachnoid biopsy revealed an H3K27M-mutant lesion with glioneuronal features, classified thereafter as DMG. She received craniospinal irradiation with a boost to the thalamic lesion. Imaging 1-month post-radiation demonstrated significant treatment response with residual enhancement at the conus.

CONCLUSIONS

This case report describes the unique presentation of an H3K27M-mutant midline lesion with significant craniospinal leptomeningeal spread on admission and atypical glioneuronal histopathological markers. With such florid leptomeningeal disease, spinal dural biopsy should be considered earlier given its diagnostic yield in classifying the lesion as DMG. Consistent with similar prior reports, this lesion additionally demonstrated synaptophysin positivity-also potentially consistent with a diagnosis of diffuse leptomeningeal glioneuronal tumor (DLGNT). In atypical DMG cases, particularly with leptomeningeal spread, further consideration of clinical and histopathological context is necessary for accurate diagnosis and prognostication.

Epidemiology of brainstem high-grade gliomas in children and adolescents in the United States, 2000-2017

BACKGROUND

Limited population-based data exist for the brainstem gliomas for children ages ≤19 years, which includes high-grade aggressively growing tumors such as diffuse intrinsic pontine glioma (DIPG). We examined the overall incidence and survival patterns in children with brainstem high-grade glioma (HGG) by age, sex, and race and ethnicity.

METHODS

We used data from Central Brain Tumor Registry of the United States (CBTRUS), obtained through data use agreements with the Centers for Disease Control (CDC) and the National Cancer Institute (NCI) from 2000 to 2017, and survival data from the CDCs National Program of Cancer Registries (NPCR), from 2001 to 2016 for malignant brainstem HGG for ages ≤19 years (per WHO ICD-O-3 codes). HGG was determined by established histologic and/or imaging criteria. Age-adjusted incidence rates and survival data were used to assess differences overall and by age, sex race, and ethnicity.

RESULTS

The incidence of brainstem HGG was higher among the female and Non-Hispanic population. Majority (69.8%) of these tumors were diagnosed radiographically. Incidence was higher in children aged 1-9 years compared to older children. Whites had a higher incidence compared to Blacks. However, the risk of death was higher among Blacks and Other race compared to Whites. There was no difference in survival by sex.

CONCLUSIONS

We report the most comprehensive incidence and survival data on these lethal brainstem HGGs. Incidence and survival among patients with brainstem HGGs differed significantly by race, ethnicity, age-groups, and grade.

5-aminolevulinic acid-guided surgery for focal pediatric brainstem gliomas: A preliminary study

Background:

There is a growing body of literature supporting the use of 5-aminolevulinic acid (5-ALA) in the pediatric population, however, its use is still considered “off label” in this setting. In this retrospective study, we report our experience using 5-ALA in pediatric patients with focal brainstem gliomas (BSGs).

Methods:

Patients younger than 16 years presenting with a newly diagnosed BSG that was focal in nature were considered suitable for treatment with 5-ALA-assisted surgery. Exclusion criteria included MRI features suggestive of a diffuse intrinsic pontine glioma. A single dose of 5-ALA was administered preoperatively. Intraoperative fluorescence was recorded as “solid,” “vague,” or “none.” The effectiveness of the fluorescence was graded as “helpful” or “unhelpful.”

Results:

Eight patients underwent 5-ALA-assisted surgery. There were four tumors located in the pons, two midbrain tumors, and two cervicomedullary tumors. Histological analysis demonstrated three diffuse astrocytomas, three pilocytic astrocytomas, and two anaplastic astrocytomas. Solid fluorescence was found in three of the eight cases, vague fluorescence was found in two cases, and no fluorescence was found in three cases. Fluorescence was useful in 3 (37%) cases. No patients experienced any complications attributable to the administration of the 5-ALA.

Conclusion:

With a total fluorescence rate of 62.5% but a subjectively assessed “usefulness” rate of only 37.5%, the role of 5-ALA in BSG surgery is limited. Given the toxicological safety, however, of the agent, caution is perhaps needed before dismissing the use of 5-ALA entirely.

The Surgical Resection of Brainstem Glioma: Outcomes and Prognostic Factors

BACKGROUND

The management of brainstem glioma remains controversial, with increasing evidence supporting surgical resection as the primary treatment for a select subgroup of tumors. However, there remains no consensus on the specific benefits and risks, the selection of surgical candidates, and prognostic factors that may further refine surgical indications.

METHODS

A retrospective single-surgeon chart review was performed for all patients who underwent surgical treatment for radiographically suspected brainstem glioma between 2000 and 2017. Preoperative and postoperative radiographic evaluations on magnetic resonance imaging were conducted. Survival outcomes were collected, and machine-learning techniques were used for multivariate analysis.

RESULTS

Seventy-seven patients with surgical treatment of brainstem glioma were identified, with a median age of 9 years (range, 0-58 years). The cohort included 64% low-grade (I and II) and 36% high-grade (III and IV) tumors. For all patients, the 1-year and 5-year overall survival were 76.4% and 62.3%, respectively. Transient neurologic deficit was present in 34% of cases, and permanent deficit in a further 29%.

CONCLUSIONS

The radical surgical resection of brainstem gliomas can be performed with acceptable risk in well-selected cases and likely confers survival advantage for what is otherwise a rapidly and universally fatal disease. Various radiographic features are useful during patient selection and may guide treatment selection.

Surgical treatment and prognosis of focal brainstem gliomas in children: A 7 year single center experience

This study aims to describe the role of open surgical treatment for focal brainstem gliomas (FBSGs) with the assistance of multimodal neuronavigation and intraoperative neurophysiological monitoring (IOM) in children to investigate the efficacy of microsurgical treatment in pediatric FBSGs. Also the prognostic factors related to the overall survival (OS) of FBSGs to describe the patient and tumor characteristics relevant to prognosis/outcome were focused on. Clinical data of 63 pediatric patients below 16 years of age with FBSGs admitted to the Neurosurgical Unit of Beijing Tiantan Hospital from January 2012 to December 2018 were retrospectively analyzed. All patients underwent initial surgical treatment, followed by magnetic resonance diffusion tensor imaging (DTI), neuronavigation and IOM. Gross or near total resection (GTR or NTR) was achieved in 57/63 (90.5%) cases, and subtotal resection (STR) was achieved in 6/63 (9.5%) cases. Postoperative adjuvant therapy was received by 27/63 (42.9%) cases. Postoperative pathological examination revealed that 36/63 (57.1%) cases had grade I gliomas, 22/63 (34.9%) had grade II, and 5/63 (8.0%) had grade III-IV gliomas according to the WHO classification. The mean Karnofsky score preoperatively was 60, and at the time of follow-up was 90. Consecutively, 6 cases demonstrated disease progression, and 5 of these were deceased. The OS in all patients was 81.2% at 5 years. Histological grade (P < .001) and age at diagnosis (P = .023) showed significant association with prolonged OS. Multimodal neuronavigation and IOM allow very precise intracranial surgery, contributing to a maximally safe resection that might decrease the postoperative disability and mortality rate. This study also showed that pediatric FBSGs were mostly low-grade tumors with excellent surgical outcomes. Consequently, it is suggested that microsurgery can be used to treat FBSGs in children in order to provide better prognosis and survival outcomes.

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.

Diffused light attenuation at 664 nm for PDT in salted cadaver brain

BACKGROUND

We investigated light attenuation at 664 nm, which is the excitation wavelength of photodynamic therapy (PDT) using talaporfin sodium, in a salted cadaver brain. Estimation of therapeutic lesions is important to ensure the effectiveness and safety of brain tumor PDT. Previously reported optical properties of the human brain vary widely. In this study, we measured the light attenuation in brain tissue using a practical method. We employed a salted cadaver brain, in which the mechanical and optical properties can be maintained as close as possible to those under operative conditions.

METHODS

A neuroendoscope was inserted into the brain until the cerebral ventricle was reached. A thin cylindrical diffuser probe was advanced 10 mm from the endoscope tip. By another path from the brain surface, an optical fiber for measurement was inserted into a puncture needle, and a pair of needles was used to puncture the tissue and reach the same cerebral ventricle in which the endoscope tip was positioned. The attenuation of light intensities in the frontal lobe and cerebellum was measured by varying the bundle tip position. The starting positions of the bundle were confirmed by the endoscopic view. The measured light intensity attenuations were fitted with an exponential curve.

RESULTS

The following attenuation coefficients were obtained: 0.20 ± 0.05 mm^-1 in the cerebrum and 0.27 ± 0.05 mm^-1 in the cerebellum.

CONCLUSION

As conventional spectroscopic measurement may overestimate attenuation in the whole tissue, in situ measurement using the withdrawal technique might be appropriate for measurement of inhomogeneous biological tissues.

Pilocytic Midbrain Astrocytoma Presenting with Fresh Bleed after Twenty-one-years Survival Following First Surgery: A Unique Case of Longest Brainstem Glioma Survival

Brainstem glioma usually carries a poor prognosis and prolonged survival is very infrequent. In a detailed Pubmed, Medline search for prolonged survival, authors could got a longest survival only up to seventeen years, reported by Umehara et al, who was subjected to gamma knife therapy and got symptomatic, MRI brain reveled large tumor growth during pregnancy necessitating emergency surgery and histopathological diagnosis was pilocytic astrocytoma. Authors report an interesting case of midbrain glioma diagnosed 21 years back, who underwent gross resection in the year 1993, histopathology was pilocytic astrocytoma, WHO grade I, and received gamma knife surgery for residual subsequently and he presented with sudden onset left sided hemiplegia on the current admission. The cranial MRI imaging revealed an infarct involving right hemi midbrain, contrast MRI brain revealed no residual glioma. To the best knowledge of authors such prolonged survival is not reported with a case of brainstem glioma survived twenty- one years with non residual tumor on the last imaging study represents first case of its kind in the western literature and probably developed hemiplegia due to bleed, highlighting bleed as delayed complication following gamma knife therapy for cranial tumors.

Surgical and molecular considerations in the treatment of pediatric thalamopeduncular tumors

OBJECTIVE Thalamopeduncular tumors are a group of pediatric low-grade gliomas that arise at the interface of the thalamus and brainstem peduncle. They typically occur within the first 2 decades of life, presenting with progressive spastic hemiparesis. Treatment strategies, including surgical intervention, have varied significantly. The authors present their experience in the treatment of 13 children, ages 2-15 years, with non-neurofibromatosis-related pilocytic astrocytomas located in the thalamopeduncular region. METHODS Between 2003 and 2016, 13 children presenting with progressive spastic hemiparesis due to a pilocytic astrocytoma at the interface of the thalamus and cerebral peduncles were identified. Medical records were reviewed retrospectively for clinical, radiological, pathological, and surgical data. Formalin-fixed, paraffin-embedded tissue was obtained for 12 cases and tested for KIAA1549-BRAF fusion and BRAF V600E point mutation. RESULTS On preoperative diffusion tensor imaging tractography (performed in 12 patients), the ipsilateral corticospinal tract was displaced laterally in 1 case (8.3%), medially in 1 case (8.3%), anterolaterally in 10 cases (83%), and posteriorly in no cases. Ten patients underwent resection via a transtemporal, transchoroidal approach, which was chosen to avoid further damage to motor function in cases of tumors that caused anterolateral or medial corticospinal tract displacement. With this approach, complications included hemianopia, oculomotor palsy, and tremor at a rate of 50%. Among the 12 patients with obtainable follow-up (mean 50.9 months), none received adjuvant therapy, and only 2 (17%) experienced recurrence or progression. KIAA1549-BRAF fusions were present in 10 cases (83%), while BRAF V600E was absent (0%). The 2 fusion-negative tumors had clinical features atypical for the series, including multi-focality and infiltration. CONCLUSIONS Transcortical, transchoroidal resection of thalamopeduncular tumors through the middle temporal gyrus allows for a high rate of gross-total resection and cure. Diffuse tensor tractography is a critical component of the preoperative planning process to determine the location of white matter tracts in proximity. Molecular status may correlate with clinical features, and the presence of BRAF lesions offers an additional target for future novel therapeutics.

Robot-Assisted Stereotactic Biopsy of Diffuse Intrinsic Pontine Glioma: A Single-Center Experience

BACKGROUND

Diffuse intrinsic pontine glioma (DIPG) is a childhood tumor with a dismal prognosis. Emerging molecular signatures have paved the way for stereotactic biopsy in selected centers. We present our experience in DIPG stereotactic needle biopsy using the Robotic Stereotactic-Assisted system (ROSA) in a series of consecutive pediatric patients.

METHODS

All stereotactic biopsy procedures for DIPG performed during the last year at our institution were considered. All procedures were carried out using the ROSA surgical assistant through a precoronary approach. All children underwent a postoperative computed tomography scan to document possible surgical complications and confirm the site of biopsy. Postoperative clinical changes were recorded to test morbidity of the procedure.

RESULTS

In the last year, we performed 7 pontine needle biopsies. Specimens were diagnostic and useful for molecular analysis in all cases. No surgical complications were observed. One child showed a transient neurologic worsening related to the biopsy that resolved within 2 weeks. The combination of the precoronary approach and use of the stereotactic ROSA system allowed single-session surgeries in all cases.

CONCLUSIONS

Pontine biopsy for DIPG is a safe procedure in selected centers. The advantages of the single-session procedure we described might be of particular interest in the pediatric setting.

Brainstem Low-Grade Gliomas in Children-Excellent Outcomes With Multimodality Therapy

Safe maximal surgical resection is the initial treatment of choice for pediatric brainstem low-grade gliomas. Optimal therapy for incompletely resected tumors or that progress after surgery is uncertain. We reviewed the clinical characteristics, therapy, and outcomes of all children with nontectal brainstem low-grade gliomas treated at the University of Michigan between 1993 and 2013. Median age at diagnosis was 6 years; histology was confirmed in 23 of 25 tumors, 64% were pilocytic astrocytoma. Nineteen patients underwent initial tumor resection; 14/19 received no upfront adjuvant therapy. Eight patients in the study had progressive disease; 5 initially resected tumors received chemotherapy at tumor relapse, all with partial or complete radiographic responses. Ten-year progression-free survival is 71% and overall survival, 100%. This single-institution retrospective study demonstrates excellent survival rates for children with brainstem low-grade gliomas. The efficacy of the well-tolerated chemotherapy in this series supports its role in the treatment of unresectable or progressive brainstem low-grade gliomas.

Diffuse Intrinsic Pontine Glioma in Children: Document or Treat?

BACKGROUND

The place of stereotactic biopsies in the management of diffuse intrinsic pontine gliomas (DIPGs) in children has changed over the years. Nonetheless, stereotactic biopsy remains a surgical procedure with its risks. One complication that has not been reported previously in case of a biopsy of a DIPG is metastatic seeding along the tract of the biopsy. We report the first 2 cases in the literature.

CASE DESCRIPTION

One 8-year-old and one 9-year-old boy were admitted for a typical DIPG. Parents choose to be included into a research protocol that required a stereotactic biopsy. The biopsy was performed in both cases without any intraoperative complications, and they both received their treatment according to protocol. Unfortunately, 3 and 1 months respectively after the biopsy, their clinical condition deteriorated. MRI showed a metastatic seeding along the tract of the biopsy, and both patients died of disease progression.

CONCLUSIONS

The era of targeted therapy with molecular and genomic discoveries has paved the way to a research protocol that requires a biopsy from the patient. The reported complications have never been described before. The purpose of this paper is not to suggest that no biopsy should be performed when a DIPG is suspected. For now, biopsy remains investigational, because no benefit in survival could be drawn so far for any patient. This subject deserves honest discussion with the children and their parents.

Radiotherapy for diffuse brainstem glioma in children and young adults

BACKGROUND

Diffuse brainstem glioma is a devastating disease with very poor prognosis. The most commonly used radiological treatment is conventional fractionated radiation. So far, there is no meta-analysis or systematic review available that assesses the benefits or harms of radiation in people with diffuse brainstem glioma.

OBJECTIVES

To assess the effects of conventional fractionated radiotherapy (with or without chemotherapy) versus other therapies (including different radiotherapy techniques) for newly diagnosed diffuse brainstem gliomas in children and young adults aged 0 to 21 years.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE/PubMed, and EMBASE to 19 August 2015. We scanned conference proceedings from the International Society for Paediatric Oncology (SIOP), International Symposium on Paediatric Neuro-Oncology (ISPNO), Society of Neuro-Oncology (SNO), and European Association of Neuro-Oncology (EANO) from 1 January 2010 to 19 August 2015. We searched trial registers including the International Standard Randomised Controlled Trial Number (ISRCTN) Register, the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP), and the register of the National Institutes of Health to 19 August 2015. We imposed no language restrictions.

SELECTION CRITERIA

All randomised controlled trials (RCTs), quasi-randomised trials (QRCTs), or controlled clinical trials (CCTs) that compared conventional fractionated radiotherapy (with or without chemotherapy) versus other therapies (including different radiotherapy techniques) for newly diagnosed diffuse brainstem glioma in children and young adults aged 0 to 21 years.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened studies for inclusion, extracted data, assessed the risk of bias in each eligible trial, and conducted GRADE assessment of included studies. We resolved disagreements through discussion. We performed analyses according to the guidelines of the Cochrane Handbook for Systematic Reviews of Interventions.

MAIN RESULTS

We identified two RCTs that fulfilled our inclusion criteria. The two trials tested different comparisons.One multi-institutional RCT included 130 participants and compared hyperfractionated radiotherapy (six-week course with twice a day treatment of 117 cGy per fraction to a total dose of 7020 cGy) with conventional radiotherapy (six-week course with once a day treatment of 180 cGy per fraction to a total dose of 5400 cGy). The median time overall survival (OS) was 8.5 months in the conventional group and 8.0 months in the hyperfractionated group. We detected no clear evidence of effect on OS or event-free survival (EFS) in participants receiving hyperfractionated radiotherapy compared with conventional radiotherapy (OS: hazard ratio (HR) 1.07, 95% confidence interval (CI) 0.75 to 1.53; EFS: HR 1.26, 95% CI 0.83 to 1.90). Radiological response (risk ratio (RR) 0.94, 95% CI 0.54 to 1.63) and various types of toxicities were similar in the two groups. There was no information on other outcomes. According to the GRADE approach, we judged the quality of evidence to be low (i.e. further research is very likely to have an important impact on our confidence in the estimate of effect and is likely to change the estimate) for OS and EFS, and very low (i.e. we are very uncertain about the estimate) for radiological response and toxicities.The second RCT included 71 participants and compared hypofractionated radiotherapy (39 Gy in 13 fractions over 2.6 weeks, 3 Gy per fraction) with conventional radiotherapy (54 Gy in 30 fractions over six weeks, 1.8 Gy per fraction). This trial reported a median OS of 7.8 months for the hypofractionated group and 9.5 months for the conventional group. It reported a progression-free survival (PFS) of 6.3 months for the hypofractionated group and 7.3 months for the conventional group. We found no clear evidence of effect on OS (HR 1.03, 95% CI 0.53 to 2.01) or PFS (HR 1.19, 95% CI 0.63 to 2.22) in participants receiving hypofractionated radiotherapy when compared with participants receiving conventional radiotherapy. The mainly observed adverse effect was local erythema and dry desquamation especially behind the auricles. There were some other toxicities, but there was no statistically significant difference between treatment groups. There was no information on other outcomes. We judged the quality of evidence to be moderate (i.e. further research is likely to have an important impact on our confidence in the estimate of effect and may change the estimate) for OS, and low for PFS and toxicities. It should be mentioned that the sample size in this RCT was small, which could lead to insufficient statistical power for a clinically relevant outcome.

AUTHORS' CONCLUSIONS

We could make no definitive conclusions from this review based on the currently available evidence. Further research is needed to establish the role of radiotherapy in the management of newly diagnosed diffuse brainstem glioma in children and young adults. Future RCTs should be conducted with adequate power and all relevant outcomes should be taken into consideration. Moreover, international multicentre collaboration is encouraged. Considering the potential advantage of hypofractionated radiotherapy to decrease the treatment burden and increase the quality of remaining life, we suggest that more attention should be paid to hypofractionated radiotherapy.

Pediatric brainstem gliomas: new understanding leads to potential new treatments for two very different tumors

Pediatric brainstem gliomas include low-grade focal brainstem gliomas (FBSG) and high-grade diffuse intrinsic pontine gliomas (DIPG). These tumors share a crucial and eloquent area of the brain as their location, which carries common challenges for treatment. Otherwise, though, these two diseases are very different in terms of presentation, biology, treatment, and prognosis. FBSG usually present with greater than 3 months of symptoms, while DIPG are usually diagnosed within 3 months of symptom onset. Surgery remains the preferred initial treatment for FBSG, with chemotherapy used for persistent, recurrent, or inoperable disease; conversely, radiation is the only known effective treatment for DIPG. Recent developments in biological understanding of both tumors have led to new treatment possibilities. In FBSG, two genetic changes related to BRAF characterize the majority of tumors, and key differences in their biological effects are informing strategies for targeted chemotherapy use. In DIPG, widespread histone H3 and ACVR1 mutations have led to new hope for effective targeted treatments. FBSG has an excellent prognosis, while the long-term survival rate of DIPG tragically remains near zero. In this review, we cover the epidemiology, biology, presentation, imaging characteristics, multimodality treatment, and prognosis of FBSG and DIPG, with a focus on recent biological discoveries.

Diffuse intrinsic pontine gliomas: treatments and controversies

Diffuse intrinsic pontine gliomas (DIPGs) are a fairly common pediatric brain tumor, and children with these tumors have a dismal prognosis. They generally are diagnosed within the first decade of life, and due to their location within the pons, these tumors are not surgically resectable. The median survival for children with DIPGs is less than 1 year, in spite of decades of clinical trial development of unique approaches to radiation therapy and chemotherapy. Novel therapies are under investigation for these deadly tumors. As clinicians and researchers make a concerted effort to obtain tumor tissue, the molecular signals of these tumors are being investigated in an attempt to uncover targetable therapies for DIPGs. In addition, direct application of chemotherapies into the tumor (convection-enhanced delivery) is being investigated as a novel delivery system for treatment of DIPGs. Overall, DIPGs require creative thinking and a disciplined approach for development of a therapy that can improve the prognosis for these unfortunate children.

Primitive neuroectodermal tumors of the brainstem in children treated according to the HIT trials: clinical findings of a rare disease

OBJECT

Primitive neuroectodermal tumors of the central nervous system (CNS-PNET) arising in the brainstem are extremely rare, and knowledge about them is limited. The few existing case series report fatal outcomes. The purpose of this study was to analyze clinical characteristics of and outcome for brainstem CNS-PNET patients treated according to the consecutive, population-based HIT studies covering a 19-year time period.

METHODS

Between September 1992 and November 2011, 6 eligible children with histologically proven brainstem CNS-PNET not otherwise specified and 2 children with brainstem ependymoblastomas (3, partial resection; 3, subtotal resection; 2, biopsy), median age 3.3 years (range 1.2-10.6 years), were treated according to consecutive multimodal HIT protocols for CNS-PNET/medulloblastoma. Postoperative treatment was according to maintenance chemotherapy protocols (3, craniospinal irradiation [CSI] followed by maintenance chemotherapy), sandwich chemotherapy protocols (2, neoadjuvant chemotherapy, CSI, maintenance chemotherapy), or a therapy protocol for children younger than 4 years (3, postoperative chemotherapy followed by CSI).

RESULTS

The median duration of prediagnostic symptoms, predominantly cranial nerve deficits (n = 7), pyramidal tract signs (n = 5), or ataxia (n = 5), was 5 weeks (range 1-13 weeks). The tumors were all located in the pons. Most involved more than half of the pontine axial diameter and were sharply marginated. All patients had postoperative residual disease, including metastasis in 1 case. With 1 exception all tumors progressed early during treatment within 3.9 months (range 2.5-10.4 months), leading to a 1-year event-free survival rate (± standard error) of 13% ± 12%. After progression, patients succumbed early to their disease resulting in a 1-year overall survival rate of 25% ± 15%. The only surviving patient had a partially resected CNS-PNET, received a sandwich chemotherapy protocol, and is without disease progression 14 months after diagnosis.

CONCLUSIONS

CNS-PNET is a rare but important differential diagnosis in childhood brainstem tumors. So far, efficient therapies are lacking. The sampling of tumor material for improved biological understanding and identification of new therapeutic targets is important.

Surgical approaches for brainstem tumors in pediatric patients

PURPOSE

To analyze the pathways to brainstem tumors in childhood, as well as safe entry zones.

METHOD

We conducted a retrospective study of 207 patients less than 18 years old who underwent brainstem tumor resection by the first author (Cavalheiro, S.) at the Neurosurgical Service and Pediatric Oncology Institute of the São Paulo Federal University from 1991 to 2011.

RESULTS

Brainstem tumors corresponded to 9.1 % of all pediatric tumors operated in that same period. Eleven previously described "safe entry zones" were used. We describe a new safe zone located in the superior ventral pons, which we named supratrigeminal approach. The operative mortality seen in the first 2 months after surgery was 1.9 % (four patients), and the morbidity rate was 21.2 %.

CONCLUSIONS

Anatomic knowledge of intrinsic and extrinsic brainstem structures, in association with a refined neurosurgical technique assisted by intraoperative monitoring, and surgical planning based on magnetic resonance imaging (MRI) and tractography have allowed for wide resection of brainstem lesions with low mortality and acceptable morbidity rates.

Neurosurgical treatment of pediatric low-grade midbrain tumors: a single consecutive institutional series of 15 patients

OBJECT

The authors delineate the long-term results of surgical treatment for pediatric low-grade midbrain glioma.

METHODS

A series of 15 consecutive patients (age range 0-15 years) who underwent primary tumor resection for a low-grade midbrain glioma during the years 1989-2010 were included in this retrospective study on surgical morbidity, mortality rate, academic achievement, and/or work participation. Gross motor function and activities of daily living were scored according to the Barthel Index.

RESULTS

Of the 15 patients, 10 were in their 1st decade (age 0-9 years) and 5 were in their 2nd decade of life (age 10-15 years) at the time of surgery. The male/female ratio was 0.50 (5:10). No patients were lost to follow-up. One patient died in the postoperative period (32 days posttreatment). Another 2 patients died during follow-up. One patient succumbed to acute bleeding in the resection cavity 8 months after surgery, and the other died of shunt failure 21 years after initial treatment. Twelve patients are alive at the time of this writing, with follow-up periods from 3 to 24 years (median 8 years). Among the 12 survivors, the Barthel Index scores were normal (100) in 11 patients and 80 in 1 patient. A total of 25 tumor resections were performed. In 1 patient, further resection was performed 5 days after initial resection due to MRI-confirmed residual tumor. Another 5 patients underwent repeat tumor resection after MRI-confirmed progressive tumor disease and clinical deterioration ranging from 3 months to 4 years after the initial operation. Three of these 5 patients also underwent a third resection, and 1 of the 3 underwent a fourth operation. Six children received adjuvant therapy: local radiotherapy in 2 patients, chemotherapy in 3 patients, and both in 1 patient. Twelve (80%) of the 15 patients needed treatment for persistent hydrocephalus.

CONCLUSIONS

Selected cases of low-grade midbrain gliomas may clearly benefit from resection with favorable results, even for prolonged periods. Three patients in the present series died, one of whom had a prolonged survival period of 21 years. Among the 12 survivors, stable long-term results appeared obtainable in at least 9. One patient died of acute hemorrhage 8 months after initial resection; otherwise, rapid tumor progression and death were not observed. Forty percent of the patients received adjuvant treatment, with local radiotherapy, chemotherapy, or both.

Brainstem gliomas: surgical indications and technical considerations in a series of 58 cases

OBJECTIVES. To analyze the indications of surgical treatment, surgical management strategies and post-surgical outcome in patients with brainstem glioma (BSG). METHODS. In this retrospective study conducted from 1998 to 2012, 58 patients of surgically treated intrinsic BSG, meeting the inclusion criterion were enrolled. There were 40 males and 18 females, with age range varying from 3 to 55 years. The most common presentation was gait disturbances, either due to cerebellar involvement or motor weakness, followed by motor weakness, ocular involvement and headache. The posteriorly located tumors were operated by midline suboccipital approach (42 patients) and supracerebellar-infratentorial approach (4 patients). Posterolaterally located tumors were operated by retromastoid (10 patients) and all the ventrolateral tumors by subtemporal approach (4 patients). RESULTS. Above 90% patients improved in their neurological status, while 5% deteriorated. Pilocytic astrocytoma was the most common histopathology (41.4%), followed by Grade II astrocytoma (34.5%) and Grade III astrocytoma (24.1%). Overall, 19% patients had postoperative complications and three patients (5%) died in the perioperative period. CONCLUSIONS. Surgery is advocated for patients with well delineated, posteriorly, posterolaterally and ventrolaterally located tumors having slow progression and relative preservation of motor power. BSG can have excellent surgical results with surgeon's experience and modern surgical facilities.

Brain stem tumors in children and adolescents: single institutional experience

PURPOSE

Pediatric brain stem tumors (BsT) are a heterogeneous group of diseases. Our aim was to analyze our experience to find out prognostic factors.

METHOD

A retrospective study with BsT patients was performed. Imaging characteristics, extension of surgery, pathology, and adjuvant therapy were analyzed and correlated with overall survival (OS) and progression-free survival (PFS) as outcome measures.

RESULT

Since 1980 to 2010, we analyzed 65 BsT patients, 41 of them girls (63%), median age of 8 years (range 13.9 months to 17.6 years). Twenty-two patients (33.8%) had diffuse intrinsic pontine gliomas (DIPG) and 43 (66.2%) presented with focal BsT. Histology was available in 42 patients; the most frequent is low-grade glioma in 24/42 patients (57%). DIPG's histology (obtained usually at necropsy) confirmed five high-grade gliomas. After median follow-up of 49.3 months (0.5-175 months), 20/22 DIPG patients have died (90.9%), while 27/43 with focal tumors were alive (62.8%). Variables related to outcome were histology (better for low-grade glioma (LGG) OS p < 0.001), surgery (better if operated OS p < 0.001), and adjuvant therapy (worse if given, PFS p = 0.001, OS p = 0.024). The outcome for DIPG was dismal, median OS/EFS of 14.2/9.4 months, significantly worse than focal BsT (p = 0.000), while OS/EFS was 122.8/87.2 months for focal intrinsic, 88.2/47.1 months for exophytic, and 124.4/54 months for cervico-medullary tumors: no differences were found among them, except the histology (OS p < 0.001 for low-grade vs high-grade tumors).

CONCLUSION

BsT in children comprised two different groups: diffuse (DIPG) and focal gliomas. The DIPGs continue having a dismal prognosis, needing new approaches, while focal tumors including LGG have better prognosis.

Convection-enhanced delivery of topotecan into diffuse intrinsic brainstem tumors in children

Convection-enhanced delivery (CED) for the treatment of malignant gliomas is a technique that can deliver chemotherapeutic agents directly into the tumor and the surrounding interstitium through sustained, low-grade positive-pressure infusion. This allows for high local concentrations of drug within the tumor while minimizing systemic levels that often lead to dose-limiting toxicity. Diffuse intrinsic pontine gliomas (DIPGs) are universally fatal childhood tumors for which there is currently no effective treatment. In this report the authors describe CED of the topoisomerase inhibitor topotecan for the treatment of DIPG in 2 children. As part of a pilot feasibility study, the authors treated 2 pediatric patients with DIPG. Stereotactic biopsy with frozen section confirmation of glial tumor was followed by placement of bilateral catheters for CED of topotecan during the same procedure. The first patient underwent CED 210 days after initial diagnosis, after radiation therapy and at the time of tumor recurrence, with a total dose of 0.403 mg in 6.04 ml over 100 hours. Her Karnofsky Performance Status (KPS) score was 60 before CED and 50 posttreatment. Serial MRI initially demonstrated a modest reduction in tumor size and edema, but the tumor progressed and the patient died 49 days after treatment. The second patient was treated 24 days after the initial diagnosis prior to radiation with a total dose of 0.284 mg in 5.30 ml over 100 hours. Her KPS score was 70 before CED and 50 posttreatment. Serial MRI similarly demonstrated an initial modest reduction in tumor size. The patient subsequently underwent fractionated radiation therapy, but the tumor progressed and she died 120 days after treatment. Topotecan delivered by prolonged CED into the brainstem in children with DIPG is technically feasible. In both patients, high infusion rates (> 0.12 ml/hr) and high infusion volumes (> 2.8 ml) resulted in new neurological deficits and reduction in the KPS score, but lower infusion rates (< 0.04 ml/hr) were well tolerated. While serial MRI showed moderate treatment effect, CED did not prolong survival in these 2 patients. More studies are needed to improve patient selection and determine the optimal flow rates for CED of chemotherapeutic agents into DIPG to maximize safety and efficacy. Clinical trial registration no.: NCT00324844.

Stereotactic iodine-125 brachytherapy for treatment of inoperable focal brainstem gliomas of WHO grades I and II: feasibility and long-term outcome

Microsurgical resection is the most frequently suggested treatment option for accessible focal brainstem gliomas (F-BSG) of World Health Organization (WHO) grades I and II. Because of their location in the highly eloquent brain, however, resection is associated with permanent postoperative morbidity, ranging from 12 to 33 %. Only a few reports have suggested stereotactic brachytherapy (SBT) with implantation of iodine-125 seeds as a local treatment alternative. Between 1993 and 2010, 47 patients were treated with SBT (iodine-125 seeds; cumulative surface dose 50-65 Gy) for inoperable F-BSG, WHO grades I and II, in one of the largest reported patient series. We evaluated procedure-related complications, clinical outcome, and progression-free and overall survival (PFS, OS). Median follow-up was 81.6 months. Procedure-related mortality was zero. Within 30 days of seed implantation six patients (12.8 %) had transient neurological deficits. Two patients (4.3 %) deteriorated permanently. Space-occupying cysts occurred in six patients (12.8 %) after a median of 28.5 months, and required surgical intervention. Nine patients (19.1 %) presented with tumor relapse after a median of 56.6 months (range 7.9-118.0 months). For the remaining 38 patients complete response was observed for 23.4 %, partial response for 29.8 %, and stable disease for 27.7 %. Actuarial PFS was 97.7 ± 2.2, 92.8 ± 4.0, 81.2 ± 6.5, and 62.0 ± 10.4 % after 1, 2, 5, and 10 years, respectively. Corresponding OS was 100 ± 0.0 % (1 and 2 years), 97.4 ± 2.6 % (5 years), and 87.6 ± 7.0 % (10 years). SBT is a comparatively safe, minimally invasive, and highly effective local treatment option for patients with inoperable F-BSG WHO grades I and II; it merits further evaluation in prospective randomized trials.

Correlation between magnetic resonance imaging findings and histological diagnosis of intrinsic brainstem lesions in adults

Management of brainstem mass lesions remains a controversial issue, especially when the lesion cannot be excised and when infiltration occurs; moreover, the benefits of a stereotactic procedure are still under debate. In most studies, treatment decisions are based solely on MRI features and do not include a histopathological diagnosis. In the current study, we compared MRI characteristics with histopathological findings of intrinsic brainstem lesions and identified the characteristics associated with the diagnosis of pathologies other than diffuse glioma. From February 1988 through August 2007, 96 brainstem biopsies were performed at the Roger Salengro Hospital in Lille, France, on adult patients with intrinsic brainstem lesions not amenable to excision. Of the 96 patients, 42 were women and 54 were men, with a mean age of 41 years (range, 18-75 years). Data analysis of the MRI findings revealed focal (P < .05) and contrast enhancing lesions (P < .05), and these lesions were significant factors associated with the diagnosis of pathologies other than diffuse glioma. Focal lesions were a significant factor associated with a diagnosis of nontumor lesions (P < .05). In conclusion, the diagnostic effect of stereotactic biopsy on intrinsic brainstem lesions was greater in patients with focal or enhancing lesions shown by MRI, in whom the diagnosis of diffuse glioma was less frequent.

Surgical management of tumors producing the thalamopeduncular syndrome of childhood

OBJECT

Thalamopeduncular tumors arise at the junction of the inferior thalamus and cerebral peduncle and present with a common clinical syndrome of progressive spastic hemiparesis. Pathologically, these lesions are usually juvenile pilocytic astrocytomas and are best treated with resection with the intent to cure. The goals of this study are to define a common clinical syndrome produced by thalamopeduncular tumors and to discuss imaging characteristics as well as surgical adjuncts, intraoperative nuances, and postoperative complications relating to the resection of these neoplasms.

METHODS

The authors present a retrospective review of their experience with 10 children presenting between 3 and 15 years of age with a thalamopeduncular syndrome. Formal preoperative MR imaging was obtained in all patients, and diffusion tensor (DT) imaging was performed in 9 patients. Postoperative MR imaging was obtained to evaluate the extent of tumor resection. A prospective analysis of clinical outcomes was then conducted by the senior author.

RESULTS

Pilocytic astrocytoma was the pathological diagnosis in 9 cases, and the other was fibrillary astrocytoma. Seven of 9 pilocytic astrocytomas were completely resected. Radical surgery was avoided in 1 child after DT imaging revealed that the corticospinal tract (CST) coursed through the center of the tumor, consistent with the infiltrative nature of fibrillary astrocytoma as identified by stereotactic biopsy. In 8 patients, tractography served as an important adjunct for designing a surgical approach that spared the CST. In 6 cases the CSTs were pushed anterolaterally, making a transsylvian approach a poor choice, as was evidenced by the first patient in the series, who underwent operation prior to the advent of tractography, and who awoke with a dense contralateral hemiparesis. Thus, subsequent patients with this deviation pattern underwent a transcortical approach via the middle temporal gyrus. One patient exhibited medial deviation of the tracts and another had lateral deviation, facilitating a transtemporal and a transfrontal approach, respectively.

CONCLUSIONS

The thalamopeduncular syndrome of progressive spastic hemiparesis presenting in children with or without symptoms of headache should alert the examiner to the possibility of a tumoral involvement of CSTs. Preoperative tractography is a useful adjunct to surgical planning in tumors that displace motor pathways. Gross-total resection of pilocytic astrocytomas usually results in cure, and therefore should be entertained when developing a treatment strategy for thalamopeduncular tumors of childhood.

Regression of recurrent glioblastoma infiltrating the brainstem after convection-enhanced delivery of nimustine hydrochloride

This 13-year-old boy with a history of cranial irradiation for the CNS recurrence of acute lymphocytic leukemia developed a glioblastoma in the right cerebellum. Resection and chemo- and radiotherapy induced remission of the disease. However, recurrence was noted in the brainstem region 8 months later. Because no effective treatment was available for this recurrent lesion, the authors decided to use convection-enhanced delivery (CED) to infuse nimustine hydrochloride. On stereotactic insertion of the infusion cannula into the brainstem lesion, CED of nimustine hydrochloride was performed with real-time MR imaging to monitor the co-infused chelated gadolinium. The patient's preinfusion symptom of diplopia disappeared after treatment. Follow-up MR imaging revealed the response of the tumor. The authors report on a case of recurrent glioblastoma infiltrating the brainstem that regressed after CED of nimustine hydrochloride.

Vincristine and carboplatin chemotherapy for unresectable and/or recurrent low-grade astrocytoma of the brainstem

BACKGROUND

Radiotherapy remains a widely accepted postoperative treatment modality for unresectable or recurrent low-grade glioma (LGG). However, there is increasing evidence to suggest that chemotherapy can delay and may obviate the need for radiotherapy in progressive/recurrent LGG. The majority of the published experience is in children with hypothalamic/optic chiasmatic lesions and little information is available regarding its use in LGG of the brainstem.

PROCEDURE

We describe clinical characteristics and course of children with LGG of the brainstem who received carboplatin-based chemotherapy in two institutions over 10 years (1996-2006). This was a retrospective review of consecutively treated children with LGG of the brainstem (midbrain, pons, medulla, and upper cervical cord). Vincristine and carboplatin were first-line chemotherapy regimen used in all patients.

RESULTS

In this series, there were 16 children (9 males) with median age at diagnosis of 4.2 years (range 0.5-8). Eight children were treated at diagnosis while the remaining eight received chemotherapy after either radiological progression or clinical deterioration. After a median follow-up of 57 months (range 20-136) from initiation of chemotherapy all children are alive and 11 remain progression free (1 complete response, 8 with partial response + minor response, and 2 stable diseases).

CONCLUSIONS

The efficacy of this chemotherapy regimen in this series supports its role in children with progressive unresectable LGG of brainstem.

Prospective neuraxis MRI surveillance reveals a high risk of leptomeningeal dissemination in diffuse intrinsic pontine glioma

Prognosis of diffuse intrinsic pontine gliomas (DIPGs) remains poor. Failure has been predominantly local, with leptomeningeal dissemination (LD) occurring in 4-33% of patients in pre-MRI era series. Routine craniospinal imaging after initial treatment may reveal other relapse patterns relapse. Sixteen consecutive pediatric patients with DIPG treated between 2006 and 2009 were retrospectively reviewed. Treatment regimens, recurrence patterns, survival, and pathologic diagnosis were recorded. Fourteen patients received involved-field radiotherapy to 54 Gy, and two patients received craniospinal irradiation for LD at presentation. Neuraxis MRI was performed at diagnosis and at 4 month intervals following radiotherapy. Fifteen patients have had progression of disease (median progression-free survival 5.0 ± 1.2 months), and 13 patients have died (median survival 9.0 ± 1.4 months). Local failure occurred in 12 patients (75%). LD occurred in nine patients (56%). LD was present at diagnosis in three patients, after initial staging and treatment in six patients, and during autopsy in two patients. Median overall survival was 12.0 ± 3.3 months without LD and 8.0 ± 2.1 months with LD (P = 0.059, log rank test). Median progression-free survival was 9.5 ± 3.9 months without LD and 3.0 ± 2.1 months with LD (P = 0.012, log rank test). The high incidence of LD probably reflects liberal use of spine MRI surveillance. All patients should undergo routine craniospinal imaging at diagnosis and follow-up. Central nervous system prophylaxis should be considered in future clinical trials.

Radical resection of focal brainstem gliomas: is it worth doing?

OBJECTIVES

Despite revolutionary technical advancement in neuroimaging and operative neurosurgery, surgical extirpation of focal brainstem glioma (BSG) remains steeped in controversy. In this study, we evaluated our senior author's (CT) surgical experience in radically treating these tumours in children to determine the safety and efficacy of such approach.

MATERIALS AND METHODS

Thirty-four consecutive patients aged between 3 and 16 years who underwent endoscope-assisted microsurgery for focal BSG with the intent of radial resection from 1999 to 2005 were evaluated. The clinical outcome at 6 months and long-term survival were analysed.

CONCLUSION

Thirty-one patients had >90% tumour resection and the remainder had >50%. There was no perioperative mortality. The average follow-up was 46 months. Twenty-three patients (74%) harboured low-grade gliomas, whilst the remainder (26%) had high-grade gliomas. Kaplan-Meier survival analysis revealed marked difference in the 5-year survival rates between the two groups (100% vs 33%). Multivariate analysis demonstrated that the degree of tumour resection was not associated with poor outcome at 6 months. This series underscores the benefits of surgical resection for focal BSG. Radical resection can be achieved in a majority of patients with favourable outcome regardless of tumour pathology.

Delayed development of radiation vasculopathy of the brain stem confirmed by F-18 FDG PET in a case of anaplastic astrocytoma

We present the imaging findings of a 38-year-old female patient who underwent resection and radiation therapy for an anaplastic astrocytoma in her left temporal lobe 12 years ago. She was symptom-free until 1 month before admission at which time she presented with symptoms of right hemiparesis, right facial droop, and slurred speech. Magnetic resonance imaging (MRI) of the brain showed a new mass lesion in the left pontine region of the brain stem. Magnetic resonance spectroscopy imaging of the lesion demonstrated an increase in choline (Ch)/N-acetyl aspartate (NAA) metabolite values which were nondiagnostic. Since viable tumor recurrence was strongly suspected, a biopsy was planned, although this posed significant risk. Therefore, an F-18 FDG brain PET scan was performed, which demonstrated no metabolic activity in the pontine lesion leading to the less common diagnosis of long-term postradiation vasculopathy. Over the next 6 months, the patient's symptoms slowly improved and a follow-up MRI scan showed a decrease in the size of the lesion, consistent with postradiation vasculopathy and infarction. This case illustrates the importance of considering the rare diagnosis of radiation-induced vasculopathy in the differential diagnosis when symptoms of recurrent brain tumor occur.

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.

Paediatric brain-stem gliomas: MRI, FDG-PET and histological grading correlation

BACKGROUND

MRI and FDG-PET may predict the histological grading of paediatric brain-stem gliomas.

OBJECTIVE

To assess MRI findings and metabolic imaging using FDG-PET of brain-stem gliomas based on histological grading.

MATERIALS AND METHODS

Included in the study were 20 paediatric patients (age 3-14 years, mean 8.2 years) with brain-stem glioma (five glioblastomas, ten anaplastic astrocytomas and five low-grade astrocytomas). MR images were assessed for the anatomical site of tumour origin, focality, pattern of tumour growth, and enhancement.

RESULTS

All glioblastomas were located in the pons and showed diffuse pontine enlargement with focally exophytic features. Eight anaplastic astrocytomas were located in the pons and demonstrated diffuse pontine enlargement without exophytic features. Low-grade astrocytomas were located in the pons, midbrain or medulla and showed focally exophytic growth features and peripheral enhancement. In 12 patients in whom FDG-PET was undertaken, glioblastomas showed hypermetabolic or hypometabolic lesions, anaplastic astrocytomas showed no metabolic change or hypometabolic lesions and low-grade astrocytomas showed hypometabolism compared with the cerebellum.

CONCLUSION

MRI findings correlated well with histological grading of brain-stem gliomas and MRI may therefore predict the histological grading. FDG-PET may be helpful in differentiating between anaplastic astrocytoma and glioblastomas among high-grade tumours.

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.

The importance of brainstem mapping in brainstem surgical anatomy before the fourth ventricle and implication for intraoperative neurophysiological mapping

Brain stem mapping (BSM) is an intraoperative neurophysiological procedure to localize cranial motor nuclei on the floor of the fourth ventricle. BSM enables neurosurgeon to understand functional anatomy on the distorted floor of the fourth ventricle, thus, it is emerging as an indispensable tool for challenging brain stem surgery. The authors described the detail of BSM with the special emphasis on its clinical application for the brain stem lesion. Surgical implications based on the result of brains stem mapping would be also informative before planning a brain stem surgery through the floor of fourth ventricle. Despite the recent advancement of MRI to depict the lesion in the brain stem, BSM remains as the only way to provide surgical anatomy in the operative field. BSM could guide a neurosurgeon to the inside of brain stem while preventing direct damage to the cranial motor nuclei on the floor of the fourth ventricle. It is expected that understanding its advantage and limitations would help neurosurgeon to perform safer surgery to the brain stem lesion.

Advances toward an understanding of brainstem gliomas

The diagnosis of brainstem glioma was long considered a single entity. However, since the advent of magnetic resonance imaging in the late 1980s, neoplasms within this anatomic region are now recognized to include several tumors of varying behavior and natural history. More recent reports of brainstem tumors include diverse sites such as the cervicomedullary junction, pons, midbrain, or the tectum. Today, these tumors are broadly categorized as either diffuse intrinsic gliomas, most often in the pons, or the nondiffuse brainstem tumors originating at the tectum, focally in the midbrain, dorsal and exophytic to the brainstem, or within the cervicomedullary junction. Although we briefly discuss the nondiffuse tumors, we focus specifically on those diffuse brainstem tumors that regrettably still carry a bleak prognosis.

Cyanotic breath-holding spell: a life-threatening complication after radical resection of a cervicomedullary ganglioglioma

Cyanotic breath-holding spell is a benign and self-limiting disease of young children but occasionally associated with sudden, unexpected death. The authors report a rare case in a 2-year-old girl with a severe form that started after radical resection of a cervicomedullary ganglioglioma. She was admitted to our hospital because of delayed and unstable gait. Since magnetic resonance imaging showed a cervicomedullary tumor, she underwent a radical resection and histology showed the tumor to be a ganglioglioma. Postoperatively, the function of the lower cranial nerves and cerebellum deteriorated and hemiparesis on the left became apparent, but she returned to the preoperative state in a few months. In addition, mild sleep apnea (Ondine curse) and severe cyanotic breath-holding spells occurred. The former responded to medication but the latter failed and continued several times per day with a rapid onset and progression of hypoxemia, loss of consciousness, sweating and opisthotonos. Five months after the operation, the patient returned home with a portable oxygen saturation monitor equipped with an alarm. This case indicates that cyanotic breath-holding spell, as well as sleep apnea, is critical during the early postoperative period. This is the first report observing that such spells may occur as a complication of radical resection of a cervicomedullary tumor.

Neurosurgical treatment of brain tumors in children

Primary brain tumors are the most common solid neoplasms of childhood. The diagnosis of brain tumors in the general pediatric population remains challenging. Nevertheless, it is clear that refinements in imaging, surgical technique, and adjunctive therapies have led to longer survival and an improving quality of life in children with brain tumors.

Gliomas del tronco encefálico

Brainstem gliomas have been increasingly understood in the last two decades and they are nowadays regarded as an heterogeneous group of tumors with tendency towards the pediatric age, where they account for 10-20% of brain neoplasms. Besides the well known diffuse tumor, several subtypes, with a different biological behaviour, amenable to surgical resection and better prognosis, have been identified, giving rise to many classifications and terms. In the other way, attention has been recently paid to adult brainstem gliomas in contrast to pediatric tumors. Based on a review of the literature, we describe the different subtypes of brainstem gliomas, with particular interest on therapeutic approaches and differences between pediatric and adult tumors, employing iconography from our series.

Gross total surgical removal of malignant glioma from the medulla oblongata: report of two adult cases with reference to surgical anatomy

Surgery was performed on the medulla oblongata of two adult patients with malignant glioma. Gross total resection of the tumors, located laterally or medially in the upper half of the medulla respectively, was achieved. The patient with the medially located tumor experienced significant postoperative neurological deterioration including sleep apnea. The other patient with the laterally located tumor showed symptomatic improvement without respiratory complications. The patient with an anaplastic astrocytoma survived approximately 4 years and the patient with a glioblastoma multiforme approximately 2 years. Although the upper half of the medulla is more critical than the lower half, a lateral approach to the upper half of the medulla appears to be relatively safer than a medial approach. Some cases of focal malignant gliomas in the medulla may be amenable to gross total resection in order to achieve improved outcome. Surgery can be undertaken when a tumor is unilateral and its margin appears relatively clear on magnetic resonance images.

Pontine malignant astrocytoma with hemorrhagic onset--case report

A 7-year-old boy presented with acute onset of left hemiparesis and headache, followed by disturbance of consciousness. Neuroimaging studies showed pontine hemorrhage. Surgery was performed to remove a massive hematoma. Histological examination of the wall revealed anaplastic astrocytoma. Postoperative radiation therapy and several types of chemotherapy were administered. However, the tumor recurred and he died 9 months after onset. Hemorrhagic onset of pontine glioma is rare and carries an extremely poor prognosis.

Magnetic resonance spectroscopy of atypical diffuse pontine masses

OBJECT

Diffuse pontine gliomas in children carry a dismal prognosis, with a mean survival of less than 1 year despite therapy. The diagnosis is based on the characteristic changes demonstrated on traditional magnetic resonance (MR) imaging. A few typically MR imaging-appearing pontine masses, however, do not behave in the expected fashion, which calls the original diagnosis into question.

METHODS

The authors conducted a retrospective review of data obtained in 42 children (age 6 months-13 years) in whom diffuse pontine glioma had been diagnosed at their institution. Five of these patients (12%) survived longer than expected (> 18 months). There were no differences in these patients in terms of demographics, presentation, traditional imaging findings, or treatment compared with the group as a whole. Magnetic resonance spectroscopy, however, demonstrated two distinct patterns not seen in typical diffuse pontine gliomas. In two patients elevated lipid and lactate levels were shown, with decreased levels of choline, myoinositol, and N-acetyl-aspartate (NAA). In the other patients strikingly elevated choline/creatinine ratios and myoinositol levels were observed in comparison with typical pontine tumors.

CONCLUSIONS

These MR spectroscopy patterns demonstrated in this retrospective study seem to convey prognostic information and may lead to an expansion of this diagnostic tool.

Combined magnetic resonance imaging- and positron emission tomography-guided stereotactic biopsy in brainstem mass lesions: diagnostic yield in a series of 30 patients

OBJECT

In the management of brainstem lesions, the place of stereotactic biopsy sampling remains debatable. The authors compared the results of magnetic resonance (MR) imaging, positron emission tomography (PET) scanning, and histological studies obtained in 30 patients who underwent MR imaging- and PET-guided stereotactic biopsy procedures for a brainstem mass lesion.

METHODS

Between July 1991 and December 1998, 30 patients harboring brainstem mass lesions underwent a stereotactic procedure in which combined MR imaging and PET scanning guidance were used. Positron emission tomography scanning was performed using [18F]fluorodeoxyglucose in 16 patients, methionine in two patients, and both tracers in 12 patients. Definite diagnosis was established on histological examination of the biopsy samples. Interpretation of MR imaging findings only or PET findings only was in agreement with the histological diagnosis in 63% and 73% of cases, respectively. Magnetic resonance imaging and PET findings were concordant in 19 of the 30 cases; in those cases, imaging data correlated with histological findings in 79%. Treatment based on information derived from MR imaging was concordant with therapy based on histological findings in only 17 patients (57%). Combining MR imaging and PET scanning data, the concordance between the neuroimaging-based treatment and treatments based on histological findings increased to 19 patients (63%). In seven patients who underwent biopsy procedures with one PET-defined and one MR imaging-defined trajectory, at histological examination the PET-guided samples were more representative of the tumor's nature and grade than the MR imaging-guided samples in four cases (57%). In 18 patients PET scanning was used to define a biopsy target and provided a diagnostic yield in 100% of the cases.

CONCLUSIONS

Although the use of combined PET and MR imaging improves radiological interpretation of a mass lesion in the brainstem, it does not accurately replace histological diagnosis that is provided by a stereotactically obtained biopsy sample. Combining information provided by MR imaging and PET scanning in stereotactic conditions improves the accuracy of targeting and the diagnostic yield of the biopsy sample; an MR imaging- and PET-guided stereotactic biopsy procedure is a safe and efficient modality for the management of mass lesions of the brainstem.

A clinicopathologic reappraisal of brain stem tumor classification. Identification of pilocystic astrocytoma and fibrillary astrocytoma as distinct entities

BACKGROUND

Brain stem tumors in children have been classified pathologically as low grade or high grade gliomas and descriptively as diffuse gliomas, intrinsic gliomas, midbrain tumors, tectal gliomas, pencil gliomas, dorsal exophytic brain stem tumors, pontine gliomas, focal medullary tumors, cervicomedullary tumors, focal gliomas, or cystic gliomas.

METHODS

To search for a simplified and prognostic clinicopathologic scheme for brain stem tumors, the authors reviewed a consecutive cohort of patients younger than age 21 years with tumors diagnosed from 1980 through 1997. Pathology specimens and neuroimaging were classified by masked review. Statistical and survival analysis along with Cox proportional hazards regression was performed.

RESULTS

Seventy-six patients were identified, with initial diagnostic magnetic resonance imaging available for 51 and pathology specimens for 48 patients. Twenty cases were classified histologically as pilocytic astrocytoma (PA), 14 as fibrillary astrocytoma (FA), and 14 as other tumors or indeterminate pathology. For all tumors, characteristics significantly associated with a worse survival rate were: symptom duration less than 6 months before diagnosis (P = 0.004); abducens palsy at presentation (P < 0.0001); pontine location (P = 0.0002); and engulfment of the basilar artery (P = 0.006). Pilocytic astrocytoma was associated with location outside the ventral pons (P = 0.001) and dorsal exophytic growth (P = 0.013); Fibrillary astrocytoma was associated with symptoms less than 6 months (P = 0. 006), abducens palsy (P < 0.001), and engulfment of the basilar artery (P = 0.002). Pilocytic astrocytoma showed 5-year overall survival (OS) of 95% (standard error [SE], 5%) compared with FA 1-year OS of 23% (SE, 11%;P < 0.0001).

CONCLUSIONS

Brain stem tumors can be succinctly and better biologically classified as diffusely infiltrative brain stem gliomas-generally FA located in the ventral pons that present with abducens palsy, often engulf the basilar artery, and carry a grim prognosis-and focal brain stem gliomas-frequently PA arising outside the ventral pons, often with dorsal exophytic growth, a long clinical prodrome, and outstanding prognosis for survival. Our findings emphasize the individuality of PA as a distinct clinicopathologic entity with an exceptional prognosis.

Combined magnetic resonance imaging– and positron emission tomography–guided stereotactic biopsy in brainstem mass lesions: diagnostic yield in a series of 30 patients

In the management of brainstem lesions, the place of stereotactic biopsy sampling remains debatable. The authors compared the results of magnetic resonance (MR) imaging, positron emission tomography (PET), and histological findings obtained in 30 patients who underwent an MR image– and PET-guided stereotactic biopsy procedure for a brainstem mass lesion.

Between July 1991 and December 1998, 30 patients harboring a brainstem mass lesion underwent a stereotactic procedure in which combined MR imaging and PET guidance was used. Positron emission tomography scanning was performed using [18F]-fluorodeoxyglucose in 16 patients, methionine in two patients, and with both tracers in 12 patients. Definite diagnosis was established on histological examination of the biopsy samples. Interpretation of MR imaging findings only or PET findings only were in agreement with the histological diagnosis in 63% and 73% of cases, respectively. Magnetic resonance imaging and PET findings were concordant in 19 of the 30 cases; in those cases, imaging data correlated with histological findings in 79%. In seven patients who underwent one PET-defined and one MR imaging–defined trajectory, at histological examination the PET-guided samples were more representative of the tumor's nature and grade than the MR imaging–guided samples in four cases (57%). In 18 patients PET scanning was used to define a biopsy target and provided a diagnostic yield in 100% of the cases.

Although the use of combined PET and MR imaging improves radiological interpretation of a mass lesion in the brainstem, it does not accurately replace histological diagnosis that is provided by a stereotactically obtained biopsy sample. Combined information provided by MR imaging and PET in stereotactic conditions improves the accuracy of targeting and the diagnostic yield of the stereotactically biopsy sample; an MR imaging– and PET-guided stereotactic biopsy procedure is a safe and efficient modality for the management of mass lesions of the brainstem.

Radiotherapy followed by high dose busulfan and thiotepa: a prospective assessment of high dose chemotherapy in children with diffuse pontine gliomas

BACKGROUND

The role of high dose chemotherapy (HDC) in patients with pediatric brain tumors currently is ill-defined. The purpose of this pilot study was to assess the feasibility and the benefit of HDC after radiotherapy in a group of children with newly diagnosed diffuse pontine gliomas.

METHODS

Patients eligible for study were ages 3-18 years with diffuse intrinsic tumors arising in the pons, who were not treated previously with radiotherapy or chemotherapy. Histologic confirmation was not mandatory, provided clinical findings and magnetic resonance imaging were typical. Patients were given focal radiotherapy followed 2-3 months later by HDC. Busulfan (150 mg/m(2) on Days 8, 7, 6, and 5) and thiotepa (300 mg/m(2) on Days 4, 3, and 2) were administered prior to autologous bone marrow transplantation. Survival was the endpoint, and the statistical procedure was based on sequential subgroup analysis.

RESULTS

Thirty-six patients were entered on to the study, 12 of whom underwent stereotactic biopsy or open surgery at the time of diagnosis. One patient eventually was excluded due to inappropriate eligibility criteria. All 35 eligible patients received irradiation. Early progression (9 patients) and parental refusal (2 patients) precluded the use of HDC in 11 patients. Three patients died of HDC-related complications. All 21 patients who survived HDC eventually died of disease progression. The median survival time was 10 months for the study group. The median survival time in the subgroup of patients who received HDC was 10 months (range, 3-26 months). Statistical analysis did not suggest any evidence of survival benefit.

CONCLUSIONS

For patients with diffuse pontine gliomas, survival using this aggressive treatment modality does not appear to be any better than that reported for conventional radiotherapy.