Posterior fossa tumors in infants and neonates

Recent Advances in Pediatric Medulloblastoma

PURPOSE OF REVIEW

Review recent advances in the understanding of pediatric medulloblastoma including etiology, biology, radiology, and management of pediatric medulloblastoma.

RECENT FINDINGS

The classic four subgroups have been reclassified and further subdivided based on new molecular findings. Research is revealing the cell origins of the different subtypes of medulloblastoma. There has been continued personalization of management based on molecular parameters. While many advances have been made in the knowledge base of this most common malignant pediatric brain tumor, there has not yet been translation into more effective therapies to prolong survival in all subgroups with the possible exception of children with group 3 disease. Quality of life remains a major challenge for long-term survivors.

Tumors of Choroid Plexus and Other Ventricular Tumors

Tumors arising inside the ventricular system are rare but represent a difficult diagnostic and therapeutic challenge. They usually are diagnosed when reaching a big volume and tend to affect young children. There is a wide broad of differential diagnoses with significant variability in anatomical aspects and tumor type. Differential diagnosis in tumor type includes choroid plexus tumors (papillomas and carcinomas), ependymomas, subependymomas, subependymal giant cell astrocytomas (SEGAs), central neurocytomas, meningiomas, and metastases. Choroid plexus tumors, ependymomas of the posterior fossa, and SEGAs are more likely to appear in childhood, whereas subependymomas, central neurocytomas, intraventricular meningiomas, and metastases are more frequent in adults. This chapter is predominantly focused on choroid plexus tumors and radiological and histological differential diagnosis. Treatment is discussed in the light of the modern acquisition in genetics and epigenetics of brain tumors.

Intracranial Tumors in the First Year of Life

Intracranial tumors in the first year of life are rare and, in this age group, are the second most common type of pediatric cancer after leukemias. As the more common solid tumor in neonates and infants, they present some peculiarities such as the high incidence of malignancies. Routine ultrasonography made easier to detect intrauterine tumors, but diagnosis can be delayed due to the lack or scarcity of recognizable symptoms. These neoplasms are often very large and highly vascular. Their removal is challenging, and there is a higher rate of morbidity and mortality than seen in older children, adolescents, and adults. They also differ from older children with respect to location, histological features, clinical behavior, and management. Pediatric low-grade gliomas represent 30% of the tumors in this age group and comprise circumscribed and diffuse tumors. They are followed by medulloblastoma and ependymoma. Other non-medulloblastoma embryonal neoplasms, former known as PNETS, are also commonly diagnosed in neonates and infants. Teratomas have an expressive incidence in newborns but decline gradually until the end of the first year of life. Immunohistochemical, molecular, and genomic advances are impacting the understanding and targeting of the treatment of some tumors, but, despite all these advances, the extent of resection remains the most important factor in the prognosis and survival of almost all types of tumors. The outcome is difficult to estimate, and 5-year survival ranges from one-quarter to three-quarters of the patients.

Resection of posterior fossa tumors in the semi-sitting position in children younger than 4 years of age

PURPOSE

The semi-sitting position for resection of posterior fossa tumors is a matter of ongoing debate. Here we report about our experience with this approach in children younger than 4 years of age.

METHODS

We retrospectively analyzed data of children younger than 4 years of age operated on in our institution in the semi-sitting position over a 15-year period. Patients were intraoperatively monitored for venous air embolism (VAE) by transthoracic Doppler (TTD) or transesophageal echocardiography (TEE). The severity of VAE was classified according to the Tübingen grading scale. Intraoperative incidents of VAE were recorded and the patients' course was followed postoperatively with a special focus on possible complications.

RESULTS

Twenty-four children (18 boys, 6 girls) were operated on in the semi-sitting position (26 operations). Mean age was 2.2 years (± 1.0), range between 0.4 and 3.9 years. External ventricular drains were inserted in 18 children with hydrocephalus preoperatively. VAE was detected in 6 instances during surgery (6/26 (23.1%)). In 3 patients with grade 1 VAE, no additional treatment was necessary. In one patient with grade 2 VAE, intracardiac air suction via the central venous catheter was performed, and in two patients with grade 4 VAE, additional cathecholamine-infusion was administered. No major intraoperative complications occurred. Postoperative CT images showed pneumocephalus in all children. In two children, small asymptomatic impression skull fractures at the site of the Mayfield pin occurred. Revision surgery was necessary in one child with a suboccipital CSF fistula.

CONCLUSION

The semi-sitting position for resection of tumors in the posterior fossa in children younger than 4 years of age can be safely performed in experienced centers taking special caution to detect and treat potential complications in an interdisciplinary setting.

Neurological vertigo in the emergency room in pediatric and adult age: systematic literature review and proposal for a diagnostic algorithm

Neurological vertigo is a common symptom in children and adults presenting to the emergency department (ED) and its evaluation may be challenging, requiring often the intervention of different medical specialties. When vertigo is associated with other specific symptoms or signs, a differential diagnosis may be easier. Conversely, if the patient exhibits isolated vertigo, the diagnostic approach becomes complex and only through a detailed history, a complete physical examination and specific tests the clinician can reach the correct diagnosis. Approach to vertigo in ED is considerably different in children and adults due to the differences in incidence and prevalence of the various causes. The aim of this systematic review is to describe the etiopathologies of neurological vertigo in childhood and adulthood, highlighting the characteristics and the investigations that may lead clinicians to a proper diagnosis. Finally, this review aims to develop an algorithm that could represent a valid diagnostic support for emergency physicians in approaching patients with isolated vertigo, both in pediatric and adult age.

Posterior Fossa Tumours in the First Year of Life: A Two-Centre Retrospective Study

Posterior fossa tumours (PFTs) in infants are very rare, and information on these tumours is scarce in the literature. This retrospective study reports their pathological characteristics and describes surgical aspects and treatment outcomes. A two-centre cohort of infants with PFTs treated from 2007 to 2018 was retrospectively reviewed. Patient characteristics, clinical, and treatment data were reviewed. Survival curves for progression-free survival (PFS) and overall survival (OS) were generated. Thirty-three infants were retrieved. There were 11 low grade and 22 high-grade tumours. The most common presenting symptom was intracranial hypertension. Fifteen children out of thirty-three progressed. Five-year PFS was significantly lower in children with high-grade tumours (38.3%) than those with low-grade tumours (69.3%), p = 0.030. High-grade pathology was the only predictor of progression (HR 3.7, 95% CI 1.1–13.31), p = 0.045. Fourteen children with high-grade tumours died, with a 5-year OS of 55.25%. PFTs in children below one year of age still represent a unique challenge. Infants with high-grade tumours display the worst outcomes and the lowest survival, indicating that more effective strategies are needed.

The semisitting position in pediatric neurosurgery: pearls and pitfalls of a 10-year experience

OBJECTIVE

The authors sought to investigate the pearls and pitfalls of using the semisitting position in pediatric neurosurgery, with special focus on related morbidity and surgical practicability.

METHODS

All pediatric cases at a single institution were evaluated retrospectively. Those patients who underwent procedures in the semisitting position between December 2010 and December 2020 were included in the final analysis. Results were compared with all children who underwent surgery in the prone position for posterior fossa lesions within the same time frame.

RESULTS

A total of 42 posterior fossa surgeries were performed in 38 children in the semisitting position between December 2010 and December 2020. The mean patient age at the time of surgery was 8.9 years (range 13 months-18 years). The data of 24 surgeries performed in the prone position in 22 children during the same time frame were analyzed in comparison. Three children (7.9%) were diagnosed with a persistent foramen ovale preoperatively. The surgery was completed in all cases. The incidence of venous air embolism (VAE) was 11.9%. There was no VAE-related hemodynamic instability, infarction, or death. Endoscopic techniques were applied safely in 14 cases (33.3%). Postoperative pneumocephalus occurred significantly more frequently in patients who had undergone procedures in the semisitting position (p < 0.05), but without the need for intervention. During 1 surgery (2.4%), the patient experienced a postoperative skull fracture and epidural bleeding due to the skull clamp application. Clinical status of the patients immediately after surgery was improved or stable in 33 of the 42 surgeries (78.6%) performed in the semisitting position.

CONCLUSIONS

With attentive performance and an experienced surgical team, the semisitting position is a safe option for posterior fossa surgery in the pediatric population. With a comparable complication profile, the semisitting position offers excellent anatomical exposure, which is ideal for the application of endoscopic visualization. Careful skull clamp application and appropriate monitoring are highly recommended.

Risk factors for surgical site infection in pediatric posterior fossa tumors

PURPOSE

Posterior fossa tumors are the most frequent pediatric solid tumor. Its main treatment is a surgical resection. Being a frequent procedure does not mean that it is exempt from complications, such as surgical site infections (SSI). The main objective of this paper is to study the risk factors associated with SSI following a resection of posterior fossa tumors in a purely pediatric population.

METHODS

A retrospective case-control study including all posterior fossa tumor surgeries performed at our hospital between January 2014 and December 2019 was conducted. All patients with a diagnosis of a postoperative SSI have been included as cases, and those who had surgery and no infectious complications have been considered as controls.

RESULTS

When analyzing risk factors, we have found that patients with ventriculoperitoneal shunt (VPS) (p = 0.03) or external ventricular drainage (EVD) (p = 0.005) placement had a greater chance of presenting a postoperative surgical site infection. Prolonged operative time (p < 0.001) and cerebrospinal fluid (CSF) leak through the wound (p = 0.002) also caused an increase in the risk of SSI in the postoperative period. A higher hemoglobin value (p = 0.002) would seem to be a preventive factor.

CONCLUSIONS

Some strategies that could help to reduce the risk of infections are managing hydrocephalus preferably with endoscopic third ventriculostomy, minimizing the needed operative time to perform the procedure, obtaining an adequate serum hemoglobin level, and avoiding CSF leak through the wound.

Edema-mass Ratio Based On Magnetic Resonance Imaging As A Preoperative Diagnostic Factor For Posterior Fossa Metastasis

BACKGROUND

Peritumoral edema of primary brain tumors is an important cause of morbidity and mortality. The number of studies currently available on the prognostic role of peritumoral brain edema in the posterior fossa is extremely limited.

OBJECTIVE

Based on the known importance of magnetic resonance imaging in diagnosing supratentorial metastases, this study aimed to investigate the effects of peritumoral edema on survival of patients with posterior fossa metastases and the preoperative diagnostic value of MRI.

METHODS

Edema and mass volumes of 49 patients with posterior fossa metastasis, who underwent surgery during 2012-2016, were measured using magnetic resonance imaging. The edema/mass indices were retrospectively calculated and interpreted by evaluating the demographic, clinical, and survival data.

RESULTS

The study consisted of 32 (65.3%) male and 17 (34.7%) female participants, with the mean age ± standard deviation of 47.25±29.25 (17-81) years. Among the 49 patients with posterior fossa metastases, 34 (69.4%) had carcinoma, while 15 (30.6%) had non-carcinoma metastases. The edema/mass indices of patients with carcinoma and non-carcinoma metastases were found to be 14.55±9.64 and 1.34±1.08, respectively, and the difference was statistically significant (p<0.001). The mean survival of patients with carcinoma and non-carcinoma metastases was found to be 642±11.52 days and 726±9.32 days, respectively; however, this difference was not statistically significant (p=0.787).

CONCLUSION

The edema/mass ratio was found to be a significant diagnostic factor for the prediction of posterior fossa metastases. Further detailed studies are warranted to investigate the effect of edema/mass ratio on survival rate.

Surgical site infection in paediatric posterior fossa surgery: does pathology matter?

OBJECTIVES

The aim of this study was to explore the rates and potential risks of surgical site infection (SSI) after posterior fossa surgery for tumour resection in children.

METHODS

We retrospectively reviewed our local paediatric (age < 16 years) database for all cases of posterior fossa (PF) brain tumour surgery between November 2008 and November 2019. We collected patient demographics, tumour histology/location, and the event of postoperative surgical site infection.

RESULTS

Overall, 22.1% (n=15) developed SSI out of sixty-eight children undergoing PF surgery for resection of brain tumours; 73.3% of them had a confirmed diagnosis of medulloblastoma. There was no statistically significant difference in the age (5.1 ± 0.60 vs. 6.2 ± 0.97 years; p=0.47) and duration of operation (262 vs. 253 min; p = 0.7655) between the medulloblastoma group and other tumours. Although the rate of postoperative hydrocephalus was higher in the medulloblastoma group (12.9% vs. 0%), this was not associated with increased SSI. Rates of CSF leak between the 2 groups were not different.

CONCLUSION

Medulloblastoma as a pathological entity seems to carry higher risk of postoperative surgical site infection compared to other types of paediatric posterior fossa tumours. Further larger studies are required to look into this causal relationship and other risk factors that might be involved.

Predicting postoperative tracheostomy requirement in children undergoing surgery for posterior fossa tumors

PURPOSE

Posterior fossa tumor (PFT) resection can be associated with postoperative respiratory failure. We aimed to identify risk factors predicting tracheostomy dependence in children after PFT resection.

METHODS

Retrospective chart review of all children undergoing PFT resection from April 2007 to May 2017 at our institution was performed.

RESULTS

A total of 197 patients were included; 12 (6.1%) required tracheostomy placement at a mean 69.1 days postoperatively (SD 112.7, range 7-388). Patients requiring tracheostomy were younger (3.4 vs. 6.8 years, p < 0.01), more likely to have postoperative dysphagia (91.7% vs. 17.3%, p < 0.01), and more likely to have an ependymoma (41.7% vs. 15.1%, p < 0.01) or astrocytoma (25.0% vs. 8.1%, p < 0.01). Patients with eventual tracheostomy were less likely extubated immediately postoperatively (45.5% vs. 79.6%, p < 0.01), had longer intubation duration postoperatively (5.7 vs. 0.5 days, p < 0.01), and had higher rates of reintubation within 48 h (63.6% vs. 1.3%, p < 0.01). Patients requiring tracheostomy had longer hospital length of stay (45.8 vs. 15.3 days, p < 0.01) and ICU stay postoperatively (13.5 vs. 2.1 days, p < 0.01). Of those requiring tracheostomy, three (25.0%) were decannulated by 1 year postoperatively. Decannulation rates did not vary by age (p < 0.47), extubation failure (p < 0.24), duration of intubation (p < 0.10), tumor histology (p < 0.23), or tumor grade (p < 0.13).

CONCLUSION

Lower cranial neuropathy following PFT resection is common. Identifying risk factors correlated with need for tracheostomy can help identify patients who may benefit from early tracheostomy, reducing prolonged intubation trauma, time on mechanical ventilation, and length of stay.

Predicting dysphagia in children undergoing surgery for posterior fossa tumors

PURPOSE

Posterior fossa tumors (PFTs) are the most common type of brain tumor in children. Dysphagia is a known complication of PFT resection in children, but data regarding risk factors and clinical course are sparse.

METHODS

The records of all children who underwent resection of posterior fossa tumor between April 2007 and May 2017 at our institution were analyzed. Clinical, radiographic, histologic data were gathered. Swallowing function was assessed immediately postoperatively and at 1-year follow-up.

RESULTS

A total of 197 patients were included. Forty-three (21.8%) patients developed dysphagia after surgery. Patients who developed dysphagia were younger (4.5 vs. 7.2 years, p < 0.01), were more likely to have brainstem compression (74.4% vs. 57.8%, p < 0.03) or invasion (14.0 vs. 9.7%, p < 0.03), and were more likely to have ependymoma (27.9% vs. 13.6%, p < 0.01) or ATRT (atypical teratoid/rhabdoid tumor) (9.3% vs. 3.9%, p < 0.01). Patients with postoperative dysphagia also had a longer length of stay (33.7 vs. 12.7 days, p < 0.01) and were more likely to be discharged to inpatient rehabilitation (25.6% vs. 9.1%, p < 0.01). Ten patients (5.1%) were PEG-dependent by 1-year follow-up. These patients were younger (2.7 vs. 5.6 years, p < 0.01), had a longer length of stay (55.5 vs. 27.4 days, p < 0.01), and were more likely to have ATRT (30.0% vs. 0.0%, p < 0.01). Recovery was not associated with tumor grade or extent of resection.

CONCLUSIONS

Dysphagia after PFT resection is associated with younger age, aggressive tumor histology, and increased healthcare utilization. While most patients recover, a small percentage are still dependent on enteral feeding at 1-year follow-up. Further research is needed to identify factors associated with persistent deficits.

Arterial Spin-Labeling in Children with Brain Tumor: A Meta-Analysis

BACKGROUND

The value of arterial spin-labeling in a pediatric population has not been assessed in a meta-analysis.

PURPOSE

Our aim was to assess the diagnostic accuracy of arterial spin-labeling-derived cerebral blood flow to discriminate low- and high-grade tumors.

DATA SOURCES

MEDLINE, EMBASE, the Web of Science Core Collection, and the Cochrane Library were used.

STUDY SELECTION

Pediatric patients with arterial spin-labeling MR imaging with verified neuropathologic diagnoses were included.

DATA ANALYSIS

Relative CBF and absolute CBF and tumor grade were extracted, including sequence-specific information. Mean differences in CBF between low- and high-grade tumors were calculated. Study quality was assessed.

DATA SYNTHESIS

Data were aggregated using the bivariate summary receiver operating characteristic curve model. Heterogeneity was explored with meta-regression and subgroup analyses. The study protocol was published at PROSPERO (CRD42017075055). Eight studies encompassing 286 pediatric patients were included. The mean differences in absolute CBF were 29.62 mL/min/100 g (95% CI, 10.43-48.82 mL/min/100 g), I2 = 74, P = .002, and 1.34 mL/min/100 g (95% CI, 0.95-1.74 mL/min/100 g), P < .001, I2 = 38 for relative CBF. Pooled sensitivity for relative CBF ranged from 0.75 to 0.90, and specificity, from 0.77 to 0.92 with an area under curve = 0.92. Meta-regression showed no moderating effect of sequence parameters TE, TR, acquisition time, or ROI method.

LIMITATIONS

Included tumor types, analysis method, and original data varied among included studies.

CONCLUSIONS

Arterial spin-labeling-derived CBF measures showed high diagnostic accuracy for discriminating low- and high-grade tumors in pediatric patients with brain tumors. The relative CBF showed less variation among studies than the absolute CBF.

Synergistic anti-cancer effects of epigenetic drugs on medulloblastoma cells

PURPOSE

Medulloblastomas are aggressive brain malignancies. While considerable progress has been made in the treatment of medulloblastoma patients with respect to overall survival, these patients are still at risk of developing neurologic and cognitive deficits as a result of anti-cancer therapies. It is hypothesized that targeted molecular therapies represent a better treatment option for medulloblastoma patients. Therefore, the aim of the present study was to test a panel of epigenetic drugs for their effect on medulloblastoma cells under mild hypoxic conditions that reflect the physiological concentrations of oxygen in the brain.

METHODS

Protein levels of histone deacetylase 1 (HDAC1) and DNA methyltransferase 1 (DNMT1) in medulloblastoma-derived cells (Daoy and D283 Med), as well as in developing and differentiated brain cells, were determined and compared. Class I and II histone deacetylase inhibitors (HDACi) and a DNMT inhibitor, 5-aza-2'-deoxycytidine (5-aza-dC), were applied to Daoy and D283 Med cells, and their effects were studied using viability, apoptosis and cancer sphere assays.

RESULTS

We found that in HDAC1 and DNMT1 overexpressing medulloblastoma-derived cells, cell death was induced under various epigenetic drug conditions tested. At low HDACi concentrations, however, a pro-proliferative effect was observed. Parthenolide, a drug that affects cancer stem cells, was found to be efficient in inducing cell death in both cell lines tested. In contrast, we found that Daoy cells were more resistant to 5-aza-dC than D283 Med cells. When suberoylanilide hydroxamic acid (SAHA) and parthenolide were individually applied to both cell lines in combination with 5-aza-dC, a synergistic effect on cell survival was observed.

CONCLUSIONS

Our current results suggest that the application of HDACi in combination with drugs that target DNMT may represent a promising option for the treatment of medulloblastoma.

SOX10 Distinguishes Pilocytic and Pilomyxoid Astrocytomas From Ependymomas but Shows No Differences in Expression Level in Ependymomas From Infants Versus Older Children or Among Molecular Subgroups

SOX10 is important in nonneoplastic oligodendroglial development, but mRNA transcripts and protein expression are identified in a wider variety of CNS glial neoplasms than oligodendrogliomas. We previously demonstrated high levels of SOX10 mRNA and protein in pilocytic astrocytomas (PAs) but not ependymomas (EPNs). We now extend these studies to investigate subsets of these 2 tumors that affect infants, pilomyxoid astrocytomas (PMAs) and infant (<1 year) ependymomas (iEPNs). By gene expression microarray analysis, we found that iEPNs and all EPNs in older children showed very low SOX10 expression levels, on average 7.1-fold below normal control tissues. EPN groups showed no significant difference in SOX10 expression between iEPN and EPN. PAs/PMAs had 24.1/29.4-fold higher transcript levels, respectively, than those in normal tissues. Using immunohistochemical analysis of adult, pediatric, and infantile EPNs and of PAs/PMAs, we found that EPNs from multiple anatomical locations and both age groups (n = 228) never showed 3+ diffuse nuclear immunostaining for SOX10; the majority were scored at 0 or 1+. Conversely, almost all pediatric and adult PAs and PMAs (n = 47) were scored as 3+. These results suggest that in select settings, SOX10 immunohistochemistry can supplement the diagnosis of PMA and PA and aid in distinguishing them from EPNs.