The Clinical and Prognostic Impact of the Choice of Surgical Approach to Fourth Ventricular Tumors in a Single-Center, Single-Surgeon Cohort of 92 Consecutive Pediatric Patients

A predictive model for cerebellar mutism syndrome based on lesion map in children with medulloblastoma

BACKGROUND

This study aimed to establish a voxel-based map to predict the occurrence of cerebellar mutism syndrome (CMS) and investigate the relationship between CMS and motor dysfunction.

METHOD

This multicenter study cohort included 224 patients diagnosed with medulloblastoma at Beijing Children's Hospital (n = 88) and Beijing Tiantan Hospital (n = 136). The dataset was randomly divided into training (n = 95), test (n = 41), and validation (n = 88) datasets. Voxel-based lesion-symptom mapping (VLSM) was used to identify the corresponding tumoral voxels for CMS and motor dysfunction. A prediction model was constructed based on the VLSM results.

RESULTS

The two cohorts showed significant differences in hydrocephalus (58.0 vs. 32.4%, p < 0.001), paraventricular edema (83.0 vs. 59.6%, p < 0.001), and presurgical ventricular-peritoneal shunt placement (53.7 vs. 10.2%, p < 0.001). The CMS group had a significantly higher rate of hydrocephalus than the non-CMS group (54.6 vs. 33.1%; p = 0.002). VLSM revealed that the left inferior cerebellar peduncle (32.26%), right dentate gyrus (24.23%), and right X lobule (21.79%) were the most impaired structures associated with CMS. CMS-related areas overlapped with motor planning and verbal fluency regions, while areas associated with motor dysfunction overlapped with motor planning. The prediction model achieved areas under the curve of 0.733, and 0.702 for the testing and external validation datasets, respectively.

CONCLUSIONS

VLSM-based models are used to predict CMS occurrence prior to surgery. CMS was related to motor planning and verbal fluency regions of the cerebellum. Motor dysfunction was associated with CMS functionally.

KEY POINTS

Question Cerebellar mutism syndrome (CMS) is a severe postoperative complication of medulloblastoma for which the specific responsible anatomical correlates remain unclear. Findings We identified areas associated with CMS in Voxel-based Lesion-Symptom Mapping (VLSM), which were used to establish the CMS predicting model. Clinical relevance VLSM analysis helps develop a reliable predictive model for CMS and explore its association with motor dysfunction, The establishment of this model will facilitate the prediction of CMS in clinical practice.

Intraventricular Glioma in Pediatric Patients: A Systematic Review of Demographics, Clinical Characteristics, and Outcomes

OBJECTIVE

We conducted a systematic review on pediatric intraventricular gliomas to survey the patient population, tumor characteristics, management, and outcomes.

METHODS

PubMed, Scopus, Web-of-Science, and Cochrane were searched using PRISMA guidelines to include studies reporting pediatric patients with intraventricular gliomas.

RESULTS

A total of 30 studies with 317 patients were included. Most patients were male (54%), diagnosed at a mean age of 8 years (0.2-19), and frequently exhibited headache (24%), nausea and vomiting (21%), and seizures (15%). Tumors were predominantly located in the fourth (48%) or lateral ventricle (44%). Most tumors were WHO grade 1 (68%). Glioblastomas were rarely reported (2%). Management included surgical resection (97%), radiotherapy (27%), chemotherapy (8%), and cerebrospinal fluid diversion for hydrocephalus (38%). Gross total resection was achieved in 59% of cases. Cranial nerve deficit was the most common postsurgical complication (28%) but most were reported in articles published prior to the year 2000 (89%). Newer cases published during or after the year 2000 exhibited significantly higher rates of gross total resection (78% vs. 39%, P < 0.01), lower rates of recurrence (26% vs. 47%, P < 0.01), longer average overall survival time (42 vs. 21 months, P = 0.02), and a higher proportion of patients alive (83% vs. 70%, P = 0.03) than in older cases.

CONCLUSIONS

Pediatric intraventricular gliomas correlate with parenchymal pediatric gliomas in terms of age at diagnosis and general outcomes. The mainstay of management is complete surgical excision and more recent studies report longer overall survival rates and less cranial nerve complications.

National multicentered retrospective review of clinical and intraoperative factors associated with the development of cerebellar mutism after pediatric posterior fossa tumor resection

BACKGROUND

Cerebellar mutism (CM) is characterized by a significant loss of speech in children following posterior fossa (PF) surgery. The biological origin of CM remains unclear and is the subject of ongoing debate. Significant recovery from CM is less likely than previously described despite rigorous multidisciplinary neuro-rehabilitational efforts.

METHODS

A national multi-centered retrospective review of all children undergoing PF resection in four midsized Canadian academic pediatric institutions was undertaken. Patient, tumor and surgical factors associated with the post-operative development of CM were reviewed. Retrospective identification of PF surgery patients including those developing and those that did not (internal control).

RESULTS

The study identified 258 patients across the 4 centers between 2010 and 2020 (mean age 6.73 years; 42.2% female). Overall, CM was experienced in 19.5% of patients (N = 50). Amongst children who developed CM histopathology included medulloblastoma (35.7%), pilocytic astrocytoma (32.6%) and ependymoma (17.1%). Intraoperative impression of adherence to the floor of the 4th ventricle was positive in 36.8%. Intraoperative abrupt changes in blood pressure and/or heart rate were identified in 19.4% and 17.8% of cases. The clinical resolution of CM was rated to be complete, significant resolution, slight improvement, no improvement and deterioration in 56.0%, 8.0%, 20.0%, 14.0% and 2.0%, respectively. In the cohort of children who experienced post-operative CM as compared to their no-CM counterpart, proportionally more tumors were felt to be adherent to the floor of the 4th ventricle (56.0% vs 49.5%), intraoperative extent of resection was a GTR (74% vs 68.8%) and changes in heart rate were noted (≥ 20% from baseline) (26.0% vs 15.9%). However, a multiple regression analysis identified only abrupt changes in HR (OR 5.97, CI (1.53, 23.1), p = 0.01) to be significantly associated with the development of post-operative CM.

CONCLUSION

As a devastating surgical complication after posterior fossa tumor surgery with variable clinical course, identifying and understanding the operative cues and revising intraoperative plans that optimizes the child's neurooncological and clinical outcome are essential.

Telovelar vs. Transvermian approach for the fourth ventricle tumors: A systematic review and meta-analysis

BACKGROUND

Tumors in the fourth ventricle can be critical due to the small size of the fourth ventricle, which causes symptoms to be detected even in the presence of lesser mass effects. A proper surgical approach to the fourth ventricle poses challenges due to its deep location and proximity to vital compartments within the brainstem. The two commonly used approaches to these tumors are the transvermian and telovelar approaches.

METHODS

A comprehensive systematic study was conducted based on a literature search of the databases. All case controls, cohorts, and case series including patients with fourth ventricle tumors, who were operated on with either telovelar or transvermian approaches were considered eligible. The evaluated outcomes were comparative postoperative complications of the telovelar vs. transvermian approach. After screening and data extraction, a meta-analysis was performed whenever adequate quantitative data were available.

RESULTS

Seven studies with a total number of 848 patients, discussed both telovelar and transvermian approaches, with comparative reporting of outcomes in each group. Postoperative outcomes including cranial nerve deficit, mutism, diplopia, CSF leak, need for CSF diversion, and postoperative gait disturbance were not significantly different between telovelar and transvermian approaches.

CONCLUSION

Postoperative complications were not significantly different between telovelar and transvermian approaches. Moreover, it could be proposed that such complications would be more likely to be a multifactorial matter concerning the patient's clinical condition, tumor characteristics, and surgeon's experience, rather than the surgical approach alone.

Pilocytic astrocytoma: The paradigmatic entity in low‑grade gliomas (Review)

Among low-grade gliomas, representing 10-20% of all primary brain tumours, the paradigmatic entity is constituted by pilocytic astrocytoma (PA), considered a grade 1 tumour by the World Health Organization. Generally, this tumour requires surgical treatment with an infrequent progression towards malignant gliomas. The present review focuses on clinicopathological characteristics, and reports imaging, neurosurgical and molecular features using a multidisciplinary approach. Macroscopically, PA is a slow-growing soft grey tissue, characteristically presenting in association with a cyst and forming a small mural nodule, typically located in the cerebellum, but sometimes occurring in the spinal cord, basal ganglia or cerebral hemisphere. Microscopically, it may appear as densely fibrillated areas composed of elongated pilocytic cells with bipolar 'hairlike' processes or densely fibrillated areas composed of elongated pilocytic cells with Rosenthal fibres alternating with loosely fibrillated areas with a varied degree of myxoid component. A wide range of molecular alterations have been encountered in PA, mostly affecting the MAPK signalling pathway. In detail, the most frequent alteration is a rearrangement of the BRAF gene, although other alterations include neurofibromatosis type-1 mutations, BRAFV600E mutations, KRAS mutations, fibroblast growth factor receptor-1 mutations of fusions, neurotrophic receptor tyrosine kinase family receptor tyrosine kinase fusions and RAF1 gene fusions. The gold standard of PA treatment is surgical excision with complete margin resection, achieving minimal neurological damage. Conventional radiotherapy is not required; the more appropriate treatment appears to be serial follow-up. Chemotherapy should only be applied in younger children to avoid the risk of long-term growth and developmental issues associated with radiation. Finally, if PA recurs, a new surgical approach should be performed. At present, novel therapy involving agents targeting MAPK signalling pathway dysregulation is in development, defining BRAF and MEK inhibitors as target therapeutical agents.

Predictors of postoperative complications and functional outcomes in pediatric patients with surgically treated fourth ventricle tumors

BACKGROUND

Tumors of the fourth ventricle are frequently treated pathologies in pediatric neurosurgery. Data regarding predictors for permanent neurological deficits, long-term functional outcomes, cerebellar mutism (CM), the extent of resection (EOR), and oncological outcomes are scarce. We attempt to contribute to this topic with an analysis of our institutional cohort.

METHODS

A retrospective single-center study of patients aged ≤ 19 years who underwent primary surgical resection of a fourth ventricular tumor over a 15-year period (2006-2021). Predictors analyzed included age, gender, surgical approach, anatomical pattern, tumor grade, EOR, tumor volume, and others as appropriate.

RESULTS

One hundred six patients were included (64 males, mean age 7.3 years). The rate of permanent neurological deficit was 24.2%; lateral tumor extension (p = 0.036) and tumor volume greater than 38 cm3 (p = 0.020) were significant predictors. The presence of a deficit was the only significant predictor of reduced (less than 90) Lansky score (p = 0.005). CM occurred in 20.8% of patients and was influenced by medulloblastoma histology (p = 0.011), lateral tumor extension (p = 0.017), and male gender (p = 0.021). No significant difference between the transvermian and telovelar approach in the development of CM was detected (p = 0.478). No significant predictor was found for the EOR. EOR was not found to be a significant predictor of overall survival for both low-grade and high-grade tumors; however, gross total resection (GTR) was protective against tumor recurrence compared to near-total or subtotal resection (p < 0.001). In addition, survival was found to be better in older patients (≥ 7.0 years, p = 0.019).

CONCLUSION

The overall rate of postoperative complications remains high due to the eloquent localization. Older patients (> 7 years) have been found to have better outcomes and prognosis. Achieving GTR whenever feasible and safe has been shown to be critical for tumor recurrence. CM was more common in patients with medulloblastoma and in patients with tumors extending through the foramen of Luschka. The telovelar approach uses a safe and anatomically sparing corridor; however, it has not been associated with a lower incidence of CM and neurological sequelae in our series, showing that each case should be assessed on an individual basis.

Posterior Fossa Laser Interstitial Thermal Therapy in Children

Real-time, MRI-guided laser interstitial thermal therapy (MRgLITT) is emerging as a minimally invasive technique for epilepsy surgery and for deep-seated tumors in the pediatric population. However, MRgLITT for posterior fossa lesions poses a unique challenge that is especially evident in this age range and remains understudied. In this study, we report our experience and analyze the current literature on MRgLITT for the treatment of posterior fossa in children.

Telovelar versus transvermian approach to tumors of the fourth ventricle and their impact on postoperative neurological complications: A multicenter study

Background

Tumors of the fourth ventricle are exceedingly rare; however, such lesions are formidable due to the severe postoperative neurological complications (pNCs) which often occur. The adoption of the telovelar approach over the transvermian was created to supposedly mitigate the pNCs; however, there is a lack of sufficient data supporting this theory.

Methods

Records from six hospitals were reviewed for patients surgically treated for a single tumor within the 4^th ventricle from 2016 to 2022. The pNCs which had 10 or more occurrences among the patients were individually assessed as the dependent variable in a binary logistic regression model against covariates which included the surgical approach.

Results

This study of 67 patients confirms no significant differences in risk for pNCs between the transvermian and telovelar approach. Rather, multivariate analysis identified neurophysiological monitoring (IONM) as a protective factor for postoperative speech and swallowing defects (odds ratio [OR]: 0.076, 95% confidence interval [CI] 0.011-0.525). Furthermore, intraoperative external ventricular drainage (EVD) was a protective factor for postoperative gait and focal motor defects (OR: 0.075, 95% CI 0.009-0.648) and for postoperative hydrocephalus (OR: 0.020, 95% CI 0.002-0.233). A univariate meta-analysis pooling the present study's patients and an additional 304 patients from the three additional studies in the literature confirms no significant differences in risk between the transvermian and telovelar approach for pNCs.

Conclusion

Intraoperative adjuncts including IONM and EVD may play a significant role in the postoperative outcome. Despite the present study's sample size being a major limitation, the findings may provide great value to neurosurgeons given the scarcity of the current literature.

Adult Medulloblastoma: Updates on Current Management and Future Perspectives

Medulloblastoma (MB) is a malignant embryonal tumor of the posterior fossa belonging to the family of primitive neuro-ectodermic tumors (PNET). MB generally occurs in pediatric age, but in 14–30% of cases, it affects the adults, mostly below the age of 40, with an incidence of 0.6 per million per year, representing about 0.4–1% of tumors of the nervous system in adults. Unlike pediatric MB, robust prospective trials are scarce for the post-puberal population, due to the low incidence of MB in adolescent and young adults. Thus, current MB treatments for older patients are largely extrapolated from the pediatric experience, but the transferability and applicability of these paradigms to adults remain an open question. Adult MB is distinct from MB in children from a molecular and clinical perspective. Here, we review the management of adult MB, reporting the recent published literature focusing on the effectiveness of upfront chemotherapy, the development of targeted therapies, and the potential role of a reduced dose of radiotherapy in treating this disease.