Risk factors for development of postoperative cerebellar mutism syndrome in children after medulloblastoma surgery

The occipital interhemispheric transtentorial approach in infants and toddlers: efficacy and complications

INTRODUCTION

Outcomes for pineal region and superior cerebellar tumors in young children often hinge on extent of microsurgical resection, and thus choosing an approach that provides adequate visualization of pathology is essential. The occipital interhemispheric transtentorial (OITT) approach provides excellent exposure while minimizing cerebellar retraction. However, this approach has not been widely accepted as a viable option for very young children due to concerns for potential blood loss when incising the tentorium. The aim of this paper is to characterize our recent institutional experience with the occipital interhemispheric transtentorial approach (OITT) for tumor resection in infants and toddlers.

METHODS

A retrospective study was performed between 2016 and 2023 of pediatric patients less than 36 months of age who underwent OITT for tumor resection at a high-volume referral center. Patients with at least 3 months of postoperative follow-up and postoperative MRI were included. Primary outcomes included extent of resection, intraoperative and postoperative complications, and neurologic outcome. Secondary outcomes included length of stay and estimated blood loss.

RESULTS

Eight patients, five male, were included. The median age at the time of surgery was 10 months (range 5-36 months). Presenting symptoms included macrocephaly, nausea/vomiting, strabismus, gait instability, or milestone regression. Hydrocephalus was present preoperatively in all patients. Average tumor volume was 38.6 cm3, ranging from 1.3 to 71.9 cm3. All patients underwent an OITT approach for tumor resection with stereotactic guidance. No intraoperative complications occurred, and no permanent neurologic deficits developed postoperatively. Gross total resection was achieved in all cases per postoperative MRI report, and no instances of new cerebellar, brainstem, or occipital lobe ischemia were noted.

CONCLUSIONS

OITT approach for tumor resection in very young children (≤ 36 months) is an effective strategy with an acceptable safety profile. In our series, no significant intraoperative or postoperative complications occurred. To our knowledge, this is the first report describing this technique specifically in patients less than 36 months of age.

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.

Pediatric Neuro-oncology

OBJECTIVE

This article reviews the most common pediatric brain tumors, neurocutaneous syndromes, treatment-related neurotoxicities, and the long-term outcomes of survivors.

LATEST DEVELOPMENTS

In the era of molecular diagnostics, the classification, management, and prognostication of pediatric brain tumors and neurocutaneous syndromes has been refined, resulting in advancements in patient management. Molecular diagnostics have been incorporated into the most recent World Health Organization 2021 classification. This knowledge has allowed for novel therapeutic approaches targeting the biology of these tumors with the intent to improve overall survival, decrease treatment-related morbidity, and improve quality of life. Advances in management have led to better survival, but mortality remains high and significant morbidity persists. Current clinical trials focus on tumor biology targeted therapy, deescalation of therapy, and multimodal intensified approaches with targeted therapy in more high-risk tumors.

ESSENTIAL POINTS

Molecular diagnostics for pediatric brain tumors and neurocutaneous syndromes have led to novel therapeutic approaches targeting the biology of these tumors with the goals of improving overall survival and decreasing treatment-related morbidity. Further understanding will lead to continued refinement and improvement of tumor classification, management, and prognostication.

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.

Molecular and functional profiling of chemotolerant cells unveils nucleoside metabolism-dependent vulnerabilities in medulloblastoma

Chemotherapy resistance is considered one of the main causes of tumor relapse, still challenging researchers for the identification of the molecular mechanisms sustaining its emergence. Here, we setup and characterized chemotherapy-resistant models of Medulloblastoma (MB), one of the most lethal pediatric brain tumors, to uncover targetable vulnerabilities associated to their resistant phenotype. Integration of proteomic, transcriptomic and kinomic data revealed a significant deregulation of several pathways in resistant MB cells, converging to cell metabolism, RNA/protein homeostasis, and immune response, eventually impacting on patient outcome. Moreover, resistant MB cell response to a large library of compounds through a high-throughput screening (HTS), highlighted nucleoside metabolism as a relevant vulnerability of chemotolerant cells, with peculiar antimetabolites demonstrating increased efficacy against them and even synergism with conventional chemotherapeutics. Our results suggest that drug-resistant cells significantly rewire multiple cellular processes, allowing their adaptation to a chemotoxic environment, nevertheless exposing alternative actionable susceptibilities for their specific targeting.

Investigating lesion location in relation to cerebellar mutism following pediatric tumor resection

Background and Objectives

Approximately 25% of pediatric patients who undergo cerebellar tumor resection develop cerebellar mutism syndrome (CMS). Our group recently showed that damage to the cerebellar outflow pathway is associated with increased risk of CMS. Here, we tested whether these findings replicate in an independent cohort.

Methods

We evaluated the relationship between lesion location and the development of CMS in an observational study of 56 pediatric patients who underwent cerebellar tumor resection. We hypothesized that individuals that developed CMS after surgery (CMS+), relative to those that did not (CMS-) would have lesions that preferentially intersected with: 1) the cerebellar outflow pathway, and 2) a previously generated 'lesion-symptom map' of CMS. Analyses were conducted in accordance with pre-registered hypotheses and analytic methods (https://osf.io/r8yjv/).

Results

We found supporting evidence for both hypotheses. Compared with CMS- patients, CMS+ patients (n=10) had lesions with greater overlap with the cerebellar outflow pathway (Cohen's d=.73, p=.05), and the CMS lesion-symptom map (Cohen's d=1.1, p=.004).

Discussion

These results strengthen the association of lesion location with risk of developing CMS and demonstrate generalizability across cohorts. These findings may help to inform the optimal surgical approach to pediatric cerebellar tumors.

A presurgical voxel-wise predictive model for cerebellar mutism syndrome in children with posterior fossa tumors

BACKGROUND

This study aimed to investigate cerebellar mutism syndrome (CMS)-related voxels and build a voxel-wise predictive model for CMS.

METHODS

From July 2013 to January 2022, 188 pediatric patients diagnosed with posterior fossa tumor were included in this study, including 38 from a prospective cohort recruited between 2020 and January 2022, and the remaining from a retrospective cohort recruited in July 2013-Aug 2020. The retrospective cohort was divided into the training and validation sets; the prospective cohort served as a prospective validation set. Voxel-based lesion symptoms were assessed to identify voxels related to CMS, and a predictive model was constructed and tested in the validation and prospective validation sets.

RESULTS

No significant differences were detected among these three data sets in CMS rate, gender, age, tumor size, tumor consistency, presence of hydrocephalus and paraventricular edema. Voxels related to CMS were mainly located in bilateral superior and inferior cerebellar peduncles and the superior part of the cerebellum. The areas under the curves for the model in the training, validation and prospective validation sets were 0.889, 0.784 and 0.791, respectively.

CONCLUSIONS

Superior and inferior cerebellar peduncles and the superior part of the cerebellum were related to CMS, especially the right side, and voxel-based lesion-symptom analysis could provide valuable predictive information before surgery.

The Cerebellar Mutism Syndrome: Risk Assessment, Prevention and Treatment

Cerebellar mutism syndrome (CMS) has received increasing attention over the last decades as a complication of posterior fossa tumour surgery in children. Risk factors, aetiological aspects, and treatment measures of the syndrome have been investigated, yet the incidence of CMS remains unchanged. Overall, we are currently able to identify patients at risk, but we are unable to prevent it from occurring.Once CMS sets in, several symptomatic pharmacological treatments have been suggested, but only in smaller case series and not in randomized controlled trials, and it is not clear whether the treatment or time itself had a helpful effect.Within weeks to months, most patients regain their ability to speak after a phase with mutism or severely reduced speech; however, many patients continue to have speech and language deficits. At this point, anti-cancer treatment with chemotherapy and radiotherapy may be of focus more than the prognosis of CMS; however, many patients continue to have speech and language problems for months and years to come, and they are at high risk of other neurocognitive sequelae as well.Without reliable measures to prevent or treat the syndrome, we may look towards improving the prognosis of speech and neurocognitive functioning in these patients. As speech and language impairment is the cardinal symptom and late effect of CMS, the effect of intense and early-onset speech and language therapy as a standard of care in these patients should be investigated in relation to its effect on regaining speech capacity.

The Entity of Cerebellar Mutism Syndrome: A Narrative Review Centered on the Etiology, Diagnostics, Prevention, and Therapeutic Options

Cerebellar mutism syndrome (CMS), also known as posterior fossa syndrome, is an entity that entails a constellation of signs and symptoms which are recorded in a limited number of pediatric patients who have been operated on mainly for tumors involving the posterior cranial fossa, and more precisely, the region of the vermis. Medulloblastoma seems to constitute the most commonly recognized pathological substrate, associated with this entity. The most prevalent constituents of this syndrome are noted to be a, often transient, although protracted, language impairment, emotional lability, along with cerebellar and brainstem dysfunction. Apart from that, a definite proportion of involved individuals are affected by irreversible neurological defects and long-lasting neurocognitive impairment. A bulk of literature and evidence based on clinical trials exist, which reflect the continuous effort of the scientific community to highlight all perspectives of this complex phenomenon. There are several circumstances that intervene in our effort to delineate the divergent parameters that constitute the spectrum of this syndrome. In summary, this is implicated by the fact that inconsistent nomenclature, poorly defined diagnostic criteria, and uncertainty regarding risk factors and etiology are all constituents of a non-well-investigated syndrome. Currently, a preliminary consensus exists about the identification of a group of diagnostic prerequisites that are managed as sine qua non, in our aim to document the diagnosis of CMS. These include language impairment and emotional lability, as proposed by the international Board of the Posterior Fossa Society in their consensus statement. It is common concept that midline tumor location, diagnosis of medulloblastoma, younger age at diagnosis, and preoperatively established language impairment should be accepted as the most determinant predisposing conditions for the establishment of this syndrome. A well-recognized pathophysiological explanation of CMS includes disruption of the cerebellar outflow tracts, the cerebellar nuclei, and their efferent projections through the superior cerebellar peduncle. Despite the relative advancement that is recorded regarding the diagnostic section of this disease, no corresponding encouraging results are reported, regarding the available treatment options. On the contrary, it is mainly targeted toward the symptomatic relief of the affected individuals. The basic tenet of our review is centered on the presentation of a report that is dedicated to the definition of CMS etiology, diagnosis, risk factors, clinical presentation, and clinical management. Apart from that, an effort is made that attempts to elucidate the paramount priorities of the scientific forum, which are directed toward the expansion our knowledge in the era of diagnostics, prevention, and therapeutic options for patients suffering from CM, or who are at risk for development of this syndrome.

The role of apparent diffusion coefficient histogram metrics for differentiating pediatric medulloblastoma histological variants and molecular groups

BACKGROUND

Medulloblastoma, a high-grade embryonal tumor, is the most common primary brain malignancy in the pediatric population. Molecular medulloblastoma groups have documented clinically and biologically relevant characteristics. Several authors have attempted to differentiate medulloblastoma molecular groups and histology variants using diffusion-weighted imaging (DWI) and apparent diffusion coefficient (ADC) maps. However, literature on the use of ADC histogram analysis in medulloblastomas is still scarce.

OBJECTIVE

This study presents data from a sizable group of pediatric patients with medulloblastoma from a single institution to determine the performance of ADC histogram metrics for differentiating medulloblastoma variants and groups based on both histological and molecular features.

MATERIALS AND METHODS

In this retrospective study, we evaluated the distribution of absolute and normalized ADC values of medulloblastomas. Tumors were manually segmented and diffusivity metrics calculated on a pixel-by-pixel basis. We calculated a variety of first-order histogram metrics from the ADC maps, including entropy, minimum, 10th percentile, 90th percentile, maximum, mean, median, skewness and kurtosis, to differentiate molecular and histological variants. ADC values of the tumors were also normalized to the bilateral cerebellar cortex and thalami. We used the Kruskal-Wallis and Mann-Whitney U tests to evaluate differences between the groups. We carried out receiver operating characteristic (ROC) curve analysis to evaluate the areas under the curves and to determine the cut-off values for differentiating tumor groups.

RESULTS

We found 65 children with confirmed histopathological diagnosis of medulloblastoma. Mean age was 8.3 ± 5.8 years, and 60% (n = 39) were male. One child was excluded because histopathological variant could not be determined. In terms of medulloblastoma variants, tumors were classified as classic (n = 47), desmoplastic/nodular (n = 9), large/cell anaplastic (n = 6) or as having extensive nodularity (n = 2). Seven other children were excluded from the study because of incomplete imaging or equivocal molecular diagnosis. Regarding medulloblastoma molecular groups, there were: wingless (WNT) group (n = 7), sonic hedgehog (SHH) group (n = 14) and non-WNT/non-SHH (n = 36). Our results showed significant differences among the molecular groups in terms of the median (P = 0.002), mean (P = 0.003) and 90th percentile (P = 0.002) ADC histogram metrics. No significant differences among the various medulloblastoma histological variants were found.

CONCLUSION

ADC histogram analysis can be implemented as a complementary tool in the preoperative evaluation of medulloblastoma in children. This technique can provide valuable information for differentiating among medulloblastoma molecular groups. ADC histogram metrics can help predict medulloblastoma molecular classification preoperatively.

Cerebellar mutism syndrome: the importance of preoperative language assessment

Children undergoing surgical removal of tumors in the posterior cranial fossa can encounter a varied and complex constellation of neurological symptoms, called cerebellar mutism, defined as a disturbance in the planning and programming of motor language with preserved understanding, behavioral disorders such as inattention, visual-spatial disorganization, personality change, as well as ataxia and dysmetria. In the last years, several groups have been trying to establish risk factors or even predictive scores in order to be able at least in part to predict the appearance of speech disorders before surgery. We report on a child with pilocytic astrocytoma of the cerebellar vermis who had already been diagnosed with developmental linguistic delay two years earlier. This disorder initially worsened after surgery and later improved in the following 12 months. The aim of this paper is to emphasize the importance of preoperative neuropsychological evaluation. The present case, along with those reported in the literature, suggests that the risk of long-term cerebellar mutism is higher in children with preoperative speech disorders. In these patients a thorough assessment of cognitive and linguistic functions is therefore necessary to better evaluate the risk of cerebellar mutism after surgery.

Male Predisposition in Cerebellar Mutism Syndrome: a Cohort Study

The aim of this study was to explore the association between sex and cerebellar mutism syndrome and to examine other potential risk factors. This ambispective cohort study examined 218 pediatric patients (132 boys) with a posterior fossa tumor who underwent tumor resection from July 2013 to March 2021. The patients' demographics and tumor characteristics were examined and statistically analyzed to explore the associations among the variables. Multivariable and subgroup analyses were conducted to validate the independent risk factors for cerebellar mutism syndrome (CMS). The male and female patients did not differ significantly in terms of age, tumor size, tumor location, tumor consistency, VP shunt placement before resection, extent of resection, or surgeon, as well as with respect to the presence of hydrocephalus or paraventricular edema. The overall incidence of CMS was 32.6%. The incidence of CMS was significantly higher in male patients than that in female patients (41.7% vs. 18.6%; P = 0.001). In the multivariable analysis, male sex (adjusted odds ratio [OR], 3.27; P = 0.001), solid tumor consistency (adjusted OR, 5.61; P = 0.001), midline location (adjusted OR, 3.78; P = 0.004), and hydrocephalus (adjusted OR, 2.56; P = 0.047) were independent risk factors for the CMS. Chi-square analysis revealed that solid tumor consistency and midline location were associated with medulloblastoma (P < 0.001). Male patients had a higher risk of developing CMS after a posterior fossa tumor resection. Midline location, solid tumor consistency, and hydrocephalus were independent risk factors for CMS.

Cerebellar Mutism Syndrome in Pediatric Neuro-oncology: A Multidisciplinary Perspective and Call for Research Priorities

Cerebellar mutism syndrome (CMS), also known as posterior fossa syndrome, occurs in a subset of children after posterior fossa tumor resection, most commonly medulloblastoma. Patients with this syndrome exhibit often transient, although protracted, symptoms of language impairment, emotional lability, cerebellar, and brainstem dysfunction. However, many patients experience persistent neurological deficits and lasting neurocognitive impairment. Historically, research and clinical care were hindered by inconsistent nomenclature, poorly defined diagnostic criteria, and uncertainty surrounding risk factors and etiology. Proposed diagnostic criteria include two major symptoms, language impairment and emotional lability, as proposed by the international Board of the Posterior Fossa Society in their consensus statement as well as other experts in this field. Risk factors most commonly associated with development of CMS include midline tumor location, diagnosis of medulloblastoma and specific tumor subtype, younger age at diagnosis, and preoperative language impairment. A proposed etiology of CMS includes disruption of the cerebellar outflow tracts, the cerebellar nuclei, and their efferent projections through the superior cerebellar peduncle. Treatment for CMS remains supportive. Herein, we present a comprehensive overview of CMS etiology, diagnosis, risk factors, clinical presentation, and clinical management. In addition, we identify essential multidisciplinary research priorities to advance diagnostics, prevention, and intervention efforts for patients with, or at risk for, development of CMS.

Postoperative speech impairment and cranial nerve deficits after secondary surgery of posterior fossa tumours in childhood: a prospective European multicentre study

PURPOSE

Brain tumours constitute 25% of childhood neoplasms, and half of them are in the posterior fossa. Surgery is a fundamental component of therapy, because gross total resection is associated with a higher progression-free survival. Patients with residual tumour, progression of residual tumour or disease recurrence commonly require secondary surgery. We prospectively investigated the risk of postoperative speech impairment (POSI) and cranial nerve dysfunction (CND) following primary and secondary resection for posterior cranial fossa tumours.

METHODS

In the Nordic-European study of the cerebellar mutism syndrome, we prospectively included children undergoing posterior fossa tumour resection or open biopsy in one of the 26 participating European centres. Neurological status was assessed preoperatively, and surgical details were noted post-operatively. Patients were followed up 2 weeks, 2 months and 1 year postoperatively. Here, we analyse the risk of postoperative speech impairment (POSI), defined as either mutism or reduced speech, and cranial nerve dysfunction (CND) following secondary, as compared to primary, surgery.

RESULTS

We analysed 426 children undergoing primary and 78 undergoing secondary surgery between 2014 and 2020. The incidence of POSI was significantly lower after secondary (12%) compared with primary (28%, p = 0.0084) surgery. In a multivariate analysis adjusting for tumour histology, the odds ratio for developing POSI after secondary surgery was 0.23, compared with primary surgery (95% confidence interval: 0.08-0.65, p = 0.006). The frequency of postoperative CND did not differ significantly after primary vs. secondary surgery (p = 0.21).

CONCLUSION

Children have a lower risk of POSI after secondary than after primary surgery for posterior fossa tumours but remain at significant risk of both POSI and CND. The present findings should be taken in account when weighing risks and benefits of secondary surgery for posterior fossa tumours.

Cerebellar mutism syndrome in pediatric head trauma with cerebellar injury

PURPOSE

Cerebellar mutism syndrome (CMS) after cerebellar injury in pediatric head trauma is a poorly recognized condition that is not properly diagnosed or treated in our daily practice. We aimed to clinically identify this syndrome after isolated posttraumatic cerebellar injury and to propose pathophysiological explanation.

METHODS

We retrospectively analyzed 8 consecutive children presenting with isolated cerebellar injury over 16 years. Clinical presentation, radiological type and localization of injury, clinical initial CMS symptoms, and long-term neurocognitive outcome were reviewed.

RESULTS

Out of 8 patients presenting with isolated traumatic cerebellar injury, we diagnosed 2 cases with initial clinical symptoms of CMS. Both patients had an injury damaging median structures of the posterior fossa, especially the fourth ventricle and dentate nuclei. Initial symptoms lasted more than 1 month for one patient, who still presented concentration difficulties almost 1 year after the head injury.

CONCLUSION

CMS after traumatic cerebellar injury does exist, even if it seems to be a very rare entity. It has to be better detected and studied in order to enrich pathophysiological knowledge about CMS of all etiologies and to bring our concerned patients the suitable follow-up and rehabilitative care that they could benefit from.

Risk factors for postoperative cerebellar mutism syndrome in pediatric patients: a systematic review and meta-analysis

OBJECTIVE

A review article assessing all the risk factors reported in the literature for postoperative cerebellar mutism syndrome (pCMS) among children remains absent. The authors sought to perform a systematic review and meta-analysis to evaluate this issue.

METHODS

PubMed, Embase, and Web of Science were queried to systematically extract potential references. The articles relating to pCMS were required to be written in the English language, involve pediatric patients (≤ 18 years of age), and provide extractable data, which included a comparison group of patients who did not develop pCMS. The quality of the included studies was evaluated using the Newcastle-Ottawa Scale. Data were pooled using RevMan 5.4, and publication bias was assessed by visual inspection for funnel plot asymmetry. The study protocol was registered through PROSPERO (ID: CRD42021256177).

RESULTS

Overall, 28 studies involving 2276 patients were included. Statistically significant risk factors identified from univariate analysis were brainstem invasion (OR 4.28, 95% CI 2.23-8.23; p < 0.0001), fourth ventricle invasion (OR 12.84, 95% CI 4.29-38.44; p < 0.00001), superior cerebellar peduncle invasion (OR 6.77, 95% CI 2.35-19.48; p = 0.0004), diagnosis of medulloblastoma (OR 3.26, 95% CI 1.93-5.52; p < 0.0001), medulloblastoma > 50 mm (OR 8.85, 95% CI 1.30-60.16; p = 0.03), left-handedness (OR 6.57, 95% CI 1.25-34.44; p = 0.03), and a vermis incision (OR 5.44, 95% CI 2.09-14.16; p = 0.0005). On the other hand, a tumor located in the cerebellar hemisphere (OR 0.23, 95% CI 0.06-0.92; p = 0.04), cerebellar hemisphere compression (OR 0.23, 95% CI 0.11-0.45; p < 0.0001), and intraoperative imaging (OR 0.36, 95% CI 0.18-0.72; p = 0.004) reduced the risk of pCMS.

CONCLUSIONS

This study provides the largest and most reliable review of risk factors associated with pCMS. Although some risk factors may be dependent on one another, the data may be used by surgeons to better identify patients at risk for pCMS and for intervention planning.

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

Objective

A single-institution cohort of 92 consecutive pediatric patients harboring tumors involving the fourth ventricle, surgically treated via the telovelar or transvermian approach, was retrospectively reviewed in order to analyze the impact of surgical route on surgery-related outcomes and cumulative survival.

Methods

Clinical, radiological, surgical, and pathology details were retrospectively analyzed. We selected n = 6 surgery-related clinical and radiological outcomes: transient and permanent neurological deficits, duration of assisted ventilation, postoperative new onset medical events, postoperative cerebellar mutism, and extent of resection. We built univariate and multivariate logistic models to analyze the significance of relationships between the surgical routes and the outcomes. Cumulative survival (CS) was estimated by the cohort approach.

Results

There were 53 girls and 39 boys (mean age, 83 months). Telovelar approach was performed in 51 cases and transvermian approach in 41 cases. Early postoperative MRI studies showed complete removal in 57 cases (62%) and measurable residual tumor in 35 cases (38%). The average tumor residual volume was 1,316 cm³ (range, 0.016-4.231 cm³; median value, 0.9875 cm³). Residual disease was more often detected on immediate postop MRI after telovelar approach, but the difference was not significant. Cerebellar mutism was observed in 10 cases (11%). No significant difference in the onset of cerebellar mutism was detected between telovelar and transvermian approach. The choice of surgical approach did not significantly modify any other postoperative outcome and 1-/3-year CS of high-grade surgically treated tumors.

Conclusions

With the limitation of a single-center, single-surgeon retrospective series, our findings offer significant data to reconsider the real impact of the choice of the surgical route to the fourth ventricle on the incidence of cerebellar mutism and surgery-related morbidity. This seems to be in line with some recent reports in the literature. Surgical approach to the fourth ventricle should be individualized according to the location of the tumor, degree of vermian infiltration, and lateral and upward extension. Telovelar and transvermian approaches should not be considered alternative but complementary. Pediatric neurosurgeons should fully master both approaches and choose the one that they consider the best for the patient based on a thorough and careful evaluation of pre-operative imaging.

Perioperative risk factors for long-term intelligence in children with postoperative cerebellar mutism syndrome after medulloblastoma surgery

OBJECTIVE

Approximately 7%-50% of children with medulloblastoma (MB) develop postoperative cerebellar mutism syndrome (pCMS). pCMS has a short-term negative impact on intelligence, but effects on long-term outcomes are contradictory. The aim of this study was to assess long-term effects of pCMS in MB patients on aspects of intelligence quotient (IQ) and its perioperative risk factors.

METHODS

In this single-center retrospective cohort study, 31 children were included (14 pCMS). Perioperative risk factors included brainstem invasion, vermis incision, hydrocephalus, tumor size, severity of pCMS, neurological symptoms, mean body temperature (BT) on days 1-4 post surgery, and age at resection. Age-appropriate Wechsler Intelligence tests were assessed at least 2 years after tumor resection.

RESULTS

Mean interval between tumor resection and neuropsychological evaluation was 3.9 years in pCMS and 4 years and 11 months in the no-pCMS group. No significant differences in IQ scores were found between groups. The pCMS group had a clinically relevant difference of 10 points when compared to age norms on verbal IQ (VIQ). Bilateral pyramidal and swallowing problems were risk factors for lower performance. In the overall group, tumor size, younger age at surgery, and raised mean BT were negatively correlated with aspects of IQ.

CONCLUSIONS

We found a clinically significant reduction of VIQ in the pCMS patient group. pCMS patients with a larger tumor size, younger age at surgery, a higher mean BT in the first days after surgery, bilateral pyramidal symptoms, and swallowing problems 10 days post surgery are more at risk for VIQ deficits at long-term.

Magnetic Resonance Imaging in the Contemporary Management of Medulloblastoma: Current and Emerging Applications

Medulloblastoma, the most common malignant primary brain tumor in children, is now considered to comprise of four distinct molecular subgroups-wingless (WNT), sonic hedgehog (SHH), Group 3, and Group 4 medulloblastoma, each associated with distinct developmental origins, unique transcriptional profiles, diverse phenotypes, and variable clinical behavior. Due to its exquisite anatomic resolution, multiparametric nature, and ability to image the entire craniospinal axis, magnetic resonance imaging (MRI) is the preferred and recommended first-line imaging modality for suspected brain tumors including medulloblastoma. Preoperative MRI can reliably differentiate medulloblastoma from other common childhood posterior fossa masses such as ependymoma, pilocytic astrocytoma, and brainstem glioma. On T1-weighted images, medulloblastoma is generally iso- to hypointense, while on T2-weighted images, the densely packed cellular component of the tumor is significantly hypointense and displays restricted diffusion on diffusion-weighted imaging. Following intravenous gadolinium, medulloblastoma shows significant but variable and heterogeneous contrast enhancement. Given the propensity of neuraxial spread in medulloblastoma, sagittal fat-suppressed T1-postcontrast spinal MRI is recommended to rule out leptomeningeal metastases for accurate staging. Following neurosurgical excision, postoperative MRI done within 24-48 h confirms the extent of resection, accurately quantifying residual tumor burden imperative for risk assignment. Post-treatment MRI is needed to assess response and effectiveness of adjuvant radiotherapy and systemic chemotherapy. After completion of planned therapy, surveillance MRI is recommended periodically on follow-up for early detection of recurrence for timely institution of salvage therapy, as well as for monitoring treatment-related late complications. Recent studies suggest that preoperative MRI can reliably identify SHH and Group 4 medulloblastoma but has suboptimal predictive accuracy for WNT and Group 3 tumors. In this review, we focus on the role of MRI in the diagnosis, staging, and quantifying residual disease; post-treatment response assessment; and periodic surveillance, and provide a brief summary on radiogenomics in the contemporary management of medulloblastoma.

A CBF decrease in the left supplementary motor areas: New insight into postoperative pediatric cerebellar mutism syndrome using arterial spin labeling perfusion MRI

Postoperative pediatric cerebellar mutism syndrome (pCMS), characterized mainly by delayed onset transient mutism is a poorly understood complication that may occur after pediatric medulloblastoma (MB) resection. Our aim was to investigate postoperative changes in whole-brain cerebral blood flow (CBF) at rest in pCMS patients using arterial spin labeling (ASL) perfusion imaging. This study compared preoperative and postoperative T2-weighted signal abnormalities and CBF using a voxel-wise, whole-brain analysis in 27 children undergoing MB resection, including 11 patients who developed mutism and 16 who did not. Comparison of postoperative T2 signal abnormalities between patients who developed pCMS (mean age 7.0 years) and those who did not showed that pCMS (mean age 8.9 years) patients were significantly more likely to present with T2-weighted hyperintensities in the right dentate nucleus (DN) (p = 0.02). Comparison of preoperative and postoperative CBF in patients with pCMS showed a significant postoperative CBF decrease in the left pre-supplementary motor area (pre-SMA) (p = 0.007) and SMA (p = 0.009). In patients who did not develop pCMS, no significant differences were observed. Findings provide evidence of an association between pCMS, injury to the right DN, and left pre-SMA/SMA hypoperfusion, areas responsible for speech. This supports the relevance of CBF investigations in pCMS.

Meta-Analysis of Apparent Diffusion Coefficient in Pediatric Medulloblastoma, Ependymoma, and Pilocytic Astrocytoma

BACKGROUND

Medulloblastoma, ependymoma, and pilocytic astrocytoma are common pediatric posterior fossa tumors. These tumors show overlapping characteristics on conventional MRI scans, making diagnosis difficult.

PURPOSE

To investigate whether apparent diffusion coefficient (ADC) values differ between tumor types and to identify optimum cut-off values to accurately classify the tumors using different performance metrics.

STUDY TYPE

Systematic review and meta-analysis.

SUBJECTS

Seven studies reporting ADC in pediatric posterior fossa tumors (115 medulloblastoma, 68 ependymoma, and 86 pilocytic astrocytoma) were included following PubMed and ScienceDirect searches.

SEQUENCE AND FIELD STRENGTH

Diffusion weighted imaging (DWI) was performed on 1.5 and 3 T across multiple institution and vendors.

ASSESSMENT

The combined mean and standard deviation of ADC were calculated for each tumor type using a random-effects model, and the effect size was calculated using Hedge's g.

STATISTICAL TESTS

Sensitivity/specificity, weighted classification accuracy, balanced classification accuracy. A P value < 0.05 was considered statistically significant, and a Hedge's g value of >1.2 was considered to represent a large difference.

RESULTS

The mean (± standard deviation) ADCs of medulloblastoma, ependymoma, and pilocytic astrocytoma were 0.76 ± 0.16, 1.10 ± 0.10, and 1.49 ± 0.16 mm² /sec × 10^-3 . To maximize sensitivity and specificity using the mean ADC, the cut-off was found to be 0.96 mm² /sec × 10^-3 for medulloblastoma and ependymoma and 1.26 mm² /sec × 10^-3 for ependymoma and pilocytic astrocytoma. The meta-analysis showed significantly different ADC distributions for the three posterior fossa tumors. The cut-off values changed markedly (up to 7%) based on the performance metric used and the prevalence of the tumor types.

DATA CONCLUSION

There were significant differences in ADC between tumor types. However, it should be noted that only summary statistics from each study were analyzed and there were differences in how regions of interest were defined between studies.

EVIDENCE LEVEL

1 TECHNICAL EFFICACY: Stage 3.

Immunosuppression in Medulloblastoma: Insights into Cancer Immunity and Immunotherapy

OPINION STATEMENT

Medulloblastoma (MB) is the most common pediatric brain malignancy, with a 5-year overall survival (OS) rate of around 65%. The conventional MB treatment, comprising surgical resection followed by irradiation and adjuvant chemotherapy, often leads to impairment in normal body functions and poor quality of life, especially with the increased risk of recurrence and subsequent development of secondary malignancies. The development and progression of MB are facilitated by a variety of immune-evading mechanisms such as the secretion of immunosuppressive molecules, activation of immunosuppressive cells, inhibition of immune checkpoint molecules, impairment of adhesive molecules, downregulation of the major histocompatibility complex (MHC) molecules, protection against apoptosis, and activation of immunosuppressive pathways. Understanding the tumor-immune relationship in MB is crucial for effective development of immune-based therapeutic strategies. In this comprehensive review, we discuss the immunological aspect of the brain, focusing on the current knowledge tackling the mechanisms of MB immune suppression and evasion. We also highlight several key immunotherapeutic approaches developed to date for the treatment of MB.

Neuropsychiatric Symptoms After Brain Tumor Resection in Children and Adolescents: A Scoping Review

BACKGROUND

Brain tumors are one of the most common solid tumors in pediatric populations, with their treatments having significant neuropsychiatric impact.

OBJECTIVE

The objective of this study was to review the literature on neuropsychiatric sequelae after surgical resection of brain tumors in children and adolescents.

METHODS

Using a scoping method, we reviewed empirical articles describing pediatric patients with brain tumors who underwent partial or total resection and examined major neuropsychiatric domains postoperatively over time.

RESULTS

The initial search yielded 15,543 articles. After duplicate removal, abstract screening, and review, 44 articles were included. Cognitive deficits were the most widely studied outcomes and found to be associated with tumor location, operative variables, perioperative complications, treatment types, and psychosocial factors. Cerebellar mutism, or posterior fossa syndrome, commonly co-occurred with emotional and behavioral dysregulation after posterior fossa resections. Depression, anxiety, and somatization were frequently grouped together as "distress," with higher rates among pediatric patients with brain tumor than among healthy peers. Problematic school behaviors, antisocial, and attention-deficit traits were increased; however, several other behaviors (e.g., risky sexual behaviors, substance use) were equal or lower when compared to peers. Posttraumatic stress disorder was highly prevalent and often interfered with social functioning. Delirium, eating disorders, and longer-term outcomes received inadequate attention.

CONCLUSION

Identifying risk factors of neuropsychiatric sequelae and their impact after pediatric brain tumor resection is important for prognostication and the development of tailored management strategies for these children and adolescents.

Cerebellar Mutism Syndrome: An Overview of the Pathophysiology in Relation to the Cerebrocerebellar Anatomy, Risk Factors, Potential Treatments, and Outcomes

Cerebellar mutism syndrome (CMS) is one the most disabling postoperative neurological complications after posterior fossa surgery in children. CMS is characterized by a transient mutism with a typical onset demonstrated within 2 days postoperatively accompanied by associated ataxia, hypotonia, and irritability. Several hypotheses for the anatomical basis of pathophysiology and risk factors have been suggested. However, a definitive theory and treatment protocols have not yet been determined. Animal histological and electrophysiological studies and more recent human imaging studies have demonstrated the existence of a compartmentalized representation of cerebellar function, the understanding of which might provide more information on the pathophysiology. Damage to the dentatothalamocortical pathway and cerebrocerebellar diaschisis have been described as the anatomical substrate to the CMS. The risk factors, which include tumor type, brainstem invasion, tumor localization, tumor size, and vermal splitting technique, have not yet been clearly elucidated. The efficacy of potential pharmacological and speech therapies has been studied in small trials. Long-term motor speech deficits and associated cognitive and behavioral disturbances have now been found to be common among CMS survivors, affecting their development and requiring rehabilitation, leading to significant financial effects on the healthcare system and distress to the family. The aim of the present review was to outline the cerebellar anatomy and function and its connections in relationship to the pathophysiology and to refine the risk factors and treatment strategies for CMS.

Association between cerebral perfusion and paediatric postoperative cerebellar mutism syndrome after posterior fossa surgery-a systematic review

BACKGROUND

Paediatric postoperative cerebellar mutism syndrome (ppCMS) is a common complication following the resection of a cerebellar tumour in children. It is hypothesized that loss of integrity of the cerebellar output tracts results in a cerebello-cerebral "diaschisis" and reduced function of supratentorial areas of the brain.

METHODS

We performed a systematic review of the literature according to the PRISMA guidelines, in order to evaluate the evidence for hypoperfusion or hypofunction in the cerebral hemispheres in patients with ppCMS. Articles were selected based on the predefined eligibility criteria and quality assessment.

RESULTS

Five studies were included, consisting of three prospective cohort studies, one retrospective cohort study and one retrospective case control study. Arterial spin labelling (ASL) perfusion MRI, dynamic susceptibility contrast (DSC) perfusion MRI and single photon emission computed tomography (SPECT) were used to measure the cerebral and cerebellar tissue perfusion or metabolic activity. Reduced cerebral perfusion was predominantly demonstrated in the frontal lobe.

CONCLUSIONS

This systematic review shows that, after posterior fossa tumour resection, cerebral perfusion is reduced in ppCMS patients compared to patients without ppCMS. Well-powered prospective studies, including preoperative imaging, are needed to ascertain the cause and role of hypoperfusion in the pathophysiology of the syndrome.

Bromocriptine for the treatment of postoperative cerebellar mutism syndrome in pediatric patients: Three case reports

INTRODUCTION

Cerebellar mutism syndrome (CMS) is a common complication after posterior fossa tumor resection. It is characterized by a significant lack or loss of speech. Its biological origin remains unclear and there are no standardized treatments. However, bromocriptine seems to be a possible treatment for this condition.

CASE REPORT

In this paper, we present three cases of pediatric patients (4, 5, and 17-year old) who developed CMS after posterior fossa tumor surgery. They were treated with bromocriptine to improve neurological symptoms.Management and outcome: Bromocriptine was started at a low dose and was progressively increased to reach the minimum effective dose. After four months of treatment, a normal and fluid speech was observed in the three patients. No discontinuation due to adverse events were reported.

DISCUSSION

Bromocriptine has shown to be an effective and safe treatment for CMS in pediatric patients after posterior fossa tumor resection.

Drug Repurposing in Medulloblastoma: Challenges and Recommendations

OPINION STATEMENT

Medulloblastoma is the most frequently diagnosed primary malignant brain tumor among children. Currently available therapeutic strategies are based on surgical resection, chemotherapy, and/or radiotherapy. However, majority of patients quickly develop therapeutic resistance and are often left with long-term therapy-related side effects and sequelae. Therefore, there remains a dire need to develop more effective therapeutics to overcome the acquired resistance to currently available therapies. Unfortunately, the process of developing novel anti-neoplastic drugs from bench to bedside is highly time-consuming and very expensive. A wide range of drugs that are already in clinical use for treating non-cancerous diseases might commonly target tumor-associated signaling pathways as well and hence be of interest in treating different cancers. This is referred to as drug repurposing or repositioning. In medulloblastoma, drug repurposing has recently gained a remarkable interest as an alternative therapy to overcome therapy resistance, wherein existing non-tumor drugs are being tested for their potential anti-neoplastic effects outside the scope of their original use.

The role of cerebellum in the child neuropsychological functioning

This chapter proposes a review of neuropsychologic and behavior findings in pediatric pathologies of the cerebellum, including cerebellar malformations, pediatric ataxias, cerebellar tumors, and other acquired cerebellar injuries during childhood. The chapter also contains reviews of the cerebellar mutism/posterior fossa syndrome, reported cognitive associations with the development of the cerebellum in typically developing children and subjects born preterm, and the role of the cerebellum in neurodevelopmental disorders such as autism spectrum disorders and developmental dyslexia. Cognitive findings in pediatric cerebellar disorders are considered in the context of known cerebellocerebral connections, internal cellular organization of the cerebellum, the idea of a universal cerebellar transform and computational internal models, and the role of the cerebellum in specific cognitive and motor functions, such as working memory, language, timing, or control of eye movements. The chapter closes with a discussion of the strengths and weaknesses of the cognitive affective syndrome as it has been described in children and some conclusions and perspectives.

Cerebellar mutism: the predictive role of preoperative language evaluation

BACKGROUND

The association between preoperative language impairment and development of cerebellar mutism after surgical treatment of posterior fossa tumors has gained increasing interest in recent years based on the concept that both local compression/infiltration of the infratentorial periventricular anatomical structures involved in speech and language, as well as an increased distraction of supratentorial periventricular anatomical structures, due to an associated hydrocephalus, involved in the coordination of speech circuits, might lead to the subclinical presence of language disturbances already at diagnosis, predicting the development of a cerebellar mutism syndrome after tumor removal.

METHODS

A thorough review of the literature on the subject has been performed, together with a review of our institutional experience reporting the related long-term (10 years) results.

RESULTS AND CONCLUSIONS

According to our institutional experience, 20/70 (28.5%) children presented preoperative language impairment and developed cerebellar mutism after surgery. A residual impairment persists in 75% of the cases at a follow-up of 2 years, and in 50% of the cases at 10 years, a finding which actually depicts cerebellar mutism no more as a transient deficit but among long-term sequelae. The appearance of complex dysarthria in the postoperative period is a negative prognostic factor for the long-term persistence of speech disturbances.

Posterior Fossa Society Consensus Meeting 2018: a synopsis

PURPOSE

The Posterior Fossa Society (PFS) was founded 4 years ago to systematically gather and exchange information on the post-operative (CMS) and cerebellar cognitive affective syndrome (CCAS). With its consensus meetings, the PFS orchestrates research studies in the field of cerebellar injury and progresses the knowledge of post-operative pediatric cerebellar mutism syndrome (CMS). In this article, we captured the 3-day program of presentations, group discussions, interactive workshops, and dialogue, highlighting the key topic areas of CMS and its research advances.

METHODS

This synopsis is based on the third consensus meeting which was held in Reykjavik, Iceland, in August 2018.

RESULTS

Three working groups have been defined to drive the future research priorities on post-surgical CMS: (i) refining definition and symptoms scoring of CMS; (ii) understanding the pathogenesis and enhancing risk-stratification strategies; and (iii) developing rehabilitation approaches and protocols.

CONCLUSIONS

The third consensus meeting highlighted a unanimous desire for data-driven information to advance the knowledge and guide future research efforts. The PFS constitutes an established and expanding network of multi-disciplinary expertise that can facilitate the development of collaborative studies and produce official guidelines on the topic.

Cerebellar mutism syndrome: current approaches to minimize risk for CMS

PURPOSE

Cerebellar mutism syndrome (CMS) is a serious source of morbidity following posterior fossa surgery in the pediatric population. However, methods for effectively decreasing its incidence and impact remain unclear. It is our aim to examine the impact of adjusting surgical factors, namely the use of a telovelar approach and avoidance of cavitronic ultrasonic aspirator, on the incidence of CMS in our population as well as outlining potential pre-, intra-, and postoperative factors that may contribute to its development.

METHODS

Retrospective review was performed to identify patients undergoing posterior fossa surgery for resection of a medulloblastoma. Demographic, surgical, and postoperative data were collected. These data were analyzed for possible correlations to the risk of developing CMS via univariate analysis. For factors found to be significant, a multivariate analysis was performed to assess their independence.

RESULTS

Seven of 65 patients (10.8%) developed CMS postoperatively. Factors found to be significantly associated with a higher risk of CMS were the degree of retraction utilized during the procedure (p = 0.0000) and incision of the vermis (p = 0.0294). Although they did not reach the threshold of statistical significance, tumor vascularity (p = 0.19), adoption of a transvermian approach (p = 0.19), and lack of intraoperative imaging (p = 0.17) exhibited strongly suggestive trends towards a correlation with CMS.

DISCUSSION

In an effort to reduce the incidence and severity of CMS in our population, our institution adopted surgical practices that minimize tissue trauma and mitigate postoperative edema. This included the use of a telovelar over a transvermian approach to obviate the need for vermian incision, avoidance of the CUSA, and minimization of heavy retraction during surgery. This was successful in reducing the incidence of CMS from 39% in our medulloblastoma patients to 10.8%. The development of CMS after posterior fossa surgery appears to be a "two-hit" phenomenon requiring a combination of existing predisposition, surgical injury, and postoperative exacerbation. Therefore, it is critical to identify the factors involved at each stage and investigate treatments to target them appropriately.

Posterior fossa syndrome and increased mean diffusivity in the olivary bodies

OBJECTIVE

Posterior fossa syndrome (PFS) is a common postoperative complication following resection of posterior fossa tumors in children. It typically presents 1 to 2 days after surgery with mutism, ataxia, emotional lability, and other behavioral symptoms. Recent structural MRI studies have found an association between PFS and hypertrophic olivary degeneration, which is detectable as T2 hyperintensity in the inferior olivary nuclei (IONs) months after surgery. In this study, the authors investigated whether immediate postoperative diffusion tensor imaging (DTI) of the ION can serve as an early imaging marker of PFS.

METHODS

The authors retrospectively reviewed pediatric brain tumor patients treated at their institution, Lucile Packard Children's Hospital at Stanford, from 2004 to 2016. They compared the immediate postoperative DTI studies obtained in 6 medulloblastoma patients who developed PFS to those of 6 age-matched controls.

RESULTS

Patients with PFS had statistically significant increased mean diffusivity (MD) in the left ION (1085.17 ± 215.51 vs 860.17 ± 102.64, p = 0.044) and variably increased MD in the right ION (923.17 ± 119.2 vs 873.67 ± 60.16, p = 0.385) compared with age-matched controls. Patients with PFS had downward trending fractional anisotropy (FA) in both the left (0.28 ± 0.06 vs 0.23 ± 0.03, p = 0.085) and right (0.29 ± 0.06 vs 0.25 ± 0.02, p = 0.164) IONs compared with age-matched controls, although neither of these values reached statistical significance.

CONCLUSIONS

Increased MD in the ION is associated with development of PFS. ION MD changes may represent an early imaging marker of PFS.

Pediatric postoperative cerebellar cognitive affective syndrome follows outflow pathway lesions

OBJECTIVE

To evaluate lesion location after pediatric cerebellar tumor resection in relation to the development of severe cognitive and affective disturbances, or cerebellar cognitive affective syndrome (CCAS).

METHODS

The postsurgical lesion location of 195 pediatric patients with cerebellar tumors was mapped onto a template brain. Individuals with CCAS were matched to 2 participants without CCAS by sex, age, and lesion volume. Lesion analyses included both a hypothesis-driven evaluation of the cerebellar outflow pathway (deep nuclei and superior cerebellar peduncles) and data-driven multivariate lesion symptom mapping. Lesion-associated networks were evaluated by comparing connectivity patterns between the lesion location of cases with and those without CCAS with resting-state functional connectivity MRI data from large normative adult and pediatric cohorts.

RESULTS

CCAS was present in 48 of 195 participants (24.6%) and was strongly associated with cerebellar outflow tract lesions (p < 0.0001). Lesion symptom mapping also highlighted the cerebellar outflow pathway, with peak findings in the fastigial nuclei extending into the inferior vermis. Lesion network mapping revealed that the cerebellar region most associated with CCAS was functionally connected to the thalamic mediodorsal nucleus, among other sites, and that higher connectivity between lesion location and the mediodorsal nucleus predicts CCAS occurrence (p < 0.01). A secondary analysis of 27 participants with mutism revealed similar localization of lesions and lesion-associated networks.

CONCLUSION

Lesions of the cerebellar outflow pathway and inferior vermis are associated with major cognitive and affective disturbances after pediatric cerebellar tumor resection, and disrupted communication between the cerebellum and the thalamic mediodorsal nucleus may be important.

Whole transcriptome sequencing analyses of DHA treated glioblastoma cells

Glioblastoma (GBM) is a typical malignant tumor, and there are no effective drugs capable of improving patient survival. Docosahexaenoic acid (DHA), a nutrient essential to animal health and neurodevelopment, exerts an anticancer effect in several types of cancer. However, the function of DHA in GBM is still unclear. Here, we showed that DHA could repress the migration and invasion of GBM U251 cells and promote their apoptosis in a dose- and time-dependent manner, indicating that DHA has an anticancer effect on GBM cells. Whole-transcriptome analysis indicated that DHA treatment mainly regulates the genes associated with receptor binding, oxidoreductase activity, organic acid transmembrane transporter activity, and carboxylic acid transmembrane transporter activity. Long non-coding RNAs (LncRNAs) involved in the regulation network of DHA were also identified, and their targets were assigned to the Gene Ontology (GO) categories. In silico analysis was conducted to predict the pathways related to the differentially expressed genes by DHA treatment. Our findings suggest that DHA acts as an antitumor agent in GBM, which may provide a suitable means of improving the efficacy of GBM treatment in the future.

Quantitative MRI in post-operative paediatric cerebellar mutism syndrome

Post-operative paediatric cerebellar mutism syndrome (pCMS) occurs in around 25% of children undergoing surgery for cerebellar and fourth ventricular tumours. Reversible mutism is the hallmark of a syndrome which comprises severe motor, cognitive and linguistic deficits. Recent evidence from advanced neuroimaging studies has led to the current theoretical understanding of the condition as a form of diaschisis contingent on damage to efferent cerebellar circuitry. Tractography data derived from diffusion MRI studies have shown disruption of the dentato-rubro-thalamo-cortical tract in patients with pCMS, and perfusion studies have indicated widespread supratentorial regions which may give rise to the florid signs and symptoms of pCMS. Given the difficulties in predicting pCMS from standard structural MRI, this review discusses findings from quantitative MRI modalities which have contributed to our understanding of this debilitating syndrome, and considers the goals and challenges which lie ahead in the field.

Post-operative paediatric cerebellar mutism syndrome: time to move beyond structural MRI

PURPOSE

To determine the value of structural magnetic resonance imaging (MRI) in predicting post-operative paediatric cerebellar mutism syndrome (pCMS) in children undergoing surgical treatment for medulloblastoma.

METHODS

Retrospective cohort study design. Electronic/paper case note review of all children with medulloblastoma presenting to Great Ormond Street Hospital between 2003 and 2013. The diagnosis of pCMS was established through a scoring system incorporating mutism, ataxia, behavioural disturbance and cranial nerve deficits. MRI scans performed at three time points were assessed by neuroradiologists blinded to the diagnosis of pCMS.

RESULTS

Of 56 children included, 12 (21.4%) developed pCMS as judged by a core symptom of mutism. pCMS was more common in those aged 5 or younger. There was no statistically significant difference in pre-operative distortion or signal change of the dentate or red nuclei or superior cerebellar peduncles (SCPs) between those who did and did not develop pCMS. In both early (median 5 days) and late (median 31 months) post-operative scans, T2-weighted signal change in SCPs was more common in the pCMS group (p = 0.040 and 0.046 respectively). Late scans also showed statistically significant signal change in the dentate nuclei (p = 0.024).

CONCLUSIONS

The development of pCMS could not be linked to any observable changes on pre-operative structural MRI scans. Post-operative T2-weighted signal change in the SCPs and dentate nuclei underlines the role of cerebellar efferent injury in pCMS. Further research using advanced quantitative MRI sequences is warranted given the inability of conventional pre-surgical MRI to predict pCMS.