Consensus paper on post-operative pediatric cerebellar mutism syndrome: the Iceland Delphi results

Secondary cerebro-cerebellar and intra-cerebellar dysfunction in cerebellar mutism syndrome

BACKGROUND

Cerebellar mutism syndrome (CMS) is characterized by deficits of speech, movement, and affect that can occur following tumor removal from the posterior fossa. The role of cerebro-cerebellar tract injuries in the etiology of CMS remains unclear, with recent studies suggesting that cerebro-cerebellar dysfunction may be related to chronic, rather than transient, symptomatology.

METHODS

We measured functional connectivity between the cerebellar cortex and functional nodes throughout the brain using fMRI acquired after tumor removal but prior to adjuvant therapy in a cohort of 70 patients diagnosed with medulloblastoma. Surgical lesions were mapped to the infratentorial anatomy, and connectivity with cerebral cortex was tested for statistical dependence on extent of cerebellar outflow pathway injury.

RESULTS

CMS diagnosis was associated with an increase in connectivity between the right cerebellar and left cerebral hemisphere, maximally between cerebellum and ventromedial prefrontal cortex (VM-PFC). Connectivity dependence on cerebellar outflow was significant for some speech nodes but not for VM-PFC, suggesting altered input to the cerebellum. Connectivity between posterior regions of cerebellar cortex and ipsilateral dentate nuclei was abnormal in CMS participants, maximally within the right cerebellar hemisphere.

CONCLUSIONS

The functional abnormalities we identified are notably upstream of where causal surgical injury is thought to occur, indicating a secondary phenomenon. The VM-PFC is involved in several functions that may be relevant to the symptomatology of CMS, including emotional control and motor learning. We hypothesize that these abnormalities may reflect maladaptive learning within the cerebellum consequent to disordered motor and limbic function by the periaqueductal gray and other critical midbrain targets.

Predicting cerebellar mutism syndrome in children using lesion map combined with clinical features

OBJECTIVE

This study aimed to develop a predictive model for cerebellar mutism syndrome (CMS) in pediatric patients with posterior fossa tumors, integrating lesion-symptom mapping (LSM) data with clinical factors, and to assess the model's performance.

METHODS

A cohort of pediatric patients diagnosed with posterior fossa tumors and undergoing surgery at Beijing Children's Hospital from July 2013 to December 2023 was analyzed. Clinical variables gender, age at surgery, tumor characteristics, hydrocephalus, surgical route and pathology were collected. LSM was used to link tumor locations with CMS outcomes. Lasso regression and logistic regression were employed for feature selection and model construction, respectively. Model performance was assessed using area under the curve (AUC) and accuracy metrics.

RESULTS

The study included 197 patients in total, with CMS rates consistent across training, validation, and prospective groups. Significant associations were found between CMS and gender, tumor type, hydrocephalus, paraventricular edema, surgical route, and pathology. A predictive model combining voxel location data from LSM with clinical factors achieved high predictive performance (C-index: training 0.956, validation 0.933, prospective 0.892). Gender, pathology, and voxel location were identified as key predictors for CMS.

CONCLUSION

The study established an effective predictive model for CMS in pediatric posterior fossa tumor patients, leveraging LSM data and clinical factors. The model's accuracy and robustness suggest its potential utility in clinical practice for early CMS risk assessment and intervention planning.

Using diffusion MRI to understand white matter damage and the link between brain microstructure and cognitive deficits in paediatric medulloblastoma patients

PURPOSE

Survivors of medulloblastoma face a range of challenges after treatment, involving behavioural, cognitive, language and motor skills. Post-treatment outcomes are associated with structural changes within the brain resulting from both the tumour and the treatment. Diffusion magnetic resonance imaging (MRI) has been used to investigate the microstructure of the brain. In this review, we aim to summarise the literature on diffusion MRI in patients treated for medulloblastoma and discuss future directions on how diffusion imaging can be used to improve patient quality.

METHOD

This review summarises the current literature on medulloblastoma in children, focusing on the impact of both the tumour and its treatment on brain microstructure. We review studies where diffusion MRI has been correlated with either treatment characteristics or cognitive outcomes. We discuss the role diffusion MRI has taken in understanding the relationship between microstructural damage and cognitive and behavioural deficits.

RESULTS

We identified 35 studies that analysed diffusion MRI changes in patients treated for medulloblastoma. The majority of these studies found significant group differences in measures of brain microstructure between patients and controls, and some of these studies showed associations between microstructure and neurocognitive outcomes, which could be influenced by patient characteristics (e.g. age), treatment, radiation dose and treatment type.

CONCLUSIONS

In future, studies would benefit from being able to separate microstructural white matter damage caused by the tumour, tumour-related complications and treatment. Additionally, advanced diffusion modelling methods can be explored to understand and describe microstructural changes to white matter.

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.

Proceedings of the first global meeting of the Posterior Fossa Society: state of the art in cerebellar mutism syndrome

PURPOSE

The Posterior Fossa Society, an international multidisciplinary group, hosted its first global meeting designed to share the current state of the evidence across the multidisciplinary elements of pediatric post-operative cerebellar mutism syndrome (pCMS). The agenda included keynote talks from world-leading speakers, compelling abstract presentations and engaging discussions led by members of the PFS special interest groups.

METHODS

This paper is a synopsis of the first global meeting, a 3-day program held in Liverpool, England, UK, in September 2022.

RESULTS

Topics included nosology, patient and family experience, cerebellar modulation of cognition, and cerebellar cognitive affective syndrome. In addition, updates from large-scale studies were shared as well as abstracts across neuroradiology, neurosurgery, diagnosis/scoring, ataxia, and rehabilitation.

CONCLUSIONS

Based on data-driven evidence and discussions, each special interest group created research priorities to target before the second global meeting, in the spring of 2024.

Catatonia associated with pediatric postoperative cerebellar mutism syndrome

OBJECTIVE

To ascertain the presence of catatonia in cases of pediatric postoperative cerebellar mutism syndrome (PPCMS).

METHOD

A systematic review of PPCMS case reports of patients aged 0-17 years with sufficient clinical information to extract catatonic phenomena was undertaken following PRISMA guidelines. Standardized catatonia rating scales were applied to selected cases retrospectively to ascertain whether diagnostic criteria for catatonia were met. A case known to the authors is also presented.

RESULTS

Two hundred twenty-one suitable full-text articles were identified. Following screening and application of inclusion criteria, 51 articles were selected plus seven more from their references, reporting on 119 subjects. All cases met Bush and Francis (BF) diagnostic criteria for catatonia, 92.5% Pediatric Catatonia Rating Scale (PCRS), 52.9% ICD-11, and 44.5% DSM-5. All patients presented with mutism. The next most frequent signs were immobility/stupor (77.3%), withdrawal (35.3%), mannerisms (23.5%), and excitement/agitation (18.5%). Most cases presented with stuporous catatonia (75.6%). Catatonia most frequently occurred following resection of medulloblastoma (64.7%). Preoperative hydrocephalus occurred in 89 patients (74.8%).

CONCLUSION

Catatonia was frequent in this PPCMS sample, with a predominant stuporous variant; it should be considered in patients with PPCMS and assessed with reliable and validated instruments for prompt diagnosis and management.

Neurosurgical short-term outcomes for pediatric medulloblastoma patients and molecular correlations: a 10-year single-center observation cohort study

This study examined the risk factors for short-term outcomes, focusing particularly on the associations among molecular subgroups. The analysis focused on the data of pediatric patients with medulloblastoma between 2013 and 2023, as well as operative complications, length of stay from surgery to adjuvant treatment, 30-day unplanned reoperation, unplanned readmission, and mortality. 148 patients were included. Patients with the SHH TP53-wildtype exhibited a lower incidence of complications (45.2% vs. 66.0%, odds ratio [OR] 0.358, 95% confidence interval [CI] 0.160 - 0.802). Female sex (0.437, 0.207 - 0.919) was identified as an independent protective factor for complications, and brainstem involvement (1.900, 1.297 - 2.784) was identified as a risk factor. Surgical time was associated with an increased risk of complications (1.004, 1.001 - 1.008), duration of hospitalization (1.006, 1.003 - 1.010), and reoperation (1.003, 1.001 - 1.006). Age was found to be a predictor of improved outcomes, as each additional year was associated with a 14.1% decrease in the likelihood of experiencing a prolonged length of stay (0.859, 0.772 - 0.956). Patients without metastasis exhibited a reduced risk of reoperation (0.322, 0.133 - 0.784) and readmission (0.208, 0.074 - 0.581). There is a significant degree of variability in the occurrence of operative complications in pediatric patients with medulloblastoma. SHH TP53-wildtype medulloblastoma is commonly correlated with a decreased incidence of complications. The short-term outcomes of patients are influenced by various unmodifiable endogenous factors. These findings could enhance the knowledge of onconeurosurgeons and alleviate the challenges associated with patient/parent education through personalized risk communication. However, the importance of a dedicated center with expertise surgical team and experienced neurosurgeon in improving neurosurgical outcomes appears self-evident.

Neuroanatomy of cerebellar mutism syndrome: the role of lesion location

Approximately 25% of paediatric patients who undergo cerebellar tumour resection develop cerebellar mutism syndrome. Our group recently showed that damage to the cerebellar deep nuclei and superior cerebellar peduncles, which we refer to as the cerebellar outflow pathway, is associated with an increased risk of cerebellar mutism syndrome. Here, we tested whether these findings replicate in an independent cohort. We evaluated the relationship between lesion location and the development of cerebellar mutism syndrome in an observational study of 56 paediatric patients ranging from five months to 14 years of age who underwent cerebellar tumour resection. We hypothesized that individuals who developed cerebellar mutism syndrome after surgery, relative to those who did not, would have lesions that preferentially intersect with: (i) the cerebellar outflow pathway and (ii) a previously generated 'lesion-symptom map' of cerebellar mutism syndrome. Analyses were conducted in accordance with pre-registered hypotheses and analytic methods (https://osf.io/r8yjv/). We found supporting evidence for both hypotheses. Compared to patients who did not develop cerebellar mutism syndrome, patients with cerebellar mutism syndrome (n = 10) had lesions with greater overlap with the cerebellar outflow pathway (Cohen's d = 0.73, P = 0.05), and the cerebellar mutism syndrome lesion-symptom map (Cohen's d = 1.1, P = 0.004). These results strengthen the association of lesion location with the risk of developing cerebellar mutism syndrome and demonstrate generalizability across cohorts. These findings may help to inform the optimal surgical approach to paediatric cerebellar tumours.

Adaption of neurosurgical resection patterns for pediatric low-grade glioma spanning two decades-Report from the German LGG-studies 1996-2018

INTRODUCTION

Neurosurgery is considered the mainstay of treatment for pediatric low-grade glioma (LGG); the extent of resection determines subsequent stratification in current treatment protocols. Yet, surgical radicality must be balanced against the risks of complications that may affect long-term quality of life. We investigated whether this consideration impacted surgical resection patterns over time for patients of the German LGG studies.

PATIENTS AND METHODS

Four thousand two hundred and seventy pediatric patients from three successive LGG studies (median age at diagnosis 7.6 years, neurofibromatosis (NF1) 14.7%) were grouped into 5 consecutive time intervals (TI1-5) for date of diagnosis and analyzed for timing and extent of first surgery with respect to tumor site, histology, NF1-status, sex, and age.

RESULTS

The fraction of radiological LGG diagnoses increased over time (TI1 12.6%; TI5 21.7%), while the extent of the first neurosurgical intervention (3440/4270) showed a reduced fraction of complete/subtotal and an increase of partial resections from TI1 to TI5. Binary logistic regression analysis for the first intervention within the first year following diagnosis confirmed the temporal trends (p < 0.001) and the link with tumor site for each extent of resection (p < 0.001). Higher age is related to more complete resections in the cerebellum and cerebral hemispheres.

CONCLUSIONS

The declining extent of surgical resections over time was unrelated to patient characteristics. It paralleled the evolution of comprehensive treatment algorithms; thus, it may reflect alignment of surgical practice to recommendations in respect to age, tumor site, and NF1-status integrated as such into current treatment guidelines. Further investigations are needed to understand how planning, performance, or tumor characteristics impact achieving surgical goals.

Postoperative cerebellar mutism syndrome is an acquired autism-like network disturbance

BACKGROUND

Cerebellar mutism syndrome (CMS) is a common and debilitating complication of posterior fossa tumor surgery in children. Affected children exhibit communication and social impairments that overlap phenomenologically with subsets of deficits exhibited by children with Autism spectrum disorder (ASD). Although both CMS and ASD are thought to involve disrupted cerebro-cerebellar circuitry, they are considered independent conditions due to an incomplete understanding of their shared neural substrates.

METHODS

In this study, we analyzed postoperative cerebellar lesions from 90 children undergoing posterior fossa resection of medulloblastoma, 30 of whom developed CMS. Lesion locations were mapped to a standard atlas, and the networks functionally connected to each lesion were computed in normative adult and pediatric datasets. Generalizability to ASD was assessed using an independent cohort of children with ASD and matched controls (n = 427).

RESULTS

Lesions in children who developed CMS involved the vermis and inferomedial cerebellar lobules. They engaged large-scale cerebellothalamocortical circuits with a preponderance for the prefrontal and parietal cortices in the pediatric and adult connectomes, respectively. Moreover, with increasing connectomic age, CMS-associated lesions demonstrated stronger connectivity to the midbrain/red nuclei, thalami and inferior parietal lobules and weaker connectivity to the prefrontal cortex. Importantly, the CMS-associated lesion network was independently reproduced in ASD and correlated with communication and social deficits, but not repetitive behaviors.

CONCLUSIONS

Our findings indicate that CMS-associated lesions may result in an ASD-like network disturbance that occurs during sensitive windows of brain development. A common network disturbance between CMS and ASD may inform improved treatment strategies for affected children.

Evaluation of safety of fluoxetine for cerebellar mutism syndrome in children after posterior fossa surgery

BACKGROUND

Cerebellar mutism syndrome (CMS) occurs in 8-29 % of children undergoing posterior fossa tumor surgery. Its main symptoms are mutism and emotional lability. Although it is always transient, recovery time can be lengthy with long-term cognitive sequelae. There is no approved drug treatment for CMS, but some drugs are used in everyday medical practice. One of these is fluoxetine, which has been used for many years in our institution. The main objective of this study was to establish the safety profile of fluoxetine in this condition.

MATERIALS AND METHODS

The records of patients admitted to the pediatric intensive care unit after brain surgery at Angers University Hospital from 2010 to 2020 were reviewed. Children aged 2 years and older who underwent a posterior fossa tumor surgery and were diagnosed with CMS were included. Data on patient characteristics, prescription of fluoxetine treatment, side effects if any, and complete mutism duration were collected.

RESULTS

Among 246 patients admitted to the pediatric intensive care unit for brain surgery during the study period, 23 had CMS and eight were prescribed fluoxetine. No serious adverse event related to fluoxetine was reported. Complete mutism duration did not differ significantly between the fluoxetine group and the non-fluoxetine group(p = 0.22). However, the treatment was initiated after recovery from complete mutism in half of the treated patients.

CONCLUSION

This study suggests a positive safety profile of fluoxetine used in postoperative CMS. It does not answer the question of whether the treatment is effective for this indication. A randomized controlled trial based on a syndrome severity scale should be conducted to provide a more reliable assessment of the efficacy and safety of fluoxetine.

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.

Characterising the Long-Term Language Impairments of Children Following Cerebellar Tumour Surgery by Extracting Psycholinguistic Properties from Spontaneous Language

Following cerebellar tumour surgery, children may suffer impairments of spontaneous language. Yet, the language processing deficits underlying these impairments are poorly understood. This study is the first to try to identify these deficits for four levels of language processing in cerebellar tumour survivors. The spontaneous language of twelve patients who underwent cerebellar tumour surgery (age range 3-24 years) was compared against his or her controls using individual case statistics. A distinction was made between patients who experienced postoperative cerebellar mutism syndrome (pCMS) and those who did not. Time since surgery ranged between 11 months and 12;3 years. In order to identify the impaired language processing levels at each processing level (i.e., lexical, semantic, phonological and/or morphosyntactic) nouns and verbs produced in the spontaneous language samples were rated for psycholinguistic variables (e.g., concreteness). Standard spontaneous language measures (e.g., type-token ratio) were calculated as well. First, inter-individual heterogeneity was observed in the spontaneous language outcomes in both groups. Nine out of twelve patients showed language processing deficits three of whom were diagnosed with pCMS. Results implied impairments across all levels of language processing. In the pCMS-group, the impairments observed were predominantly morphosyntactic and semantic, but the variability in nature of the spontaneous language impairments was larger in the non-pCMS-group. Patients treated with cerebellar tumour surgery may show long-term spontaneous language impairments irrespective of a previous pCMS diagnosis. Individualised and comprehensive postoperative language assessments seem necessary, given the inter-individual heterogeneity in the language outcomes.

Language outcomes in children who underwent surgery for the removal of a posterior fossa tumor: A systematic review

BACKGROUND

Children who underwent posterior fossa tumor removal may have spoken or written language impairments. The present systematic review synthesized the literature regarding the language outcomes in this population. Benefits of this work were the identification of shortcomings in the literature and a starting point toward formulating guidelines for postoperative language assessment.

METHODS

A systematic literature search was conducted, identifying studies with patients who had posterior fossa surgery before 18 years of age. Included studies were narratively synthesized to understand language outcomes by language function (e.g., phonology, morphosyntax) at a group and individual level. Furthermore, the influence of several mediators (e.g., postoperative cerebellar mutism syndrome (pCMS), tumor type) was investigated. A critical evaluation of the language assessment tools was conducted.

RESULTS

The narrative synthesis of 66 studies showed that a broad spectrum of language impairments has been described, characterized by a large interindividual heterogeneity. Patients younger at diagnosis, receiving treatment for a high-grade tumor and/or radiotherapy and diagnosed with pCMS seemed more prone to impairment. Several gaps in language assessment remain, such as a baseline preoperative assessment and the assessment of pragmatics and morphosyntax. Further, there were important methodological differences in existing studies which complicated our ability to accurately guide clinical practice.

CONCLUSION

Children who had posterior fossa surgery seem to be at risk for postoperative language impairment. These results stress the need for language follow-up in posterior fossa tumor survivors.

Preoperative word-finding difficulties in children with posterior fossa tumours: a European cross-sectional study

PURPOSE

Posterior fossa tumour surgery in children entails a high risk for severe speech and language impairments, but few studies have investigated the effect of the tumour on language prior to surgery. The current crosslinguistic study addresses this gap. We investigated the prevalence of preoperative word-finding difficulties, examined associations with medical and demographic characteristics, and analysed lexical errors.

METHODS

We included 148 children aged 5-17 years with a posterior fossa tumour. Word-finding ability was assessed by means of a picture-naming test, Wordrace, and difficulties in accuracy and speed were identified by cut-off values. A norm-based subanalysis evaluated performance in a Swedish subsample. We compared the demographic and medical characteristics of children with slow, inaccurate, or combined slow and inaccurate word finding to the characteristics of children without word-finding difficulties and conducted a lexical error analysis.

RESULTS

Thirty-seven percent (n = 55) presented with slow word finding, 24% (n = 35) with inaccurate word finding, and 16% (n = 23) with both slow and inaccurate word finding. Children with posterior fossa tumours were twice as slow as children in the norming sample. Right-hemisphere and brainstem location posed a higher risk for preoperative word-finding difficulties, relative to left-hemisphere location, and difficulties were more prevalent in boys than in girls. The most frequent errors were lack of response and semantically related sideordinated words.

CONCLUSION

Word-finding difficulties are frequent in children with posterior fossa tumours, especially in boys and in children with right-hemisphere and brainstem tumours. Errors resemble those observed in typical development and children with word-finding difficulties.

REhabilitation Approaches in CHildren with cerebellar mutism syndrome (REACH): An international cross-disciplinary survey study

OBJECTIVE

Pediatric cerebellar mutism syndrome (pCMS) can occur following resection of a posterior fossa tumor and, although some symptoms are transient, many result in long-lasting neurological deficits. A multi-disciplinary rehabilitation approach is often used in cases of pCMS; however, there have been no clinical trials to determine gold standards in rehabilitation practice in this population, which remains a research priority. The purpose of this study was to identify and compare intervention practices used in pCMS throughout the disciplines of occupational and physical therapy, speech-language pathology, and neuropsychology across geographic regions.

METHODS

A 55-question e-survey was created by an international multidisciplinary research group made up of members of the Posterior Fossa Society and sent to rehabilitation professionals in pediatric neuro-oncology centers in the US, Canada, and Europe.

RESULTS

Although some differences in the type of intervention used in pCMS were identified within each discipline, many of the targeted interventions including dose, frequency, and intensity were similar within disciplines across geographic regions. In addition, there were common themes identified across disciplines regarding challenges in the rehabilitation of this population.

CONCLUSION

These results provide a foundation of current practices on which to build future intervention-based clinical trials.

Presurgical MRI-Based Radiomics Models for Predicting Cerebellar Mutism Syndrome in Children With Posterior Fossa Tumors

BACKGROUND

Current studies have indicated that tumoral morphologic features are associated with cerebellar mutism syndrome (CMS), but the radiomics application in CMS is scarce.

PURPOSE

To develop a model for CMS discrimination based on multiparametric MRI radiomics in patients with posterior fossa tumors.

STUDY TYPE

Retrospective.

POPULATION

A total of 218 patients (males 132, females 86) with posterior fossa tumors, 169 of which were included in the MRI radiomics analysis. The MRI radiomics study cohort (169) was split into training (119) and testing (50) sets with a ratio of 7:3.

FIELD/SEQUENCE

All the MRI were acquired under 1.5/3.0 T scanners. T2-weighted image (T2W), T1-weighted (T1W), fluid attenuated inversion recovery (FLAIR), diffusion-weighted imaging (DWI).

ASSESSMENT

Apparent diffusion coefficient (ADC) maps were generated from DWI. Each MRI dataset generated 1561 radiomics characteristics. Feature selection was performed with univariable logistic analysis, correlation analysis, and least absolute shrinkage and selection operator (LASSO) penalized logistic regression. Significant clinical features were selected with multivariable logistic analysis and used to constructed the clinical model. Radiomics models (based on T1W, T2W, FLAIR, DWI, ADC) were constructed with selected radiomics features. The mix model was based on the multiparametric MRI radiomics features.

STATISTICAL TEST

Multivariable logistic analysis was utilized during clinical features selection. Models' performance was evaluated using the area under the receiver operating characteristic (AUC) curve. Interobserver variability was assessed using Cohen's kappa. Significant threshold was set as P < 0.05.

RESULTS

Sex (aOR = 3.72), tumor location (aOR = 2.81), hydrocephalus (aOR = 2.14), and tumor texture (aOR = 5.08) were significant features in the multivariable analysis and were used to construct the clinical model (AUC = 0.79); totally, 33 radiomics features were selected to construct radiomics models (AUC = 0.63-0.93). Seven of the 33 radiomics features were selected for the mix model (AUC = 0.93).

DATA CONCLUSION

Multiparametric MRI radiomics may be better at predicting CMS than single-parameter MRI models and clinical model.

EVIDENCE LEVEL

4.

TECHNICAL EFFICACY

2.

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.

Cerebellar mutism is linked to midbrain volatility and desynchronization from speech cortices

Cerebellar mutism syndrome is a disorder of speech, movement and affect that can occur after tumour removal from the posterior fossa. Projections from the fastigial nuclei to the periaqueductal grey area were recently implicated in its pathogenesis, but the functional consequences of damaging these projections remain poorly understood. Here, we examine functional MRI data from patients treated for medulloblastoma to identify functional changes in key brain areas that comprise the motor system for speech, which occur along the timeline of acute speech impairment in cerebellar mutism syndrome. One hundred and twenty-four participants, all with medulloblastoma, contributed to the study: 45 with cerebellar mutism syndrome, 11 patients with severe postoperative deficits other than mutism, and 68 without either (asymptomatic). We first performed a data-driven parcellation to spatially define functional nodes relevant to the cohort that align with brain regions critical for the motor control of speech. We then estimated functional connectivity between these nodes during the initial postoperative imaging sessions to identify functional deficits associated with the acute phase of the disorder. We further analysed how functional connectivity changed over time within a subset of participants that had suitable imaging acquired over the course of recovery. Signal dispersion was also measured in the periaqueductal grey area and red nuclei to estimate activity in midbrain regions considered key targets of the cerebellum with suspected involvement in cerebellar mutism pathogenesis. We found evidence of periaqueductal grey dysfunction in the acute phase of the disorder, with abnormal volatility and desynchronization with neocortical language nodes. Functional connectivity with periaqueductal grey was restored in imaging sessions that occurred after speech recovery and was further shown to be increased with left dorsolateral prefrontal cortex. The amygdalae were also broadly hyperconnected with neocortical nodes in the acute phase. Stable connectivity differences between groups were broadly present throughout the cerebrum, and one of the most substantial differences-between Broca's area and the supplementary motor area-was found to be inversely related to cerebellar outflow pathway damage in the mutism group. These results reveal systemic changes in the speech motor system of patients with mutism, centred on limbic areas tasked with the control of phonation. These findings provide further support for the hypothesis that periaqueductal grey dysfunction (following cerebellar surgical injury) contributes to the transient postoperative non-verbal episode commonly observed in cerebellar mutism syndrome but highlights a potential role of intact cerebellocortical projections in chronic features of the disorder.

Ferdinando Rossi Lecture: the Cerebellar Cognitive Affective Syndrome-Implications and Future Directions

The notion that the cerebellum is devoted exclusively to motor control has been replaced by a more sophisticated understanding of its role in neurological function, one that includes cognition and emotion. Early clinical reports, as well as physiological and behavioral studies in animal models, raised the possibility of a nonmotor role for the cerebellum. Anatomical studies demonstrate cerebellar connectivity with the distributed neural circuits linked with autonomic, sensorimotor, vestibular, associative and limbic/paralimbic brain areas. Identification of the cerebellar cognitive affective syndrome in adults and children underscored the clinical relevance of the role of the cerebellum in cognition and emotion. It opened new avenues of investigation into higher order deficits that accompany the ataxias and other cerebellar diseases, as well as the contribution of cerebellar dysfunction to neuropsychiatric and neurocognitive disorders. Brain imaging studies demonstrate the complexity of cerebellar functional topography, revealing a double representation of the sensorimotor cerebellum in the anterior lobe and lobule VIII and a triple cognitive representation in the cerebellar posterior lobe, as well as representation in the cerebellum of the intrinsic connectivity networks identified in the cerebral hemispheres. This paradigm shift in thinking about the cerebellum has been advanced by the theories of dysmetria of thought and the universal cerebellar transform, harmonizing the dual anatomic realities of homogeneously repeating cerebellar cortical microcircuitry set against the heterogeneous and topographically arranged cerebellar connections with extracerebellar structures. This new appreciation of the cerebellar incorporation into circuits that subserve cognition and emotion enables deeper understanding and improved care of our patients with cerebellar ataxias and novel cerebellar-based approaches to therapy in neuropsychiatry.

Medulloblastomas, CNS embryonal tumors, and cerebellar mutism syndrome: advances in care and future directions

Central nervous system (CNS) embryonal tumors, commonly found in pediatric patients, represent a heterogeneous mix of lesions with an overall poor (though improving) prognosis. Medulloblastomas are by far the most frequently encountered and most widely studied subtype, though others include atypical teratoid/rhabdoid tumors (AT/RTs), embryonal tumor with multilayered rosettes (ETMRs), and CNS neuroblastomas, FOX-R2 activated. The classification, diagnosis, and treatment of these lesions have evolved drastically over the years as their molecular underpinnings have been elucidated. We describe the most recent 2021 WHO Classification system, discuss current understanding of the genetic basis, and demonstrate current thinking in treatment for these highly complex tumors. Since surgical resection continues to remain a mainstay of treatment, preventing and managing surgical complications, especially cerebellar mutism syndrome (CMS), is paramount. We describe the current theories for the etiology of CMS and two centers' experience in mitigating its risks. As our surgical toolbox continues to evolve along with our understanding of these tumors, we hope future patients can benefit from both improved overall survival and quality of life.

The insertion and management of an external ventricular drain in pediatric patients with hydrocephalus associated with medulloblastoma

An external ventricular drain (EVD) is used to facilitate cerebrospinal fluid (CSF) removal in medulloblastoma patients suffering from hydrocephalus. It is essential to recognize that EVD management plays a crucial role in influencing the incidence of drain-related complications. However, the ideal method for EVD management remains undetermined. Our research sought to examine the safety of EVD placement and the impact of EVD on the incidences of intracranial infections, postresection hydrocephalus, and posterior fossa syndrome (PFS). We conducted a single-center observational study involving a cohort of 120 pediatric medulloblastoma patients who were treated from 2017 to 2020. The rates of intracranial infection, postresection hydrocephalus, and PFS were 9.2%, 18.3%, and 16.7%, respectively. EVD did not influence the occurrence of intracranial infection (p = 0.466), postresection hydrocephalus (p = 0.298), or PFS (p = 0.212). A gradual EVD weaning protocol correlated with an elevated incidence of postresection hydrocephalus (p = 0.033), whereas a rapid weaning approach resulted in 4.09 ± 0.44 fewer drainage days (p < 0.001) than the gradual weaning strategy. EVD placement (p = 0.010) and intracranial infection (p = 0.002) were linked to delayed speech return, whereas a longer duration of drainage was conducive to the recovery of language function (p = 0.010). EVD insertion was not correlated with the incidence of intracranial infection, postoperative hydrocephalus, or PFS. The optimal EVD management method should encompass a rapid EVD weaning strategy, followed by prompt drain closure. We have presented additional evidence to improve the safety of EVD insertion and management in neurosurgical patients to ultimately facilitate the establishment of standardized institutional/national implementation and management protocols.

A joint international consensus statement for measuring quality of survival for patients with childhood cancer

The aim of treating childhood cancer remains to cure all. As survival rates improve, long-term health outcomes increasingly define quality of care. The International Childhood Cancer Outcome Project developed a set of core outcomes for most types of childhood cancers involving relevant international stakeholders (survivors; pediatric oncologists; other medical, nursing or paramedical care providers; and psychosocial or neurocognitive care providers) to allow outcome-based evaluation of childhood cancer care. A survey among healthcare providers (n = 87) and online focus groups of survivors (n = 22) resulted in unique candidate outcome lists for 17 types of childhood cancer (five hematological malignancies, four central nervous system tumors and eight solid tumors). In a two-round Delphi survey, 435 healthcare providers from 68 institutions internationally (response rates for round 1, 70-97%; round 2, 65-92%) contributed to the selection of four to eight physical core outcomes (for example, heart failure, subfertility and subsequent neoplasms) and three aspects of quality of life (physical, psychosocial and neurocognitive) per pediatric cancer subtype. Measurement instruments for the core outcomes consist of medical record abstraction, questionnaires and linkage with existing registries. This International Childhood Cancer Core Outcome Set represents outcomes of value to patients, survivors and healthcare providers and can be used to measure institutional progress and benchmark against peers.

Neuroanatomy of Cerebellar Mutism Syndrome: The Role of Lesion Location

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

Cerebellar mutism syndrome of non-tumour surgical aetiology-a case report and literature review

Cerebellar mutism syndrome (CMS) is a well-known complication of posterior fossa (PF) tumour surgery. CMS has previously been reported in cases of non-tumour surgical aetiology in a limited number of publications. We report a case of a 10-year-old girl who suffered a cerebellar haemorrhage and subsequent CMS following surgical treatment of a ruptured arteriovenous malformation (AVM) in the cerebellar vermis. The AVM was removed acutely through a transvermian access, and hydrocephalus was treated with temporary external drainage. In the postoperative period, she suffered diffuse vasospasms of the anterior cerebral circulation and had a permanent shunt placed for hydrocephalus. Her mutism resolved after 45 days but severe ataxia persisted. To our knowledge, this is the first reported case of CMS related to a vermian haemorrhagic stroke with postoperative diffuse vasospasms. Based on this case, we present a literature review on CMS of non-tumour surgical origin in children.

Promoting Completion of Cranial Radiation Therapy Without Sedation in Young Patients With Brain Tumors: A Case Series Illustrating Flexible Application of Empirically Supported Intervention

Repeated anesthesia poses risks to patients but is often utilized to immobilize young children undergoing cranial radiation therapy for brain tumors. To enable young patients to remain still during cranial radiation therapy and thereby avoid sedation, medical and psychosocial clinicians can use behavioral and other supportive interventions. This case series illustrates the utility of behavioral training for motion control in 3 children 6 years old or younger who were treated for brain tumors. We demonstrate the efficacy of flexible, individualized intervention approaches to accommodate patients with brain tumors in the context of emotional dysregulation, significant communication barriers, and profound sensory deficits.

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.

Sociocultural variables have a major impact on participation in patients treated for paediatric posterior fossa tumours

BACKGROUND

This study investigates the severeness of participation barriers in patients surviving paediatric posterior fossa tumours (PFT) many years after treatment. In the past, aetiological studies on adverse outcome have primarily focused on pathobiological risk factors. The current analysis aims to investigate the importance of environmental variables.

METHODS

On average, 10 years after diagnosis, educational and social difficulties of 42 patients surviving paediatric PFT (mean age 17 years) were inquired using a self-constructed questionnaire following the Psychosocial Resource-Orientated Assessment (PREDI). Educational or social participation barriers were defined by self- and/or proxy-reported difficulties in school or in peer relationships. Accordingly, the children and adolescents were categorized into groups of adequate and limited participation. Subsequently, the study identified potential pathobiological (treatment type, hydrocephalus, tumour relapse, gender, age at diagnosis, seizures and cerebellar mutism) and environmental (parental and maternal education, siblings, main language, discrepancies between personal and environmental values, regular physical activity and private living space) risk factors and investigated whether patients with adequate and limited participation differed in the number of risk factors.

RESULTS

Almost one decade after treatment, two thirds of patients experienced educational and/or social difficulties. Patients with limited participation were more frequently associated with environmental factors such as low maternal education degree, siblings, main language other than German, discrepancies between societal and personal values and irregular physical activity, as well as the pathobiological risk factors treatment type, hydrocephalus, tumour relapse, cerebellar mutism and seizures. These variables significantly discriminated between patients with and without limited participation.

CONCLUSIONS

Limited participation in patients treated for paediatric PFT is common. Next to pathobiological, also environmental risk factors play a major role in educational and social participation barriers. This highlights the fact that solely considering pathobiology is not sufficient when investigating risk factors for the emergence of late sequelae. Future aetiological studies must adopt a biopsychosocial perspective.

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.

Long-term postoperative quality of life in childhood survivors with cerebellar mutism syndrome

Background

To investigate the long-term quality of life (QoL) of children with cerebellar mutism syndrome (CMS) and explore the risk factors for a low QoL.

Procedure

This cross-sectional study investigated children who underwent posterior fossa surgery using an online Pediatric Quality of Life Inventory questionnaire. CMS and non-CMS patients were included to identify QoL predictors.

Results

Sixty-nine patients were included (male, 62.3%), 22 of whom had CMS. The mean follow-up time was 45.2 months. Children with CMS had a significantly lower mean QoL score (65.3 vs. 83.7, p < 0.001) and subdomain mean scores (physical; 57.8 vs. 85.3, p < 0.001; social: 69.5 vs. 85.1, p = 0.001; academic: p = 0.001) than those without CMS, except for the emotional domain (78.0 vs. 83.7, p = 0.062). Multivariable analysis revealed that CMS (coefficient = -14.748.61, p = 0.043), chemotherapy (coefficient = -7.629.82, p = 0.013), ventriculoperitoneal (VP) shunt placement (coefficient = -10.14, p = 0.024), and older age at surgery (coefficient = -1.1830, p = 0.007) were independent predictors of low total QoL scores. Physical scores were independently associated with CMS (coefficient = -27.4815.31, p = 0.005), VP shunt placement (coefficient = -12.86, p = 0.025), and radiotherapy (coefficient = -13.62, p = 0.007). Emotional score was negatively associated with age at surgery (coefficient = -1.92, p = 0.0337) and chemotherapy (coefficient = -9.11, p = 0.003). Social scores were negatively associated with male sex (coefficient = -13.68, p = 0.001) and VP shunt placement (coefficient = -1.36, p = 0.005), whereas academic scores were negatively correlated with chemotherapy (coefficient = -17.45, p < 0.001) and age at surgery (coefficient = -1.92, p = 0.002). Extent of resection (coefficient = 13.16, p = 0.021) was a good predictor of higher academic scores.

Conclusion

CMS results in long-term neurological and neuropsychological deficits, negatively affecting QoL, and warranting early rehabilitation.

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.

Case Report: Zolpidem's paradoxical restorative action: A case report of functional brain imaging

Zolpidem is a sedative drug that has been shown to induce a paradoxical effect, restoring brain function in wide range of neurological disorders. The underlying functional mechanism of the effect of zolpidem in the brain in clinical improvement is still poorly understood. Thus, we aimed to investigate rest brain function to study zolpidem-induced symptom improvement in a patient who developed postoperative pediatric cerebellar mutism syndrome, a postoperative complication characterized by delayed onset transient mutism/reduced speech that can occur after medulloblastoma resection. The patient experienced clinical recovery after a single dose of zolpidem. Brain function was investigated using arterial spin labeling MRI and resting-state functional MRI. Imaging was performed at three time-points: preoperative, postoperative during symptoms, and after zolpidem intake when the symptoms regressed. Whole brain rest cerebral blood flow (CBF) and resting state functional connectivity using Pearson coefficient correlations between pairs of regions of interest were investigated two-by-two at the different time points. A comparison between postoperative and preoperative images showed a significant decrease in rest CBF in the left supplementary motor area, Broca's area, and the left striatum and a decrease in functional connectivity within the dentato-thalamo-cortical and cortico-striato-pallido-thalamo-cortical loops. Post-zolpidem images showed increased CBF in the left striatum and increased functional connectivity within the disrupted loops relative to postoperative images. Thus, we observed functional changes within the broader speech network and thalamo-subcortical interactions associated with the paradoxical effect of zolpidem in promoting clinical recovery. This should encourage further functional investigations in the brain to better understand the mechanism of zolpidem in neurological recovery.

Diffusion Tensor Imaging Technique Delineating the Prognosis for Cerebellar Mutism in Posterior Fossa Tumors: A New Tool

AIM

Cerebellar mutism syndrome (CMS) is a morbid complication of posterior fossa surgery in children. This review focuses on the current understanding of pathophysiology in the white matter tracts (WMT) using diffusion tensor imaging (DTI).

MATERIAL AND METHODS

A series of 38 patients operated on for posterior fossa tumors in our institute between December 2019 till May 2021 were evaluated neurologically along with characteristics of mutism and DTI imaging (fractional anisotropy) in preoperative and postoperative periods. We also noted tumor size, location, volume, brainstem compression, cerebellar peduncle involvement, extent of resection, surgical approach, and histopathology.

RESULT

Cerebellar mutism developed in five patients. The mean age, male sex, tumor size >5 cm, superior cerebellar peduncle involvement, and vermian incision were found to have positive correlation with the development of CMS. They showed reduction in fractional anisotropy in superior cerebellar peduncle (SCP) following resection; however, others' WMT did not show any significant change in fractional anisotropy values pre- or post-surgery.

CONCLUSION

Our study suggests that functional disruption of WMT, i.e., superior cerebellar peduncle and dentato-thalamo-cortical tract (DTC) is the underlying pathophysiological component of CMS. Taking this into consideration, we need to deploy techniques to limit the damage to the superior cerebellar peduncle and DTC using neurophysiological monitoring.

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.

Cerebellar mutism syndrome: From pathophysiology to rehabilitation

Cerebellar mutism syndrome (CMS) is a common complication following surgical resection of childhood tumors arising in the posterior fossa. Alteration of linguistic production, up to muteness and emotional lability, generally reported at least 24 h after the intervention, is the hallmark of post-operative CMS. Other associated traits include hypotonia and other cerebellar motor signs, cerebellar cognitive-affective syndrome, motor deficits from the involvement of the long pathways, and cranial neuropathies. Recovery usually takes 6 months, but most children are burdened with long-term residual deficits. The pathogenic mechanism is likely due to the damage occurring to the proximal efferent cerebellar pathway, including the dentate nucleus, the superior cerebellar peduncle, and its decussation in the mesencephalic tegmentum. Proven risk factors include brain stem invasion, diagnosis of medulloblastoma, midline localization, tumor size, invasion of the fourth ventricle, invasion of the superior cerebellar peduncle, left-handedness, and incision of the vermis. Currently, rehabilitation is the cornerstone of the treatment of patients with cerebellar mutism syndrome, and it must consider the three main impaired domains, namely speech, cognition/behavior, and movement.

Postoperative MRI features of cerebellar mutism syndrome: a retrospective cohort study

OBJECTIVE

In this study, the authors aimed to investigate the relationship between postoperative MRI features and cerebellar mutism syndrome.

METHODS

A retrospective cohort of patients who underwent tumor resection from July 2013 to March 2021 for midline posterior fossa tumors was investigated. All patients were followed up at least once. Clinical data were extracted from medical records and follow-up databases. Two neuroradiologists independently reviewed preoperative and postoperative MRI. Univariable and multivariable analyses were performed to compare the postoperative cerebellar mutism syndrome (pCMS) and non-pCMS groups. Correlation analysis was performed using the Spearman correlation coefficient analysis.

RESULTS

Of 124 patients, 47 (37.9%) developed pCMS. The median follow-up duration was 45.73 (Q1: 33.4, Q3: 64.0) months. The median duration of mutism was 45 days. The median tumor size was 48.8 (Q1: 42.1, Q3: 56.8) mm. In the univariable analysis, abnormal T2-weighted signal of the left dentate nucleus (DN) (74.5% in the pCMS group vs 36.4% in the non-pCMS group, p < 0.001), right DN (83.0% vs 40.3%, p < 0.001), left superior cerebellar peduncle (SCP) (74.5% vs 27.3%, p < 0.001), right SCP (63.8% vs 23.4%, p < 0.001), left middle cerebellar peduncle (MCP) (51.1% vs 26.0%, p = 0.008), and right MCP (61.7% vs 26.0%, p < 0.001); male sex (83.0% vs 45.5%, p < 0.001); vermis 3 impairment (49.4% vs 19.1%, p = 0.002); solid tumor (91.5% vs 72.7%, p = 0.022); and hydrocephalus (72.3% vs 45.5%, p = 0.006) were more frequent in the pCMS group than in the non-pCMS group. Multivariable logistic analysis showed that male sex (adjusted OR 4.08, p = 0.010) and the cerebro-cerebellar circuit score of T2-weighted images (adjusted OR 2.15, p < 0.001) were independent risk factors for pCMS. The cerebro-cerebellar circuit score positively correlated with the duration of mutism. In Cox regression analysis, the cerebro-cerebellar integrated circuit injury score of T2 (adjusted HR 0.790, 95% CI 0.637-0.980; p = 0.032) and injury of vermis 3 (adjusted HR 3.005, 95% CI 1.197-7.547; p = 0.019) were independently associated with the duration of mutism.

CONCLUSIONS

Male sex and cerebro-cerebellar circuit damage are independent risk factors for pCMS. The cerebro-cerebellar circuit score indicates the duration of mutism.

Power and connectivity changes on electroencephalogram in postoperative cerebellar mutism

INTRODUCTION

Cerebellar mutism syndrome is a debilitating postoperative neurological complication following posterior fossa surgery in children. It is characterized by a significant lack or loss of speech. Injury to the dentato-thalamo-cortical pathway is thought to be the main anatomical substrate of cerebellar mutism syndrome; however, few studies have investigated the physiological changes using computed electroencephalogram.

CASE REPORT

Herein, we report a case of a nine-year-old girl who developed cerebellar mutism syndrome after excision of an ependymoma of the fourth ventricle and was followed up with evaluation of aphasia, gross motor function, and scalp electroencephalograms. Her language, dysmetria and gait ataxia gradually improved until day 605 after onset. Computed electroencephalogram analyses were performed for the relative power spectrum and connectivity at each frequency band. On the three electroencephalograms at days 109, 299, and 605 after onset, the relative power spectrum at the delta band transiently decreased and then increased, and the relative power spectrums at theta, beta, and gamma bands transiently increased and then decreased. Only the relative power spectrum in the alpha band continuously increased in the occipital area. Additionally, brain connectivity in the delta, beta, and gamma bands increased continuously.

CONCLUSION

We report a case of cerebellar mutism syndrome with recovery of language, dysmetria and gait ataxia in 20 months. Electroencephalogram analyses indicated transient changes in the powers of brain activity and continuous improvements in connectivity during the long follow-up, reflecting the plasticity and remodeling of brain function after cerebellar mutism syndrome. Power and connectivity analyses for EEG might be a tool to investigate underlying pathophysiology of cerebellar mutism syndrome.

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.

Hydrocephalus surveillance following CSF diversion: a modified Delphi study

OBJECTIVE

Long-term follow-up is often recommended for patients with hydrocephalus, but the frequency of clinical follow-up, timing and modality of imaging, and duration of surveillance have not been clearly defined. Here, the authors used the modified Delphi method to identify areas of consensus regarding the modality, frequency, and duration of hydrocephalus surveillance following surgical treatment.

METHODS

Pediatric neurosurgeons serving as institutional liaisons to the Hydrocephalus Clinical Research Network (HCRN), or its implementation/quality improvement arm (HCRNq), were invited to participate in this modified Delphi study. Thirty-seven consensus statements were generated and distributed via an anonymous electronic survey, with responses structured as a 4-point Likert scale (strongly agree, agree, disagree, strongly disagree). A subsequent, virtual meeting offered the opportunity for open discussion and modification of the statements in an effort to reach consensus (defined as ≥ 80% agreement or disagreement).

RESULTS

Nineteen pediatric neurosurgeons participated in the first round, after which 15 statements reached consensus. During the second round, 14 participants met virtually for review and discussion. Some statements were modified and 2 statements were combined, resulting in a total of 36 statements. At the conclusion of the session, consensus was achieved for 17 statements regarding the following: 1) the role of standardization; 2) preferred imaging modalities; 3) postoperative follow-up after shunt surgery (subdivided into immediate postoperative imaging, delayed postoperative imaging, routine clinical surveillance, and routine radiological surveillance); and 4) postoperative follow-up after an endoscopic third ventriculostomy. Consensus could not be achieved for 19 statements.

CONCLUSIONS

Using the modified Delphi method, 17 consensus statements were developed with respect to both clinical and radiological follow-up after a shunt or endoscopic third ventriculostomy. The frequency, modality, and duration of surveillance were addressed, highlighting areas in which no clear data exist to guide clinical practice. Although further studies are needed to evaluate the clinical utility and cost-effectiveness of hydrocephalus surveillance, the current study provides a framework to guide future efforts to develop standardized clinical protocols for the postoperative surveillance of patients with hydrocephalus. Ultimately, the standardization of hydrocephalus surveillance has the potential to improve patient care as well as optimize the use of healthcare resources.

Left-handedness should not be overrated as a risk factor for postoperative speech impairment in children after posterior fossa tumour surgery: a prospective European multicentre study

PURPOSE

Cerebellar mutism syndrome (CMS) is a severe neurological complication of posterior fossa tumour surgery in children, and postoperative speech impairment (POSI) is the main component. Left-handedness was previously suggested as a strong risk factor for POSI. The aim of this study was to investigate the relationship between handedness and the risk of POSI.

METHODS

We prospectively included children (aged < 18 years) undergoing surgery for posterior fossa tumours in 26 European centres. Handedness was assessed pre-operatively and postoperative speech status was categorised as either POSI (mutism or reduced speech) or habitual speech, based on the postoperative clinical assessment. Logistic regression was used in the risk factor analysis of POSI as a dichotomous outcome.

RESULTS

Of the 500 children included, 37 (7%) were excluded from the present analysis due to enrolment at a reoperation; another 213 (43%) due to missing data about surgery (n = 37) and/or handedness (n = 146) and/or postoperative speech status (n = 53). Out of the remaining 250 (50%) patients, 20 (8%) were left-handed and 230 (92%) were right-handed. POSI was observed equally frequently regardless of handedness (5/20 [25%] in left-handed, 61/230 [27%] in right-handed, OR: 1.08 [95% CI: 0.40-3.44], p = 0.882), also when adjusted for tumour histology, location and age.

CONCLUSION

We found no difference in the risk of POSI associated with handedness. Our data do not support the hypothesis that handedness should be of clinical relevance in the risk assessment of CMS.

Communication and swallowing management in childhood brain tumour or leukaemia: A survey of health professionals and consumers

Purpose: Brain tumour and leukaemia represent the most common childhood cancers and can result in communication and swallowing difficulties. The purpose of this study was to survey health professionals and consumers regarding the management of communication and swallowing difficulties in children with brain tumour or leukaemia (CBTL).Method: In this study participants completed a survey focussing on (1) communication and swallowing assessment and intervention, (2) multidisciplinary team (MDT) practices and (3) risk factors. Quantitative data were reported using descriptive statistics. Qualitative data were analysed using NVivo12 Qualitative Data Analysis Software.Result: Twenty-four participants were included (22 health professionals; two consumers). Most participants (≥80%) agreed that comprehensive and regular communication and swallowing assessments improved outcomes. Communication and swallowing interventions were reported to improve outcomes by 96% of participants. MDT care was considered essential in improving outcomes. Speech-language pathologists were the primary health professional identified in communication management; additional multidisciplinary health professionals were highlighted in swallowing management. Risk factors were identified across three categories: cancer-related, treatment-related and child-factors.Conclusion: This study collates the expertise and experience of multidisciplinary health professionals and consumers which can be used to guide assessment and intervention for communication and swallowing in CBTL. It also provides perspectives on MDT care and consideration of patient values and risk factors.

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.

Fastigial nuclei surgical damage and focal midbrain disruption implicate PAG survival circuits in cerebellar mutism syndrome

BACKGROUND

Pediatric postoperative cerebellar mutism syndrome (CMS) is a rare but well-known complication of medulloblastoma (Mb) resection with devastating effects on expressive language, mobility, cognition, and emotional regulation that diminishes quality of life for many Mb survivors. The specific anatomical and neuronal basis of CMS remains obscure. We address this issue by identifying patterns of surgical damage and secondary axonal degeneration in Mb survivors with CMS.

METHODS

Children with Mb deemed high risk for CMS based on intraventricular location of the tumor had T1 images analyzed for location(s) of surgical damage using a specially developed algorithm. We used three complementary methods of spatial analysis to identify surgical damage linked to CMS diagnosis. Magnetization transfer ratio (MTR) images were analyzed for evidence of demyelination in anatomic regions downstream of the cerebellum, indicating neuronal dysfunction.

RESULTS

Spatial analyses highlighted damage to the fastigial nuclei and their associated cerebellar cortices as the strongest predictors of CMS. CMS-related MTR decrease was greatest in the ventral periaqueductal gray (PAG) area and highly consistent in the left red nucleus.

CONCLUSION

Our evidence points to disruption of output from the fastigial nuclei as a likely causal trigger for CMS. We propose that core CMS symptoms result from a disruption in the triggering of survival behaviors regulated by the PAG, including the gating of vocalization and volitional movement. The fastigial nuclei provide the densest output to the PAG from the cerebellum, thus sparing these structures may provide a greater likelihood of CMS prevention.

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.

Cerebellar Mutism Syndrome in Children After Surgery for a Posterior Fossa Tumor: Patient Characteristics and Recovery

Background: Cerebellar mutism syndrome (CMS) is a potential complication that may be experienced by children undergoing a resection of a posterior fossa tumor. Symptoms include mutism and emotional lability; additional symptoms may include hypotonia, difficulty swallowing, ataxia, and changes in cognition. The recovery of children experiencing CMS symptoms can be variable. In this retrospective chart review study, we identified the presenting characteristics of CMS in a cohort of children and compared them to matched-controls who did not develop CMS and examined recovery patterns during the year after diagnosis. Methods: Patients were identified through the program database. Children between ages 3 and 18 years who had a craniotomy for a posterior fossa tumor at our institution were included. For each CMS case, two control cases were selected to match the type of central nervous system tumor, sex, age group, and surgery date. Patient characteristics were abstracted from the patient's electronic medical record and the CMS survey was used to score CMS cases. Results: Seventeen children with CMS and 34 children without CMS were included in the review. Among children with CMS, 53% experienced mutism for less than 4 weeks; ataxia persisted beyond 4 weeks for more than 88% of the children and was still present in 71% 1 year after diagnosis. Clinical characteristics did not differ between the case and control groups. Discussion: CMS symptoms interfere with the child's quality of life and ongoing development. Study findings inform nurses providing anticipatory guidance and support to patients experiencing CMS and their families.

Posterior fossa syndrome in a population of children and young adults with medulloblastoma: a retrospective, multicenter Italian study on incidence and pathophysiology in a histologically homogeneous and consecutive series of 136 patients

INTRODUCTION

Posterior fossa syndrome (PFS) is a set of debilitating complications that can occur after surgery for posterior fossa tumors. This study aimed to assess the preoperative radiological and surgical risk factors for the onset of PFS in a histologically homogeneous population of children with medulloblastoma and compare it to a similar population of young adults.

METHODS

Included patients underwent posterior fossa surgery for medulloblastoma at 11 Italian neurosurgical wards (2003-2019) and were referred to Fondazione IRCCS Istituto Nazionale dei Tumori in Milan (INT) for postoperative treatments. We collected patients' pre- and post-operative clinical, surgical and radiological data from the INT charts. To compare the distribution of variables, we used the Mann-Whitney and Fisher tests for continuous and categorical variables, respectively.

RESULTS

136 patients (109 children and 27 young adults) were included in the study. Among children, 29 (27%) developed PFS, and all of them had tumors at midline site with invasion of the fourth ventricle. Radiological evidence of involvement of the right superior (39% versus 12%; p = 0.011) or middle cerebellar peduncles (52% versus 18%; p = 0.002) seemed more common in children who developed PFS. Young adults showed an expected lower incidence of PFS (4 out of 27; 15%), that may be due to anatomical, physiological and oncological elements.

CONCLUSIONS

This study confirmed some factors known to be associated with PFS onset and shed light on other debated issues. Our findings enhance an already hypothesized role of cerebellar language lateralization. The analysis of a population of young adults may shed more light on the often-neglected existence of PFS in non-pediatric patients.

Posterior Fossa Tumor Rehabilitation: An Up-to-Date Overview

This narrative review highlights the latest achievements in the field of post-surgical rehabilitation of posterior fossa tumors. Studies investigating the effects of cognitive rehabilitation programs have been considered, following a comprehensive literature search in the scientific electronic databases: Pubmed, Scopus, Plos One, and ScienceDirect. This review investigates the effects of cognitive remediation, with specific highlights for single cognitive domains. The results revealed that in spite of the increasing number of children who survive into adulthood, very few studies investigated the effects of rehabilitation programs in this specific population. This study details new, promising therapeutic opportunities for children after brain surgery. More research in this filed is needed to identify the most effective protocols for clinical use.