Cerebellar mutism

Pediatric hemispheric cerebellar low-grade gliomas: clinical approach, diagnosis, and management challenges-experience at a tertiary care children's hospital

PURPOSE

This study aims to provide an exhaustive analysis of pediatric low-grade gliomas (pLGGs) in the cerebellar hemispheres, focusing on incidence, clinical characteristics, surgical outcomes, and prognosis. It seeks to enhance understanding and management of pLGGs in the pediatric population.

METHODS

We conducted an observational, descriptive, retrospective, and cross-sectional study at a pediatric hospital, reviewing medical records of 30 patients with cerebellar hemispheric pLGGs treated from December 2014 to January 2023. Data collection included demographics, clinical presentation, imaging findings, surgical approach, postoperative complications, histopathological diagnosis, hydrocephalus management, and follow-up. Molecular markers and adjuvant therapies were also analyzed.

RESULTS

The cohort predominantly presented with cerebellar symptoms, with 60% showing hydrocephalus at diagnosis. MRI with gadolinium was crucial for diagnosis. Surgical focus was on achieving gross total resection (GTR), accomplished in 70% of cases. Postsurgical hydrocephalus was less common, and cerebellar mutism was not reported. While a complete molecular analysis was not performed in all cases, available data suggest significant influence of molecular markers on prognosis and therapeutic options of pLGGs.

CONCLUSIONS

This study highlights the unique clinical and molecular characteristics of cerebellar hemispheric pLGGs in children. The lower incidence of postoperative hydrocephalus and absence of cerebellar mutism are notable findings. Emphasizing a multidisciplinary approach, our findings contribute to a deeper understanding of pediatric pLGGs, underscoring the need for personalized treatment strategies and vigilant follow-up.

Medical management for cerebellar mutism syndrome following posterior fossa surgery: A systematic review

INTRODUCTION

Cerebellar mutism syndrome (CMS) is a serious complication of posterior fossa surgeries affecting mainly pediatric age group. The pathophysiology is still not fully understood. It adversely affects the recovery of patients. There is no definitive and standardized management for CMS. However pharmacological therapy has been used in reported cases with variable effectiveness. We aim through this review to summarize the available evidence on pharmacological agents used to treat CMS.

METHOD

A thorough systematic review until December 2022, was conducted using PubMed Central, Embase, and Web of Science, databases to identify case reports and case series of CMS patients who underwent posterior fossa surgery and received pharmacological treatment. Patients with pathologies other than posterior fossa lesions were excluded from the study.

RESULTS

Of 592 initial studies, 8 studies met our eligibility criteria for inclusion, with 3 more studies were added through manual search; reporting on 13 patients. The median age of 13 years (Standard deviation SD=10.60). The most frequent agent used was Bromocriptine. Other agents were fluoxetine, midazolam, zolpidem, and arpiprazole. Most patients recovered within 48 hours of initiating medical therapy. The median follow-up period was 4 months (SD=13.8). All patients showed complete recovery at the end of follow-up period.

CONCLUSION

Cerebellar mutism syndrome is reported after posterior fossa surgeries, despite attempts to identify risk factors, pathophysiology, and management of CMS, it remains a challenging condition with significant morbidity. Different Pharmacological treatments have been proposed with promising results. Further studies and formalized clinical trials are needed to evaluate available options and their effectiveness.

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.

Neuroanatomy of autism: what is the role of the cerebellum?

Autism (or autism spectrum disorder) was initially defined as a psychiatric disorder, with the likely cause maternal behavior (the very destructive "refrigerator mother" theory). It took several decades for research into brain mechanisms to become established. Both neuropathological and imaging studies found differences in the cerebellum in autism spectrum disorder, the most widely documented being a decreased density of Purkinje cells in the cerebellar cortex. The popular interpretation of these results is that cerebellar neuropathology is a critical cause of autism spectrum disorder. We challenge that view by arguing that if fewer Purkinje cells are critical for autism spectrum disorder, then any condition that causes the loss of Purkinje cells should also cause autism spectrum disorder. We will review data on damage to the cerebellum from cerebellar lesions, tumors, and several syndromes (Joubert syndrome, Fragile X, and tuberous sclerosis). Collectively, these studies raise the question of whether the cerebellum really has a role in autism spectrum disorder. Autism spectrum disorder is now recognized as a genetically caused developmental disorder. A better understanding of the genes that underlie the differences in brain development that result in autism spectrum disorder is likely to show that these genes affect the development of the cerebellum in parallel with the development of the structures that do underlie autism spectrum disorder.

Pearls & Oy-sters: Cognitive and Affective Dysfunction Caused by a Small Cerebellar Hemangioblastoma

The primary function of the cerebellum is the coordination and regulation of movement; therefore, cerebellar tumors usually present with ataxia, dysarthria, and vertigo. Large tumors also cause elevated intracranial pressure that may lead to a disturbance of consciousness. Furthermore, it has become increasingly evident that the cerebellum plays a substantial role in cognitive and affective processing. A 44-year-old female patient presented with a 1-month history of depression and flat affect. She had no cerebellar symptoms including no coordination dysfunction or dysarthria. Cognitive function tests revealed impairments in attention, execution, and processing speed. Hamilton Depression Scale and Hospital Anxiety Depression Scale indicated moderate-to-severe depression. Magnetic resonance (MR) imaging revealed a 7-mm enhancing lesion in the culmen of the cerebellar vermis with surrounding edema. Technetium-99m ethyl cysteinate dimer single-photon emission tomography (SPECT) showed hypoperfusion in the left frontal lobe. Although she was initially treated with corticosteroids for presumed sero-negative autoimmune encephalitis, her symptoms persisted. She then underwent cerebellar lesion resection. The histologic diagnosis was hemangioblastoma. The patient's symptoms dramatically improved within 1 week of resection, including improved batteries for cognitive function and depression. Complete regression of cerebellar edema and left frontal lobe hypoperfusion was observed on MR and SPECT images, respectively. This case reiterates the crucial influence of the cerebellum on cognitive and affective function. Moreover, cognitive dysfunction may be masked in cases with focal cerebellar symptoms or elevated intracranial pressure and, consequently, not adequately evaluated.

Cerebellar pilocytic astrocytoma. Retrospective cohort study assessing postoperative functional outcome, cerebellar mutism and hydrocephalus

Objective

Analyze a series of pediatric patients with cPAs evaluating factors that may modify or determine the final outcome in terms of neurological status, CMS and hydrocephalus.

Materials and methods

Single Center, retrospective cohort study of surgical patients with cPA and at least 12 months of follow-up. Clinical, imaging and surgical features, histopathology and adjuvancy were assessed. Clinical outcome was categorized using the FSS and modified Bloom-Scale in the short and long term. Recurrency, PFS and mortality were also analyzed.

Results

A total of 100 patients with a mean follow-up of 53.9 months, with no gender predilection, and a mean age of 7.6 years were included. The most frequent location was central and 24% of the tumors presented brainstem invasion. 79 patients had hydrocephalus at diagnosis and 48% required preoperative treatment. RT was achieved in 67% of cases. CMS was observed in 15 patients, statistically associated with location, pontine invasion, preoperative Bloom-score, and postoperative meningitis/ventriculitis. The functional "outcome" was correlated with complications such as meningitis/ventriculitis and cerebellar hematoma, mutism and recurrence. Recurrence was observed in 26% of cases and surgical reintervention was the chosen therapy.

Conclusion

The treatment of cPAs in pediatric patients is associated with relatively favorable results. Recurrence, CMS and surgical complications play a prognostic value in the outcome and therefore must be managed appropriately. Early treatment with the intention of GTR should be considered, opting, if this is not possible, to leave a tumor residue over neurological damage. The treatment of hydrocephalus in the preoperative instance requires individualized management.

Little brain, little minds: The big role of the cerebellum in social development

Seminal work in the 1990's found alterations in the cerebellum of individuals with social disorders including autism spectrum disorder and schizophrenia. In neurotypical populations, distinct portions of the posterior cerebellum are consistently activated in fMRI studies of social cognition and it has been hypothesized that the cerebellum plays an essential role in social cognition, particularly in theory of mind. Here we review the lesion literature and find that the effect of cerebellar damage on social cognition is strongly linked to the age of insult, with dramatic impairments observed after prenatal insult, strong deficits observed after childhood damage, and mild and inconsistent deficits observed following damage to the adult cerebellum. To explain the developmental gradient, we propose that early in life, the forward model dominates cerebellar computations. The forward model learns and uses errors to help build schemas of our interpersonal worlds. Subsequently, we argue that once these schemas have been built up, the inverse model, which is the foundation of automatic processing, becomes dominant. We provide suggestions for how to test this, and also outline directions for future research.

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.

A case of postoperative cerebellar mutism with hyperphagia in a child following gross total resection of medulloblastoma occupying the cerebellar vermis

INTRODUCTION

Cerebellar mutism syndrome is a well-known complication following posterior fossa tumor resection. Its incidence is markedly increased among patients with medulloblastoma. Patients typically present with an inability to communicate verbally due to disruption of the dentato-thalamocortical pathway.

CASE DESCRIPTION

We present a unique case of cerebellar mutism in a three-year-old girl who underwent gross total resection of medulloblastoma occupying the cerebellar vermis. In addition to mutism, the patient developed hyperphagia.

DISCUSSION

This case report aims to contribute to current understanding of the role of cerebello-hypothalamic connections in cerebellar mutism and their clinical significance.

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.

Improved prediction of postoperative paediatric cerebellar mutism syndrome using an artificial neural network

Background

Postoperative paediatric cerebellar mutism syndrome (pCMS) is a common but severe complication which may arise following the resection of posterior fossa tumours in children. Two previous studies have aimed to preoperatively predict pCMS, with varying results. In this work, we examine the generalisation of these models and determine if pCMS can be predicted more accurately using an artificial neural network (ANN).

Methods

An overview of reviews was performed to identify risk factors for pCMS, and a retrospective dataset collected as per these defined risk factors from children undergoing resection of primary posterior fossa tumours. The ANN was trained on this dataset and its performance evaluated in comparison to logistic regression and other predictive indices via analysis of receiver operator characteristic curves. Area under the curve (AUC) and accuracy were calculated and compared using a Wilcoxon signed rank test, with p<0.05 considered statistically significant.

Results

204 children were included, of whom 80 developed pCMS. The performance of the ANN (AUC 0.949; accuracy 90.9%) exceeded that of logistic regression (p<0.05) and both external models (p<0.001).

Conclusion

Using an ANN, we show improved prediction of pCMS in comparison to previous models and conventional methods.

Sensory and motor electrophysiological mapping of the cerebellum in humans

Cerebellar damage during posterior fossa surgery in children can lead to ataxia and risk of cerebellar mutism syndrome. Compartmentalisation of sensorimotor and cognitive functions within the cerebellum have been demonstrated in animal electrophysiology and human imaging studies. Electrophysiological monitoring was carried out under general anaesthesia to assess the limb sensorimotor representation within the human cerebellum for assessment of neurophysiological integrity to reduce the incidence of surgical morbidities. Thirteen adult and paediatric patients undergoing posterior fossa surgery were recruited. Sensory evoked field potentials were recorded in response to mapping (n = 8) to electrical stimulation of limb nerves or muscles. For motor mapping (n = 5), electrical stimulation was applied to the surface of the cerebellum and evoked EMG responses were sought in facial and limb muscles. Sensory evoked potentials were found in two patients (25%). Responses were located on the surface of the right inferior posterior cerebellum to stimulation of the right leg in one patient, and on the left inferior posterior lobe in another patient to stimulation of left forearm. No evoked EMG responses were found for the motor mapping. The present study identifies challenges with using neurophysiological methods to map functional organization within the human cerebellum and considers ways to improve success.

Cerebellar Mutism Treated Successfully With Zolpidem in a Patient With Learning Difficulties

Posterior fossa tumors constitute the most common brain tumor in pediatrics with 25% development postresection. Cerebellar mutism can manifest as neurobehavioral abnormalities that can occur within days to months after surgery but usually peak on the third postoperative day. It can be caused by discontinuation of dento-thalamo-cortical pathway in the vermian lesion, due to edema, tumors, and hypoperfusion. We report a seven-year-old patient with posterior fossa lesion (pilocytic astrocytoma in histopathology) and learning difficulties with symptoms of urinary retention, pseudobulbar palsy, and motor incoordination that were treated successfully with zolpidem 2.5 mg with regain of function by the third month.

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.

The Understanding of Pediatric Akinetic Mutism

Pediatric akinetic mutism syndrome is a clinical disease resulting from cerebellar injury and characterized by the absence of speech or reduced speech, emotional lability, there may also be hypotonia, oropharyngeal dysfunction/dysphagia, bladder and intestinal incontinence, or other behavioral disorders and neurological signals. It is described as the most recurrent complication in children, after posterior fossa tumor surgery, mainly related to cerebellar midline injuries. An increasing number of research and prospective reviews have provided valuable information on cerebellar mutism syndrome in recent years. The purpose of this review was to elucidate the pathophysiological basis and the predictive factors for this syndrome. Most cases of mutism are due to injury cerebellar tracts and cerebellar-cerebral circuits, involving particularly distinct points of the dentate-thalamus-cortical and dentato-rubro-thalamus-cortical. Advanced neuroimaging techniques, such as tractography and perfusion studies, have contributed to demonstrating changes in these pathways in patients with pediatric cerebellar mutism.

Pediatric posterior fossa tumors outcomes: Experience in a tertiary care center in the Middle East

BACKGROUND

Among all childhood cancers, brain tumors are second only to leukemia in incidence and are the most common solid pediatric tumors. More than 60 % of pediatric brain tumors are infra-tentorial. The first-line treatment for most infra-tentorial tumors in pediatric patients is surgical resection, with the goal of gross-total resection, relief of symptoms and hydrocephalus, and increased survival. The proximity to the fourth ventricle, and therefore, the cerebrospinal fluid (CSF) pathways, predisposes children with posterior fossa tumors to the development of obstructive hydrocephalus and multiple other co-morbidities pre and post-surgery.

OBJECTIVES

This study aims to present our series of pediatric posterior fossa tumor surgeries in the Neurosurgical Department at the American University of Beirut Medical Center(AUBMC) and perform internal quality control for our single-institution consecutive series as one of the largest referral and tertiary care centers in the region. The second purpose of this retrospective study is to weigh the risks of surgery against the presumed advantages and to have specific knowledge about the complication rates, especially those related to the CSF pathway, comparing our results to those in the literature.

METHODS

All pediatric patients (< 18 years of age), referred to our center from different regions in the middle east, and surgically treated for a posterior fossa tumor from June 2006 to June 2018 at the American University of Beirut Medical Center were included. A thorough review of all medical charts was performed to validate all the database records.

RESULTS

The patient sample consisted of 64 patients having a mean age of 6.19 ± 4.42 years and 59.37 % of whom were males. The most common tumor pathology was pilocytic astrocytoma (40.62 %) followed by medulloblastoma (35.93 %) and ependymoma. The most common type of tumor that was seen in patients that developed mutism postoperatively (n = 6, 9.37 %) was medulloblastoma (n = 4, 66.66 %). In this patient sample, 12.28 % (n = 7) of the patients developed hydrocephalus postoperatively.Midline tumors were more associated with the development of mutism(OR = 4.632, p = 0.306) and hydrocephalus (OR = 5.056, p = 0.135) postoperatively, albeit not statistically significantly.The presence of a preoperative shunt was shown to be protective against the development of CSF leak (OR = 0.636, p = 0.767), as none of the patients that came in with CSF diversion developed a CSF leak after their surgery.

CONCLUSION

This study from a single center experience accompanied by a thorough literature review sheds light on the complications frequently encountered after posterior fossa tumor surgery in children. These included transient cerebellar mutism, CSF leak, and hydrocephalus as seen in some of our patients. Our findings highlight the need for prospective studies with well-defined protocols directed at assessing novel ways and approaches to minimize the risk of these complications.

The supplementary motor area syndrome and the cerebellar mutism syndrome: a pathoanatomical relationship?

PURPOSE

The supplementary motor area (SMA) syndrome affects adults after tumour resection in SMA neighbouring motor cortex. Cerebellar mutism syndrome (CMS) affects children after tumour resection in the posterior fossa. Both syndromes include disturbances in speech and motor function. The causes of the syndromes are unknown; however, surgical damage to the dentato-thalamo-cortical pathway (DTCP) has been associated with CMS. Thus, an anatomical link between the areas associated with the syndromes is possible. We discuss the syndromes and their possible relationship through the DTCP.

METHODS

We identified 61 articles (cohort studies, case reports and reviews) in MEDLINE and Embase searching for CMS, SMA syndrome or DTCP or synonyms and reviewed for evidence linking CMS and SMA.

RESULTS

We found that SMA syndrome and CMS are similar regarding (1) surgical causation; (2) symptoms including speech impairment, disturbance in motor function and facial dysfunction; (3) delayed onset; (4) the courses of the syndromes are transient; and (5) long-term sequelae are seen in both. Relevant differences include age predominance of adults in SMA syndrome versus children in CMS.

CONCLUSIONS

The similarities of the two syndromes could be traced back to their mutual connection through the DTCP and their membership to a cerebro-cerebellar circuit. The connectivity network could explain the emotional changes and speech reduction in CMS. The difference in time of post-surgical onset may be related to the anatomical distance between the surgical damage to the cerebellum and the SMA, respectively, and the effector neural loop underpinning symptoms.

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 after posterior fossa tumor resection in children: a multicenter international retrospective study to determine possible modifiable factors

PURPOSE

A preliminary survey of pediatric neurosurgeons working at different centers around the world suggested differences in clinical practice resulting in variation in the risk of pediatric cerebellar mutism (CM) and cerebellar mutism syndrome (CMS) after posterior fossa (PF) tumor resection. The purposes of this study were (1) to determine the incidence and severity of CM and CMS after midline PF tumor resection in children treated at these centers and (2) to identify potentially modifiable factors related to surgical management (rather than tumor biology) that correlate with the incidence of CM/CMS.

METHODS

Attending pediatric neurosurgeons at British Columbia's Children's Hospital (BCCH) and neurosurgeons who completed a pediatric neurosurgery fellowship at BCCH were invited to provide data from the center where they currently practiced. Children aged from birth to less than 18 years who underwent initial midline PF tumor resection within a contemporary, center-selected 2-year period were included. Data was obtained by retrospective chart and imaging review. Modifiable surgical factors that were assessed included pre-resection surgical hydrocephalus treatment, surgical positioning, ultrasonic aspirator use, intraoperative external ventricular drain (EVD) use, surgical access route to the tumor, and extent of resection. CM was defined as decreased or absent speech output postoperatively and CMS as CM plus new or worsened irritability.

RESULTS

There were 263 patients from 11 centers in 6 countries (Canada, Germany, the Netherlands, India, Indonesia, and the USA). Median age at surgery was 6 years (range < 1 to 17 years). The overall incidence of postoperative CM was 23.5% (range 14.7-47.6% for centers with data on ≥ 20 patients). The overall incidence of CMS was 6.5% (range 0-10.3% for centers contributing data on ≥ 20 patients). A multivariate logistic regression on the full data set showed no significant association between pre-resection surgical hydrocephalus treatment, prone position, ultrasonic aspirator use, EVD use, telovelar approach, complete or near total resection, or treating center and either postoperative CM or CMS.

CONCLUSIONS

While there was variation in surgical management of midline PF tumors among centers participating in this study, the factors in management that were examined did not predict postoperative CM or CMS.

Diffusion Tensor Imaging Connectomics Reveals Preoperative Neural Connectivity Changes in Children with Postsurgical Posterior Fossa Syndrome

BACKGROUND AND PURPOSE

Posterior fossa syndrome (PFS), characterized by loss of language and other neurological impairments within the immediate postoperative period, occurs in approximately 25% of children who undergo surgical resection of posterior fossa tumors. Diffusion tensor imaging connectomics offer promise for elucidation of pathway-level disruption in neural connectivity of patients with this disorder. We aim to determine differences in pre- and postoperative connectomics between children with PFS and children with mild or no language deficit after surgery.

METHODS

Pre- and postoperative diffusion tensor imaging connectomics were applied and compared among patients with PFS, mild deficits, and intact language.

RESULTS

A total of 35 patients were included in the study. Twenty-three patients with preoperative data and 24 patients with postoperative data were included in the analysis. Mean ages: PFS-8.5 years, mild-3.1 years, intact language-9.4 years (P = .02). Diagnoses included medulloblastoma (44.1%), pilocytic astrocytoma (28.6%), ependymoma (8.6%), other (11.4%), and unknown (8.6%). Five (21.7%) patients had PFS, 4 (17.4%) had mild deficits, and 14 (60.9%) had intact language. The assortativity coefficient was significantly higher in patients with PFS when compared to patients with mild deficits (P = .023). In the connectometry analyses, decreased connectivity was found involving the corpus callosum, right corticothalamic pathway, and right corticostriatal pathway in patients with PFS when compared to patients with intact language.

CONCLUSIONS

Our findings revealed significant differences in preoperative neural connectivity involving the corticothalamic and other pathways among children who did, versus who did not, develop PFS postoperatively. Diffusion tensor imaging connectomics offers a unique opportunity to study the effect of the posterior fossa tumors on cerebello-cerebral networks and provide new insights into the mechanism of the structural plasticity/reorganization after surgery.

Preoperative prediction of postoperative cerebellar mutism syndrome. Validation of existing MRI models and proposal of the new Rotterdam pCMS prediction model

PURPOSE

Postoperative cerebellar mutism syndrome (pCMS) is a complication that may occur after pediatric fossa posterior tumor surgery. Liu et al. developed an MRI-based prediction model to estimate pCMS risk preoperatively. The goal of this study was to validate the model of Liu et al. and if validation was not as sensitive in our group as previously described to develop an easy to use, reliable, and sensitive preoperative risk prediction model for pCMS.

METHODS

In this study, 121children with a fossa posterior tumor who underwent surgery at ErasmusMC/Sophia Children's Hospital, the Netherlands between 2004 and 2018 could be included. Twenty-six percent of them developed pCMS. Preoperative MRI were scored using the Liu et al. model.

RESULTS

The Liu et al. model reached an accuracy of 78%, a sensitivity of 58%, and a specificity of 84% in our cohort. In a new risk model some of the variables of Liu et al. were included as well as some of the recently described preoperative MRI characteristics in pCMS patients by Zhang et al. The new model reached an accuracy of 87%, a sensitivity of 97%, and a specificity of 84% in our patient group.

CONCLUSION

Because the Liu et al. model did not provide an as accurate risk prediction in our cohort as was expected, we created a new risk prediction model that reached high model accuracy in our cohort that could assist neurosurgeons in determining their surgical tactics and help prepare high risk patients and their parents for this severe complication.

Modafinil in the rehabilitation of a patient with post-surgical posterior fossa syndrome: a lesson to be learned?

Disorders of the cerebellum may present with motor, cognitive, behavioral and affective symptoms. There is a growing interest in developing neuroanatomical models of symptoms generation that involve the cerebellum and the cerebello-cortical connections. We describe an exciting first case report of successful use of Modafinil in an adult patient with post-operative posterior fossa syndrome. Following resection of a melanoma metastasis in the cerebellum the patient developed striking affective and behavioral symptoms in the form of withdrawn flat mood and disengagement. This neurobehavioral presentation severely impacted on his quality of life, independence, and ability to engage in the neuro-rehabilitative program. Pharmacological treatment with Modafinil ameliorated these emotional and behavioral aspects, and also fatigue. Treatment with Modafinil hence affected recovery and outcome for the patient. To our knowledge, this is the first description of a successful pharmacological intervention in an adult with post-surgical posterior fossa syndrome and negative neurobehavioral presentation. Our findings illustrate the variability of the presentation of post-operative posterior fossa syndrome in adults, and the importance of delivering targeted treatment to maximize the benefits of neurorehabilitation. The manuscript highlights the following points: 1. post-operative consequences currently under the wide umbrella of posterior fossa syndrome, can indeed manifest in adults; 2. a wide spectrum of neurobehavioral symptoms can occur, including a presentation with predominantly negative features; 3. the type of neurobehavioral presentation should guide the treatment choice with particular consideration of drugs that potentially modulate the cerebello-frontal connections; 4. Modafinil can be a candidate for effective treatment in presentations with predominantly negative behavioral symptoms.

Sensorimotor, language, and working memory representation within the human cerebellum

The cerebellum is involved in a wide range of behaviours. A key organisational principle from animal studies is that somatotopically corresponding sensory input and motor output reside in the same cerebellar cortical areas. However, compelling evidence for a similar arrangement in humans and whether it extends to cognitive functions is lacking. To address this, we applied cerebellar optimised whole‐brain functional MRI in 20 healthy subjects. To assess spatial overlap within the sensorimotor and cognitive domains, we recorded activity to a sensory stimulus (vibrotactile) and a motor task; the Sternberg verbal working memory (VWM) task; and a verb generation paradigm. Consistent with animal data, sensory and motor activity overlapped with a somatotopic arrangement in ipsilateral areas of the anterior and posterior cerebellum. During the maintenance phase of the Sternberg task, a positive linear relationship between VWM load and activity was observed in right Lobule VI, extending into Crus I bilaterally. Articulatory movement gave rise to bilateral activity in medial Lobule VI. A conjunction of two independent language tasks localised activity during verb generation in right Lobule VI‐Crus I, which overlapped with activity during VWM. These results demonstrate spatial compartmentalisation of sensorimotor and cognitive function in the human cerebellum, with each area involved in more than one aspect of a given behaviour, consistent with an integrative function. Sensorimotor localisation was uniform across individuals, but the representation of cognitive tasks was more variable, highlighting the importance of individual scans for mapping higher order functions within the cerebellum.

Contemporary Management of Increased Intraoperative Intracranial Pressure: Evidence-Based Anesthetic and Surgical Review

Increased intracranial pressure (ICP) is frequently encountered in the neurosurgical setting. A multitude of tactics exists to reduce ICP, ranging from patient position and medications to cerebrospinal fluid diversion and surgical decompression. A vast amount of literature has been published regarding ICP management in the critical care setting, but studies specifically tailored toward the management of intraoperative acute increases in ICP or brain bulk are lacking. Compartmentalizing the intracranial space into blood, brain tissue, and cerebrospinal fluid and understanding the numerous techniques available to affect these individual compartments can guide the surgical team to quickly identify increased brain bulk and respond appropriately. Rapidly instituting measures for brain relaxation in the operating room is essential in optimizing patient outcomes. Knowledge of the efficacy, rapidity, feasibility, and risks of the various available interventions can aid the team to properly tailor their approach to each individual patient. In this article, we present the first evidence-based review of intraoperative management of ICP and brain bulk.

Long-term impairment of social behavior, vocalizations and motor activity induced by bilateral lesions of the fastigial nucleus in juvenile rats

The cerebellum is increasingly recognized to be involved in limbic and cognitive-associative functioning. Cerebellar cognitive affective syndromes may result from various types of injuries. Cerebellar mutism may occur in children after resection of midline tumors in the posterior fossa, which has been thought to be related to damage to the cerebellar vermis. Here, we investigated whether bilateral lesions of the fastigial nucleus, which is located within the upper vermis, would affect social behavior in a rat model. Juvenile male Sprague-Dawley rats, aged 23 days, underwent bilateral thermocoagulation of the fastigial nucleus via stereotaxically implanted electrodes under general anesthesia. Electrodes were inserted without application of electric current in a sham-lesion group and naïve rats served as additional controls. All groups underwent standardized examination before surgery and on specific time points up to 49 days after surgery to investigate locomotor activity, motor coordination, social behavior, and ultrasound vocalizations during social interaction. Finally, lesions were verified histologically. Playing behavior and vocalizations were reduced up to 4 weeks after surgery in rats of the lesion group compared to rats with sham-lesions and controls. After surgery in rats of the lesion group, locomotor activity was disturbed for 3 days as compared to sham-lesion rats, but for 4 weeks as compared to controls. Motor coordination measured by the rotarod and balance beam test was compromised until adulthood. Bilateral lesions of the fastigial nucleus in juvenile rats cause a severe and long-lasting reduction of social interaction and motor coordination in juvenile rats, which has some similarities to cerebellar cognitive affective syndromes in the human context. This indicates a modulating role of the fastigial nucleus with regard to neural circuitries relevant for social behavior, such as the limbic system and the prefrontal cortex.

Cerebellar mutism syndrome: cause and rehabilitation

PURPOSE OF REVIEW

Mutism of cerebellar origin may occur in the context of various causes but is most frequent in children after resection of a large midline cerebellar tumour. In this review, the endeavour to reach a consensus on name and definition of postoperative mutism of cerebellar origin and associated symptoms is highlighted. In addition, progress in understanding of cause and risk factors for the syndrome is discussed as well as the rehabilitation issues.

RECENT FINDINGS

Consensus on the term cerebellar mutism syndrome (CMS) has been reached. The exact pathogenesis of CMS remains unclear. Recently, attention was drawn to the hypothesis that thermal injury might be an important mechanism in the pathogenesis of CMS. Diffusion tensor imaging tractography was found to visualize the damage to relevant pathways that are associated with persistent impairments after recovery of CMS. There is still no established treatment for CMS to date.

SUMMARY

By reaching a consensus on terminology and description of CMS, a firm basis has been created for future research. The pathogenesis of CMS seems multifactorial and important risk factors have been found. However, CMS cannot be effectively prevented yet and no established or specific treatment is available, apart from very general rehabilitation and cognitive interventions.

Neuropsychological consequences of childhood medulloblastoma and possible interventions: A review

BACKGROUND

Children who have been treated for a medulloblastoma often suffer long-term cognitive impairments that often negatively affect their academic performance and quality of life. In this article, we will review the neuropsychological consequences of childhood medulloblastoma and discuss the risk factors known to influence the presence and severity of these cognitive impairments and possible interventions to improve their quality of life.

METHODS

This narrative review was based on electronic searches of PubMed to identify all relevant studies.

RESULTS

Although many types of cognitive impairments often emerge during a child's subsequent development, the core cognitive domains that are most often affected in children treated for a medulloblastoma are processing speed, attention and working memory. The emergence and magnitude of these deficits varies greatly among patients. They are influenced by demographic (age at diagnosis, parental education), medical and treatment-related factors (perioperative complications, including posterior fossa syndrome, radiation therapy dose, etc.), and the quality of interventions such as school adaptations provided to the child or rehabilitation programs that focus on cognitive skills, behavior and psychosocial functioning.

CONCLUSION

These patients require specialized and coordinated multidisciplinary rehabilitation follow-up that provides timely and adapted assessments and culminates in personalized intervention goals being set with the patient and the family. Follow-up should be continued until referral to adult services.

Cerebellar mutism syndrome

Cerebellar mutism most commonly, but not exclusively, develops in children after surgery for midline cerebellar or intraventricular tumors in the posterior fossa, typically medulloblastoma. Cerebellar mutism syndrome (CMS) comprises a complex set of neurologic and neurocognitive signs and symptoms, the cardinal and central component of which is an initially profound but usually reversible speech disorder. As such, CMS is currently recognized as an extreme form of the so-called cerebellar cognitive affective syndrome (Schmahmann syndrome). The putative cause of CMS is a substantial surgical injury to the proximal components of the bilateral efferent cerebellar pathways, disrupting cerebellar input to the supratentorial brain. The resultant cerebellocerebral diaschisis may lead to supratentorial cortical perfusion depression with frontal predominance. The speech disorder is, therefore, likely an apraxia. As our understanding of the mechanism and the clinical spectrum of CMS evolves, clinically useful preoperative risk stratification schemes, adjustments to surgical strategies and techniques, and possible early therapeutic-rehabilitative measures are being sought and developed to reduce the burden of this severe and particularly handicapping chronic morbidity on affected individuals and their families.

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

OBJECTIVE Postoperative cerebellar mutism syndrome (pCMS) occurs in 7%-50% of children after cerebellar tumor surgery. Typical features include a latent onset of 1-2 days after surgery, transient mutism, emotional lability, and a wide variety of motor and neurobehavioral abnormalities. Sequelae of this syndrome usually persist long term. The principal causal factor is bilateral surgical damage (regardless of tumor location) to any component of the proximal efferent cerebellar pathway, which leads to temporary dysfunction of cerebral cortical regions as a result of diaschisis. Tumor type, cerebellar midline location, and brainstem involvement are risk factors for pCMS that have been identified repeatedly, but they do not explain its latent onset. Ambiguous or negative results for other factors, such as hydrocephalus, postoperative meningitis, length of vermian incision, and tumor size, have been reached. The aim of this study was to identify perioperative clinical, radiological, and laboratory factors that also increase risk for the development of pCMS. The focus was on factors that might explain the delayed onset of pCMS and thus might provide a time window for taking precautionary measures to prevent pCMS or reduce its severity. The study was focused specifically on children who had undergone surgery for medulloblastoma. METHODS In this single-center retrospective cohort study, the authors included 71 children with medulloblastoma, 28 of whom developed pCMS after primary resection. Clinical and laboratory data were collected prospectively and analyzed systematically. Variables were included for univariate and multivariate analysis. RESULTS Univariate regression analysis revealed 7 variables that had a significant influence on pCMS onset, namely, tumor size, maximum tumor diameter > 5 cm, tumor infiltration or compression of the brainstem, significantly larger decreases in hemoglobin (p = 0.010) and hematocrit (p = 0.003) in the pCMS group after surgery than in the no-pCMS group, significantly more reported incidents of severe bleeding in the tumor bed during surgery in the pCMS group, preoperative hydrocephalus, and a mean body temperature rise of 0.5°C in the first 4 days after surgery in the pCMS group. Multiple regression analysis revealed that tumor size, tumor infiltration into or compression of the brainstem, and higher mean body temperature in the first 4 postoperative days were independent and highly significant predictors for pCMS. CONCLUSIONS The authors confirmed earlier findings that tumor-associated preoperative conditions, such as a maximum tumor diameter ≥ 5 cm and infiltration into or compression of the brainstem, are associated with a higher risk for the development of pCMS. Most importantly, the authors found that a 0.5°C higher mean body temperature in the first 4 postoperative days increased the odds ratio for the development of pCMS almost 5-fold. These data suggest that an important focus for the prevention of pCMS in children who have undergone medulloblastoma surgery might be rigorous maintenance of normothermia as standard care after surgery.

Cerebellar mutism syndrome in children with brain tumours of the posterior fossa

Background

Central nervous system tumours constitute 25% of all childhood cancers; more than half are located in the posterior fossa and surgery is usually part of therapy. One of the most disabling late effects of posterior fossa tumour surgery is the cerebellar mutism syndrome (CMS) which has been reported in up to 39% of the patients but the exact incidence is uncertain since milder cases may be unrecognized. Recovery is usually incomplete. Reported risk factors are tumour type, midline location and brainstem involvement, but the exact aetiology, surgical and other risk factors, the clinical course and strategies for prevention and treatment are yet to be determined.

Methods

This observational, prospective, multicentre study will include 500 children with posterior fossa tumours. It opened late 2014 with participation from 20 Nordic and Baltic centres. From 2016, five British centres and four Dutch centres will join with a total annual accrual of 130 patients. Three other major European centres are invited to join from 2016/17. Follow-up will run for 12 months after inclusion of the last patient. All patients are treated according to local practice. Clinical data are collected through standardized online registration at pre-determined time points pre- and postoperatively. Neurological status and speech functions are examined pre-operatively and postoperatively at 1–4 weeks, 2 and 12 months. Pre- and postoperative speech samples are recorded and analysed. Imaging will be reviewed centrally. Pathology is classified according to the 2007 WHO system. Germline DNA will be collected from all patients for associations between CMS characteristics and host genome variants including pathway profiles.

Discussion

Through prospective and detailed collection of information on 1) differences in incidence and clinical course of CMS for different patient and tumour characteristics, 2) standardized surgical data and their association with CMS, 3) diversities and results of other therapeutic interventions, and 4) the role of host genome variants, we aim to achieve a better understanding of risk factors for and the clinical course of CMS - with the ultimate goal of defining strategies for prevention and treatment of this severely disabling condition.

Trial registration

Clinicaltrials.gov: NCT02300766, date of registration: November 21, 2014.

Postoperative Pediatric Cerebellar Mutism After Posterior Fossa Surgery: A Case Report

Cerebellar mutism syndrome (CMS) is a common complication of posterior fossa surgery that can confound the postanesthetic examination and have long-lasting impacts. There is confusion surrounding its precise description, diagnostic features, and associated morbidity. Here, we discuss the most up-to-date knowledge of CMS drawing from a clinical case in the context of 3 new reports: (1) an international consensus paper presenting a new proposed working definition by the Iceland Delphi Group, (2) a knowledge update by Gadgil et al, (3) and a review of neuroimaging-based data elucidating the etiology of CMS by Patay.

Sudden benzodiazepine-induced resolution of post-operative pediatric cerebellar mutism syndrome: a clinical-SPECT study

Post-operative pediatric cerebellar mutism syndrome (PPCMS) is a clinical syndrome arising from cerebellar injury and characterized by absence of speech and other possible symptoms and signs. Rare reports described some benefit after administration of dopamine agonist therapy, but no treatment has proven efficacy. In this paper, we report on the dramatic, sudden resolution of PPCMS induced by midazolam administration in a boy who underwent posterior fossa surgery for choroid plexus papilloma of the fourth ventricle. In addition to clinical improvement, post-midazolam single-photon emission computed tomography also demonstrated amelioration of brain perfusion.

Post-operative diffusion weighted imaging as a predictor of posterior fossa syndrome permanence in paediatric medulloblastoma

PURPOSE

Posterior fossa syndrome (PFS) is a serious complication faced by neurosurgeons and their patients, especially in paediatric medulloblastoma patients. The uncertain aetiology of PFS, myriad of cited risk factors and therapeutic challenges make this phenomenon an elusive entity. The primary objective of this study was to identify associative factors related to the development of PFS in medulloblastoma patient post-tumour resection.

METHODS

This is a retrospective study based at a single institution. Patient data and all related information were collected from the hospital records, in accordance to a list of possible risk factors associated with PFS. These included pre-operative tumour volume, hydrocephalus, age, gender, extent of resection, metastasis, ventriculoperitoneal shunt insertion, post-operative meningitis and radiological changes in MRI. Additional variables included molecular and histological subtypes of each patient's medulloblastoma tumour. Statistical analysis was employed to determine evidence of each variable's significance in PFS permanence.

RESULTS

A total of 19 patients with appropriately complete data was identified. Initial univariate analysis did not show any statistical significance. However, multivariate analysis for MRI-specific changes reported bilateral DWI restricted diffusion changes involving both right and left sides of the surgical cavity was of statistical significance for PFS permanence.

CONCLUSION

The authors performed a clinical study that evaluated possible risk factors for permanent PFS in paediatric medulloblastoma patients. Analysis of collated results found that post-operative DWI restriction in bilateral regions within the surgical cavity demonstrated statistical significance as a predictor of PFS permanence-a novel finding in the current literature.

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

INTRODUCTION

Confusion has surrounded the description of post-operative mutism and associated morbidity in pediatric patients with cerebellar tumors for years. The heterogeneity of definitions and diagnostic features has hampered research progress within the field, and to date, no international guidelines exist on diagnosis, prevention, treatment, or follow-up of this debilitating condition. An international group of clinicians and researchers from multiple relevant disciplines recently formed a cohesive panel to formulate a new working definition and agree upon standardized methods for diagnosis and follow-up.

METHODS

Consensus was obtained using the modified nominal group technique, involving four rounds of online Delphi questionnaires interspersed with a structured consensus conference with lectures, group work, and open discussion sessions.

RESULTS

A new, proposed definition of "post-operative pediatric CMS" was formed, preliminary recommendations for diagnostic and follow-up procedures were created, two working groups on a new scoring scale and risk prediction and prevention were established, and areas were identified where further information is needed.

DISCUSSION

The consensus process was motivated by desire to further research and improve quality of life for pediatric brain tumor patients. The Delphi rounds identified relevant topics and established basic agreement, while face-to-face engagement helped resolve matters of conflict and refine terminology. The new definition is intended to provide a more solid foundation for future clinical and research work. It is thought as a consensus for moving forward and hopefully paves the way to developing a standard approach to this challenging problem with the advent of better scoring methods and ultimate goal of reducing the risk of CMS.

Strategies to improve the quality of survival for childhood brain tumour survivors

BACKGROUND

Tumours of the central nervous system (CNS) are the most frequent solid tumours and the second most frequent type of cancer in children and adolescents. Overall survival has continuously improved in Germany, since an increasing number of patients have been treated according to standardised, multicentre, multimodal treatment recommendations, trials of the German Paediatric Brain Tumour Consortium (HIT-Network) or the International Society of Paediatric Oncology-Europe (SIOP-E) during the last decades. Today, two out of three patients survive. At least 8000 long-term childhood brain tumour survivors (CBTS) are currently living in Germany. They face lifelong disease- and treatment-related late effects (LE) and associated socioeconomic problems more than many other childhood cancer survivors (CCS).

METHOD

We review the LE and resulting special needs of this particular group of CCS.

RESULTS

Despite their increasing relevance for future treatment optimisation, neither the diversity of chronic and cumulative LE nor their pertinent risk factors and subsequent impact on quality of survival have yet been comprehensively addressed for CBTS treated according to HIT- or SIOP-E-protocols. Evidence-based information to empower survivors and stakeholders, as well as medical expertise to manage their individual health care, psychosocial and educational/vocational needs must still be generated and established.

CONCLUSION

The establishment of a long-term research- and care network in Germany shall contribute to a European platform, that aims at optimising CBTSs' transition into adulthood as resilient individuals with high quality of survival including optimal levels of activity, participation and acceptance by society.

Posterior fossa syndrome following brain tumour resection: review of pathophysiology and a new hypothesis on its pathogenesis

INTRODUCTION

Posterior fossa syndrome (PFS), also known as cerebellar mutism syndrome (CMS), is a severe complication affecting children following surgery for posterior fossa brain tumours. Its incidence varies between 8 and 31 %, and its exact pathogenesis remains unclear. In this article, we aim to review the existing theories on its pathogenesis and propose a new hypothesis.

DISCUSSION

There is varying level of evidence on existing theories on the pathogenesis of PFS following surgery. These include cerebellar perfusion deficits due to vasospasm, oedema or axonal injury due to direct surgical injury and neuronal dysfunction. There is emerging evidence that interruption of the dentato-thalamo-cortical (DTC) pathway is responsible for PFS. Based on our experience with intraoperative MRI, radiological and pathological evidence on heat-related brain injury, we propose a new hypothesis implicating thermal injury resulting from the use of the Cavitron Ultrasonic Aspirator (CUSA) as an important mechanism in the pathogenesis of PFS.

CONCLUSION

The pathogenesis of PFS is likely to be multifactorial with direct injury from surgery being a major factor. We believe that thermal injury in addition to mechanical injury to the proximal segment of the DTC plays an important role in the pathogenesis of PFS and should be considered in future research related to the aetiology, prevention and management of PFS.

Cerebellar mutism

INTRODUCTION

Cerebellar mutism (CM) is defined as a peculiar form of mutism that may complicate the surgical excision of posterior cranial fossa tumor. The incidence is variable in the literature, occurring in up to one third of cases in some series. Commonly occurring peculiar features of CM are delayed onset following surgery, limited duration, and spontaneous recovery usually associated with dysarthria.

METHODS

A review has been performed concerning anatomical substrates and circuits actually considered to be involved in the development of cerebellar mutism, as well as risk factors for its development that have been documented in the literature. Attention has also been given to the long-term prognosis and the possibilities of rehabilitation that can be considered in these children, which has been compared with the authors' institutional experience.

RESULTS AND CONCLUSIONS

Tumor infiltration of the brainstem seems to represent the most relevant feature related to the development of CM, along with the histological diagnosis of medulloblastoma. On the other hand, hydrocephalus does not represent an independent risk factor. The higher rate of CM in children seems to be related to the higher incidence in children of tumors with malignant histology and brain stem involvement. Surgical technique does not seem to have a definite role; in particular, the use of a telovelar approach as compared to vermian split to reach the fourth ventricle extension of the tumor has not been demonstrated to prevent the development of cerebellar mutism. Concerning long-term prognosis, around one third of the children who develop cerebellar mutism after surgery have a persistent dysarthria, the remaining ones showing a residual phonological impairment. Long-term dysarthric features tend to be more severe and less prone to recovery in children presenting at diagnosis with associated combined procedural memory and defective neurocognitive functions.

Surgical approaches to IV ventricle--anatomical study

PURPOSE

Knowledge of anatomy of the IV ventricle is basic to surgical approach of any kind of lesion in its compartment as well as for those located in its neighborhood. The purpose of this study is to demonstrate the surgical approach options for the IV ventricle, based on the step by step dissection of anatomical specimens.

METHODS

Fifty formalin-fixed specimens provided were the material for this study. The dissections were performed in the microsurgical laboratory in Gainesville, Florida, USA.

RESULTS

The IV ventricle in a midline sagittal cut shows a tent-shaped cavity with its roofs pointing posteriorly and the floor formed by the pons and the medulla. The superior roof is formed by the superior cerebellar peduncles laterally and the superior medullary velum on the midline. The inferior roof is formed by the tela choroidea, the velum medullary inferior, and the nodule. The floor of the IV ventricle has a rhomboid shape. The rostral two thirds are related to the pons, and the caudal one third is posterior to the medulla. The median sulcus divides the floor in symmetrical halves. The sulcus limitans runs laterally to the median sulcus, and the area between the two sulci is called the median eminence. The median eminence contains rounded prominence related to the cranial nucleus of facial, hypoglossal, and vagal nerves. The lateral recesses are extensions of the IV ventricle that opens into the cerebellopontine cistern. The cerebellomedullary fissure is a space between the cerebellum and the medulla and can be used as a surgical corridor to the IV ventricle.

CONCLUSIONS

We obtained in this study a didactic dissection of the different anatomical structures, whose recognition is important for addressing the IV ventricle lesions.

[Evolution of the management of pediatric and adult medulloblastoma]

Medulloblastoma are cerebellar tumours belonging to the group of primitive neuroectodermal tumours (PNET) and are the most common malignant brain tumours of childhood. These tumours are rare and heterogeneous, requiring some multicentric prospective studies and multidisciplinary care. The classical therapeutic approaches are based on clinical, radiological and surgical data. They involve surgery, radiation therapy and chemotherapy. Some histological features were added to characterize risk. More recently, molecular knowledge has allowed to devise risk-adapted strategies and helped to define groups with good outcome and reduce long-term sequelae, improve the prognostic of high-risk medulloblastoma and develop new therapeutic tools.

Behavioral disorders and cognitive impairment associated with cerebellar lesions

In the last decade evidence has accumulated that suggests that the cerebellum is involved not only in motor but also in behavioral and cognitive functions. A myriad of anatomical, clinical and imaging studies support that assumption. The lengthened survival of patients with cerebellar tumors has also brought an increased awareness of neurocognitive deficits to the neurooncological community. Although evidence from neurosurgical case series exists that clearly demonstrates that patients afflicted from posterior fossa tumors are at high risk for long-term cognitive or adaptive deficits, there is still a lack of systematic translational review on this issue. Accordingly a systematic review was conducted to summarize the impact of cerebellar lesions on behavior and cognition. The findings and clinical implications are discussed in the light of the recent advances in neuroimaging techniques.

Does size matter? Minimally invasive approach in pediatric neurosurgery--a review of 125 minimally invasive surgeries in children: clinical history and operative results

OBJECTIVE

Surgery is an integral component and typically the first line of therapy for children with central nervous system tumors. Conventional aims of neurosurgery including tumor removal, management of hydrocephalus, and diagnostic sampling have been radically modified with innovative technologies such as navigational guidance, functional mapping, endoscopic surgery, second-look surgery, and physiologic imaging. The aim of the study was to investigate our operative results using minimally invasive technique in children.

METHODS

Clinical features, surgical technique and results, length of hospital stay, and complications were reviewed retrospectively. Pre- and early postoperative MRI was evaluated for degree of surgical resection. Correlation of tumor localization, lengths of hospital stay as well as surgical techniques and clinical outcome with follow-up was investigated.

RESULTS

One hundred ten patients underwent 125 tumor resections using minimally invasive approaches (image- and functional guided tailored keyhole approaches for supratentorial, retrosigmoidal, and suboccipital keyhole approaches for infratentorial lesions). Most tumors were located supratentorial (62.4 %). In 29.6 % of the cases, the surgery was performed endoscope-assisted or endoscope-controlled; neuronavigation was used in 45.6 % and ultrasound in 24 % of the cases. Astrocytomas were diagnosed in 26.4 % of cases, ependymomas in 9.6 %, and medulloblastomas in 14.4 %. Gross total resection was achieved in 60.8 %. The most common complication was CSF fistula (n = 9), and the occurrence was significantly higher in younger children (p = 0.0001) and infratentorial located tumors (p = 0.02). Surgery for posterior fossa lesions was associated with a longer hospital stay (p = 0.02) compared to surgery of supratentorial lesions. Mean follow-up was 29.7 months (range 0.3-79.1 months), and most of the children recovered during the further course of the follow-up (symptoms better or idem in 74.4 %).

CONCLUSION

In conclusion, our study shows that it is possible to achieve surgical results in the pediatric population applying minimal invasive techniques comparable to those described in the literature.