The evaluation and comparison of cerebellar mutism in children and adults after posterior fossa surgery: report of two adult cases and review of the literature

Pediatric-Like Brain Tumors in Adults

Pediatric brain tumors are different to those found in adults in pathological type, anatomical site, molecular signature, and probable tumor drivers. Although these tumors usually occur in childhood, they also rarely present in adult patients, either as a de novo diagnosis or as a delayed recurrence of a pediatric tumor in the setting of a patient that has transitioned into adult services.Due to the rarity of pediatric-like tumors in adults, the literature on these tumor types in adults is often limited to small case series, and treatment decisions are often based on the management plans taken from pediatric studies. However, the biology of these tumors is often different from the same tumors found in children. Likewise, adult patients are often unable to tolerate the side effects of the aggressive treatments used in children-for which there is little or no evidence of efficacy in adults. In this chapter, we review the literature and summarize the clinical, pathological, molecular profile, and response to treatment for the following pediatric tumor types-medulloblastoma, ependymoma, craniopharyngioma, pilocytic astrocytoma, subependymal giant cell astrocytoma, germ cell tumors, choroid plexus tumors, midline glioma, and pleomorphic xanthoastrocytoma-with emphasis on the differences to the adult population.

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.

Adult Medulloblastoma: Updates on Current Management and Future Perspectives

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

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.

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.

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.

Functional tracts of the cerebellum-essentials for the neurosurgeon

The cerebellum is historically implicated in motor coordination, but accumulating modern evidence indicates involvement in non-motor domains, including cognition, emotion, and language. This correlates with the symptoms observed in postoperative cerebellar mutism syndrome (CMS). Profound knowledge of cerebellar functional topography and tractography is important when approaching cerebellar tumors, as surgical trauma to relevant structures of cerebellar pathways plays a role in the pathogenesis of CMS. The aim of this systematic review is to provide a concise overview of relevant modern neuroimaging data and cerebellar functional tracts with regard to neurosurgical procedures.

EANO-EURACAN clinical practice guideline for diagnosis, treatment, and follow-up of post-pubertal and adult patients with medulloblastoma

The European Association of Neuro-Oncology (EANO) and EUropean RAre CANcer (EURACAN) guideline provides recommendations for the diagnosis, treatment, and follow-up of post-pubertal and adult patients with medulloblastoma. The guideline is based on the 2016 WHO classification of tumours of the CNS and on scientific developments published since 1980. It aims to provide direction for diagnostic and management decisions, and for limiting unnecessary treatments and cost. In view of the scarcity of data in adults with medulloblastoma, we base our recommendations on adult data when possible, but also include recommendations derived from paediatric data if justified. Our recommendations are a resource for professionals involved in the management of post-pubertal and adult patients with medulloblastoma, for patients and caregivers, and for health-care providers in Europe. The implementation of this guideline requires multidisciplinary structures of care, and defined processes of diagnosis and treatment.

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.

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.

Neurological Complications of the Treatment of Pediatric Neoplastic Disorders

Neurological complications resulting from childhood cancer treatments are common. Treatment for childhood neoplastic disorders is often multimodal and may include procedures, cranial irradiation, chemotherapy, transplant, and immunotherapy, each of which carries distinct neurological risks. Procedures, such as lumbar punctures, are commonly used in this population for diagnostic purposes as well as intrathecal medication administration. Surgery is associated with an array of potential neurological complications, with posterior fossa syndrome being a common cause of morbidity in pediatric brain tumor patients after neurosurgical resection. Cranial irradiation can cause late neurological sequelae such as stroke, cerebral vasculopathy, secondary malignancy, and cognitive dysfunction. Neurotoxic effects of chemotherapeutic agents are common and include neuropathy, coagulopathy causing stroke or cerebral sinovenous thrombosis, encephalopathy, seizures, cerebellar dysfunction, myelopathy, and neuropsychologic difficulties. Hematopoietic stem cell transplant has a high risk of neurological complications including central nervous system infection, seizures, and stroke. Immunotherapies, including chimeric antigen receptor-modified T-cells (CAR T-cells) and immune checkpoint inhibitors, are emerging as potentially effective strategies to treat some types of childhood cancer, but may carry with them substantial neurotoxicity which is just beginning to be recognized and studied. With evolving treatment protocols, childhood cancer survivorship is increasing, and the role of the neurologist in managing both the acute and chronic neurological consequences of treatment is becoming more important. Prevention, early recognition, and treatment of therapy-associated neurotoxicity are imperative to ensuring children can remain on the most effective therapeutic regimens and to improve the neurological function and quality of life of childhood cancer survivors.

Infradentate Approach to the Fourth Ventricle

BACKGROUND

The use of minimally invasive transcranial ports for the resection of deep-seated lesions has been shown to be safe and effective for supratentorial lesions. The routine use of this surgical modality for posterior fossa masses has not been well established in the literature. In particular, fourth ventricular tumors are not the typical target for neuro-port surgery because of potential injury to the dentate nucleus.

OBJECTIVE

To describe the use of a tubular retractor system to reach the fourth ventricle while sparing the cerebellar vermis and the dentate nucleus. Three cases illustrations are presented.

METHODS

Surgical access to the fourth ventricle was developed sparing the cerebellar vermis and the dentate nucleus. The authors reviewed 3 cases to illustrate the feasibility of minimal access transcerebellar port surgery for the resection of these lesions using an infradentate access.

RESULTS

None of the patients developed new neurological deficits and the pathology was successfully resected in all cases. There were no major complications related to surgery and no mortalities.

CONCLUSION

The infradentate approach obviates the need for traditional approaches to the fourth ventricle, thus making this challenging target in the posterior fossa more accessible to neurosurgeons. The authors observed successful removal of lesions involving the fourth ventricle while avoiding any associated morbidity or mortality.

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.

Cerebellar Mutism Syndrome and Other Complications After Surgery in the Posterior Fossa in Adults: A Prospective Study

BACKGROUND

Cerebellar mutism syndrome (CMS) is rarely described in adults; however, data on self-assessed linguistic complications after posterior fossa surgery do not exist.

METHODS

Through a prospective single-center study, data on 59 tumor operations in the posterior fossa were collected preoperatively as well as 1 week and 1 month postoperatively. Data on self-assessed problems in 5 CMS-related domains, CMS scores, and neurology as well as surgical procedure and complications were obtained.

RESULTS

Data on CMS-related complications were obtained on 56 of the 59 operations. None was found to have CMS according to the CMS score. Within each of the 5 domains, at least 9 operations (16%) were followed by development or worsening of self-assessed CMS-related complications. Self-assessed complications were found to be most frequent after primary tumor surgeries, although they were significant only for speech and motor complications (P value = 0.01 and 0.02). Speech and language complications occurred more frequently in midline tumors compared with lateral tumors (40% vs. 7%; P = 0.004). Surgical complications were similar to other studies.

CONCLUSIONS

We propose that speech and language problems in adults undergoing surgery in the posterior fossa occur more frequently than previously assumed. Some of the self-assessed complications might reflect components of the cerebellar cognitive affective syndrome. Our findings are consistent with the fact that midline location of the tumor is one of the few known risk factors for CMS in children. Thus, the cerebellar midline seems to be a vulnerable region for speech and language complications also in adults.

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.

Cerebellar Mutism Syndrome following Midline Posterior Fossa Tumor Resection in Children: An Institutional Experience

Aim:

Cerebellar mutism (CM) syndrome is a well-known and annoying complication of posterior fossa surgery in the pediatric age group. Risk factors such as the type of tumor, size, involvement of posterior fossa structures and hydrocephalus, and postoperative cerebellar swelling for CM were investigated in this study.

Materials and Methods:

A consecutive series of 33 children with midline posterior fossa tumors were operated at the SMS Medical College and Hospital, Department of Neurosurgery, Jaipur India, between September 2015 and December 2016. Their speech and neuroradiological studies were systematically analyzed both preoperatively and postoperatively.

Results:

CM syndrome (CMS) developed in six children (18.18%) in the early postoperative period. The pre- and post-operative irritability, medulloblastoma histology, maximum size more than 45 mm, involvement of superior cerebellar peduncles, and vermian incision were significant single independent risk factors. In addition, male gender also associated with a higher risk for CMS. The latency for the development of mutism ranged from 1 to 12 days (mean 3.5 days). The speech returned to normal in all patients. All cases with CMS accompanied by cerebellar ataxia.

Conclusion:

The medulloblastoma, irritability, maximum size more than 45 mm, involvement of superior cerebellar peduncles, and vermian incision were significant single independent risk factors for postoperative pediatric CMS. Mutism after posterior fossa tumor resection is also accompanied with ataxia. CM usually has a self-limiting course and a favorable prognosis.

Longitudinal cerebellar diffusion tensor imaging changes in posterior fossa syndrome

Posterior fossa syndrome is a severe transient loss of language that frequently complicates resection of tumors of the cerebellum. The associated pathophysiology and relevant anatomy to this language deficit remains controversial. We performed a retrospective analysis of all cerebellar tumor resections at Seattle Children's Hospital from 2010 to 2015. Diffusion tensor imaging was performed on each of the patients as part of their clinical scan. Patients included in the study were divided into groups based on language functioning following resection: intact (N = 19), mild deficit (N = 19), and posterior fossa syndrome (N = 9). Patients with posterior fossa syndrome showed white matter changes evidenced by reductions in fractional anisotropy in the left and right superior cerebellar peduncle following resection, and these changes were still evident 1-year after surgery. These changes were greater in the superior cerebellar peduncle than elsewhere in the cerebellum. Prior to surgery, posterior fossa patients did not show changes in fractional anisotropy however differences were observed in mean and radial diffusivity measures in comparison to other groups which may provide a radiographic marker of those at greatest risk of developing post-operative language loss.

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.

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.

Cerebellar Mutism Syndrome After Posterior Fossa Surgery: A Report of Two Cases of Pilocytic Astrocytoma

Cerebellar mutism is a type of syndrome including decreased speech, hypotonia, ataxia and emotional instability which occurs after posterior fossa surgery. It has been first reported by Rekate et al. and Yonemasu in 1985. It is well known that long tract signs and lower cranial nerve involvement are not seen with this syndrome and understanding is preserved. However, the pathophysiology of cerebellar mutism has not been well clarified yet. It is mainly seen in patients with medulloblastoma and brainstem involvement. In this report, we present two extraordinary cases of cerebellar mutism after posterior fossa surgery. They were considered extraordinary because their hystopathological analysis results yielded pilocytic astrocytoma which is out of the predefined risk factors.

Cerebellar mutism

Cerebellar mutism occurs in about 25% of children following posterior fossa tumor surgery. It is usually accompanied by other neurological and behavioral disturbances. Mutism is transient in nature lasting several days to months and is frequently followed by dysarthria. In addition, impairment of language and other neuropsychological functions can be found after long term follow up in the majority of patients. The pathophysiological background of mutism may be higher speech dysfunction mediated by crossed cerebello-cerebral diaschisis which is frequently found during the mute period. Foremost injury to the bilateral dentatothalamocortical tract appears to be critical for the development of cerebello-cerebral diaschisis and subsequent mutism. Direct cerebellar injury is the likely reason for persisting deficits after the mute period. Minimization of injury to the dentatothalamocortical tract during surgery may be promising in the prevention of mutism. While there is no established treatment of mutism, early speech and rehabilitation therapy is recommended.

Cerebellar mutism

Mutism of cerebellar origin is a well-described clinical entity that complicates operations for posterior fossa tumors, especially in children. This review focuses on the current understanding of principal pathophysiological aspects and risk factors, epidemiology, clinical characteristics, treatment strategies, and outcome considerations. The PubMed database was searched using the term cerebellar mutism and relevant definitions to identify publications in the English-language literature. Pertinent publications were selected from the reference lists of the previously identified articles. Over the last few years an increasing number of prospective studies and reviews have provided valuable information regarding the cerebellar mutism syndrome. Importantly, the clarification of principal terminology that surrounds the wide clinical spectrum of the syndrome results in more focused research and more effective identification of this entity. In children who undergo surgery for medulloblastoma the incidence of cerebellar mutism syndrome was reported to be 24%, and significant risk factors so far are brainstem involvement and midline location of the tumor. The dentate-thalamo-cortical tracts and lesions that affect their integrity are considered significant pathophysiological issues, especially the tract that originates in the right cerebellar hemisphere. Moderate and severe forms of the cerebellar mutism syndrome are the most frequent types during the initial presentation, and the overall neurocognitive outcome is not as favorable as thought in the earlier publications. Advanced neuroimaging techniques could contribute to identification of high-risk patients preoperatively and allow for more effective surgical planning that should focus on maximal tumor resection with minimal risk to important neural structures. Properly designed multicenter trials are needed to provide stronger evidence regarding effective prevention of cerebellar mutism and the best therapeutic approaches for such patients with a combination of pharmacological agents and multidisciplinary speech and behavior augmentation.

Auditory-perceptual speech analysis in children with cerebellar tumours: a long-term follow-up study

Mutism and Subsequent Dysarthria (MSD) and the Posterior Fossa Syndrome (PFS) have become well-recognized clinical entities which may develop after resection of cerebellar tumours. However, speech characteristics following a period of mutism have not been documented in much detail. This study carried out a perceptual speech analysis in 24 children and adolescents (of whom 12 became mute in the immediate postoperative phase) 1-12.2 years after cerebellar tumour resection. The most prominent speech deficits in this study were distorted vowels, slow rate, voice tremor, and monopitch. Factors influencing long-term speech disturbances are presence or absence of postoperative PFS, the localisation of the surgical lesion and the type of adjuvant treatment. Long-term speech deficits may be present up to 12 years post-surgery. The speech deficits found in children and adolescents with cerebellar lesions following cerebellar tumour surgery do not necessarily resemble adult speech characteristics of ataxic dysarthria.

Postoperative cerebellar mutism and autistic spectrum disorder

PURPOSE

I read the article "An Inside View of Autism" written by a 44-year-old autistic woman who had a successful international career designing livestock equipment. In this article, she wrote about her life, disease, and experiences as an autistic individual. She stated that "It is interesting that my speech resembled the stressed speech in young children who have had tumors removed from the cerebellum".

METHODS

In this article, we intend to review and extensively document both postoperative cerebellar mutism and autistic spectrum disorder.

RESULTS

We reviewed the clinical and neurological findings, etio-pathogenesis, neuroanatomy, mechanisms of development, and similarities between the etio-pathogenesis of both diseases.

CONCLUSIONS

Cerebellar lesions can produce mutism and dysarthria, symptoms sometimes seen in autistic spectrum disorder. In mammals, cerebellar lesions disturb motivated behavior and reduce social interactions, functions that are disturbed in autistic spectrum disorder and cerebellar mutism. The cerebellum and two regions within the frontal lobes are active in certain language tasks. Language is abnormal in autistic spectrum disorder and cerebellar mutism.

Trans-postpyramidal fissure approach for ventral vermian cavernous hemangioma

A 54-year-old man presented with a rare case of cavernous angioma located in the ventral vermis manifesting as sudden onset of vertigo, followed by cerebellar ataxia. T(1)-weighted magnetic resonance imaging revealed a 1.5-cm homogeneously enhanced lesion in the ventral vermis. The postpyramidal fissure was opened widely, and upward exploration through the incision enabled piecemeal removal of the lesion without deterioration of the symptoms. The histological diagnosis was cavernous hemangioma with ruptured enlarged varices. The trans-postpyramidal fissure approach allows visualization of the entire fourth ventricle and avoids damaging the cerebellar nuclei and major postoperative cerebellar dysfunction.

Posterior fossa syndrome after posterior fossa surgery in children with brain tumors

BACKGROUND

Posterior fossa syndrome (PFS) is defined as the temporary and complete loss of speech after posterior fossa surgery. The goal of this study was to identify incidence and risk factors for PFS and to determine accompanying neurobehavioral and psychologic problems.

PROCEDURE

Between May 2007 and April 2009, children with brain tumors having posterior fossa surgery were evaluated neurologically and psychologically in preoperative and postoperative period.

RESULTS

PFS developed in 9 patients among 36 (25%) included in the study. Mutism continued for 120 days in one patient. Histopathological diagnosis (P = 0.05), location of the tumor (P = 0.05) and socioeconomic level of the family (P = 0.06) gave the significant results in relation with the PFS by univariate analyses. In multivariate analysis the risk of developing PFS was found 7.2 times higher in patients with medulloblastoma, 6.7 times higher in tumors located at the midline, 5.7 times higher in families with low socioecnomic level. Intelligence quotients of the patients in PFS and other group (P = 0.85) with Wechsler Intelligence Scale for Children and the results of the Denver II Developmental Screening Test were not significant statistically (P = 0.5).

CONCLUSION

The diagnosis of medulloblastoma, midline location of the tumor and low socioeconomic level of the families are important risk factors for the development of PFS. These findings support the hypothesis that temporary ischemia and edema due to retracted and manipulated dentate nuclei and superior cerebellar pedincles may be the cause of mutism.

Correlation between pre- or postoperative MRI findings and cerebellar sequelae in patients with medulloblastomas

INTRODUCTION

Immediate and delayed cerebellar dysfunction may be expected after surgical resection of a medulloblastoma. We investigated whether pre-operative and delayed post-operative MRI may correlate with such sequelae.

MATERIAL AND METHODS

The data of 31 patients in continuous complete remission after removal of medulloblastoma, irradiation and chemotherapy, were retrospectively reviewed. Magnetic Resonance Imaging (MRI) was analyzed for the following items: preoperative MRI (ratio of the surface of the tumor/posterior fossa, presence of ventricular dilatation or tonsilar hernia, involvement of the dentate nucleus) and delayed post-operative MRI (amount of cerebellar parenchyma removed, degree of cerebellar atrophy, presence of T1 hypointense regions in remaining cerebellar area and removal of region containing dentate nucleus). These data were correlated with immediate and long-term cerebellar syndrome and daily life repercussions.

RESULTS

On preoperative MRI, the ratio of the surface of the tumor/posterior fossa and the presence of tonsilar hernia were significantly correlated with long-term sequelae on speech (respectively P = 0.027 and P = 0.05). Initial supratentorial ventricular dilatation was correlated with ability to sustain adequately daily tasks (P = 0.002). On delayed MRI, cerebellar atrophy was inversely correlated with ability to sustain daily tasks (P = 0.002). Hypointense T1 territory in remaining cerebellar parenchyma significantly correlated with immediate post-operative cerebellar syndrome (P = 0.01) and showed a tendency for post-operative mutism (P = 0.087) but was not correlated with any long-term sequelae.

CONCLUSION

Increased cranial pressure on initial MRI and cerebellar atrophy detected on subsequent MRI studies correlated with immediate and long-term cerebellar sequelae.

Incidence, risks, and sequelae of posterior fossa syndrome in pediatric medulloblastoma

PURPOSE

To investigate the incidence, risks, severity, and sequelae of posterior fossa syndrome (PFS) in children with medulloblastoma.

METHODS AND MATERIALS

Between 1990 and 2007, 63 children with medulloblastoma at Emory University and Children's Healthcare of Atlanta were treated with craniectomy followed by radiation. Fifty-one patients were assigned to a standard-risk group, and 12 patients were assigned to a high-risk group. Five patients had <1.5-cm(2) residual tumor, 4 had >or=1.5-cm(2) residual tumor, and the remainder had no residual tumor. Eleven patients had disseminated disease. Patients received craniospinal irradiation at a typical dose of 23.4 Gy or 36 Gy for standard- or high-risk disease, respectively. The posterior fossa was given a total dose of 54 or 55.8 Gy. Nearly all patients received chemotherapy following cooperative group protocols.

RESULTS

Median follow-up was 7 years. PFS developed in 18 patients (29%). On univariate analysis, brainstem invasion, midline tumor location, younger age, and the absence of radiographic residual tumor were found to be predictors of PFS; the last two variables remained significant on multivariate analysis. From 1990 to 2000 and from 2001 to 2007, the proportions of patients with no radiographic residual tumor were 77% and 94%, respectively. During the same eras, the proportions of patients with PFS were 17% and 39%. Only 4 patients had complete recovery at last follow-up.

CONCLUSIONS

The incidence of PFS increased in the latter study period and is proportional to more aggressive surgery. Children with midline tumors exhibiting brainstem invasion are at increased risk. With the increased incidence of PFS and the permanent morbidity in many patients, the risks and benefits of complete tumor removal in all patients need to be reexamined.

The cerebellar mutism syndrome and its relation to cerebellar cognitive function and the cerebellar cognitive affective disorder

The postoperative cerebellar mutism syndrome (CMS), consisting of diminished speech output, hypotonia, ataxia, and emotional lability, occurs after surgery in up to 25% of patients with medulloblastoma and occasionally after removal of other posterior fossa tumors. Although the mutism is transient, speech rarely normalizes and the syndrome is associated with long-term adverse neurological, cognitive, and psychological sequelae. The clinical, neuroradiographic, and neuropsychological findings associated with CMS as well as possible mechanisms of injury are reviewed. Theories about the pathophysiology of CMS have evolved along with our understanding of the cerebellum as an important structure in the distributive neurocircuitry underlying complex speech, cognition, and behavior. CMS shares many similarities with the cerebellar cognitive affective syndrome, more commonly described in adults and consisting of disturbances of executive function, visuospatial skills, nonmotor language, and affect regulation. Future directions include more thorough neuropsychological characterization, functional and diffusion tensor imaging studies, and investigations into the underlying differences that may make some patients more vulnerable to CMS.

Cerebellar mutism after spontaneous intratumoral bleeding involving the upper cerebellar vermis: a contribution to the physiopathogenic interpretation

BACKGROUND

Transient mutism as a consequence of posterior fossa surgery is a well-known phenomenon. However, it has rarely been reported after focal nonsurgically induced cerebellar damage.

CASE REPORT

We describe a 7-year-old child affected by a tumor arising from the quadrigeminal plate who developed transient cerebellar mutism after a spontaneous bleeding which extended to the upper cerebellar vermis. The recovery from mutism started about a week after the bleeding. At the time of the surgical treatment, 8 weeks after the spontaneous intratumoral bleeding, she was only dysarthric.

DISCUSSION

To our knowledge, this is the first pediatric case of presurgical cerebellar mutism due to a hemorrhage of a neoplastic lesion. Moreover, the focality of bleeding allows the confirmation of the role played by the upper vermis in speech control as well as exclusion of surgically induced lesions commonly suggested as possible cause of the cerebellar mutism.

[Cerebellar mutism after removal of a vermian medulloblastoma in an adult]

Cerebellar mutism is a rare postoperative phenomenon that generally occurs in children after resection of a cerebellar mass lesion. A 22-year-old man developed cerebellar mutism after posterior fossa surgery for a mass lesion in the vermis. Histological examination showed a medulloblastoma. The tumor was totally removed via a suboccipital approach. The patient developed mutism on the first postoperative day, which persisted for two weeks. Thereafter, this condition gradually improved. Although pathophysiology and the anatomical substrate of cerebellar mutism still remain unclear, it is important that neurosurgeons be aware of this syndrome after posterior fossa surgery in adults. This phenomenon usually has a self-limiting course and a favorable prognosis for resolution within the first three months.

Postoperative motor speech production in children with the syndrome of 'cerebellar' mutism and subsequent dysarthria: a critical review of the literature

Transient cerebellar mutism is a well-known clinical entity which may develop after surgery to the cerebellum. As the period of mutism is followed by motor speech deficits, the condition has also been termed the syndrome of (cerebellar) Mutism and Subsequent Dysarthria (MSD). In children, its incidence is estimated between 8% and 31%. Unfortunately, the literature provides contradictory information regarding motor speech production post-mutism. We therefore critically reviewed data on 283 childhood cases to chart the mode of recovery of motor speech production after the mute period. After applying stringent exclusion criteria, we found that 98.8% of the children displayed motor speech deficits. This percentage is much higher than commonly reported in the literature. In addition, recovery of speech appeared to be less favourable than previously ascertained. Future studies should investigate more carefully the patients' speech characteristics in order to be able to offer children an adequate and complete rehabilitation program.

[Severe cerebellar mutism after posterior fossa tumor resection]

Cerebellar mutism is an infrequent but important complication after posterior fossa surgery in children. Dysarthria, irritability and ataxia are among the signs and symptoms of this disorder, which are usually mild and self-limiting. However, in severe cases, there can be impairment of higher-level cognitive functions, affecting the child's future personal and social relations. This disorder has been described in many other situations and consequently pediatricians should be familiar with its symptoms, physiopathology, diagnosis, degrees of severity, treatment, and prognosis, since a multidisciplinary approach is required. We present the case of a 5-year-old boy who underwent surgery for a low-grade ependymoma in the fourth ventricle; 48 hours after surgical resection, the boy developed irritability, cranial nerve involvement and stereotyped movements in the context of active hydrocephalus. His symptoms progressively improved 6 weeks after the intervention. We review the literature on cerebellar mutism and discuss the physiopathology of this disorder, which seems to confirm that the cerebellum not only acts as a simple coordinator of motor function, but also plays an important role in higher-level cognitive functions, such as language.

Incidence and severity of postoperative cerebellar mutism syndrome in children with medulloblastoma: a prospective study by the Children's Oncology Group

OBJECT

Cerebellar mutism syndrome (CMS) is a unique postoperative syndrome typically arising 1 to 2 days after resection of a midline posterior fossa tumor; it consists of diminished speech progressing to mutism, emotional lability, hypotonia, and ataxia. Most descriptions have been limited to small institutional series using a retrospective chart review methodology.

METHODS

The authors incorporated a CMS questionnaire in two large clinical trials (Children's Cancer Group [CCG] 9931, treatment for high-risk medulloblastoma/primitive neuroectodermal tumor; and CCG/Pediatric Oncology Group [POG] A9961, treatment for average-risk medulloblastoma) to prospectively survey for incidence, severity, and possible causes of CMS in children with newly diagnosed medulloblastoma. Information pertaining to 450 of the 463 patients enrolled in the studies was available for review (82 patients in CCG 9931, and 368 patients in CCG/POG A9961). Cerebellar mutism syndrome occurred in 107 (24%) of 450 children. Symptom intensity was judged to have been severe in 43%, moderate in 49%, and mild in 8% of these 107 patients. Mutism and ataxia were the features most frequently judged as severe. In both cohorts, preoperative brainstem invasion was the only feature that correlated with risk of CMS. One year after diagnosis, nonmotor speech/language deficits, neurocognitive deficits, and/or ataxia persisted in a significant fraction of patients.

CONCLUSIONS

Nearly one quarter of patients who underwent resection of a medulloblastoma developed symptoms of CMS, of which 92% were judged to be of moderate or severe intensity. Brainstem invasion by tumor was the only risk factor that correlated positively with CMS occurrence; there was a negative correlation with cerebellar hemisphere tumor location. As more radical resections are attempted for medulloblastoma, the potential for increased morbidity must be carefully weighed against prognostic factors, especially in patients with brainstem invasion.

The pathophysiologic mechanism of cerebellar mutism

OBJECTIVE

Cerebellar mutism (CM) is a postoperative complication of mainly pediatric posterior fossa surgery. Multiple theories exist for explaining this phenomenon. We have made an attempt to further understand this entity given a particularly interesting case as it relates to multiple pathophysiologic pathways.

METHODS

We have reviewed the details surrounding a particularly interesting case of CM. A retrospective analysis of this patient's clinical history and recovery is described. An extensive literature review has been performed in conjunction with an attempt to help elucidate details and a better understanding of CM.

RESULTS

A thorough analysis of existing theories as to the pathophysiologic mechanism of CM has been performed as it relates to the details of this particular case. A case is described in which a child exhibiting CM abruptly improved and made a relatively quick recovery after the triggering of the melodic speech pathway by way of watching and beginning to sing along with a video. It appears that this incident involving a familiar song catalyzed various speech pathways, which apparently were in some state of shock. This phenomenon seems to be a temporary entity involving not only the mechanical coordination of speech production, but also the initiation of speech itself.

CONCLUSIONS

Evidence exists for a pathophysiologic pathway for speech by way of coordinating phonation and articulation. In addition, there seems to exist a pathway by which the initiation of speech may be altered or halted by posterior fossa pathology, namely, vermian or dentate nuclear injury. In particular to this case, we found that the incidental appreciation of other forms of speech, melodic in this instance, may be the key to help stimulate and accelerate the recovery from CM.

Emotional task-dependent low-frequency fluctuations and methylphenidate: Wavelet scaling analysis of 1/f-type fluctuations in fMRI of the cerebellar vermis

Ion channel currents, neural firing patterns, and brain BOLD signals display 1/f-type fluctuations or fractal properties in time. By design, fMRI methods attempt to minimize the contribution of variance from low-frequency physiological 1/f-noise. New fMRI methods are described to visualize and measure 1/f-type BOLD fluctuations in volunteers recalling affectively neutral or emotional memories or meditating (i.e., attending to breathing) then retrospectively rating emotional content. A wavelet scaling exponent (alpha) was used to characterize signals from 0.015625 to 0.5Hz in cerebellar lobules VIII to X of the vermis (posterior inferior vermis; PIV), a region coordinating balance, eye tracking, locomotion, and vascular tone, and a possible site of pathology in attention deficit hyperactivity disorder (ADHD).

RESULTS

Changes in alpha and emotional measures were correlated in PIV voxels (r = 0.622, d.f .= 14, P < 0.0005), but not other regions examined. In contrast, conventional means and standard deviations of PIV voxels were unchanged. Methylphenidate, shown to decrease slow oscillations in rodent basal ganglia [Ruskin DN, Bergstrom DA, Shenker A, Freeman LE, Baek D, Walters JR. Drugs used in the treatment of attention-deficit/hyperactivity disorder affect postsynaptic firing rate and oscillation without preferential dopamine autoreceptor action. Biol Psychiatry 2001;49:340-50.], abolished task-dependent alpha changes in the PIV of an adult with ADHD. Wavelet analysis of long BOLD time series appears well suited to fractal physiology and studies of pharmacologically modulated cerebellar-thalamic-cortical function in ADHD or other psychiatric disorders.

Cerebellar mutism in adults after posterior fossa surgery: a report of 2 cases

BACKGROUND

Mutism has been associated with injury to midline cerebellar structures secondary to degenerative disease, tumors, hemorrhage, or surgery. Typically, cerebellar mutism syndrome (CMS) has been seen in children and only rarely described in adults after surgery of the posterior fossa. This syndrome typically arises 48 hours after the initiating event and resolves approximately 7 to 8 weeks later. Characteristics of CMS include complete absence of speech without impaired consciousness, other cranial nerve deficits, or long tract signs.

CASE DESCRIPTION

The authors report on 2 patients each of whom developed cerebellar mutism after tumor resection using a posterior fossa approach. The first patient underwent gross total resection of a pineal region tumor via a supracerebellar approach. The second patient underwent posterior fossa decompression for a left cerebellar hemispheric renal cell carcinoma metastasis with adjacent hemorrhage. One patient displayed a variant of cerebellar mutism with severe ataxic dysarthria without complete absence of speech, whereas the other demonstrated frank mutism. After neuroimaging studies confirmed the absence of a surgically treatable postoperative cause for the patients' symptoms, they were managed in a supportive fashion (eg, speech therapy) and improved within 3.5 months and 1 year, respectively.

CONCLUSION

It is paramount that neurosurgeons be aware of cerebellar mutism with regard to its very rare occurrence in adults, its time of onset, and typical self-limiting course.

Cerebellar mutism

The aim of the present study was to investigate the manifestations of mutism after surgery in children with cerebellar tumors. Speech impairment following cerebellar mutism in children was investigated based on standardized acoustic speech parameters and perceptual criteria. Mutistic and non-mutistic children after cerebellar surgery as well as orthopedic controls were tested pre-and postoperatively. Speech impairment was compared with the localization of cerebellar lesions (i. e. affected lobules and nuclei). Whereas both control groups showed no abnormalities in speech and behavior, the mutistic group could be divided into children with dysarthria in post mutistic phase and children with mainly behavioral disturbances. In the mutistic children involvement of dentate and fastigial nuclei tended to be more frequent and extended than in the nonmutistic cerebellar children. Cerebellar mutism is a complex phenomenon of at least two types. Dysarthric symptoms during resolution of mutism support the anarthria hypothesis, while mainly behavioral changes suggest an explanation independent from speech motor control.