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.

Alemtuzumab significantly improves posterior fossa syndrome presented as a relapse of multiple sclerosis.

BACKGROUND: Posterior fossa syndrome (PFS) is a rare manifestation of ponto-mesencephalic lesions frequently reported in post-surgical pediatric tumors, rarely described as a consequence of vascular, infective or inflammatory lesions. OBJECTIVE: The aim of this article is to report the clinical and neuroradiological characteristics of a patient with an acute PFS presentation as a relapse in relapsing-remitting MS, significantly responsive to Alemtuzumab treatment. CASE REPORT: 24-year-old patient affected by multiple sclerosis developed motor-cognitive and behavioral syndrome related to an extensive ponto-mesencephalic lesion under Fingolimod treatment. CONCLUSION: Our case highlights the significant and rapid effect of Alemtuzumab therapy on both cognitive and motor symptoms occurring during a MS relapse with atypical neuroradiological localization.

Liver Transplant Can Resolve Severe Neuropsychiatric Manifestations of Wilson Disease: A Case Report.

Although liver transplant for decompensated cirrhosis secondary to Wilson disease is well accepted, the use of transplant for patients with severe neurologic manifestations of this condition remains controversial, and these can be perceived as a contraindication. Here, we describe a 45-year-old woman who presented with an incidental hepatocellular carcinoma at the time of transplant. The patient had severe neurologic manifestations of Wilson disease pretransplant, including dysarthria, hyperreflexia, asymmetrical ataxia, tremor, bradyphrenia, and shuffling gait. She underwent successful transplant from a hepatic and surgical standpoint, but her postoperative course was marked by protracted mutism, hypophonia, and fluctuating akinesia and immobility that did not respond promptly to withdrawal of calcineurin inhibitors or pramipexole but did respond robustly to amantadine. At 9 months posttransplant, there was marked neurologic improvement, and, at 18 months, she exhibited subtle memory and organizational difficulties but was fully ambulatory and otherwise completely functional. Our experience suggests that even patients with severe neurologic Wilson disease may recover after transplant, albeit slowly, demonstrating the need for a multidisciplinary approach, including pre- and posttransplant neurologic and neuropsychiatric consultations.

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.

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.

Fluorodeoxyglucose positron emission tomography/computed tomography findings in a patient with cerebellar mutism after operation in posterior fossa.

Cerebellar mutism is a transient period of speechlessness that evolves after posterior fossa surgery in children. Although direct cerebellar and brain stem injury and supratentorial dysfunction have been implicated in the mediation of mutism, the pathophysiological mechanisms involved in the evolution of this kind of mutism remain unclear. Magnetic resonance imaging revealed dentatothalamocortical tract injuries and single photon emission computed tomography showed cerebellar and cerebral hypoperfusion in patients with cerebellar mutism. However, findings with 18F-fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT) in this group of patients have not been documented previously. In this clinical case, we report a patient who experienced cerebellar mutism after undergoing a posterior fossa surgery. Right cerebellar and left frontal lobe hypometabolism was shown using FDG PET/CT. The FDG metabolism of both the cerebellum and the frontal lobe returned to normal levels after the resolution of the mutism symptoms.

Posterior fossa syndrome: Review of the behavioral and emotional aspects in pediatric cancer patients.

Medulloblastoma, the most common malignant brain tumor of childhood, occurs in the posterior fossa, the part of the intracranial cavity that contains the brainstem and the cerebellum. The cerebellum is involved in many complex aspects of human behavior and function, and when it is disrupted or insulted, this can lead to significant sequelae in children with posterior fossa tumors. A constellation of impairing and distressing symptoms, including mutism, ataxia/hypotonia, and emotional lability, develops in approximately 25% of children after the surgical resection of posterior fossa tumors. These symptoms may impede treatment and frequently require intervention in order for children to be able to participate in their care. The eventual recovery of speech occurs for most, but with slowly improving dysarthria over many months. Behavioral changes and emotional lability also occur. This phenomenon has been classified differently by different investigators over the past 35 years. For the purposes of this article, the term posterior fossa syndrome is used to refer to the neuropsychiatric and behavioral features that compose this condition. The current review summarizes the development of the clinical understanding of this phenomenon with a focus on near- and long-term psychosocial and psychiatric implications. Also, clinical examples of the presentation, management, and lasting implications of this syndrome are provided. This review is intended to be a resource for clinicians who treat affected children. Cancer 2017;123:551-559. © 2016 American Cancer Society.

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.

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.

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.

Reversal of lifelong mutism after anterior cervical discectomy and fusion for myelopathy.

A 34-year-old man with a history of spina bifida occulta, fetal alcohol syndrome and mutism presented with an acute on chronic decline of unsteady gait and right arm and leg weakness over the period of a few months. The patient was non-verbal and communicated using hand gestures. MRI of the cervical spine showed severe stenosis at C4-5 with T2 signal abnormalities. Brain MRI demonstrated mild ventriculomegaly. The patient underwent an anterior cervical discectomy and fusion for severe cervical spine stenosis. Postoperatively the patient's myelopathic symptoms improved. He also became verbal and engaged in conversation. Ten months after surgery, the patient who had previously been non-verbal had developed a vocabulary of more than 50 words.

Laryngotracheal separation in neonatal brainstem dysfunction.

INTRODUCTION: Neonatal brainstem dysfunction (NBD) associates four symptoms of variable presence and intensity: suction-swallowing dysfunction, abnormal laryngeal sensitivity and motility, gastroesophageal reflux, and cardiac vagal overactivity. MATERIALS AND METHODS: We report three cases of severe NBD with chronic aspiration which required surgical management. Successive failures and clinical deterioration led us to perform laryngotracheal separation. The surgical procedure consisted in suturing the distal segment of the trachea to the cervical skin after complete closure of the larynx. RESULTS: After surgery, these children did not present any pulmonary infection and were allowed oral nutrition. However, oral communication was no longer possible. Although it is a theoretically reversible procedure, the decision is ethically difficult in children free of mental deficiency, because of the vocal loss and the unpredictable NBD outcome. CONCLUSION: Laryngotracheal separation may be recommended after multidisciplinary decision for severe chronic aspiration in the particular case of children presenting with NBD.

Rhesus macaque as an animal model for posterior fossa syndrome following tumor resection.

BACKGROUND/AIMS: Posterior fossa tumors are the most common brain tumors in children. Surgeons usually remove these tumors via a midline incision through the posterior vermis of the cerebellum. Though often effective, this surgery causes hypotonia, ataxia, oculomotor deficits, transient mutism, difficulty in swallowing and nausea. To date, there is no animal model that mimics these complications. We found that the rhesus macaque is a good model for the consequences of this surgery. METHODS: We made a midline incision through the cerebellar vermis of one monkey to mimic the posterior fossa surgery. Then, we closely monitored the monkey for deficits following the surgery. RESULTS: In the first few days, the monkey exhibited nausea, hypotonia, ataxia, difficulty in swallowing and an absence of vocalization. At 28 days, we recorded eye movements and found severe deficits in the accuracy of rapid eye movements and smooth pursuit of a target. Additionally, the animal had trouble fixating and a rightward-beating nystagmus. Oculomotor signs persisted until we sacrificed the animal 99 days after surgery, but the other effects resolved by 37 days. CONCLUSION: Our surgery in a monkey caused the same postsurgical signs observed in humans. We expect to use this model to improve the posterior fossa surgery methods.

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.

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.