Long-term supratentorial brain structure and cognitive function following cerebellar tumour resections in childhood

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

Parent ratings of executive functioning in pediatric survivors of medulloblastoma and pilocytic astrocytoma

The present study compared parent-rated executive functioning in pediatric medulloblastoma (MB) and pilocytic astrocytoma (PA) survivors. Although standard care for both includes surgical resection, children with MB additionally receive chemotherapy and craniospinal irradiation. Given well-documented neurocognitive late effects associated with the latter, we anticipated poor parent-reported executive functioning in MB survivors. Parents/guardians of 36 MB survivors and 20 PA survivors completed the Behavior Rating Inventory of Executive Functioning (BRIEF). PA survivors were younger at diagnosis (t[51.97] = 3.07, p < .001, d = 0.86) and demonstrated higher IQ (t[54] = -3.51, p < .001, d = 0.95). However, relative to the MB group, the PA group was rated as having significantly more problems on all BRIEF scales (all p ≤ .05; d = 0.30 - 1.10), except the Shift scale. Additionally, all mean BRIEF scores for MB survivors were within normal limits, whereas for PA survivors, all mean BRIEF scores except for Organization of Materials were significantly discrepant from normative means. Overall, PA survivors were rated as demonstrating poorer executive function than MB survivors. Five theories are discussed as possible explanations for these surprising findings: two related to group differences, two related to potential sources of parental bias, and one related to the nature of questionnaire-based assessment. All these theories represent directions for future research. Parent questionnaires such as the BRIEF may have real-world implications for pediatric brain tumor survivors. Future research should explore factors affecting parent ratings of executive functioning in these populations, along with comparison to performance-based measures.

Transmorphic phage-guided systemic delivery of TNFα gene for the treatment of human pediatric medulloblastoma

Medulloblastoma is the most common childhood brain tumor with an unfavorable prognosis and limited options of harmful treatments that are associated with devastating long-term side effects. Therefore, the development of safe, noninvasive, and effective therapeutic approaches is required to save the quality of life of young medulloblastoma survivors. We postulated that therapeutic targeting is a solution. Thus, we used a recently designed tumor-targeted bacteriophage (phage)-derived particle, named transmorphic phage/AAV, TPA, to deliver a transgene expressing the tumor necrosis factor-alpha (TNFα) for targeted systemic therapy of medulloblastoma. This vector was engineered to display the double-cyclic RGD4C ligand to selectively target tumors after intravenous administration. Furthermore, the lack of native phage tropism in mammalian cells warrants safe and selective systemic delivery to the tumor microenvironment. In vitro RGD4C.TPA.TNFα treatment of human medulloblastoma cells generated efficient and selective TNFα expression, subsequently triggering cell death. Combination with the chemotherapeutic drug cisplatin used clinically against medulloblastoma resulted in augmented effect through the enhancement of TNFα gene expression. Systemic administration of RGD4C.TPA.TNFα to mice-bearing subcutaneous medulloblastoma xenografts resulted in selective tumor homing of these particles and consequently, targeted tumor expression of TNFα, apoptosis, and destruction of the tumor vasculature. Thus, our RGD4C.TPA.TNFα particle provides selective and efficient systemic delivery of TNFα to medulloblastoma, yielding a potential TNFα anti-medulloblastoma therapy while sparing healthy tissues from the systemic toxicity of this cytokine.

A review of long-term deficits in memory systems following radiotherapy for pediatric posterior fossa tumor

INTRODUCTION

In recent years, progress in pediatric posterior fossa tumor (PFT) treatments has improved survival rates. However, the majority of survivors present neurocognitive sequelae that impact academic achievement.

METHODS

This review examines the literature from 2000 to 2020 on long-term outcomes in different memory systems for survivors of pediatric PFT, considering the impact of radiotherapy which is a well-known prognostic factor for global neurocognitive function.

RESULTS

Of the 43 articles selected, 31 explored working memory, 19 episodic memory, 9 semantic memory and 2 procedural memory. Irradiated survivors had scores of < -2 standard deviation (SD) (n = 4 studies/25) or between -2SD and -1SD (n =7 studies/25) for working memory; < -1SD for anterograde memory (n = 11/13), with a progressive decline in these two memory systems; < -1SD (n = 4/7) in semantic memory, and a deficit in perceptual-motor procedural learning (n = 1/1). Reducing craniospinal irradiation dose, limiting tumor bed boosts, and using proton therapy seem to have had a beneficial effect with better preservation of the memory score and a reduction in the decline over time. Non-irradiated survivors had memory systems that were less affected, with preservation of anterograde memory and maintenance of long-term stability.

CONCLUSION

Memory deficits are a core feature in survivors of pediatric PFT, especially when treatment requires radiotherapy. To limit these effects, dose constraints for specific brain areas involved in memory should be defined. During long-term follow-up, specific attention is essential to identify these deficits in order to limit their impact on the quality of life.

Impact of childhood cerebellar tumor surgery on cognition revealed by precuneus hyperconnectivity

Background

Childhood cerebellar pilocytic astrocytomas harbor excellent overall survival rates after surgical resection, but the patients may exhibit specific cognitive and behavioral problems. Functional MRI has catalyzed insights into brain functional systems and has already been linked with the neuropsychological performance. We aimed to exploit the question of whether resting-state functional MRI can be used as a biomarker for the cognitive outcome assessment of these patients.

Methods

We investigated 13 patients (median age 22.0 years; range 14.9-31.3) after a median interval between surgery and examination of 15.0 years (range 4.2-20.5) and 16 matched controls. All subjects underwent functional 3-Tesla MRI scans in a resting-state condition and battery neuropsychological tests.

Results

Patients showed a significantly increased functional connectivity in the precuneus compared with controls (P < .05) and at the same time impairments in various domains of neuropsychological functioning such as a lower mean Wechsler Intelligenztest für Erwachsene (WIE) IQ percentile (mean [M] = 48.62, SD = 29.14), lower scores in the Trail Making Test (TMT) letter sequencing (M = 49.54, SD = 30.66), worse performance on the WIE subtest Digit Symbol Coding (M = 38.92, SD = 35.29), subtest Symbol Search (M = 40.75, SD = 35.28), and test battery for attentional performance (TAP) divided attention task (M = 783.92, SD = 73.20).

Conclusion

Childhood cerebellar tumor treated by resection only strongly impacts the development of precuneus/posterior cingulate cortex functional connectivity. Functional MRI has the potential to help deciphering the pathophysiology of cerebellar-related cognitive impairments in these patients and could be an additional tool in their individual assessment and follow-up.

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

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

A multimodal approach to the study of children treated for posterior fossa tumor: A review of the literature and a pilot study

OBJECTIVE

The aims of the present study were: (1) to review the literature on long-lasting cognitive sequelae in children treated for Posterior Fossa Tumor and (2) to investigate anatomic functional relations in a case series of 7 children treated for PFT using magnetic resonance imaging (MRI) post-processing methods.

METHODS

We retrospectively analyzed MRIs of children who underwent complete surgical resection of PFT and performed extensive neuropsychological evaluation. Tumor, ventricular volumes, and VPS insertion site were drawn on T1 volumetric MRI scans and normalized to a pediatric template. Children showed worse performances on tasks tapping executive functions, memory, visuo-motor precision, and expressive language.

RESULTS

Volumes of interest related to these functions showed a maximum overlap on the left vermis and the lateral ventricle enlargement, except for impaired narrative fluency -which was associated with left lateral ventricle enlargement- and narrative memory -which was related to the right vermis and the enlarged fourth ventricle.

CONCLUSION

Results suggest that anatomic functional relations in children treated for PFT are related to a combination of different pathophysiological factors.

Functional Connectivity Networks and Their Recruitment During Working Memory Tasks in Adult Survivors of Childhood Brain Tumors

Background: Assessments of functional connectivity of default mode network (DMN) and positive task-related networks (TRNs) using independent component analysis (ICA) may help describe long-term effects of childhood brain tumors and adjuvant treatments. Methods: Aiming to identify potential neuronal markers that may aid in prognosis and inform interventions to optimize outcomes, this study used ICA to evaluate the presence of functional connectivity networks and their recruitment during a letter n-back task in 23 adult survivors of childhood posterior fossa tumors (9 low grade, 14 high grade) at least 5 years past diagnosis compared with 40 age- and sex-matched healthy peers. Results: DMN components generally demonstrated increasing disengagement as task difficulty increased, and relationships between effective DMN disengagement and improved performance were observed in healthy controls (HCs). Low-grade brain tumor survivors (LGS) demonstrated unique patterns in DMN recruitment that suggested increased involvement of the medial prefrontal cortex in LGS during tasks. TRN components generally demonstrated increasing engagement, which was related to improved task performance in HCs for one executive control network (ECN) component. High-grade brain tumor survivors (HGS) demonstrated distinct challenges recruiting an ECN component at more difficult task levels and showed a relationship between recruitment of another ECN component and task performance, indicating a potential compensatory mechanism for some HGS. Conclusions: Findings suggest the importance of cognitive intervention in both survivor groups and the necessity to track LGS despite their cognitive abilities often resembling those of their healthy peers. Impact statement Distinct functional connectivity patterns were identified between both adult survivor of childhood brain tumor groups and peers during attention and working memory tasks, reflecting different damage and recovery from treatment. Survivors of low-grade tumors demonstrated unique patterns of recruitment of default mode network components in the context of similar cognitive abilities, whereas survivors of high-grade tumors demonstrated poorer cognitive abilities and may be utilizing compensatory executive control network components in the face of challenging tasks. Long-term clinical follow-up and cognitive remediation is warranted for both groups, including low grade cerebellar tumor patients who have traditionally not been monitored as closely.

Cerebellar-Subcortical-Cortical Systems as Modulators of Cognitive Functions

Over the past few decades, research has established that the cerebellum is involved in executive functions; however, its specific role remains unclear. There are numerous theories of cerebellar function and numerous cognitive processes falling under the umbrella of executive function, making investigations of the cerebellum's role in executive functioning challenging. In this review, we explored the role of the cerebellum in executive functioning through clinical and cognitive neuroscience frameworks. We reviewed the neuroanatomical systems and theoretical models of cerebellar functions and the multifaceted nature of executive functions. Using attention deficit hyperactivity disorder and cerebellar tumor as clinical developmental models of cerebellar dysfunction, and the functional magnetic resonance imaging literature, we reviewed evidence for cerebellar involvement in specific components of executive function in childhood, adolescence, and adulthood. There is evidence for posterior cerebellar contributions to working memory, planning, inhibition, and flexibility, but the heterogeneous literature that largely was not designed to study the cerebellum makes it difficult to determine specific functions of the cerebellum or cerebellar regions. In addition, while it is clear that cerebellar insult in childhood affects executive function performance later in life, more work is needed to elucidate the mechanisms by which executive dysfunction occurs and its developmental course. The limitations of the current literature are discussed and potential directions for future research are provided.

The role of cerebellum in the child neuropsychological functioning

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

The impact of neuroimaging advancement on neurocognitive evaluation in pediatric brain tumor survivors: A review

Pediatric brain tumors are a type of tumors that are commonly present in children and young adults. With the improvement of treatment, the quality of life, especially the cognitive functioning, is gaining increasingly more attention. Apart from cognitive evaluations, neuroimaging studies begin to play an important part in neurocognitive functioning investigation. In this way, the brain tissue changes caused by tumor variables (including tumor location and tumor size) and treatment variables (including surgery, chemotherapy and radiotherapy) can be detected by neuroimaging. Recent advancement of neuroimaging techniques, such as functional-MRI (fMRI) and diffusion tensor imaging (DTI), made great contributions to understanding cognitive dysfunction and quantifying the effects of tumor variables and treatment variables. In recent years, laminar-fMRI provided a potentially valuable tool for examining the exact origins of neural activity and cognitive function. On the other hand, molecular fMRI might guide diagnosis and treatment of brain disease in the future by using new biomarkers, and DTI can detect white matter changes and obtain some anatomically specific information.

Late effects of pediatric brain tumors

PURPOSE OF REVIEW

Adverse late effects of pediatric brain tumors can be numerous and complex and potentially alter the life trajectories of survivors in a multitude of ways. We review these inter-related late effects that compromise neurocognitive function, general health, social and psychological adjustment, and overall adaptive and vocational outcomes, and threaten to undermine the ability of survivors to transition independently into adulthood and effectively manage their care. Intervention/prevention strategies and advances in treatment that may reduce such late effects are discussed.

RECENT FINDINGS

Studies of neuropsychological late effects have revealed specific deficits in core cognitive functions of attention, working memory and processing speed, with many survivors demonstrating decline in working memory and processing speed over time, irrespective of tumor type or treatment. This in turn affects the ongoing development of higher order neurocognitive skills. Research also highlights the increasing burden of health-related, neuropsychological and psychosocial late effects into adulthood and impact across life outcomes.

SUMMARY

Pediatric brain tumor survivors require coordinated interdisciplinary care, ongoing evaluation and management of late effects, and timely interventions focused on mitigating the impact of late effects. The transition to adulthood can be especially vulnerable and addressing barriers to care is of paramount importance.

Posterior Fossa Arachnoid Cyst in a Pediatric Population is Associated with Social Perception and Rest Cerebral Blood Flow Abnormalities

Posterior fossa arachnoid cysts (PFAC) may produce not only neurological symptoms but also other symptoms still poorly understood such as behavioral and learning deficits, awkwardness, and difficulties in social interaction. These subtle social impairments have not been formally described and their underlying brain mechanisms remain unknown. In the present case-control study, we aimed to empirically characterize social impairments in a pediatric population with PFAC using eye tracking. In addition, we investigated putative functional cortical abnormalities in these children using arterial spin labeling magnetic resonance imaging. Overall, 15 patients with PFAC (3f, age = 9.4 ± 4 years) and 43 typically developing volunteer children (16f, age = 9.3 ± 3.6 years) were enrolled in this study. Eye tracking was used to record gaze patterns during visualization of social interaction scenes. Viewing times to faces of characters and non-social background were analyzed. A voxel-wise whole-brain analysis was performed to investigate rest cerebral blood flow (CBF) abnormalities. Significantly reduced viewing time to faces was observed in patients compared with controls (p < 0.01). A ROC curve analysis revealed that 30% of PFAC patients presented viewing time to the face lower than the cutoff, while none of the controls did. The whole-brain analysis revealed a significant decrease in rest CBF in PFAC patients compared with controls bilaterally in the superior temporal gyrus and the temporoparietal junction (TPJ) (p < 0.05 FWE). These results suggest that early life PFAC may have an impact on functional activity of the temporal lobe, which could be associated with social perception deficits.

Social attainment in physically well-functioning long-term survivors of pediatric brain tumour; the role of executive dysfunction, fatigue, and psychological and emotional symptoms

The purpose of this cross-sectional study was to investigate long-term social attainment in physically well-functioning adult survivors of pediatric brain tumour (PBT) and identify demographic, medical, and psychological factors related to poor social outcomes, with a special focus on the significance of executive dysfunction. One hundred and fourteen PBT survivors and a healthy control group provided personal data on social outcomes, i.e., education, work, and government benefits, and completed questionnaires on executive function (EF), psychological and emotional difficulties, and fatigue. A significantly higher number of survivors compared to healthy controls reported having received educational adjustments and substantial government benefits, and significantly more survivors than controls were currently not engaged in regular employment/training. PBT survivors and healthy controls did not differ on educational level or living situation. The factors most strongly associated with poor social outcomes were self-reported executive dysfunction, difficulties with adaptive functioning, and fatigue. The findings show that physically well-functioning PBT survivors are at risk of poorer social outcomes and financial dependence in adulthood compared to their healthy peers, and underline the importance of investigating EF in short- and long-term follow-ups. Future rehabilitation efforts should focus more on compensatory strategies for executive dysfunction and improving EF skills.

Active HHV-6 Infection of Cerebellar Purkinje Cells in Mood Disorders

Early-life infections and associated neuroinflammation is incriminated in the pathogenesis of various mood disorders. Infection with human roseoloviruses, HHV-6A and HHV-6B, allows viral latency in the central nervous system and other tissues, which can later be activated causing cognitive and behavioral disturbances. Hence, this study was designed to evaluate possible association of HHV-6A and HHV-6B activation with three different groups of psychiatric patients. DNA qPCR, immunofluorescence and FISH studies were carried out in post-mortem posterior cerebellum from 50 cases each of bipolar disorder (BPD), schizophrenia, 15 major depressive disorder (MDD) and 50 appropriate control samples obtained from two well-known brain collections (Stanley Medical Research Institute). HHV-6A and HHV-6B late proteins (indicating active infection) and viral DNA were detected more frequently (p < 0.001 for each virus) in human cerebellum in MDD and BPD relative to controls. These roseolovirus proteins and DNA were found less frequently in schizophrenia cases. Active HHV-6A and HHV-6B infection in cerebellar Purkinje cells were detected frequently in BPD and MDD cases. Furthermore, we found a significant association of HHV-6A infection with reduced Purkinje cell size, suggesting virus-mediated abnormal Purkinje cell function in these disorders. Finally, gene expression analysis of cerebellar tissue revealed changes in pathways reflecting an inflammatory response possibly to HHV-6A infection. Our results provide molecular evidence to support a role for active HHV-6A and HHV-6B infection in BPD and MDD.

Cerebellar volume and cerebellocerebral structural covariance in schizophrenia: a multisite mega-analysis of 983 patients and 1349 healthy controls

Although cerebellar involvement across a wide range of cognitive and neuropsychiatric phenotypes is increasingly being recognized, previous large-scale studies in schizophrenia (SZ) have primarily focused on supratentorial structures. Hence, the across-sample reproducibility, regional distribution, associations with cerebrocortical morphology and effect sizes of cerebellar relative to cerebral morphological differences in SZ are unknown. We addressed these questions in 983 patients with SZ spectrum disorders and 1349 healthy controls (HCs) from 14 international samples, using state-of-the-art image analysis pipelines optimized for both the cerebellum and the cerebrum. Results showed that total cerebellar grey matter volume was robustly reduced in SZ relative to HCs (Cohens's d=-0.35), with the strongest effects in cerebellar regions showing functional connectivity with frontoparietal cortices (d=-0.40). Effect sizes for cerebellar volumes were similar to the most consistently reported cerebral structural changes in SZ (e.g., hippocampus volume and frontotemporal cortical thickness), and were highly consistent across samples. Within groups, we further observed positive correlations between cerebellar volume and cerebral cortical thickness in frontotemporal regions (i.e., overlapping with areas that also showed reductions in SZ). This cerebellocerebral structural covariance was strongest in SZ, suggesting common underlying disease processes jointly affecting the cerebellum and the cerebrum. Finally, cerebellar volume reduction in SZ was highly consistent across the included age span (16-66 years) and present already in the youngest patients, a finding that is more consistent with neurodevelopmental than neurodegenerative etiology. Taken together, these novel findings establish the cerebellum as a key node in the distributed brain networks underlying SZ.

Cognitive aspects: sequencing, behavior, and executive functions

The question posed today is not whether the cerebellum plays a role in cognition, but instead, how the cerebellum contributes to cognitive processes, even in the developmental age. The central role of the cerebellum in many areas of human abilities, motor as well as cognitive, in childhood as well as in adulthood, is well established but cerebellar basic functioning is still not clear and is much debated. Of particular interest is the changing face of cerebellar influence on motor, higher cognitive, and behavioral functioning when adult and developmental lesions are compared. The idea that the cerebellum might play quite different roles during development and in adulthood has been proposed, and evidence from experimental and clinical literature has been provided, including for sequencing, behavioral aspects, and executive functions Still, more data are needed to fully understand the changes of cerebrocerebellar interactions within the segregated loops which connect cerebrum and cerebellum, not only between childhood and adulthood but also in health and disease.

Language and the cerebellum

During the past decades neuroanatomic, neuroimaging, and clinical studies have substantially changed the long-standing view of the role of the cerebellum as a sole coordinator of sensorimotor function. Currently, the cerebellum is considered to be crucially implicated in a variety of cognitive, affective, social, and behavioral processes as well. In this chapter we aim to summarize a number of critical insights from different research areas (neuroanatomy, functional neuroimaging, clinical practice) that provide evidence for a role of the cerebellum in motor speech and nonmotor language processing in both adults and children. Neuroanatomic studies have provided a robust basis for the development of new insights in the modulatory role of the cerebellum in neurocognition, including nonmotor language processing by means of identifying a dense network of crossed reciprocal connections between the cerebellum and the supratentorial association areas. A topologic distinction has been established between the "motor" cerebellum, projecting to the cortical motor areas, and the "cognitive/affective" cerebellum, connected with the cortical and limbic association areas. Neuroimaging studies have demonstrated cerebellar involvement in several different language tasks, even after controlling for motor aspects. In addition, several clinical studies have identified a variety of nonmotor linguistic deficits after cerebellar disease in both children and adults, implying a prominent role for the cerebellum in linguistic processes. Functional neuroimaging has confirmed the functional impact of cerebellar lesions on remote, structurally intact cortical regions via crossed cerebellocerebral diaschisis. Overall, evidence from neuroanatomic, neuroimaging, and clinical studies shows a (strongly lateralized) involvement of the cerebellum in a broad spectrum of nonmotor language functions through a dense network of crossed and reciprocal cerebellocerebral connections. It is argued that the cerebellum is involved in language in a similar manner as it is involved in motor functions: through monitoring/coordinating cortical functions via timing and sequencing mechanisms.

Brain Perfusion and Diffusion Abnormalities in Children Treated for Posterior Fossa Brain Tumors

OBJECTIVE

To compare cerebral perfusion and diffusion in survivors of childhood posterior fossa brain tumor with neurologically normal controls and correlate differences with cognitive dysfunction.

STUDY DESIGN

We analyzed retrospectively arterial spin-labeled cerebral blood flow (CBF) and apparent diffusion coefficient (ADC) in 21 patients with medulloblastoma (MB), 18 patients with pilocytic astrocytoma (PA), and 64 neurologically normal children. We generated ANCOVA models to evaluate treatment effects on the cerebral cortex, thalamus, caudate, putamen, globus pallidus, hippocampus, amygdala, nucleus accumbens, and cerebral white matter at time points an average of 5.7 years after original diagnosis. A retrospective review of patient charts identified 12 patients with neurocognitive data and in whom the relationship between IQ and magnetic resonance imaging variables was assessed for each brain structure.

RESULTS

Patients with MB (all treated with surgery, chemotherapy, and radiation) had significantly lower global CBF relative to controls (10%-23% lower, varying by anatomic region, all adjusted P?<?.05), whereas patients with PA (all treated with surgery alone) had normal CBF. ADC was decreased specifically in the hippocampus and amygdala of patients with MB and within the amygdala of patients with PA but otherwise remained normal after therapy. In the patients with tumor previously evaluated for IQ, regional ADC, but not CBF, correlated with IQ (R²?=?0.33-0.75).

CONCLUSIONS

The treatment for MB, but not PA, was associated with globally reduced CBF. Treatment in both tumor types was associated with diffusion abnormalities of the mesial temporal lobe structures. Despite significant perfusion abnormalities in patients with MB, diffusion, but not perfusion, correlated with cognitive outcomes.

Structure-function relationships in the developing cerebellum: Evidence from early-life cerebellar injury and neurodevelopmental disorders

The increasing appreciation of the role of the cerebellum in motor and non-motor functions is crucial to understanding the outcomes of acquired cerebellar injury and developmental lesions in high-risk fetal and neonatal populations, children with cerebellar damage (e.g. posterior fossa tumors), and neurodevelopmental disorders (e.g. autism). We review available data regarding the relationship between the topography of cerebellar injury or abnormality and functional outcomes. We report emerging structure-function relationships with specific symptoms: cerebellar regions that interconnect with sensorimotor cortices are associated with motor impairments when damaged; disruption to posterolateral cerebellar regions that form circuits with association cortices impact long-term cognitive outcomes; and midline posterior vermal damage is associated with behavioral dysregulation and an autism-like phenotype. We also explore the impact of age and the potential role for critical periods on cerebellar structure and child function. These findings suggest that the cerebellum plays a critical role in motor, cognitive, and social-behavioral development, possibly via modulatory effects on the developing cerebral cortex.

Core deficits and quality of survival after childhood medulloblastoma: a review

Background

Medulloblastoma is the most common malignant central nervous system tumor in children. Treatment most often includes surgical resection, craniospinal irradiation, and adjuvant chemotherapy. Although survival has improved dramatically, the tumor and its treatments have devastating long-term side effects that negatively impact quality of survival (QoS). The objective was to review the literature on QoS following childhood medulloblastoma.

Methods

This narrative review is based on a Medline database search and examination of the reference lists of papers selected.

Results

Frequent problems after medulloblastoma treatment include medical complications, such as long-term neurological and sensory (hearing loss) impairments; endocrine deficits, including growth problems; and secondary tumors. Neurocognitive impairment is repeatedly reported, with decreasing cognitive performances over time. Although all cognitive domains may be affected, low processing speed, attention difficulties, and working memory difficulties are described as the core cognitive deficits resulting from both cerebellar damage and the negative effect of radiation on white matter development. Long-term psychosocial limitations include low academic achievement, unemployment, and poor community integration with social isolation. Important negative prognostic factors include young age at diagnosis, conventional craniospinal radiotherapy, presence of postoperative cerebellar mutism, and perioperative complications. The influence of environmental factors, such as family background and interventions, remains understudied.

Conclusion

Future studies should focus on the respective impact of radiation, cerebellar damage, genomic and molecular subgroup parameters, and environmental factors on cognitive and psychosocial outcomes. Long-term (probably lifelong) follow-up into adulthood is required in order to monitor development and implement timely, suitable, multi-disciplinary rehabilitation interventions and special education or support when necessary.

Behavior Rating Inventory of Executive Function Adult Version in Patients with Neurological and Neuropsychiatric Conditions: Symptom Levels and Relationship to Emotional Distress

OBJECTIVES

The present study explored the level of self-and informant reported executive functioning in daily living using the Behavior Rating Inventory of Executive Function-Adult Version (BRIEF-A) in a large sample comprising healthy adults and patient cohorts with neurological and neuropsychiatric disorders. The relationship to neuropsychological test performance and self-reported emotional distress was explored, as well as the applicability of U.S. normative data.

METHODS

Scores on the self- and informant reported BRIEF-A are presented, along with scores on standardized cognitive tests, and on rating scales of self-reported emotional distress in a Norwegian healthy comparison group (n=115), patients with severe traumatic brain injury (n=125), focal frontal lobe damage (n=29), focal cerebellar lesion (n=24), Parkinson's disease (n=42), attention deficit hyperactivity disorder (n=34), type II bipolar disorder (n=21), and borderline personality disorder (n=18).

RESULTS

Strong associations were observed between the BRIEF-A and emotional distress in both the healthy group and in neurological groups, while no or weak relationships with IQ and performance-based tests of executive function were seen. The relationship between BRIEF-A and emotional distress was weaker in the neuropsychiatric patient groups, despite high symptom load in both domains. Healthy participants tended to have BRIEF-A scores 1/2-3/4 SD below the U.S. normative mean of T score=50.

CONCLUSIONS

The study demonstrates the need to interpret BRIEF-A results within a broad differential diagnostic context, where measures of psychological distress are included in addition to neuropsychological tests. Uncertainty about the appropriateness of U.S. normative data in non-U.S. countries adds to the need for interpretive caution. (JINS, 2016, 22, 682-694).

Complementing the Latest APA Definition of Hypnosis: Sensory-Motor and Vascular Peculiarities Involved in Hypnotizability

The aim of this article is to complement the recently revised American Psychological Association (APA) definition of hypnotizability. It (a) lists a few differences in sensorimotor integration between subjects with high (highs) and low (lows) hypnotizability scores in the ordinary state of consciousness and in the absence of suggestions, (b) proposes that hypnotizability-related cerebellar peculiarities may account for them,