Psychologic and neurologic function following treatment for childhood temporal lobe astrocytoma

Dopamine receptor antagonism disrupts social preference in zebrafish: a strain comparison study

Zebrafish form shoals in nature and in the laboratory. The sight of conspecifics has been found reinforcing in zebrafish learning tasks. However, the mechanisms of shoaling, and those of its reinforcing properties, are not known. The dopaminergic system has been implicated in reward among other functions and it is also engaged by drugs of abuse as shown in a variety of vertebrates including zebrafish. The ontogenetic changes in dopamine levels and, to a lesser degree, in serotonin levels, have been found to accompany the maturation of shoaling in zebrafish. Thus, we hypothesized that the dopaminergic system may contribute to shoaling in zebrafish. To test this we employed a D1-receptor antagonist and quantified behavioral responses of our subjects using a social preference (shoaling) paradigm. We found significant reduction of social preference induced by the D1-R antagonist, SCH23390, in the AB strain of zebrafish, an alteration that was not accompanied by changes in motor function or vision. We also detected D1-R antagonist-induced changes in the level of dopamine, DOPAC, serotonin and 5HIAA, respectively, in the brain of AB zebrafish as quantified by HPLC with electrochemical detection. We found the antagonist-induced behavioral changes to be absent and the levels of these neurochemicals to be lower in another zebrafish population, SF, demonstrating naturally occurring genetic variability in these traits. We conclude that this variability may be utilized to unravel the mechanisms of social behavior in zebrafish, a line of research that may be extended to other vertebrates including our own species.

Late effects of therapy for pediatric brain tumor survivors

Approximately 2 of every 3 of all pediatric patients with brain tumors will be long-term survivors. However, there is a steep cost for pediatric brain tumor survivors, and the group as a whole faces significantly more late effects than many other survivors of pediatric cancers. Most of these effects can be attributed to direct neurologic damage to the developing brain caused by the tumor and its removal, the long-term toxicity of chemotherapy, or the effects of irradiation on the central nervous system. The late effects experienced by childhood brain tumor survivors involve multiple domains. This article will review the significant late effects that occur within the medical, neurocognitive, psychosocial, and economic domains of the survivorship experience. We conclude by discussing how the late effects in different domains often coexist and can create a complex set of obstacles that pose significant challenges for a survivor of a pediatric brain tumor on a daily basis.

Neonatal administration of a vaccine preservative, thimerosal, produces lasting impairment of nociception and apparent activation of opioid system in rats

Thimerosal (THIM), an organomercury preservative added to many child vaccines is a suspected factor in pathogenesis of neurodevelopmental disorders. We examined the pharmacokinetics of Hg in the brain, liver and kidneys after i.m. THIM injection in suckling rats and we tested THIM effect on nociception. THIM solutions were injected to Wistar and Lewis rats in a vaccination-like mode on PN days 7, 9, 11 and 15 in four equal doses. For Wistar rats these were: 12, 48, 240, 720, 1440, 2160, 3000 microg Hg/kg and for Lewis: 54, 216, 540 and 1080 microg Hg/kg. Pharmacokinetic analysis revealed that Hg from THIM injections accumulates in the rat brain in significant amounts and remains there longer than 30 days after the injection. At the 6th week of age animals were examined for pain sensitivity using the hot plate test. THIM treated rats of both strains and sexes manifested statistically significantly elevated pain threshold (latency for paw licking, jumping) on a hot plate (56 degrees C). Wistar rats were more sensitive to this effect than Lewis rats. Protracted THIM-induced hypoalgesia was reversed by naloxone (5 mg/kg, i.p.) injected before the hot plate test, indicative of involvement of endogenous opioids. This was confirmed by augmented catalepsy after morphine (2.5 mg/kg, s.c.) injection. Acute THIM injection to 6-week-old rats also produced hypoalgesia, but this effect was transient and was gone within 14 days. Present findings show that THIM administration to suckling or adult rats impairs sensitivity to pain, apparently due to activation the endogenous opioid system.

Cognitive Deficits and Predictors 3 Years After Diagnosis of a Pilocytic Astrocytoma in Childhood

Purpose

To prospectively study cognitive deficits and predictors 3 years after diagnosis in a large series of pediatric patients treated for pilocytic astrocytoma (PA).

Patients and Methods

Sixty-one of 67 children were grouped according to infratentorial, supratentorial midline, and supratentorial hemispheric site. Intelligence, memory, attention, language, visual-spatial, and executive functions were assessed. Included predictors were sex, age, relapse, diagnosis-assessment interval, hydrocephalus, kind of treatment, and tumor variables.

Results

All children with PA had problems with sustained attention and speed. In the infratentorial group, there also were deficits in verbal intelligence, visual-spatial memory, executive functioning, and naming. Verbal intelligence and verbal memory problems occurred in the brainstem tumor group. The supratentorial hemispheric tumor group had additional problems with selective attention and executive functioning, and the supratentorial midline tumor group displayed no extra impairments. More specifically, the dorsal supratentorial midline tumor group displayed problems with language and verbal memory. Predictors for lower cognitive functioning were hydrocephalus, radiotherapy, residual tumor size, and age; predictors for better functioning were chemotherapy or treatment of hydrocephalus. Almost 60% of children had problems with academic achievement, for which risk factors were relapse and younger age at diagnosis.

Conclusion

Despite normal intelligence at long-term follow-up, children treated for PA display invalidating cognitive impairments. Adequate treatment of hydrocephalus is important for a more favorable long-term cognitive outcome. Even children without initial severe deficits may develop cognitive impairments years after diagnosis, partly because of the phenomenon of growing into deficit, which has devastating implications for academic achievement and quality of life (QOL).

Brain structural abnormalities in survivors of pediatric posterior fossa brain tumors: a voxel-based morphometry study using free-form deformation

Voxel-based morphometry was used to compare brain structure of survivors of posterior fossa brain tumor (PFBT) with that of normal sibling controls to investigate disease- or cancer treatment-induced changes. Two different spatial normalization approaches that are available in public domain software (free-form deformation (FFD) and discrete cosine transform (DCT)) were compared for accuracy of normalization in the PFBT patients. Anatomical landmark matching demonstrated that spatial normalization was more accurate with FFD than with DCT. Voxel-based morphometry of the FFD-normalized magnetic resonance images from PFBT survivors and sibling controls detected reduced gray matter density in the thalamus and entorhinal cortex and reduced white matter density in the internal capsule, hypothalamus, corpus callosum, and cuneus of the occipital lobe in the PFBT survivors. Identification of these morphologic lesions may help localize the neural substrates of disease- or therapy-induced cognitive deficits in survivors of childhood cancer.

The sequelae of cranial irradiation on human cognition

Cranial irradiation (CI) confers remediation of many CNS anomalies. CI, however, carries risks to cognitive performance. A wealth of data describes such deficits specifically in humans. Risk factors that promote increased susceptibility to cognitive decline have also been identified. This paper discusses and grades these risk factors, including age, gender, and the inclusion of chemotherapy, that increase the likelihood of pathologic cognitive development in the human population.

BOLD responses to visual stimulation in survivors of childhood cancer

Children surviving certain cancers have a high incidence of cognitive deficits caused by central nervous system (CNS) disease or treatments directed at the CNS. To establish the feasibility of using blood oxygen level-dependent (BOLD) functional magnetic resonance imaging (fMRI) to study cognitive deficits in survivors of childhood cancer, we tested the hypothesis that this population has the same BOLD response to visual stimulation as healthy subjects. We used BOLD fMRI to measure spatial and temporal patterns of brain activity after brief visual stimulation in 16 survivors of childhood cancer, 11 age-similar healthy siblings of survivors, and 16 healthy adults. Functional data for the survivors were analyzed with two general linear models, one used a canonical hemodynamic response function (HRF) and the other used a Fourier set as basis functions. The measured BOLD signal and brain activation patterns were similar in the survivors with both models. The BOLD signal for survivors was qualitatively similar in timing and shape, but there were significant quantitative differences as compared with healthy subjects. The activation was normally located in the primary visual cortex in 13 survivors, but the activation volume was significantly smaller in brain tumor survivors than in other groups. These findings demonstrate the feasibility of using BOLD fMRI to investigate brain function in survivors of childhood cancer. However, fMRI studies in this population must take into account effects of quantitative differences in their BOLD responses as compared to healthy subjects.

Psychosocial and behavioral functioning among pediatric brain tumor survivors

OBJECTIVE

To describe the psychosocial and behavioral functioning, as described by patient, parent and teacher, of a cohort of adolescents who have been previously treated for a brain tumor.

METHODS

A cohort of 32 patients, 12-18 years old, were evaluated between 1 and 5 years post-treatment for brain tumor during the patient's regularly scheduled follow-up clinic appointment at the Dana-Farber Cancer Institute. The Self-Report questionnaire and the Parent-Report of the Behavioral Assessment System for Children (BASC) were administered to the patient and to one of the patient's parents, respectively. In addition, the BASC Teacher-Report was completed by the patient's teacher. Descriptive statistics were generated; binomial distribution analyses were carried out to assess whether the proportion of individuals with impaired performance on each measure exceeded normative expectations.

RESULTS

Comparison of the proportion of patients with elevated scores to normative expectations indicated no excess of elevated scores on any of the BASC scales of the Self-Report. However, parents endorsed items in the areas of attention problems and leadership; teachers endorsed items concerning learning problems; and both parents and teachers endorsed items indicative of somatization behaviors.

CONCLUSIONS

Parent and teacher feedback indicate some level of psychosocial and behavioral morbidity for adolescents treated for a brain tumor; this finding contrasts with adolescent Self-Report indicating no difficulties in behavioral and psychosocial functioning. The extent to which these vulnerabilities impact quality of life and the discrepancy between reporters should be assessed in follow-up studies with a larger cohort of patients.

Neuropsychological functioning after surgery in children treated for brain tumor

OBJECTIVE

To describe the neuropsychological functioning of children treated with surgery only for localized brain tumors in Dana-Farber Cancer Institute Protocol 92-077. Subsequent reports will describe the neuropsychological functioning of children treated with surgery and stereotactic radiation therapy on Dana-Farber Cancer Institute 92-077.

METHODS

The intellectual functioning of 106 patients was evaluated within 3 months after surgery. An in-depth assessment of the neuropsychological functioning, including an impairment index, was conducted for a subset of 77 school-age children (6-16 yr old) across six functional domains. Descriptive statistics were generated; binomial distribution analyses were performed to assess whether the proportion of individuals with impaired performance on each measure exceeded normative expectations. The impairment index assessed whether poor performance was attributable to a few children or reflected the performance of the cohort as a whole.

RESULTS

Although the Full Scale IQ was within normative expectations, the Verbal IQ was higher than the Performance IQ with 45% of individuals showing a significant discrepancy (P < 0.01) between these scales. There was an increased prevalence of poor performance for measures of motor output, verbal memory, and visuospatial organization. The distribution of the impairment index indicated moderate impairment across the school-age cohort rather than severe impairment in a few patients.

CONCLUSION

The results document a moderate level of neuropsychological morbidity among children with brain tumors before stereotactic radiation therapy, presumably referable to the tumor itself and the surgery. The extent to which stereotactic radiation therapy may increase this burden will be assessed in follow-up studies evaluating the longitudinal neuropsychological data.

Survivors of childhood brain tumors: behavioral, emotional, and social adjustment

This paper reviews the literature on the psychological adjustment and quality of life in children who survive brain tumors. A total of 31 studies were reviewed. Findings are discussed in terms of the rates of general psychological adjustment, internalizing behavior problems, externalizing behavior problems, social competence, correlates or predictors of adjustment, and quality of life among survivors. Although these survivors appear to be at risk for compromised social competence and long-term quality of life, reports in the literature on rates of psychological adjustment in this population vary widely. Limitations in the current literature are discussed including inadequate assessment techniques, lack of appropriate comparison groups, and small sample sizes. Directions for future research are offered.

Single and Dual Pathologies of the Temporal Lobe: Effects on Cognitive Function in Children with Epilepsy

The neuropathologies associated with temporal lobe epilepsy (TLE) are heterogeneous. The performance of 61 children with single pathology of hippocampal sclerosis (HS), temporal lobe tumor, or cortical dysplasia (CD) or dual pathology of HS + tumor or HS + CD was examined on measures of intelligence, language, memory, and executive function. Children with single pathologies performed significantly better than did children with HS + CD on all standardized measures of IQ. Children with tumors performed significantly better than children with dual pathology on receptive vocabulary. These results support prior research of an association between neuropathology and cognitive function in children with epilepsy and extend the findings to include additional neuropathologies and measures of cognitive functioning.

[Neuropsychological sequelae of children treated for brain tumors: evaluation and risk factors]

The analysis of neuropsychological sequelae in children with brain tumors is a major concern in the debate for the definition of the therapeutic strategies. The authors review the recent literature in this field in the light of their own experience at the Gustave-Roussy Institute. Three main risk factors emerge from the analysis: radiation, age and surgical complications. The need for a longitudinal evaluation in these patients is emphasized in order to plan the subsequent appropriate readaptation.

Correlation of medical and neurosurgical events with neuropsychological status in children at diagnosis of astrocytoma: utilization of a neurological severity score

Neuropsychological studies of children who have brain tumors have yielded diverse results with respect to identifying factors that contribute to poor intellectual outcome. The purpose of this study was to evaluate the relationship between pre- and perioperative events, tumor-related factors, and the neuropsychological status of children diagnosed with astrocytoma. Events that could potentially be detrimental to neuropsychological outcome were quantified utilizing a new "neurological severity score." The Neurological Severity Score was developed as a research tool to test our hypothesis that ultimate intellectual outcome is a result of cumulative, interactive insults on the central nervous system. This study constitutes a first step in examining the predictive value of the Neurological Severity Score by evaluating its correlation with baseline neuropsychological status. Fifty-nine children who had astrocytoma (36 supratentorial and 23 infratentorial) received complete neurological and neuropsychological evaluations within 3 months of diagnosis. Each child's neurological history and examination results were scored by an independent observer using the Neurological Severity Score. Neuroimages obtained at diagnosis and at the time of neuropsychological testing were evaluated as well. For the group as a whole, memory, attention, and motor abilities were significantly below age-appropriate norms, whereas intelligence, language, and academic skills were preserved. Patterns of deficits were identified and related to tumor site. There were no significant differences in mean neuropsychological domain scores between groups based on gender, pre-versus post-operative status, ethnicity, tumor grade, or abnormalities on magnetic resonance imaging (MRI). The Neurological Severity Score was significantly inversely correlated with visual-spatial skills, memory, attention, performance IQ, and global IQ. In conclusion, among all the medical and neurological factors present at diagnosis, the neurological severity score had the highest correlation with neuropsychological scores. This instrument has promise as a research tool in investigations of the psychological effects of cancer and its treatment on children.

Radiotherapy in the treatment of low-grade astrocytomas. II. The physical and cognitive sequelae

The purpose of the present study was to define the late effects, both physical and psychological, of treating low-grade astrocytomas with radiotherapy. Fifty patients, half of whom received radiotherapy, underwent an assessment of neurological and neuropsychological function. There was no difference in neurological function between the two groups. The radiotherapy recipients, including those with cerebellar tumours, performed significantly worse on measures of intelligence and information processing. In addition, there was a greater incidence of special education needs in the irradiated group. We conclude that children with low-grade astrocytomas who receive radiotherapy have no greater neurological deficit but that the use of radiotherapy carries a penalty in terms of long-term cognitive function and confirmed the findings of many previous reports that supratentorial irradiation is detrimental. More surprisingly, it has been demonstrated that local field irradiation to the posterior fossa can also produce significant cognitive impairment.

Follow-up and quality of survival of 67 consecutive children with CNS tumors

We report the findings at follow-up in 67 consecutive children with central nervous system tumors treated over a 5-year-period at a single institution. The diagnoses were supratentorial astrocytoma (n = 12), cerebellar astrocytoma (n = 10), ependymoma (n = 9), medulloblastoma (n = 9), brain stem glioma (n = 6), optic pathway glioma (n = 5), and others (n = 16). The survival rates were 83% for supratentorial astrocytomas at a median of 46.5 months, 90% for cerebellar astrocytomas and 55% for ependymomas at 40 months, respectively, 55% for medulloblastomas at 22 months, 33% for brain stem gliomas at 23 months, and 80% for optic pathway gliomas at 49 months. With regard to neurological sequelae, 13 patients were treated for epilepsy, 13 patients had mild to moderate neurological deficits, and 4 patients were severely disabled. Seventeen of 37 tested patients performed below average on formal neuropsychometric testing, one-fourth attended special education courses, and at least one-fourth suffered from behavioral and adjustment problems.

Long-term neurobehavioral outcome in pediatric brain-tumor patients: review and methodological critique

This paper provides an overview of pediatric brain tumors and reviews the literature on long-term neurobehavioral outcomes for these children. Progress in this area has been slow due to numerous methodological and practical complications. While some general conclusions can be drawn, the development of comprehensive models awaits more research into the multiplicity of biological and nonbiological events, and their interactions, potentially affecting outcome. Increased theoretical and methodological sophistication will be needed to address this complex classification of diseases. Barriers to research in this area are enumerated as are suggestions for future efforts.

Cognitive functioning in long-term survivors of high-grade glioma

In a pilot study, two groups of patients with malignant glioma underwent sequential neuropsychological evaluations after successful tumor treatment. Group 1 included nine patients treated from 1981 to 1985; all patients received irradiation and eight underwent chemotherapy. The baseline neuropsychological assessment was performed 1 to 63 months after tumor diagnosis, with follow-up evaluations at irregular intervals over the next 3 to 7 years. Six patients in Group 1 exhibited impairment on most measures at baseline; subsequently, two patients developed profound cognitive impairment. Initially, three patients functioned in the average range on most tasks; thereafter, two deteriorated on one measure each. Group 2 was ascertained prospectively and included 16 patients treated from 1985 to 1987, all of whom received irradiation and chemotherapy. The first evaluation was performed 18 months after diagnosis, then every 6 months for 2 years, and then yearly. Compared to a control group, those in Group 2 had significant cognitive impairment at baseline. Cognitive performance did not change over the next 12 months in 10 patients who remained free of tumor, but within 2 years of baseline testing, deterioration on specific tasks was evident in two of seven disease-free survivors. When last tested, five of six disease-free survivors had deteriorated on one or more measures. Unlike Group 1, severe global cognitive impairment was not seen, perhaps because Group 2 was followed for a shorter time. Verbal and nonverbal composite scores derived from intelligence quotient (IQ) tests showed less impairment at baseline than did other measures and were more likely to remain stable subsequently. Verbal memory and sustained attention were the most impaired at baseline, and verbal learning and flexibility in thinking showed the greatest tendency to decline over time. Cognitive functioning in survivors of high-grade glioma is best measured and monitored by tests that probe a broader spectrum of abilities than IQ. Neuropsychological measures used in this analysis lacked sensitivity at the lower end of the impaired range. Future studies should use tests better able to discern cognitive differences at low performance levels. Based on this experience, the authors conclude that most long-term survivors of high-grade glioma will have significant cognitive difficulties, usually evident by the first assessment; some patients will develop profound impairment years later, and few are capable of fully independent living.

Neuropsychological status of children treated for brain tumors: a critical review and integrative analysis

The literature on the neuropsychological status of children with primary brain tumors was reviewed to identify English-language publications reporting the results of standardized, quantitative measures of patient function. The 22 studies that met these review criteria, representing 544 patients, were evaluated to assess the relationship between traditional risk factors (age at diagnosis, tumor location, radiation therapy, and time since completion of treatment), as well as subsequent intellectual development, academic achievement, psychosocial adjustment, and neuropsychological status. The impact of other potentially salient factors, such as seizures and sensory and motor deficits, was evaluated when possible. Despite inconsistent reporting of demographic and treatment-related effects across studies which precluded formal meta-analysis, we were able to confirm the primary importance of radiation therapy volume and age at treatment on IQ. No effects were detected for tumor location. Younger children treated with cranial (whole brain) irradiation showed a 14-point deficit in IQ as compared with their older counterparts. No significant differences were noted between older children receiving local or cranial irradiation, although both groups had IQ levels 12-14 points lower than those not irradiated. The high-risk groups identified in this study require increased clinical surveillance. Definitive evaluation of potential risk factors for neuropsychological impairment will depend on more complete reporting of relevant patient characteristics and interinstitutional studies.

Cognitive deficits in long-term survivors of childhood brain tumors

Improvements in survival for patients who had childhood brain tumors has led to an increasing emphasis on the quality of life for these long-term survivors. Initial survival studies relied on global descriptions of functional abilities to assess cognitive deficits and reported that from 20% to 40% of long-term survivors had obvious partial disability and less than 10% were severely disabled. Formal neuropsychological testing has revealed that from 40% to 100% of long-term survivors have some form of cognitive deficit in various intelligence quotients, visual/perceptual skills, learning abilities, and adaptive behavior. Prospective, controlled studies have found a younger age at diagnosis, radiotherapy, methotrexate chemotherapy, tumor location and time interval to testing to be important (alone or in combination) and related to a high risk of subsequent cognitive deficits. Some variables play an as yet unresolved role. However, despite the progress of the last decade, future prospective studies are needed to define the role of certain variables in the development of cognitive deficits that maximize survival while minimizing cognitive deficits.

Frontal lobe seizures in autism

The set of features that constitute 'autism' has been traced to numerous etiologies. Certain autistic features have been localized to dysfunction in certain neural areas, most notably frontal and temporal regions. The author hypothesizes that many of the symptoms characteristic of autism fit the clinical picture of frontal lobe seizures. Facial, vocal, and other body movements in autism are catalogued in parallel with facial, vocal and body movements that occur during frontal lobe seizures. The variety of etiologies that cause frontal lobe seizures also accounts for the variety of etiologies traced to autism.