A longitudinal magnetic resonance imaging study of the brain in survivors of childhood acute lymphoblastic leukemia

The Psychoneuroimmunology of Stress Regulation in Pediatric Cancer Patients

Stress is a ubiquitous experience that can be adaptive or maladaptive. Physiological stress regulation, or allostasis, can be disrupted at any point along the regulatory pathway resulting in adverse effects for the individual. Children with cancer exhibit significant changes to these pathways in line with stress dysregulation and long-term effects similar to those observed in other early-life stress populations, which are thought to be, in part, a result of cytotoxic cancer treatments. Children with cancer may have disruption to several steps in the stress-regulatory pathway including cognitive-affective function, neurological disruption to stress regulatory brain regions, altered adrenal and endocrine function, and disrupted tissue integrity, as well as lower engagement in positive coping behaviours such as physical activity and pro-social habits. To date, there has been minimal study of stress reactivity patterns in childhood illness populations. Nor has the role of stress regulation in long-term health and function been elucidated. We conclude that consideration of stress regulation in childhood cancer may be crucial in understanding and treating the disease.

Brain Microstructural Changes Associated With Neurocognitive Outcome in Intracranial Germ Cell Tumor Survivors

Background

Childhood intracranial germ cell tumor (GCT) survivors are prone to radiotherapy-related neurotoxicity, which can lead to neurocognitive dysfunctions. Diffusion kurtosis imaging (DKI) is a diffusion MRI technique that is sensitive to brain microstructural changes. This study aimed to investigate the association between DKI metrics versus cognitive and functional outcomes of childhood intracranial GCT survivors.

Methods

DKI was performed on childhood intracranial GCT survivors (n = 20) who had received cranial radiotherapy, and age and gender-matched healthy control subjects (n = 14). Neurocognitive assessment was performed using the Hong Kong Wechsler Intelligence Scales, and functional assessment was performed using the Lansky/Karnofsky performance scales (KPS). Survivors and healthy controls were compared using mixed effects model. Multiple regression analyses were performed to determine the effects of microstructural brain changes of the whole brain as well as the association between IQ and Karnofsky scores and the thereof.

Results

The mean Intelligence Quotient (IQ) of GCT survivors was 91.7 (95% CI 84.5 – 98.8), which was below the age-specific normative expected mean IQ (P = 0.013). The mean KPS score of GCT survivors was 85.5, which was significantly lower than that of controls (P < 0.001). Cognitive impairments were significantly associated with the presence of microstructural changes in white and grey matter, whereas functional impairments were mostly associated with microstructural changes in white matter. There were significant correlations between IQ versus the mean diffusivity (MD) and mean kurtosis (MK) of specific white matter regions. The IQ scores were negatively correlated with the MD of extensive grey matter regions.

Conclusion

Our study identified vulnerable brain regions whose microstructural changes in white and grey matter were significantly associated with impaired cognitive and physical functioning in survivors of pediatric intracranial GCT.

Anatomical brain MRI study of pediatric cancer survivors treated with chemotherapy: Correlation with behavioral measures

The negative impacts of chemotherapy on pediatric patients treated with chemotherapy during the formative years of brain development are understudied compared to adult chemotherapy cancer patients. This work investigated the morphometry, cortical thickness, and subcortical volumes using MRI and their correlations with behavioral measures in pediatric oncology survivors treated with chemotherapy. Chemotherapy-treated childhood cancer survivors (N = 15, 15.12 ± 5.98 years old) diagnosed with a non-central nervous system malignancy and healthy age-matched controls (N = 15, 15.13 ± 4.21 years old) were studied. MRI was acquired at 3 Tesla. Behavioral Rating Inventory of Executive Functioning (BRIEF) Parental Rating, Purdue Pegboard manual dexterity and n-back working memory measures were administered. Structural MRI scans at 3 Tesla were acquired. Voxel-based morphometry, cortical thickness and subcortical volumes were analyzed and correlated with behavioral scores. Parametric statistics with a p < .05 and adjusted for multiple comparison corrections were performed. Patients exhibited significantly smaller gray-matter volumes in the left globus pallidum, bilateral thalami, left caudate and left nucleus accumbens (p < .05) and thinner cortex in the right parahippocampal gyrus (p < .05) compared to controls. BRIEF scores were similar to normative values. Purdue Pegboard revealed manual dexterity deficits compared to normative values, and the n-back task showed working-memory deficits in patients compared to controls. Left thalamus volume positively correlated with dexterity performance (p = .029). The number of correct answers positively correlated and the number of incorrect answers negatively correlated with total-brain and white-matter volume (p < .05), but not gray-matter volume (p > .05). Our results support the hypothesis that the neurotoxicity of systemic chemotherapy has widespread negative effects on brain development in pediatric oncology patients with relatively mild cognitive deficits. MRI identified neuroanatomical changes have the potential to provide neural correlates of the sequelae associated with pediatric chemotherapy.

Brain morphology and information processing at the completion of chemotherapy-only treatment for pediatric acute lymphoblastic leukemia

Background: Approximately 50% of survivors of childhood acute lymphoblastic leukemia (ALL) demonstrate cognitive impairments. However, the trajectory of change and contributing neuropathology is unclear, limiting our ability to tailor intervention content and timing. This study aimed to explore information processing abilities and brain morphology early post-treatment for pediatric ALL. Procedure: Twenty-one children at the end of ALL treatment and 18 controls underwent neuropsychological assessment. A subset also completed structural magnetic resonance imaging. Results: A principal component analysis generated two cognitive factors: information processing capacity and information processing speed. Compared to control group, the ALL group displayed deficits in capacity, but not speed. No group differences were identified in morphology. No relationship was identified between capacity or speed and morphology. Conclusion: Early cognitive intervention should target information processing abilities using a system-wide approach. Future studies should employ alternative imaging techniques sensitive to white-matter microstructure when exploring pathology underlying information processing deficits.

Neurodevelopmental consequences of pediatric cancer and its treatment: applying an early adversity framework to understanding cognitive, behavioral, and emotional outcomes

Today, children are surviving pediatric cancer at unprecedented rates, making it one of modern medicine's true success stories. However, we are increasingly becoming aware of several deleterious effects of cancer and the subsequent "cure" that extend beyond physical sequelae. Indeed, survivors of childhood cancer commonly report cognitive, emotional, and psychological difficulties, including attentional difficulties, anxiety, and posttraumatic stress symptoms (PTSS). Cognitive late- and long-term effects have been largely attributed to neurotoxic effects of cancer treatments (e.g., chemotherapy, cranial irradiation, surgery) on brain development. The role of childhood adversity in pediatric cancer - namely, the presence of a life-threatening disease and endurance of invasive medical procedures - has been largely ignored in the existing neuroscientific literature, despite compelling research by our group and others showing that exposure to more commonly studied adverse childhood experiences (i.e., domestic and community violence, physical, sexual, and emotional abuse) strongly imprints on neural development. While these adverse childhood experiences are different in many ways from the experience of childhood cancer (e.g., context, nature, source), they do share a common element of exposure to threat (i.e., threat to life or physical integrity). Therefore, we argue that the double hit of early threat and cancer treatments likely alters neural development, and ultimately, cognitive, behavioral, and emotional outcomes. In this paper, we (1) review the existing neuroimaging research on child, adolescent, and adult survivors of childhood cancer, (2) summarize gaps in our current understanding, (3) propose a novel neurobiological framework that characterizes childhood cancer as a type of childhood adversity, particularly a form of early threat, focusing on development of the hippocampus and the salience and emotion network (SEN), and (4) outline future directions for research.

Evaluation of Pre-Hematopoietic Cell Transplantation (HCT) Brain MRI and Neurologic Complications of Pediatric Patients Undergoing HCT for Hematologic Malignancies

Adverse neurologic complications (NC) occur commonly in pediatric patients with hematologic malignancies both pre- and post-allogeneic hematopoietic cell transplant (HCT). Given this known risk, we previously obtained pre-HCT brain magnetic resonance imaging (MRI) to document baseline abnormalities but utility of this and findings are not well described. This study aimed to ( a) determine the prevalence and risk factors for abnormal brain MRI and ( b) determine prevalence and risk factors for development of new NC during and 2 years post-HCT. Retrospective chart review included 102 patients with hematologic malignancies who underwent allogeneic HCT between 2000 and 2009 at University of California San Francisco (UCSF) Children's Hospital and included standard HCT data, brain MRI reports, and NC and symptoms pre- and post-HCT. Forty-three percent of patients had abnormal findings on pre-MRI, most commonly nonspecific white matter changes. Neurologic symptoms pre-HCT was the only significant risk factor for abnormal MRI. Eleven patients (11%) developed post-HCT NC. Non-Caucasian race was the only significant risk factor for new NC. Although abnormal pre-HCT brain MRI is common, these findings are not predictive of subsequent NC post-HCT. Therefore routine surveillance may not be informative for that purpose, particularly when general anesthesia is required, which can have detrimental neurocognitive effects. Etiology of NC in pediatric HCT is likely multifactorial and may include genetic and ethnic predispositions.

Reduced neuroanatomic volumes in long-term survivors of childhood acute lymphoblastic leukemia

PURPOSE

To compare regional brain volumes in adult long-term survivors of childhood acute lymphoblastic leukemia (ALL) and healthy controls.

PATIENTS AND METHODS

We investigated 130 survivors of childhood ALL diagnosed between 1970 and 2002 with magnetic resonance imaging (MRI) and neuropsychological testing at a median of 22.5 years after diagnosis. Morphometric analyses including whole-brain segmentation were performed using a validated automated procedure; 130 healthy adults served as controls.

RESULTS

Compared with healthy controls, ALL survivors showed significantly smaller volumes of cortical gray matter, cerebral white matter, amygdala, caudate, hippocampus, thalamus, and estimated intracranial volume. Effect sizes ranged from small to medium. The strongest effect was found for the caudate, which on average was 5.2% smaller in ALL survivors. Caudate volumes were also smaller when controlling for intracranial volume, suggesting a specific effect. Neither age at diagnosis nor treatment variables such as radiation therapy or drug dose had a major impact on neuroanatomic volumes. Neuropsychological assessment revealed reduced processing speed, executive function, and verbal learning/memory in survivors compared with controls but no difference in estimated general intellectual ability. In ALL survivors, but not in controls, neuropsychological test results correlated with volumes of cortical gray matter, caudate, and thalamus as well as intracranial volume.

CONCLUSION

Structural MRI of long-term survivors of childhood ALL demonstrated smaller volumes of multiple brain structures compared with healthy controls. Because of possible selection biases, these results must be interpreted with caution. Future studies are required to clarify the significance of these findings and the neurobiologic mechanisms involved.

Long-term neurocognitive outcomes in young adult survivors of childhood acute lymphoblastic leukemia

Five-year survival rates of childhood acute lymphoblastic leukemia (ALL) exceed 80% due to central nervous system-directed treatment including cranial radiation (CRT) and chemotherapy. However, these treatments are associated with neurocognitive compromise, the extent of which is correlated with higher dose and younger age at treatment. The aims of this study were to explore long-term neurocognitive outcomes in adult survivors of childhood ALL, and to identify measures sensitive to neurotoxicity in long-term survivors. We examined 24 adults who received 18 Gy CRT and chemotherapy for treatment of ALL between ages 2 and 15 years (median, 5.5). Time since diagnosis ranged from 6 to 26 years (median, 16.6). Younger age at diagnosis and longer time since diagnosis were associated with lower scores on a computerized battery that requires speed and accuracy across a number of domains (MicroCog), and other standardized neurocognitive tests. When compared with population norms, MicroCog indices were below average in survivors diagnosed with ALL before age 5, but only the reasoning/calculation index was below average in survivors diagnosed with ALL after age 5. In contrast, intelligence quotient (IQ) scores were average. In addition to confirming earlier studies showing that younger children are more vulnerable to treatment-related neurotoxicity, here we show that deficits exist many years post treatment even with a relatively lower dose of CRT, and that these deficits are especially evident on tasks involving rapid processing of information.

Somatosensory evoked potential for detection of subclinical neuropathy in Egyptian children with acute lymphoblastic leukaemia

To evaluate neurological changes developing during paediatric Acute Lymphoblastic Leukaemia (ALL) therapy clinically and through electrophysiological Study of Somatosensory Evoked Potentials (SSEPs) changes in different phases of therapy. Thirty five-ALL patients with age range from 3-14 years were included compared to 30 healthy controls. History, neurological examination, complete blood counts, cytological examination of bone marrow aspirate and cerebrospinal fluid with Measurement of Serum Methotrexate (MTX) were done. The SSEPs were performed and patients subjected to another SSEP with measurement of serum MTX level before and 10 days after intra-thecal injection (IMTX). Clinical neurological findings in patients after induction were depressed deep tendon reflexes (43.3%), hypotonia (28.6%), lost pain sensation (28.6%), muscle weakness (17.1%) and movement disorders (17.1%). Percentage of delayed SSEPs after induction were at levels of brachial plexus (28.6%), spinal cord (68.6%), cortical conduction (31.4%), ERB-N13 Inter Peak Latency (IPL) (74.3%) and N13-N20 IPL (17.1%) in the studied patients. Significant prolonged latency of N13 (p = 0.005), N20 (p = 0.04) and IPL of ERB-N 13 (p = 0.005), N13-N20 (p = 0.01), Inter-Side Difference (ISD) of N13 (p = 0.01), ERB-N13 (p = 0.02) and N13-N20 (p = 0.03) after induction compared to values at diagnosis. Significant positive correlation were found between serum MTX after IMTX with N13-N20 IPL (p = 0.01), N20 ISD (p = 0.03) with significant prolongation in N20 latency, N13-N20 IPL and ISD of N20 compared to values before injection. ALL patients have prolonged latency of SSEPs at cervical cord and cortical levels which increased after IMTX due to axonal injury throughout the cord. SSEPs could be an early diagnostic tool for subclinical neuropathy.

Voxel-based analysis of T2 hyperintensities in white matter during treatment of childhood leukemia

BACKGROUND AND PURPOSE

White matter (WM) hyperintensities on T2-weighted MR imaging are the most common imaging manifestation of neurotoxic effects of therapy for central nervous system (CNS) prophylaxis in childhood acute lymphoblastic leukemia (ALL). This study uses voxel-based analyses (VBA) of T2-weighted imaging of patients during treatment to identify which WM regions are preferentially damaged.

MATERIALS AND METHODS

Two sets of conventional T2-weighted axial images were acquired on a 1.5T MR imaging scanner from 197 consecutive patients (85 female, 112 male; aged 1.0-18.9 years) enrolled on an institutional ALL treatment protocol. Images were acquired after completion of induction therapy and after the final of the 4 courses of intravenous high-dose methotrexate in consolidation therapy (3.9 +/- 0.8 months apart). Voxel-wise statistical testing of the incremental change between normalized longitudinal T2 images was performed with radiologist reading (normal or abnormal) and treatment risk-group as covariates.

RESULTS

Two highly significant bilateral clusters of T2 signal intensity change were identified in both 1-group and 2-group analyses. The regions were symmetric in size, shape, and average signal intensity. Increased T2-weighted signal intensity from these regions both within and between examinations were nonlinear functions of age at examination, and the difference between the examinations was greater for older subjects who received more intense therapy.

CONCLUSIONS

These analyses identified specific WM tracts involving predominantly the anterior, superior, and posterior corona radiata and superior longitudinal fasciculus, which were at increased risk for the development of T2-weighted hyperintensities during therapy for childhood ALL. These vulnerable regions may be the cause of subsequent cognitive difficulties consistently observed in survivors.

Neurodevelopmental sequelae of pediatric acute lymphoblastic leukemia and its treatment

This review will describe the neurocognitive outcomes associated with pediatric acute lymphoblastic leukemia (ALL) and its treatment. The literature is reviewed with the aim of addressing methodological issues, treatment factors, risks and moderators, special populations, relationship to neuroimaging findings, and directions for future research. It is concluded that neurocognitive outcomes for the majority of children with standard-risk ALL treated according to current chemotherapy protocols is relatively good, but subgroups of children are more significantly compromised. As medical treatments advance and survival rates continue to improve, neurocognitive outcomes and other quality of life indicators will become increasingly important. Preventing or ameliorating treatment-related neuropsychological sequelae represents the next major challenge in pediatric ALL.

Cognitive outcome in children and adolescents treated for acute lymphoblastic leukaemia with chemotherapy only

Objective: To examine cognitive outcome in children and adolescents with acute lymphoblastic leukaemia (ALL) in remission, treated with central nervous system prophylactic chemotherapy only.

Method: Thirty-five children and adolescents, age 8.4–15.3 years in long-term remission from ALL, 4.2–12.4 years post diagnosis, without relapse and no prediagnosis history of neurodevelopmental disorder were compared with 35 healthy controls matched for gender and age, on measures of intellectual functioning Wechsler Intelligence Scale for Children-Third Edition (WISC-III).

Results: All but two of the ALL survivors treated by chemotherapy only obtained WISC-III Total Intelligence Quotient (IQ) scores in the normal range (M = 95.3), but their scores were significantly below levels for their matched controls and below normative standards for WISC-III. The difference between patients and controls was significant at the p < 0.001 level for the following measures: Total IQ, Verbal IQ, Verbal Comprehension Index, Freedom from Distraction Index and three verbal subtest scores.

Conclusion: The results indicate long-term sequelae in global cognitive functions, and indicate that verbal function, processing speed, attention and complex visual-spatial problem solving may be affected in the chemotherapy only group.

Reduced frontal white matter volume in long-term childhood leukemia survivors: a voxel-based morphometry study

BACKGROUND AND PURPOSE

To our knowledge, no published studies have examined whole-brain regional differences to identify more discrete volumetric changes in the brains of childhood leukemia survivors. We used voxel-based morphometry (VBM) to examine regional gray and white matter differences in a group of long-term survivors of acute lymphoblastic leukemia (ALL) compared with a group of healthy controls. Differences in regional white matter volume were expected, given previous reports of white matter changes during treatment for ALL and reduced brain white matter volumes in long-term survivors. Follow-up analyses examined the relationship of regional brain volumes to cognitive function.

MATERIALS AND METHODS

We compared 9 long-term survivors of ALL with 14 healthy controls. Survivors of ALL were treated with systemic and intrathecal chemotherapy only. T1-weighted axial 3D spoiled gradient high-resolution images collected on a 1.5T MR imaging scanner were used for the VBM analysis. Neuropsychological evaluations were conducted within 2 months of the MR imaging to assess cognitive function.

RESULTS

VBM analysis revealed 2 specific regions of reduced white matter in the right frontal lobes of survivors of ALL compared with healthy controls. Survivors of ALL had lower performances on tests of attention, visual-constructional skills, mental flexibility, and math achievement compared with healthy individuals. Decreased performance on neuropsychological measures was associated with decreased regional white matter volumes. No differences were found between the groups with respect to gray matter regions.

CONCLUSION

These findings are consistent with previous literature describing the long-term cognitive, academic, and imaging findings of survivors of ALL and suggest that right frontal white matter is particularly vulnerable to disruption following intensive chemotherapy for ALL. Future studies should focus on further clarifying the white matter changes observed.

Late magnetic resonance imaging features of leukoencephalopathy in children with central nervous system tumours following high-dose methotrexate and neuraxis radiation therapy

High-dose methotrexate (HDMTX) is used increasingly to treat children with central nervous system (CNS) tumours. Although the neuro-imaging features of leukoencephalopathy associated with systemic or intrathecal methotrexate administered after cranial radiation have been well described, the extent to which the sequencing of HDMTX prior to cranial radiation in infants and children predisposes to late neuroradiological features of leukoencephalopathy is unknown. This report describes the National Cancer Institute (NCI) toxicity grade of leukoencephalopathy based on magnetic resonance imaging (MRI) findings in all patients who survived 4 or more years after treatment on an earlier phase II study. These patients, with newly diagnosed CNS embryonal tumours, were in the age range 3.5-14.2 years (median 6.9 years) at diagnosis, and received four courses of pre-irradiation combination chemotherapy, including HDMTX 8 g/m(2). Following completion of the 'up-front' phase II study, all patients received conventionally fractionated whole brain doses of 36-50.4 Gy. The radiation dose and treatment volumes were determined individually according to the primary tumour location and results of extent of disease evaluations. The most recent MRI brain scans, obtained 4.0-10.5 years (median 6.5 years) after radiation therapy and comprising a minimum of T1, T1 following gadolinium and T2 sequences, were reviewed centrally to assess the neuroradiological grade of leukoencephalopathy, based on the NCI Common Terminology Criteria for Adverse Events, v3.0. Grade I changes (mild increase in subarachnoid space, and/or mild ventriculomegaly, and/or small/focal T2 hyperintensities) were evident in 8 of the 12 patients and grade II changes (moderate increase in subarachnoid space and/or moderate ventriculomegaly, and/or focal T2 hyperintensities extending to the centrum ovale) were found in the remaining 4. In conclusion, treatment with multiple courses of HDMTX prior to 36-50.4 Gy cranial radiation did not result in moderate to severe MRI features of leukoencephalopathy. Future studies in paediatric neuro-oncology patients, involving HDMTX combined with prospective neuropsychological evaluations appear justified.

Cognitive changes in children treated for acute lymphoblastic leukemia with chemotherapy only according to the Pediatric Oncology Group 9605 protocol

The purpose of this study was to examine cognitive functioning and neuroimaging in children with leukemia treated with the Pediatric Oncology Group 9605 protocol at the Children's Hospital of Eastern Ontario. Mean age at diagnosis was 4.88 +/- 2.54 years. The mean (n = 24) Wechsler Verbal and Performance IQ fell in the low-average range (87.33 +/- 15.69 and 84.83 +/- 19.11, respectively). Mean (n = 20) Verbal and Visual Memory Indexes of 82.95 +/- 15.46 and 88.30+/- 10.80, respectively, were obtained. The proportion of scores on measures of intelligence and memory falling > 1 SD below the normative mean was substantially higher than expected. Paired t-test suggested that Wechsler Verbal IQ and memory remained stable, whereas Wechsler Performance IQ declined significantly. The results of growth curve analyses replicated these findings and suggested a significant adverse effect of cumulative dosage of intrathecal methotrexate on estimated Wechsler Performance IQ. Although only two children experienced seizures, 78% of the group showed leukoencephalopathy on at least one magnetic resonance image. Reliance on seizures as a predictor of leukoencephalopathy might underestimate the incidence of neurotoxicity.

Central nervous system imaging in childhood leukaemia

The aim of this study was to document the imaging abnormalities seen in the central nervous system (CNS) in cases of childhood leukaemia or as complications of its treatment. Magnetic Resonance (MR) images and Computed Tomographic (CT) scans were reviewed retrospectively in 22 children and adolescents with neurological manifestations/complications of leukaemia or its treatment. Among the 22 patients, nine had two or more different CNS abnormalities. The imaging abnormalities seen in 15 patients before or during treatment included sinus thrombosis, cortical vein thrombosis, cerebral haemorrhage, meningeal leukaemia, infections, skull leukaemic infiltration and treatment-related neurotoxicity. After therapy, seven patients had CNS abnormalities, including secondary brain tumours, skull tumour, mineralising microangiopathy, leucoencephalopathy, transient white matter abnormalities, spinal intradural haematoma, chronic subdural haematoma, radiation necrosis, meningeal leukaemia and leukaemic infiltration at the vertebral body. CNS complications are related to the inherent risk of leukaemia itself, to the treatment method and to the duration of survival.

MRI morphometric and neuropsychological correlates of long-term memory in survivors of childhood leukemia

BACKGROUND

Long-term survivors of acute lymphoblastic leukemia (ALL) are reported to have post-treatment neurological changes as well as neuropsychological changes. Few studies have investigated the relationship between magnetic resonance imaging (MRI) volumetric measurements of brain regions of interest and cognitive functioning. This study examined the relationship between hippocampal volumes and long-term memory abilities in survivors of ALL.

PROCEDURE

Ten survivors of ALL and ten matched controls underwent MRI acquisition. The participants completed a battery of tests measuring both visual and verbal long-term memory. Volumetric measurements of the hippocampus were obtained by consecutive manual tracing using the NIH Image 1.52 program. Estimates of whole brain volume were also obtained.

RESULTS

No significant group differences were found in right or left hippocampi. Nor were there significant differences between the two groups on measures of long-term memory. Correlations between volumetric measurements of the hippocampus and measures of long-term memory were non-significant.

CONCLUSIONS

Our hypothesis of deficits in both long-term memory and its neural substrates was not supported. It was concluded that the hippocampus, as an early developing structure, may be less vulnerable to chemotherapy treatment. Children surviving ALL are able to retain and retrieve once learned information comparable with peers.

White Matter and Cerebral Metabolite Changes in Children Undergoing Treatment for Acute Lymphoblastic Leukemia: Longitudinal Study with MR Imaging and1H MR Spectroscopy

PURPOSE

To assess the development of white matter and cerebral metabolite changes during and after treatment in children with acute lymphoblastic leukemia.

MATERIALS AND METHODS

Twenty-three children (10 boys, mean age of 6.3 years; 13 girls, mean age of 6.6 years) with acute lymphoblastic leukemia were examined prospectively with magnetic resonance (MR) imaging and MR spectroscopy at 0, 8, and 20 weeks and 1, 2, and 3 years after diagnosis. White matter changes were diagnosed on the basis of hyperintense abnormalities on T2-weighted MR images. Single-voxel hydrogen 1 MR spectroscopy results from the right frontoparietal region of 21 children who received intravenous high-dose methotrexate were analyzed for cerebral metabolite changes. Multilevel models were used to assess the change in metabolites from baseline levels at subsequent follow-up.

RESULTS

At 20 weeks, MR spectroscopy showed a significant reduction (P <.05) of mean N-acetylaspartate to choline ratio and increase in mean choline to creatine ratio (P <.05) in the children given high-dose methotrexate. This decline in N-acetylaspartate to choline ratio subsequently reversed and increased, possibly because of normal age-related brain maturation. Seventeen of 21 (81%) children showed metabolite changes at MR spectroscopy, while five of 22 (23%) showed white matter changes at MR imaging at 20 weeks. One more child developed white matter changes at 32 weeks. The associated changes resolved or reduced with time.

CONCLUSION

MR spectroscopy demonstrated metabolite changes in the brain after high-dose methotrexate treatment in the absence of structural white matter abnormalities at MR imaging. MR spectroscopy might thus be a more sensitive method of monitoring the effects of high-dose methotrexate in the brain.

Seizures in children with systemic cancer

Children with cancer are a population with specific risk factors for the development of seizures. They present distinct problems in assessment and management that sets them apart from the usual pediatric patients. We reviewed the information gathered on our pediatric neurooncology database regarding 47 children with systemic cancer complicated by seizures. Leukemia was the most frequent underlying cancer (47%). In children with hematologic cancers, toxic-metabolic disturbances were the most frequent cause of seizures, whereas in patients with solid cancers, metastases were the single most common etiology. Children undergoing bone marrow transplant were particularly susceptible to seizures (34%), but only a minority progressed to develop a chronic seizure disorder (19.1%). Neuroimaging studies provided useful etiologic information in 62%. The choice of the antiseizure medication should take into account the potential interaction with the chemotherapy or supportive drugs often administered to these patients.

Motor nervous pathway function is impaired after treatment of childhood acute lymphoblastic leukemia: a study with motor evoked potentials

BACKGROUND

The objective was to evaluate whether motor nervous pathways are affected when patients are treated for childhood acute lymphoblastic leukemia (ALL).

PROCEDURE

Thirty-two children with ALL were studied at the end of treatment by means of motor evoked potentials (MEPs) elicited by magnetic stimulation (MS) transcranially and peripherally and underwent a detailed neurological examination. Thirty-two healthy children matched with them for age, sex, and height served as a control group.

RESULTS

The latencies of the MEPs were significantly prolonged along the entire motor nervous pathway in the patients with ALL compared with the healthy controls, indicating demyelination in the thick motor fibres. The MEP amplitudes of the distal extremities elicited by stimulation at the brachial plexus and LV spinal level were significantly lowered in the patients treated for ALL, also indicating anatomical or functional loss of descending motor fibres and/or muscle fibres. The MEP amplitudes elicited by cortical MS showed wider variation and no clear abnormalities were found. Neurological signs and symptoms were common after treatment: 41% of the patients had depressed deep tendon reflexes, 31% had fine motor difficulties and 63% gross motor difficulties, and 34% had dysdiadochokinesia. The conduction delay within the peripheral nerve was related to the post-therapeutic interval after administration of vincristine and the lesions within the CNS to the number of injections of intrathecal methotrexate.

CONCLUSIONS

The present results show adverse effects of the ALL treatment on the entire motor nervous pathways. In our experience, the measurement of MEPs by MS provides an objective, painless, and practical tool for assessing the treatment-related neurotoxicity in both the CNS and the peripheral nerves. These disturbances in the motor nervous pathways at the end of treatment raise the question of the long-term effects of ALL treatment on the motor nerve tracts, and have led us to employ MEPs to study these effects in long-term survivors of ALL.

White matter changes on MRI during treatment in children with acute lymphoblastic leukemia: correlation with neuropsychological findings

BACKGROUND

Treatment of childhood acute lymphoblastic leukemia (ALL) may cause structural and functional brain damage. To find out the incidence of white matter changes during therapy, a prospective MRI study was designed, and the findings were correlated with neuropsychological evaluation.

PROCEDURE

Thirty-three children with ALL underwent serial cranial MRI before, during, and after therapy. Twenty-eight of these children underwent also neuropsychological assessment at the end of treatment. They all received intravenous and intrathecal methotrexate for central nervous system (CNS) therapy, 15 patients received cranial irradiation in addition.

RESULTS

Transient high-intensity white matter changes were observed by MRI in three children 9% (95% CI, 2-24%) who received chemotherapy only. The high-intensity changes were most prominent in the frontal lobes in two of these children. The children with white matter changes were significantly younger than those with normal MRI (2.8 vs. 7.4 years; mean). There was no correlation between neuropsychological tests and white matter changes, except in attention and in tests referring to the frontal areas in general.

CONCLUSIONS

White matter changes are occasionally observed during therapy with the current Nordic protocols. Young children may be more susceptible to developing white matter changes after repeated intravenous methotrexate injections. There is no systematic correlation between neuropsychological deficits and MRI findings.

Cerebral blood flow and glucose metabolism in long-term survivors of childhood acute lymphoblastic leukaemia

Central nervous system treatment for childhood acute lymphoblastic leukaemia (ALL) has been reported to cause changes in cerebral blood flow and glucose metabolism. Little is known about the association of these functional changes with neuropsychological defects and structural changes. The aim of the present study was to assess the relationship between changes in regional cerebral blood flow and glucose utilisation in long-term survivors of ALL, and the association of these functional abnormalities with neurocognitive and structural defects. 8 survivors of childhood ALL were studied with single photon emission tomography (SPECT) using Tc99m-ethyl cysteinate dimer (ECD) as tracer and with positron emission tomography (PET) using 18F-fluorodeoxyglucose (FDG) as tracer. 8 healthy controls also underwent FDG-PET. All subjects also underwent magnetic resonance imaging and neuropsychological assessment 5 years after cessation of the therapy. Focal cerebral blood flow abnormalities were found in ECD-SPECT in 5 of the 8 survivors. Glucose utilisation appeared normal in the corresponding regions. However, glucose utilisation was decreased in thalamus and cerebellum in the survivors of ALL as compared with healthy controls. 3 patients had severe and 5 patients mild neurocognitive difficulties. The changes in cerebral blood flow and FDG uptake did not correspond neuroanatomically with the neurocognitive defects. Focal defects in cerebral blood flow in long-term survivors of ALL are not associated with changes in local cerebral glucose utilisation. Neurocognitive difficulties are not consistently associated with either changes in cerebral blood flow or with decreased glucose utilisation. Therefore, based on the present set of studies FDG-PET and ECD-SPECT cannot yet be recommended for the evaluation of long-term neurocognitive defects associated with treatment of ALL.