Cognitive deficits associated with frontal-lobe infarction in children with sickle cell disease

Executive Function and Processing Speed in Children Living with Sickle Cell Anemia

Executive function and processing speed difficulties are observed in children living with sickle cell anemia (SCA). The influence of processing speed on executive function is not well understood. We recruited 59 children living with SCA and 24 matched controls aged 8-18 years between 2010 and 2016 from clinics in the UK. Children completed tests in processing speed and cognitive flexibility, subdomains of executive function. MRI scans were conducted within one year of testing; oxygen saturation was obtained on the day of testing. Hemoglobin levels were obtained from medical records. Caregivers completed the executive function questionnaire. Hierarchical linear regressions found that hemoglobin, oxygen saturation, age, infarct status, and processing speed were not independent predictors for any model. However, for all cognitive flexibility tests, there was a significant interaction between infarct status and processing speed; children without silent cerebral infarction (SCI) with faster processing speed had better cognitive flexibility. Our findings indicate that, when interpreting executive function difficulties, it is important to account for the relationship between SCI status and processing speed. More research is needed to elucidate the mechanisms, but clinically, including executive function testing as part of clinic visits by embedding psychologists within the healthcare team would appear to be a critical step.

Neuroimaging and Cognitive Function in Sickle Cell Disease: A Systematic Review

Sickle cell disease (SCD) is the most common inherited single-gene disease. Complications include chronic anaemia, reduced oxygen-carrying capability, and cerebral vasculopathy, resulting in silent cerebral infarction, stroke, and cognitive dysfunction with impairments in measures of executive function, attention, reasoning, language, memory, and IQ. This systematic review aims to investigate the association between neuroimaging findings and cognition in children with SCD. Searches of PubMed and Embase were conducted in March 2022. Studies were included if participants were <18 years, if original data were published in English between 1960 and 2022, if any genotype of SCD was included, and if the relationship between cognition and neuroimaging was examined. Exclusion criteria included case studies, editorials, and reviews. Quality was assessed using the Critical Appraisal Skills Programme Case Control Checklist. A total of 303 articles were retrieved; 33 met the eligibility criteria. The presence of overt or silent strokes, elevated blood flow velocities, abnormal functional connectivity, and decreased fMRI activation were associated with neuropsychological deficits in children with SCD when compared to controls. There is a critical need to address the disease manifestations of SCD early, as damage appears to begin at a young age. Most studies were cross-sectional, restricting the interpretation of the directionality of relationships. Future research employing longitudinal neuroimaging and neuropsychological assessments could improve our understanding of the cumulative consequences of SCD on the developing brain.

The Development of Neuroimaging Biomarkers for Cognitive Decline in Sickle Cell Disease

Sickle cell disease (SCD) is complicated by neurologic complications including vasculopathy, hemorrhagic or ischemic overt stroke, silent cerebral infarcts and cognitive dysfunction. Patients with SCD, even in the absence of vasculopathy or stroke, have experience cognitive dysfunction that progresses with age. Transcranial Doppler ultrasound and structural brain MRI are currently used for primary and secondary stroke prevention, but laboratory or imaging biomarkers do not currently exist that are specific to the risk of cognitive dysfunction in patients with SCD. Recent investigations have used advanced MR sequences assessing cerebral hemodynamics, white matter microstructure and functional connectivity to better understand the pathophysiology of cognitive decline in SCD, with the long-term goal of developing neuroimaging biomarkers to be used in risk prediction algorithms and to assess the efficacy of treatment options for patients with SCD.

Neurocognitive Changes in Sickle Cell Disease: A Comprehensive Review

Background:

Sickle cell disease (SCD) is a type of hemoglobinopathy characterized by abnormal hemoglobin molecules, which includes numerous acute and chronic complications. Ischemic stroke, silent cerebral infarction, headache, and neurocognitive impairment are the most common neurological complications associated with SCD.

Summary:

Acute anemia because of SCD can cause cognitive impairments because of cerebral hypoxia. Cognitive abnormalities in SCD manifest in various aspects such as working memory, verbal learning, executive functions, and attention. These neurocognitive impairments have been associated with poor functional results, such as transitioning from juvenile to adult care, adherence to medications, and unemployment.

Key message:

In this review, we focus on neurocognitive aspects of SCD patients based on different imaging techniques, psychological batteries, associated neuromarkers, and interventions for managing of cognitive deficiencies..

Neurocognitive risk in sickle cell disease: Utilizing neuropsychology services to manage cognitive symptoms and functional limitations

Sickle cell disease (SCD) is an inherited blood disorder that is associated with developmental delays and neurocognitive deficits. This review details key findings related to neurocognitive outcomes for children and adults with emphasis on the impact of neurological correlates and disease severity. Associations between neurocognition, demographic factors and social determinants of health are also reviewed. Emerging literature has reported on the neurocognitive impact of SCD in children and adolescents in Africa and Europe, including children from immigrant communities. Neurocognitive deficits are linked to poor functional outcomes, including transition from paediatric to adult care, medication adherence and unemployment. Integrating neuropsychology into multidisciplinary care for individuals with SCD can assist with identification and management of neurocognitive concerns, intervention development, individualized care plan development and continued multidisciplinary research.

The Epidemiology of Neurological Complications in Adults With Sickle Cell Disease: A Retrospective Cohort Study

Introduction: Risk factors for neurological complications in sickle cell disease differ in the adult and pediatric populations. Here, we focused on neurological complications in adults with sickle cell disease.

Methods: Patients were selected using the audit data from the St George's Hospital Red Cell Database. The genotyping, demographics, clinical data, and investigation findings were collected.

Results: A total of 303 patients were enrolled in the study: hemoglobin S homozygosity (HbSS) genotype 56%, hemoglobin S and C coinheritance (HbSC) genotype 35%, and hemoglobin S and β-thalassemia coinheritance (HbSβ) thalassemia genotype 9%; the mean age was 38.8 years (±13.5 SD) with 46% males. The most common neurological complication was cerebrovascular disease (n = 37, 12%) including those with ischemic stroke (10%), cerebral vasculopathy (3%), and intracranial hemorrhage (1%). Ischemic stroke was common among the HbSS genotype compared with other genotypes (8 vs. 1.6%, p = 0.001). Comparing the patients with sickle cell disease who had suffered a stroke to those who had not, there was a higher proportion of intracranial vasculopathy (p = 0.001, in particular, Moyamoya) and cognitive dysfunction (p < 0.0001).

Conclusion: Our cohort supports previous reports that the most common neurological complication in adult sickle cell patients is cerebrovascular disease. Strategies to prevent cerebral vasculopathy and cognitive impairment should be explored.

Neuronal injuries in cerebral infarction and ischemic stroke: From mechanisms to treatment (Review)

Stroke is the leading cause of disabilities and cognitive deficits, accounting for 5.2% of all mortalities worldwide. Transient or permanent occlusion of cerebral vessels leads to ischemic strokes, which constitutes the majority of strokes. Ischemic strokes induce brain infarcts, along with cerebral tissue death and focal neuronal damage. The infarct size and neurological severity after ischemic stroke episodes depends on the time period since occurrence, the severity of ischemia, systemic blood pressure, vein systems and location of infarcts, amongst others. Ischemic stroke is a complex disease, and neuronal injuries after ischemic strokes have been the focus of current studies. The present review will provide a basic pathological background of ischemic stroke and cerebral infarcts. Moreover, the major mechanisms underlying ischemic stroke and neuronal injuries are summarized. This review will also briefly summarize some representative clinical trials and up-to-date treatments that have been applied to stroke and brain infarcts.

A Traditional Review of Sickle Cell Disease and the Associated Onset of Dementia: Hematological and Neurocognitive Crossroads

Sickle cell trait and disease are potential risk factors for dementia and cognitive dysfunction in African Americans, as are genetic variants. This illness affects around 300 million people globally. Due to its ability to defend against severe malaria, it represents an evolutionary survival advantage. It has been shown that sickle cell disease and trait are independent risk factors for the prevalence and incidence of albuminuria and chronic renal disease. Sickle cell anemia impairs cognitive performance in people with minimal or mild manifestations of the genetic blood disorder, owing mostly to its cerebrovascular implications. Similarly, various cerebral minor vascular disorders, such as silent cerebral infarcts, have been linked to the sickle cell trait, which is associated with impaired cognitive ability. It has been found that patients with sickle cell disease have a significantly decreased subcortical and cortical brain volume. Adults and children with sickle cell disease have been documented to have attention-related issues, particularly reduced sustained attention.

Silent cerebral infarcts in patients with sickle cell disease: a systematic review and meta-analysis

BACKGROUND AND PURPOSE

Silent cerebral infarcts (SCIs) are the most common neurological complication in children and adults with sickle cell disease (SCD). In this systematic review, we provide an overview of studies that have detected SCIs in patients with SCD by cerebral magnetic resonance imaging (MRI). We focus on the frequency of SCIs, the risk factors involved in their development and their clinical consequences.

METHODS

The databases of Embase, MEDLINE ALL via Ovid, Web of Science Core Collection, Cochrane Central Register of Trials via Wiley and Google Scholar were searched from inception to June 1, 2019.

RESULTS

The search yielded 651 results of which 69 studies met the eligibility criteria. The prevalence of SCIs in patients with SCD ranges from 5.6 to 80.6% with most studies reported in the 20 to 50% range. The pooled prevalence of SCIs in HbSS and HbSβ⁰ SCD patients is 29.5%. SCIs occur more often in patients with the HbSS and HbSβ⁰ genotype in comparison with other SCD genotypes, as SCIs are found in 9.2% of HbSC and HbSβ⁺ patients. Control subjects showed a mean pooled prevalence of SCIs of 9.8%. Data from included studies showed a statistically significant association between increasing mean age of the study population and mean SCI prevalence. Thirty-three studies examined the risk factors for SCIs. The majority of the risk factors show no clear association with prevalence, since more or less equal numbers of studies give evidence for and against the causal association.

CONCLUSIONS

This systematic review and meta-analysis shows SCIs are common in patients with SCD. No clear risk factors for their development were identified. Larger, prospective and controlled clinical, neuropsychological and neuroimaging studies are needed to understand how SCD and SCIs affect cognition.

Targeting pain at its source in sickle cell disease

Sickle cell disease (SCD) is a genetic disorder associated with hemolytic anemia, end-organ damage, reduced survival, and pain. One of the unique features of SCD is recurrent and unpredictable episodes of acute pain due to vasoocclusive crisis requiring hospitalization. Additionally, patients with SCD often develop chronic persistent pain. Currently, sickle cell pain is treated with opioids, an approach limited by adverse effects. Because pain can start at infancy and continue throughout life, preventing the genesis of pain may be relatively better than treating the pain once it has been evoked. Therefore, we provide insights into the cellular and molecular mechanisms of sickle cell pain that contribute to the activation of the somatosensory system in the peripheral and central nervous systems. These mechanisms include mast cell activation and neurogenic inflammation, peripheral nociceptor sensitization, maladaptation of spinal signals, central sensitization, and modulation of neural circuits in the brain. In this review, we describe potential preventive/therapeutic targets and their targeting with novel pharmacologic and/or integrative approaches to ameliorate sickle cell pain.

Silent cerebral infarct definitions and full-scale IQ loss in children with sickle cell anemia

OBJECTIVE

To evaluate whether application of the adult definition of silent cerebral infarct (SCI) (T2-weighted hyperintensity ≥5 mm with corresponding T1-weighted hypointensity on MRI) is associated with full-scale IQ (FSIQ) loss in children with sickle cell anemia (SCA), and if so, whether this loss is greater than that of the reference pediatric definition of SCI (T2-weighted hyperintensity ≥3 mm in children on MRI; change in FSIQ -5.2 points; p = 0.017; 95% confidence interval [CI] -9.48 to -0.93).

METHODS

Among children with SCA screened for SCI in the Silent Cerebral Infarct Transfusion trial, ages 5-14 years, a total of 150 participants (107 with SCIs and 43 without SCIs) were administered the Wechsler Abbreviated Scale of Intelligence. A multivariable linear regression was used to model FSIQ in this population, with varying definitions of SCI independently substituted for the SCI covariate.

RESULTS

The adult definition of SCI applied to 27% of the pediatric participants with SCIs and was not associated with a statistically significant change in FSIQ (unstandardized coefficient -3.9 points; p = 0.114; 95% CI -8.75 to 0.95), with predicted mean FSIQ of 92.1 and 96.0, respectively, for those with and without the adult definition of SCI.

CONCLUSIONS

The adult definition of SCI may be too restrictive and was not associated with significant FSIQ decline in children with SCA. Based on these findings, we find no utility in applying the adult definition of SCI to children with SCA and recommend maintaining the current pediatric definition of SCI in this population.

Differences in Activation and Deactivation in Children with Sickle Cell Disease Compared with Demographically Matched Controls

BACKGROUND AND PURPOSE

Declines in both functional activation and functional connectivity have been reported in patients with sickle cell disease. In this study, we derived the functional and default mode responses to a word stem paradigm in age-, ethnicity-, and background-matched subjects with sickle cell disease and control groups, with the aim of testing whether both networks were similarly attenuated and whether the changes were related to physiologic parameters that characterize sickle cell disease.

MATERIALS AND METHODS

Both the functional and default mode responses were obtained from age- and background-matched controls and the sickle cell population by using a visually presented word stem paradigm on a 3T scanner.

RESULTS

We observed an attenuated response to both activation and deactivation in the sickle cell disease group. There were no significant differences in the activation response between the 2 groups for the contrast control > sickle cell disease; however, significant differences were observed in the medial parietal cortex, the auditory cortex, and the angular gyrus for the default mode. For the sickle cell group, a significant correlation between the activation z scores and the physiologic parameters was observed; for the deactivation, the results were not significant but the trend was similar.

CONCLUSIONS

The results indicate that the physiologic parameters modulate the activation in the expected fashion, but that the effect was weaker for deactivation. Given that significant differences between the 2 groups were only seen for deactivation, additional factors must modulate the deactivation in sickle cell disease.

Utility of the Montreal Cognitive Assessment as a Screening Test for Neurocognitive Dysfunction in Adults with Sickle Cell Disease

OBJECTIVES

Neurocognitive dysfunction is an important complication of sickle cell disease (SCD), but little is published on the utility of screening tests for cognitive impairment in people with the disease. The purpose of this study was to evaluate the Montreal Cognitive Assessment (MoCA) as a screening tool and identify predictors of MoCA performance in adults with sickle cell disease.

METHODS

We conducted a retrospective, cross-sectional study of the first 100 adult patients with SCD who completed the MoCA as part of routine clinical care at the Johns Hopkins Sickle Cell Center for Adults. We abstracted demographic, laboratory, and clinical data from each participant's electronic medical record up to the date that the MoCA was administered. The factorial validity of each MoCA domain was analyzed using standard psychometric statistics. We evaluated the abstracted data for associations with the composite MoCA score and looked for independent predictors of performance using multivariable regressions.

RESULTS

Components of the MoCA performed well in psychometric analyses and identified deficits in executive function that were described in other studies. Forty-six percent of participants fell below the cutoff for mild cognitive impairment. Increased education was an independent predictor of increased MoCA score (3.1, 95% confidence interval [CI] 1.5-4.7), whereas cerebrovascular accidents and chronic kidney disease were independent predictors of decreased score (-3.3, 95% CI -5.7 to -0.97 and -3.2, 95% CI -6.2 to -0.11, respectively). When analysis was restricted to patients with SCA, increased education (3.7, 95% CI 2.2-5.2) and a history of hydroxyurea therapy (2.0, 95% CI -0.022 to 4.0) were independent predictors of a higher score, whereas chronic kidney disease (-3.3, 95% CI -6.4 to -0.24) and increased aspartate transaminase (-0.045, 95% CI -0.089 to -0.0010) were independent predictors of a decreased score.

CONCLUSIONS

The MoCA showed promise by identifying important cognitive deficits and associations with chronic complications and therapy.

Intelligence quotient in paediatric sickle cell disease: a systematic review and meta-analysis

AIM

Sickle cell disease (SCD) is the commonest cause of childhood stroke worldwide. Magnetic resonance imaging (MRI) is routinely used to detect additional silent cerebral infarction (SCI), as IQ is lower in SCI as well as stroke. This review assesses the effect of infarction on IQ, and specifically whether, compared to healthy controls, IQ differences are seen in children with SCI with no apparent MRI abnormality.

METHOD

A systematic review was conducted to include articles with an SCD paediatric population, MRI information, and Wechsler IQ. A meta-analysis of 19 articles was performed to compare IQ in three groups: stroke vs SCI; SCI vs no SCI; and no SCI vs healthy controls.

RESULTS

Mean differences in IQ between all three groups were significant: stroke patients had lower IQ than patients with SCI by 10 points (six studies); patients with SCI had lower IQ than no patients with SCI by 6 points (17 studies); and no patients with SCI had lower IQ than healthy controls by 7 points (seven studies).

INTERPRETATION

Children with SCD and no apparent MRI abnormality have significantly lower IQ than healthy controls. In this chronic condition, other biological, socioeconomic, and environmental factors must play a significant role in cognition.

Central nervous system complications and management in sickle cell disease

With advances in brain imaging and completion of randomized clinical trials (RCTs) for primary and secondary stroke prevention, the natural history of central nervous system (CNS) complications in sickle cell disease (SCD) is evolving. In order of current prevalence, the primary CNS complications include silent cerebral infarcts (39% by 18 years), headache (both acute and chronic: 36% in children with sickle cell anemia [SCA]), ischemic stroke (as low as 1% in children with SCA with effective screening and prophylaxis, but ∼11% in children with SCA without screening), and hemorrhagic stroke in children and adults with SCA (3% and 10%, respectively). In high-income countries, RCTs (Stroke Prevention in Sickle Cell Anemia [STOP], STOP II) have demonstrated that regular blood transfusion therapy (typically monthly) achieves primary stroke prevention in children with SCA and high transcranial Doppler (TCD) velocities; after at least a year, hydroxycarbamide may be substituted (TCD With Transfusions Changing to Hydroxyurea [TWiTCH]). Also in high-income countries, RCTs have demonstrated that regular blood transfusion is the optimal current therapy for secondary prevention of infarcts for children with SCA and strokes (Stroke With Transfusions Changing to Hydroxyurea [SWiTCH]) or silent cerebral infarcts (Silent Infarct Transfusion [SIT] Trial). For adults with SCD, CNS complications continue to be a major cause of morbidity and mortality, with no evidence-based strategy for prevention.

Novel insights in the management of sickle cell disease in childhood

Sickle cell disease (SCD) is a life-threatening genetic disorder characterized by chronic hemolytic anemia, vascular injury and multiorgan dysfunctions. Over the last few decades, there have been significant improvements in SCD management in Western countries, especially in pediatric population. An early onset of prophylaxis with Penicillin and a proper treatment of the infections have increased the overall survival in childhood. Nevertheless, management of painful episodes and prevention of organ damage are still challenging and more efforts are needed to better understand the mechanisms behind the development of chronic organ damages. Hydroxyurea (Hydroxycarbamide, HU), the only medication approved as a disease-modifying agent by the United States Food and Drug Administration and the European Medicines Agency, is usually under-used, especially in developing countries. Currently, hematopoietic stem-cell transplantation is considered the only curative option, although its use is limited by lack of donors and transplant-related toxicity. SCD symptoms are similar in children and adults, but complications and systemic organ damages increase with age, leading to early mortality worldwide. Experts in comprehensive care of young patients with SCD, especially those approaching the transition age to adulthood, are missing, leading people to rely on urgent care, increasing health care utilization costs and inappropriate treatments. It would be important to establish programs of comprehensive healthcare for patients with SCD from birth to adulthood, to improve their quality and expectancy of life.

Hypoxia and inflammation in children with sickle cell disease: implications for hippocampal functioning and episodic memory

Children with sickle cell disease (SCD) suffer from systemic processes (e.g., chronic anemia, recurrent hypoxic-ischemic events, chronic inflammation) that have been associated with neurocognitive impairment in a range of clinical populations, but which have been largely understudied in relation to specific domains of cognitive functioning in children with SCD. This review focuses on episodic memory, as the hippocampus may be especially vulnerable to the systemic processes associated with SCD. The first part of the paper outlines the pathophysiology of SCD and briefly reviews the extant literature on academic and cognitive functioning in children with SCD, emphasizing the dearth of research on episodic memory. Next, the complex systemic processes of hypoxia and inflammation associated with SCD are reviewed, along with research that has associated these processes with hippocampal damage and memory impairment. The paper concludes with suggestions for future research that are informed, in part, by the literature on developmental amnesia.

Neuroimaging abnormalities in adults with sickle cell anemia: associations with cognition

OBJECTIVE

This study was conducted to determine the relationship of frontal lobe cortical thickness and basal ganglia volumes to measures of cognition in adults with sickle cell anemia (SCA).

METHODS

Participants included 120 adults with SCA with no history of neurologic dysfunction and 33 healthy controls (HCs). Participants were enrolled at 12 medical center sites, and raters were blinded to diagnostic group. We hypothesized that individuals with SCA would exhibit reductions in frontal lobe cortex thickness and reduced basal ganglia and thalamus volumes compared with HCs and that these structural brain abnormalities would be associated with measures of cognitive functioning (Wechsler Adult Intelligence Scale, 3rd edition).

RESULTS

After adjusting for age, sex, education level, and intracranial volume, participants with SCA exhibited thinner frontal lobe cortex (t = -2.99, p = 0.003) and reduced basal ganglia and thalamus volumes compared with HCs (t = -3.95, p < 0.001). Reduced volume of the basal ganglia and thalamus was significantly associated with lower Performance IQ (model estimate = 3.75, p = 0.004) as well as lower Perceptual Organization (model estimate = 1.44, p = 0.007) and Working Memory scores (model estimate = 1.37, p = 0.015). Frontal lobe cortex thickness was not significantly associated with any cognitive measures.

CONCLUSIONS

Our findings suggest that basal ganglia and thalamus abnormalities may represent a particularly salient contributor to cognitive dysfunction in adults with SCA.

Parent education and biologic factors influence on cognition in sickle cell anemia

Children with sickle cell anemia have a high prevalence of silent cerebral infarcts (SCIs) that are associated with decreased full-scale intelligence quotient (FSIQ). While the educational attainment of parents is a known strong predictor of the cognitive development of children in general, the role of parental education in sickle cell anemia along with other factors that adversely affect cognitive function (anemia, cerebral infarcts) is not known. We tested the hypothesis that both the presence of SCI and parental education would impact FSIQ in children with sickle cell anemia. A multicenter, cross-sectional study was conducted in 19 US sites of the Silent Infarct Transfusion Trial among children with sickle cell anemia, age 5-15 years. All were screened for SCIs. Participants with and without SCI were administered the Wechsler Abbreviated Scale of Intelligence. A total of 150 participants (107 with and 43 without SCIs) were included in the analysis. In a multivariable linear regression model for FSIQ, the absence of college education for the head of household was associated with a decrease of 6.2 points (P = 0.005); presence of SCI with a 5.2 point decrease (P = 0.017); each $1000 of family income per capita with a 0.33 point increase (P = 0.023); each increase of 1 year in age with a 0.96 point decrease (P = 0.023); and each 1% (absolute) decrease in hemoglobin oxygen saturation with 0.75 point decrease (P = 0.030). In conclusion, FSIQ in children with sickle cell anemia is best accounted for by a multivariate model that includes both biologic and socioenvironmental factors.

Neurologic complications of sickle cell disease

Sickle cell disease (SCD) is a group of genetic blood disorders that vary in severity, but the most severe forms, primarily homozygous sickle cell anemia, are associated with neurologic complications. Over the last 90 years it has become established that some patients will develop severe arterial disease of the intracranial brain arteries and suffer brain infarction. Smaller infarctions and brain atrophy may also be seen and over time there appear to be negative cognitive effects in some patients, with or without abnormal brain imaging. Focal mononeuropathies and pneumococcal meningitis are also more common in these patients. Brain infarction in children can largely be prevented screening children beginning at age 2 years and instituting regular blood transfusion when the Doppler indicates high stroke risk (>200cm/sec). Iron overload and the uncertain duration of transfusion are disadvantages but overall this approach, tested in a randomized clinical trial, reduced first stroke by over 90%. Secondary stroke prevention has not been subjected to a randomized controlled trial except for one recently stopped comparison of regular transfusions compared to hydroxuyrea (results favored transfusion). The usual stroke prevention agents (such as aspirin or warfarin) have not been rigorously tested. Magnetic resonance imaging and positron emission tomography give evidence of subtle and sometimes overt brain injury due to stroke in many adults, but a preventive strategy for adults with SCD has not been developed. Bone marrow transplantation is the only cure, but some non-neurologic symptoms can be controlled in adults with hydroxuyrea.

Precursors of executive function in infants with sickle cell anemia

Executive dysfunction occurs in sickle cell anemia, but there are few early data. Infants with sickle cell anemia (n = 14) and controls (n = 14) performed the "A-not-B" and Object Retrieval search tasks, measuring precursors of executive function at 9 and 12 months. Significant group differences were not found. However, for the A-not-B task, 7 of 11 sickle cell anemia infants scored in the lower 2 performance categories at 9 months, but only 1 at 12 months (P = .024); controls obtained scores at 12 months that were statistically comparable to the scores they had already obtained at 9 months. On the Object Retrieval task, 9- and 12-month controls showed comparable scores, whereas infants with sickle cell anemia continued to improve (P = .027); at 9 months, those with lower hemoglobin oxygen saturation passed fewer trials (R s = 0.670, P = .024) and took longer to obtain the toy (R s = -0.664, P = .013). Subtle delays in acquiring developmental skills may underlie abnormal executive function in childhood.

Intellectual function evaluation of first generation immigrant children with sickle cell disease: the role of language and sociodemographic factors

Background

Sickle Cell Disease (SCD) is the most common genetic disease worldwide. Neurological events are among the most worrisome clinical complications of SCD and are frequently accompanied by cognitive impairment. Intellectual function in SCD may vary according to genetic and environmental factors. Immigrant children with SCD are increasing at a global level and display specific health care needs. The aim of our multicenter study was to describe the intellectual function of first generation African immigrants with SCD and the influence of sociodemographic factors on its characteristics.

Methods

The Wechsler Intelligence Scales were administered to evaluate broad intellectual functions in children with SCD and in age-matched healthy siblings. Patients’ clinical, socio-demographic, Magnetic Resonance Imaging (MRI) and Angiography (MRA) data were correlated to intellectual function scores.

Results

68 children, mean age 8.95 years were evaluated. 72% spoke three languages, 21% two. FSIQ was <75 in 25% of the children. Mean VIQ was lower than PIQ in 75%. Mean verbal subtest scores were lower than performance scores. Female gender, number of languages spoken at home and mother’s employment were associated with single subtest performances (p < 0.05). MRA was abnormal in 73.4% and MRI in 35.9%. No significant correlation was established between silent lesions and intellectual function, even if patients with lesions performed worse. Fifteen siblings performed better than patients on cognitive domains, including language (p < 0.05).

Conclusions

Immigrant bilingual children with SCD seem to display a rate of cognitive impairment similar to their monolingual counterparts but a more pronounced and precocious onset of language difficulties. Adjunctive tests need to be considered in this group of patients to better define their specific deficits.

White matter damage in asymptomatic patients with sickle cell anemia: screening with diffusion tensor imaging

BACKGROUND AND PURPOSE

Ischemic injury to the brain is a common complication of SCA. To better understand the neurologic impact of SCA, TBSS were applied to DTI data to investigate white matter injuries in pediatric patients with SCA.

MATERIALS AND METHODS

TBSS comparisons of a range of anisotropy and diffusion measures were carried out between age- and background-matched population groups: patients with SCA with no visible lesions, patients with SCA with mild gliosis, and normal controls.

RESULTS

TBSS analysis revealed that both SCA populations exhibited reduced anisotropy and increased diffusivity compared with normal controls in multiple brain regions, including the corpus callosum and centrum semiovale. Furthermore, the results suggest that the severity of SCA is positively correlated with the white matter changes in the corpus callosum.

CONCLUSIONS

The study demonstrates that TBSS is a viable technique in detecting subtle white matter damage in patients with SCA whose conventional anatomic MR imaging scans show no, or minimal, abnormalities and has the potential to evaluate the neurologic impact of the treatment of SCA.

Barriers in transition from pediatrics to adult medicine in sickle cell anemia

Transition of care from pediatric to adult providers is an essential step in the care of young adults with sickle cell anemia. Transition programs should be developed by individual institutions to systematically enhance the transition process for their patients. Prior to transfer, patients must be educated about their disease and personal medical history and develop skill sets required to navigate the adult health care setting. The objective of this literature review is to identify key concepts associated with transition of care for patients with sickle cell anemia. First, transition programs should be developed so that education about transition can begin at an early age. The readiness of patients and families should be assessed and education tailored to meet individual patient needs. Finally, the emotions and fears about transition should be recognized and addressed prior to transition.

Silent cerebral infarcts: a review on a prevalent and progressive cause of neurologic injury in sickle cell anemia

Silent cerebral infarct (SCI) is the most common form of neurologic disease in children with sickle cell anemia (SCA). SCI is defined as abnormal magnetic resonance imaging (MRI) of the brain in the setting of a normal neurologic examination without a history or physical findings associated with an overt stroke. SCI occurs in 27% of this population before their sixth, and 37% by their 14th birthdays. In adults with SCA, the clinical history of SCI is poorly defined, although recent evidence suggests that they too may have ongoing risk of progressive injury. Risk factors for SCI include male sex, lower baseline hemoglobin concentration, higher baseline systolic blood pressure, and previous seizures. Specific morbidity associated with SCI includes a decrement in general intellectual abilities, poor academic achievement, progression to overt stroke, and progressive SCI. In addition, children with previous stroke continue to have both overt strokes and new SCI despite receiving regular blood transfusion therapy for secondary stroke prevention. Studies that only include overt stroke as a measure of CNS injury significantly underestimate the total cerebral injury burden in this population. In this review, we describe the epidemiology, natural history, morbidity, medical management, and potential therapeutic options for SCI in SCA.

Ameliorating attention problems in children with sickle cell disease: a pilot study of methylphenidate

OBJECTIVE

This pilot study examined whether methylphenidate (MPH) was effective in enhancing cognitive performance and attention for children with sickle cell disease (SCD) with cerebrovascular complications who evidence attention problems.

METHODS

In this multisite, pilot study, we evaluated 2 separate double-blind controlled clinical trials, including a laboratory trial of the short-term efficacy of MPH, with the second study a 3-week home/school crossover trial evaluating the efficacy of MPH. The laboratory trial included 14 participants between the age of 7 and 16 years. Assessments included measures of sustained attention, reaction time, executive functions, and verbal memory. The home/school trial included 20 participants. The outcome measures were parent and teacher ratings of attention. The first study compared MPH with placebo, while the second trial compared placebo, low-dose (LD) MPH, and moderate-dose MPH.

RESULTS

In the laboratory trial, significant effects were revealed for measures of memory and inhibitory control. Parent and teacher reports from the home/school trial indicate that moderate-dose MPH produced superior improvement in attention relative to the placebo and LD MPH.

CONCLUSIONS

Stimulant medication positively impacted select measures of memory and inhibitory control in some children with SCD. Attention, as rated by parent and teachers, was improved for a greater number of children and adolescents on higher doses of MPH relative to LD MPH and placebo. Stimulant medication may provide an effective intervention for some children with SCD and cerebrovascular complications who demonstrate attention problems.

Neurocognitive screening with the Brigance preschool screen-II in 3-year-old children with sickle cell disease

BACKGROUND

Neurocognitive deficits have been described in school age children with sickle cell disease (SCD), even in the absence of stroke or silent infarcts. However, the age of onset and factors contributing to this problem have not been well studied. We hypothesized that in children with SCD the failure rate with Brigance screening would be higher than in the normal population.

METHODS

We reviewed retrospectively the Brigance Preschool Screen-II test results in 3-year-old children with SCD. Findings were correlated with hemoglobinopathy genotype, hemoglobin level, transcranial Doppler ultrasound (TCD) velocities, and treatment with hydroxyurea, as well as with psychosocial factors.

RESULTS

Eighty-eight children with SCD followed by the St. Jude Sickle Cell Center (mean age 3.5 years) had neurocognitive screening during their regular clinic visits. Forty-four (50%) children had scores below the normal cut-off value for their age (twice the national failure rate of 25%). Failures were associated with less parental education (P = 0.005 for maternal and P = 0.03 for paternal education levels) and with speech deficits (P = 0.01), but were not associated with sickle cell genotype or hemoglobin concentration.

CONCLUSION

These preliminary data suggest that psychosocial factors may have more profound effects on early childhood development than disease-related factors in this group of young sickle cell patients. A larger prospective study with appropriate controls is warranted to validate these findings, which have implications for the etiology and prevention of neurocognitive decline in children with SCD.

Event-based prospective memory in children with sickle cell disease: effect of cue distinctiveness

Event-based prospective memory (EB-PM) is the formation of an intention and remembering to perform it in response to a specific event. Currently, EB-PM performance in children with sickle cell disease (SCD) is unknown. In this study, we designed a computer-based task of EB-PM; No-Stroke, Silent-Infarct, and Overt-Stroke groups performed significantly below the demographically similar control group without SCD. Cue distinctiveness was varied to determine if EB-PM could be improved. All groups, with the exception of the Overt-Stroke group, performed significantly better with a perceptually distinctive cue. Overall, these results suggest that EB-PM can be improved significantly in many children with SCD.

Neuroimaging in assessment of risk of stroke in children with sickle cell disease

PURPOSE

Stroke and subclinical "silent infarcts" are major causes of morbidity in children with Sickle Cell Disease (SCD). Ischemic strokes are more common in younger children while hemorrhagic strokes are more frequent in adults. The goal of neuroimaging in acute stroke is to document whether the stroke is ischemic or hemorrhagic, to assess the extent of parenchymal abnormalities and to determine the presence of other cerebrovascular lesions. Computed Tomography (CT) is the primary modality for the assessment of acute stroke patients because of its 24/7 availability and ability to exclude hemorrhagic causes. Magnetic resonance imaging (MRI) and MR angiography (MRA) are recommended to determine precisely extent of infarction and detect cerebrovascular abnormalities. The goal of neuroimaging in patients with hemorrhagic stroke is to identify an arteriovenous malformation or aneurysm(s) amenable to surgery or catheter intervention.The risk of first stroke is very high in asymptomatic children with intracranial arterial mean velocities over 200 cm/s on transcranial Doppler (TCD) examination. The risk can be substantially reduced if chronic blood transfusions are timely implemented. Large cerebral vessel disease detected by TCD can be confirmed or excluded by MRI/MRA. Those with evidence of parenchymal and/or cerebrovascular lesions should be followed by preventive therapy. In patients with neurologic symptoms and negative MRI/MRA findings Positron Emission Tomography or single photon emission CT is recommended. There are no specific neuroimaging findings that suggest that blood transfusions can be safely halted in children with SCD.

Regionally specific cortical thinning in children with sickle cell disease

Sickle cell disease (SCD) is a chronic disease with a significant rate of neurological complications in the first decade of life. In this retrospective study, cortical thickness was examined in children with SCD who had no detectable abnormalities on conventional magnetic resonance imaging/magnetic resonance angiography. Regional differences in cortical thickness from SCD were explored using age-matched healthy controls as comparison. A comparison analysis was done for SCD (n = 28) and controls (n = 29) based on age (5-11; 12-21 years), due to the age-dependent variation in cortex maturation. Distinct regions of thinning were found in SCD patients in both age groups. The number, spatial extent, and significance (P < 0.001) of these areas of thinning were increased in the older SCD group. Regions of interest (ROIs) were defined on the areas of highly significant thinning in the older group and then mapped onto the younger cohort; a multiparametric linear regression analysis of the ROI data demonstrated significant (P < 0.001) cortical thinning in SCD subjects, with the largest regions of thinning in the precuneus and the posterior cingulate. The regionally specific differences suggest that cortical thickness may serve as a marker for silent insults in SCD and hence may be a useful tool for identifying SCD patients at risk for neurological sequelae.

Detection and assessment of stroke in patients with sickle cell disease: neuropsychological functioning and magnetic resonance imaging

Sickle cell disease (SCD) is associated with increased risk of stroke and cognitive impairment. This study describes a retrospective review of 65 patients who underwent routine neuropsychological testing and MRI during treatment at a comprehensive sickle cell center. It was hypothesized that (1) children with no evidence of CVA would perform lower than expected on cognitive tasks compared to population-based normative data, (2) children with strokes and children with silent infarcts would perform lower on cognitive tasks and motor skills as compared to patients with no evidence of CVA, and (3) children with evidence of silent infarcts would perform better than children with known overt strokes. This final hypothesis has not been studied previously, as children with known overt stroke and silent infarct were grouped together. Sixty-five children with SCD who were sent for routine neuropsychological testing and brain MRI were identified via retrospective chart review. Patients had been administered neuropsychological tests to assess cognitive, executive and motor function. Brain MRI was obtained from each patient and was analyzed for evidence of cerebrovascular accident (CVA). Based on MRI analysis, 27% of patients with SCD had experienced a stroke and 13% a silent infarct. The majority (59%) of patients diagnosed with stroke or infarct sustained cortical damage to the frontal lobe. Patients with SCD and no evidence of CVA functioned normally on tests of cognitive ability and achievement, but patients with CVA displayed impairments in cognitive function and comparatively lower scores on verbal and performance scales. Neuropsychological testing can identify impairments in patients with SCD with no known cerebrovascular accident. Investigations of neurocognitive functioning will help characterize patterns of deficits and can inform the ability to implement comprehensive care strategies for patients with SCD and cognitive impairment.

Neurocognitive sequelae of pediatric sickle cell disease: a review of the literature

This literature review summarizes all studies relating neuropsychological performance to neuroimaging findings in pediatric sickle cell disease (N=28; published 1991-2005). Although inconsistencies exist within and across domains, deficits in intelligence (IQ), attention and executive functions, memory, language, visuomotor abilities, and academic achievement have been identified. Overall neurocognitive compromise was revealed to be related to the level of neurological injury and the location of silent infarct. Attentional and executive dysfunction is prevalent and related to frontal lobe abnormalities.

Therapy Insight: stroke risk and its management in patients with sickle cell disease

Children with sickle cell disease, a chronic hemolytic anemia, present with a wide variety of neurological syndromes, including ischemic and hemorrhagic stroke, transient ischemic attacks, 'soft neurological signs', seizures, headache, coma, visual loss, altered mental status, cognitive difficulties, and covert or 'silent' infarction. Those with ischemic stroke usually have stenosis or occlusion of the distal internal carotid and proximal middle cerebral arteries. Indefinite transfusion prevents recurrence in most patients who have had a stroke, and can prevent first stroke in those with high transcranial Doppler velocities. High white cell count, low hemoglobin and oxyhemoglobin desaturation predict neurological complications. Other risk factors for overt ischemic stroke include hypertension, previous transient ischemic attack, covert infarction and chest crisis. For hemorrhagic stroke, aneurysms are common in adults but not children, who often present with hypertension after transfusion or corticosteroids. Seizures are particularly common in patients with cerebrovascular disease and covert infarction; the latter is also associated with hyposplenism and infrequent pain. Factors associated with cognitive difficulties include thrombocytosis, infarction, large-vessel disease, and perfusion abnormality on neuroimaging. As well as investigating the role of genes and the possibility that hydroxyurea or blood pressure control reduce neurological complications, we should explore the modifiable effects of poor nutrition, chronic infection, hemolysis and oxyhemoglobin desaturation on stroke risk.

Neuropsychological Functioning in Preschool-age Children with Sickle Cell Disease: The Role of Illness-related and Psychosocial Factors

Cognitive and academic deficits have been identified in school-aged children with sickle cell disease (SCD). However, there have been very few identified studies that examine neuropsychological functioning in preschool-age children with SCD. It is important to understand effects of SCD from a developmental perspective and to consider the contribution of environmental factors in this at-risk population. Neuropsychological functioning of preschool-age children with SCD and no history of overt stroke (n = 26) was examined across several domains (language, immediate memory/brief attention, visuospatial/visuoconstructional, motor/visuomotor). The mean Full Scale IQ for the sample was 89.0. Performance on the Immediate Memory/ Brief Attention domain was significantly higher than the other domains, although the pattern of performance was relatively consistent, with mean standard scores ranging from 88.0 to 95.0. Disease severity was not significantly related to cognitive functioning in this group of young children with SCD. Socioeconomic status (SES) was significantly correlated with most domain scores and, based on regression analyses, accounted for 18% to 47% of the variance in functioning. Psychosocial factors, such as number of children living in the home and parental stress levels, were negatively associated with Motor/Visuomotor skills, and weekly hours in school/day care was positively associated with language-related skills. Results suggest that, at this young age, psychosocial risk factors appear to be appropriate targets for intervention, with the goal of improving long-term outcome in children with SCD. Further investigations should include comparison to a matched control group.

Physiological correlates of intellectual function in children with sickle cell disease: hypoxaemia, hyperaemia and brain infarction

Lowered intelligence relative to controls is evident by mid-childhood in children with sickle cell disease. There is consensus that brain infarct contributes to this deficit, but the subtle lowering of IQ in children with normal MRI scans might be accounted for by chronic systemic complications leading to insufficient oxygen delivery to the brain. We investigated the relationship between daytime oxyhaemoglobin saturation (SpO2), cerebral blood flow velocity (CBFV) and intellectual function (IQ) using path-analysis in 30 adolescents with sickle cell disease (mean age 17.4 years, SD 4.2). Initial analyses revealed that the association between SpO2 and Full Scale IQ (FSIQ) was fully mediated by increased CBFV, whereby SpO2 was negatively correlated with CBFV and CBFV was negatively correlated with FSIQ, i.e. decreases in oxygen saturation are associated with increases in velocity, and increased velocity is associated with lowered IQ scores. The mediated relationship suggests that lowered IQ may be a function of abnormal oxygen delivery to the brain. Further analyses showed that the association between CBFV and IQ was significant for verbal but not for performance IQ. The pathophysiology characteristic of SCD can interfere with brain function and constrain intellectual development, even in the absence of an infarct. This supports the hypothesis that lowered intellectual function is partly explained by chronic hypoxia, and has wider implications for our understanding of SCD pathophysiology.

Detecting white matter injury in sickle cell disease using voxel-based morphometry

OBJECTIVE

Sickle cell disease (SCD) is associated with cerebrovascular disease, cerebral infarction, and cognitive dysfunction. This study aimed to detect the presence and extent of white matter abnormalities in individuals with SCD using voxel-based morphometry (VBM).

METHODS

Thirty-six children and adolescents with SCD (age range, 9-24 years) and 31 controls (8-25 years) underwent magnetic resonance investigations using T1- and T2-weighted protocols. White and gray matter density maps were obtained from three-dimensional magnetic resonance imaging (MRI) data sets. Using VBM, we compared the maps between controls and SCD individuals with silent white matter infarct lesions (SCD+L; n = 16), and those without visible abnormality (SCD-L; n = 20).

RESULTS

In comparison with controls, intelligence quotients (IQs) were lower in both SCD groups irrespective of presence of visible lesions. VBM showed widespread bilateral white matter abnormalities in the SCD+L group, extending beyond the regions of focal infarction in the deep anterior and posterior white matter borderzones. Bilateral white matter abnormalities were also observed in the SCD-L group, in locations similar to those in the SCD+L group.

INTERPRETATION

VBM is sensitive to detection of widespread white matter injury in SCD patients in borderzones between arterial territories even in the absence of evidence of infarction. Those changes may contribute to cognitive deficits in this population.

Trials in sickle cell disease

Children with sickle cell disease are at risk of developing neurologic complications, including stroke, transient ischemic attack, seizures, coma, and a progressive reduction in cognitive function. Transcranial Doppler ultrasound, magnetic resonance imaging, and overnight pulse oximetry appear to predict, making prevention an achievable goal so that there is now a focus on randomized controlled trials. The Stroke Prevention Trial in Sickle Cell Anemia (STOP) reported a reduction in the number of overt clinical strokes experienced by those children with critically high transcranial Doppler velocities (>200 centimeters per second) who were chronically transfused. Two additional Phase III studies and two pilot trials have been funded. STOP II focused on whether it is safe to discontinue blood in prophylactically transfused children when their velocities had remained normal for at least 30 months. The Silent Infarct Transfusion trial is designed to determine whether children with sickle cell anemia and silent cerebral infarcts, approximately 20% of the population, will have a decrease in the progressive neurologic complications after receiving regular blood transfusion therapy. Pilot safety and feasibility trials of low-dose aspirin and overnight respiratory support are also beginning. The collaboration provides an infrastructure for future clinical trials in this vulnerable group of children.

Executive cognitive dysfunction without stroke after long-term mechanical circulatory support

Among patients who receive heart transplantation (HTx) after long-term mechanical circulatory support (MCS), some show executive cognitive dysfunction without a history of stroke. Fifty HTx patients (19 patients on MCS for longer than 3 months before HTx and 31 patients without MCS as control group) were enrolled in the study. All subjects were men aged between 20 and 59 years without a history of stroke. Patients with MCS were divided into two groups: the AH-Thr group (n = 11), in which thrombus was detected in the left ventricular assist device (LVAD) and quickly removed (mean 3.3 times); and the AH group (n = 8), in which there was no detectable thrombus in the LVAD. The Trail Making Test (TMT) and the Wisconsin Card Sorting Test (WCST) were administered. The AH-Thr group showed poorer cognitive performance both in the TMT part B, with longer completion time (p < 0.05 versus the other two groups), and in the WCST, with more perseverative errors (p < 0.001 versus the other two groups). These data indicate that patients in the AH-Thr group showed executive cognitive dysfunction in set-shifting ability, suggesting frontal lobe damage. The conditions that facilitate thrombus formation in the LVAD may induce executive cognitive dysfunction without stroke.

Radiographic predictors of neurocognitive functioning in pediatric Sickle Cell disease

We compared magnetic resonance imaging (MRI), magnetic resonance angiography, and transcranial Doppler ultrasonography as predictors of specific neurocognitive functions in children with sickle cell disease. Participants were 27 children with sickle cell anemia (hemoglobin SS) who were participants in the Stroke Prevention Trial in Sickle Cell Anemia (STOP) and had no documented history of stroke. Children's MRIs were classified as normal or silent infarct, and their magnetic resonance angiograms were classified as normal or abnormal. The highest time-averaged mean flow velocity on transcranial Doppler ultrasonographic examination of the major cerebral arteries was analyzed. Age and hematocrit also were analyzed as predictor variables. The battery of neurocognitive tests included measures of intellectual functioning, academic achievement, attention, memory, visual-motor integration, and executive functions. MRI, magnetic resonance angiography, transcranial Doppler ultrasonography, age, and hematocrit were analyzed as predictors of participants' performance on the various measures of neurocognitive functioning. Age and hematocrit were robust predictors of a number of global and specific neurocognitive functions. When age and hematocrit were controlled, transcranial Doppler ultrasonography was a significantly unique predictor of verbal memory. We found an association between low hemoglobin and neurocognitive impairment. We also found that abnormalities on transcranial Doppler ultrasonography can herald subtle neurocognitive deficits. (J Child Neurol 2006;21:37-44).

Decreased corpus callosum size in sickle cell disease: relationship with cerebral infarcts and cognitive functioning

We assessed midsagittal corpus callosum size in sickle cell disease (SCD) and its relationship to lesion volume, lesion location, and cognitive functioning. Twenty-eight children with SCD and 16 demographic controls completed magnetic resonance imaging (MRI) and neuropsychological testing. Corpus callosum (CC) size was smaller for children with silent infarcts (n = 8) or overt stroke (n = 8) than for those without visible infarcts (n = 12) or control participants. Lesion volume was a robust predictor of IQ and other cognitive scores; total CC size did not typically add explanatory power for these measures. The size of the rostral body of the CC, however, independently predicted measures of distractibility, speeded production, and working memory. Posterior CC size was also decreased among many of the children with SCD, even in the absence of visible infarcts in this region. Brain morphology appears to provide additional information about SCD-related effects on the brain above and beyond visible infarcts.

Cognitive deficits in children with sickle cell disease

We tested a hypothesis that children with sickle cell disease who are completely normal by magnetic resonance imaging can still be cognitively impaired, as predicted by a model of diffuse brain injury. Fifty-four patients with hemoglobin SS (average age 10.9 years +/- 2.9 years SD) were examined with the Wechsler Intelligence Scale for Children-III (WISC-III) and were randomly matched by age, race, and gender with healthy children from the Wechsler normative database. Patients were also imaged at 1.5 Tesla with standard imaging sequences. Among 30 patients who were normal by magnetic resonance imaging, there were substantial deficits in Wechsler Full-Scale IQ, Verbal IQ, and Performance IQ (all P < .01) compared with African-American controls. The patient Wechsler Full-Scale IQ was 12.9 points lower than that of controls and decreased as a function of age (probability = .014). The findings suggest that there is diffuse brain injury in patients and that patient deficits increase with age.

Stroke in children with sickle cell disease

Children with sickle disease are at high risk for ischemic stroke and transient ischemic attacks, usually secondary to intracranial arteriopathy involving the terminal internal carotid and proximal middle cerebral and anterior cerebral arteries, which may be diagnosed using transcranial Doppler ultrasound or magnetic resonance angiography (MRA). Other central nervous system (CNS) complications include seizures and coma, which may be secondary to ischemic stroke, sinovenous thrombosis, reversible posterior leukoencephalopathy, or acute demyelination. The immediate priority after an acute CNS event is to improve cerebral oxygenation with oxygen supplementation to maintain peripheral saturation measured using pulse oximetry between 96% and 99%, and a simple transfusion of packed cells within an hour of presentation if the patient's hemoglobin is less than 10 g/dL. The patient then should have erythrocytapheresis or manual exchange to reduce the hemoglobin S percentage to below 30%. Computed tomography to exclude hemorrhage is mandatory and MR T2-weighted imaging with MRA, fat-saturated imaging of the neck (dissection), MR venography (sinovenous thrombosis), and diffusion-weighted imaging usually distinguishes between arterial ischemic stroke and the differential diagnoses. Comatose patients with widespread focal or global cerebral edema may have good functional outcome after surgical decompression. Anticoagulation may be indicated for dissection or sinovenous thrombosis and steroids for demyelination. Blood pressure should be reduced slowly if raised in patients with reversible posterior leukoencephalopathy. Seizures should be treated aggressively and electroencephalogram monitoring should be done to exclude subclinical seizures if the patient is unconscious. Hemorrhagic stroke may require craniectomy and drainage and/or management of vasospasm. Interventional neuroradiology with coils is an alternative to surgical clipping for aneurysms. For secondary prevention, regular blood transfusion to hemoglobin S of less than 30% reduces the risk of recurrent stroke from approximately 67% to approximately 10%. Hydroxyurea and phlebotomy may be used in patients who are alloimmunized. Moyamoya syndrome is a risk factor for recurrence despite prophylactic blood transfusion. Revascularization may prevent additional stroke. Bone marrow transplantation may be offered to patients with human leukocyte antigen-compatible siblings. Blood transfusion prevents stroke in patients with velocities greater than 200 cm per second on TCD; a phase III trial studying the prevention of the progression of silent infarction is being done. Emerging primary prophylaxis regimens being tested include citrulline and arginine, aspirin, and overnight oxygen supplementation. Physicians caring for children with sickle cell disease also should ensure adequate nutrition, including five servings of fruit and vegetables a day. The role of vitamin supplementation is controversial, particularly when patients must take daily penicillin prophylaxis.

The clinical outcomes of neonatal and childhood stroke: review of the literature and implications for future research

A detailed assessment of clinical outcomes after ischemic stroke in childhood is necessary to evaluate prognostic factors. Previous studies are difficult to compare because of differences in test instruments, study design, heterogeneity of cohorts and number of included cases. Depending on neurodevelopmental assessment methods, major and subtle/minor disabilities, especially in infants, may not have been detected. Most outcome studies reveal only limited information about behavioral changes and quality of life in children with ischemic stroke. Thus the assumption that children make a better recovery from stroke than adults due to the immature brain's capacity to reorganize function is not evidence-based. We systematically review the current literature with regard to the neurological and psychosocial development of affected children as well as their quality of life. Implications for future research strategies follow the review to encourage further clinical study of the neurobehavioral trajectory of childhood stroke.

Central nervous system abnormalities in asymptomatic young patients with Sbeta-thalassemia

Twenty-one children and young adults with sickle/beta-thalassemia without overt stroke were examined with magnetic resonance imaging and angiography (MRA), transcranial Doppler (TCD), visual (VEP) and median nerve somatosensory (SEP)-evoked potential recordings, and neuropsychological testing (Wechsler Intelligence Scale [WISC-III]). Eight (38%) had silent infarction in the parietooccipital cortex, deep white matter, or basal ganglia, including two of three with previous seizures. Of 17 undergoing TCD, none had maximum middle cerebral artery (MCA) velocities greater than 126cm/sec, but 9 were abnormal, with low velocities and difficulty in tracking the MCA and/or asymmetry. Three patients had abnormal MRA, one of whom also had silent infarction. One patient had pathological VEP recordings, whereas all SEP recordings were normal. WISC-III was performed in all 11 children, 4 with silent infarction: all but 1 had IQ scores greater than 85 (mean, 97.7; standard deviation, 14.2). We conclude that Greek children and young adults with Sbeta-thalassemia and no history of clinical stroke have TCD abnormalities and silent infarction similar to those reported in children and adolescents with sickle cell anemia, but cognitive function is not necessarily compromised. International collaboration is needed to establish the risk factors for central nervous system sequelae in patients with sickle cell disease, including Sbeta-thalassemia, leading to evidence-based prevention.

Stroke and elevated blood flow velocity in the anterior cerebral artery in sickle cell disease

Transcranial Doppler ultrasonography provides a noninvasive method of predicting stroke risk in children with sickle cell disease. Elevated cerebral blood flow velocity in the terminal internal carotid or middle cerebral artery is associated with an increased stroke risk, but the clinical significance of elevated velocities in the other large intracranial vessels is unknown. The authors report stroke in two children with sickle cell disease and high blood flow velocity limited to the anterior cerebral artery. This suggests that elevated velocity in this vessel may be associated with an increased risk of stroke.

Validity of the WCST-64 After Traumatic Brain Injury in Children

The Wisconsin Card Sorting Test-64 (WCST-64) is a recently normed modification of the Wisconsin Card Sorting Test (WCST) that utilizes only one deck of cards. The present study investigated the validity of the WCST-64 in a sample of fifty-six 10- to 16-year-old children with traumatic brain injury (TBI). Standard scores for perseverative responses from the WCST-64 and from the full-length WCST shared 83% of common variance. Less than 10% of this sample had a discrepancy between the respective indexes that was greater than one standard deviation. Correlations with external criteria such as length of coma and Full Scale IQ were not significantly different between the two versions of the instrument. The findings suggest that the WCST-64 may be used interchangeably with the original WCST in older children with TBI.