Relationship of structural magnetic resonance imaging, magnetic resonance perfusion, and other disease factors to neuropsychological outcome in sickle cell disease

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.

Cognitive Functioning and Educational Support Plans in Youth With Sickle Cell Disease

Children with sickle cell disease (SCD) face academic challenges because of direct and indirect disease-related events. This study examined the proportion of youth with SCD with educational plans and whether cognitive functioning is associated with educational support. Ninety-one youth (7 to 16 y) with SCD completed the WISC-V; caregivers reported educational support (504 Plan/Individualized Education Program) and completed the Behavior Rating Inventory of Executive Function. χ2 square and t test analyses explored whether overall intelligence (full-scale intelligence quotient [FSIQ]), relative weaknesses in processing speed and working memory (> 1SD below FSIQ), and parent-reported executive functioning were associated with educational plans. Participants with a FSIQ<90 were more likely to have support (74%) compared with youth with a FSIQ≥90 (47%; P=0.012). Those with FSIQ≥90 and FSIQ=80 to 89 were less likely to have support (47%, 58%, respectively) compared with those with FSIQ≤79 (89%; P=0.004). Relative weaknesses in processing speed were associated with educational support (83% vs. 52%, P=0.018) as well as behavioral aspects of executive functioning (Ps<0.05). Despite universal eligibility for a 504 Plan, 42% of youth with SCD in our sample did not have educational support. Significant deficits in intellectual functioning, processing speed, and parent-observed executive functioning are associated with having a plan, but children with subtle deficits seem less likely to be identified for educational support.

MRI detection of brain abnormality in sickle cell disease

Introduction: Over the past decades, neuroimaging studies have clarified that a significant proportion of patients with sickle cell disease (SCD) have functionally significant brain abnormalities. Clinically, structural magnetic resonance imaging (MRI) sequences (T2, FLAIR, diffusion-weighted imaging) have been used by radiologists to diagnose chronic and acute cerebral infarction (both overt and clinically silent), while magnetic resonance angiography and venography have been used to diagnose arteriopathy and venous thrombosis. In research settings, imaging scientists are increasingly applying quantitative techniques to shine further light on underlying mechanisms.Areas covered: From a June 2020 PubMed search of 'magnetic' or 'MRI' and 'sickle' over the previous 5 years, we selected manuscripts on T1-based morphometric analysis, diffusion tensor imaging, arterial spin labeling, T2-oximetry, quantitative susceptibility, and connectivity.Expert Opinion: Quantitative MRI techniques are identifying structural and hemodynamic biomarkers associated with risk of neurological and neurocognitive complications. A growing body of evidence suggests that these biomarkers are sensitive to change with treatments, such as blood transfusion and hydroxyurea, indicating that they may hold promise as endpoints in future randomized clinical trials of novel approaches including hemoglobin F upregulation, reduction of polymerization, and gene therapy. With further validation, such techniques may eventually also improve neurological and neurocognitive risk stratification in this vulnerable population.

Do chronic pain and comorbidities affect brain function in sickle cell patients? A systematic review of neuroimaging and treatment approaches

Sickle cell disease (SCD) is a medical condition in which chronic pain is common and negatively impacts psychosocial function and quality of life. Although the brain mechanisms underlying chronic pain are well studied in other painful conditions, the brain mechanisms underlying chronic pain and the associated psychosocial comorbidities are not well established in SCD. A growing literature demonstrates the effect of treatment of chronic pain, including pharmacological and nonpharmacological treatments, on brain function. The present systematic review aimed to (1) determine the effects of chronic pain and psychosocial comorbidities on brain function of patients with SCD; (2) summarize pharmacological and nonpharmacological approaches to treat these symptoms; and (3) identify areas for further investigation of potential beneficial effects of treatments on brain function. Titles were screened using predefined criteria, including SCD, and abstracts and full texts were reviewed by 2 independent reviewers. A total of 1167 SCD articles were identified, and 86 full articles were included covering 3 sections: chronic pain (4 studies), psychosocial comorbidities (11 studies), and pharmacological and nonpharmacological treatments (71 studies). Neuroimaging evidence demonstrates aberrant neural processing related to chronic pain and psychosocial comorbidities in SCD beyond ischemic stroke and cerebral hemorrhage. Although neuroimaging studies show an important role for psychological factors, pain management is nearly exclusively based on opioids. Behavior therapy seems useful to improve psychological symptoms as well as chronic pain and quality of life. Further investigation is required with larger cohorts, matched controls, and examination of treatment-related neural mechanisms.

Visual Motor Integration in Children With Sickle Cell Disease

BACKGROUND

Children with sickle cell disease (SCD) demonstrate deficits in cognitive and academic functioning. This study compared the visual motor integration (VMI) skills of children with SCD to non-SCD sibling controls.

PROCEDURE

In total, 105 participants (67 patients with SCD, 38 controls) were recruited during a routine clinic visit. Each participant was administered the Grooved Pegboard Test, a test of manual dexterity and the Beery-Buktenica Developmental Test of VMI, a measure of graphomotor skills.

RESULTS

Children with SCD demonstrated average (M=89.61, SE=3.08) fine manual dexterity and speed, but more complex fine motor functioning (graphomotor skills) (M=77.61, SE=1.65) was impaired. Relative to healthy siblings, children with SCD were not found to have different fine manual dexterity and speed (P=0.617). Patients with SCD were found to have significantly worse graphomotor skills (P=0.04).

CONCLUSIONS

Children with SCD were found to have average basic fine motor dexterity and speed, but impaired VMI, a more complex fine motor skill. This finding is significant given the functional importance of complex fine motor skills in early academic activities.

Cerebral perfusion characteristics show differences in younger versus older children with sickle cell anaemia: Results from a multiple-inflow-time arterial spin labelling study

Sickle cell anaemia (SCA) is associated with chronic anaemia and oxygen desaturation, which elevate cerebral blood flow (CBF) and increase the risk of neurocognitive complications. Arterial spin labelling (ASL) provides a methodology for measuring CBF non-invasively; however, ASL techniques using only a single inflow time are not sufficient to fully characterize abnormal haemodynamic behaviour in SCA. This study investigated haemodynamic parameters from a multi-inflow-time ASL acquisition in younger (8-12 years) and older (13-18 years) children with SCA with and without silent cerebral infarction (SCI+/-) (n = 20 and 19 respectively, 6 and 4 SCI+ respectively) and healthy controls (n = 9 and 7 respectively). Compared with controls, CBF was elevated globally in both groups of patients. In the younger SCA patients, blood oxygen content was negatively correlated with CBF in the middle and posterior cerebral artery territories and significantly positively correlated with bolus arrival time (BAT) in the anterior and middle cerebral artery territories. In older children, SCA patients had significantly shorter BAT than healthy controls and there was a significant negative correlation between CBF and oxygen content only in the territory of the posterior cerebral artery, with a trend for a correlation in the anterior cerebral artery but no relationship for the middle cerebral artery territory. In the younger group, SCI+ patients had significantly higher CBF in the posterior cerebral artery territory (SCI+ mean = 92.78 ml/100 g/min; SCI- mean = 72.71 ml/100 g/min; F = 4.28, p = 0.04), but this no longer reached significance when two children with abnormal transcranial Doppler and one with haemoglobin SC disease were excluded, and there were no significant differences between patients with and without SCI in the older children. With age, there appears to be increasing disparity between patients and controls in terms of the relationship between CBF and oxygen content in the anterior circulation, potentially predicting the risk of acute and chronic compromise of brain tissue.

Implications of a paediatrician-psychologist tandem for sickle cell disease care and impact on cognitive functioning

Sickle cell disease (SCD), a life-threatening chronic disease, necessitates a paediatric treatment plan that considers the influence of psychological, family and intercultural factors. At the Louis-Mourier Hospital (APHP) in Colombes, France, we introduced an original paediatric-psychological partnership where a clinical psychologist accompanies the paediatrician at programmed consultations. We evaluated children and their parents treated in Colombes and in two other paediatric units using standardized culture-free tools and clinical interviews to evaluate the psychological repercussions of SCD. We first present a global view of the different ways that SCD affects both children and their families. We then discuss findings from a study evaluating the overall efficacy of an integrated psycho-medical treatment model as compared to the usual medical care model. Children in the integrated care model improved their cognitive functioning assessed using the Rey-Osterrieth complex figure test compared to treatment as usual.

CONCLUSION

Findings suggest that the concept of a "partnership practice" can improve children's ability to grapple with SCD and is a promising approach for long-term care of SCD. What is Known: • Painful crises of sickle cell disease are unpredictable and appear in early childhood • Stress as well as the complex psychological and intercultural issues associated with SCD may aggravate the children's symptoms • Standard pediatric care and research deal primarily with medical issues What is New: • Evidence-based research examining the psychological repercussions of SCD in pediatric treatment as well as the parental distress • First study using standardized culture-free tools • Cognitive functioning improves under an innovative "partnership" model.

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.

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.

Cerebral blood flow abnormalities in children with sickle cell disease: a systematic review

A systematic review was performed to assess whether cerebral blood flow with different imaging modalities could identify brain abnormalities in children with sickle cell disease where structural magnetic resonance imaging and transcranial Doppler velocity appeared normal. A total of 11 studies were identified which reported cerebral blood flow abnormalities alongside structural magnetic resonance imaging or transcranial Doppler velocity abnormalities in patients with sickle cell disease. Potential for bias was assessed with the quality assessment of diagnostic accuracy studies scale in addition to treatment bias. Subjects of each study were categorized into patients with and without stroke. The prevalence of abnormalities for each modality was then separately calculated in each group. The included studies had mostly moderate degrees of bias. The prevalence of blood flow abnormalities compared with structural magnetic resonance imaging abnormalities was equal to or lower in patients with stroke and equal to or greater in patients without stroke. Blood flow abnormalities were more prevalent than transcranial Doppler abnormalities in four studies of patients without stroke and in one study of patients with stroke. The studies suggest that the assessment of cerebral blood flow in sickle cell disease can be of potential value in addressing brain abnormalities at the tissue level; however, further studies are warranted.

Association of Pulsatility Index in the Middle Cerebral Artery with Intelligence Quotient in Children with Sickle Cell Disease

The aim of this study was to explore whether intellectual performance in children with Sickle Cell Disease and with low risk of stroke as determined with conventional transcranial Doppler ultrasonography (TCD) criteria was associated with hemodynamic parameters in imaging TCD, when controlling for hematological and socio-economical variables and presence of silent infarcts. We performed neuropsychological testing with Kaufman Brief Intelligence Test (K-BIT-IQ) and imaging TCD examinations to measure blood flow velocities and pulsatility indexes (PI) in the middle cerebral arteries (MCA) In 46 children with homozygous HbSS (mean age 108±34 months, range limits: 47–166 months; 24 females), without a history of stroke or transient ischemic attack, with no stenosis on magnetic resonance angiography and with velocities below 170 cm/s in screening conventional TCD. Mean K-BIT IQ Composite and Vocabulary scores (91±13 and 86±14 respectively) were significantly below the average scores of 100 for the age-matched population (one sample t-test=5.21, p<0.001). Using univariate and multivariate regression models, we found that lower PI in the right MCA was associated with lower K-BIT-IQ Composite and Vocabulary scores. Furthermore, we found that interhemispheric differences in PIs were even more strongly associated with neuropsychological performance, whereas flow velocities were not associated with the K-BIT-IQ score. Using a model of chronic anemia, we found that cognitive functioning was associated with cerebral hemodynamics.

Magnetic resonance imaging abnormalities in children with epilepsy

BACKGROUND AND PURPOSE

The aim of this study is to analyze the proportional distribution of epilepsy and epileptic syndromes in children and to describe the magnetic resonance imaging (MRI) abnormalities found in these patients.

METHODS

Data from 457 children aged 1 month to 15 years at the time of diagnosis of epilepsy were recorded. A routine MRI has been requested in all patients with epilepsy at diagnosis according to a standardized pediatric seizure protocol. Abnormalities on MRI were classified as either significant or non-significant (standardized scoring system). International League Against Epilepsy criteria were used for diagnoses.

RESULTS

The prevalence of significant MRI abnormalities was 21.9% (in infants 42.3%, in childhood 18.2%, and in adolescents 15.9%). The most common abnormalities included white-matter lesions (27.6%), volume loss (19.6%), gray-matter lesions (19.6%), and ventricular enlargement (12%).

CONCLUSIONS

The use of MRI and a reliable standardized scoring system at diagnosis of epilepsy in children identified a high rate of significant abnormalities findings. This may have important implications for practice guidelines in this population.

Safety of gadolinium-based contrast material in sickle cell disease

PURPOSE

To assess the safety of intravenously administered gadolinium-based contrast material in sickle cell disease (SCD) patients.

MATERIALS AND METHODS

All pediatric and adult SCD patients evaluated by magnetic resonance imaging (MRI) at our institution between January 1995 and July 2009 were identified. The medical records of SCD patients who underwent contrast-enhanced MRI as well as an equal-sized cohort of SCD patients who underwent unenhanced MRI were reviewed for adverse (vaso-occlusive and hemolytic) events within 1 week following imaging.

RESULTS

Eight (five mild and three moderate) adverse events were documented within 1 week following contrast-enhanced MRI (38 patients and 61 contrast injections), while six (five mild and one moderate) similar events occurred within 1 week following unenhanced MRI (61 patients and 61 unenhanced MRI examinations). This difference in the number of adverse events was not statistically significant (odds ratio = 1.4; 95% confidence interval [CI] 0.4, 5.2). No severe adverse event occurred in either patient cohort.

CONCLUSION

Gadolinium-based contrast materials do not appear to be associated with increased risk of vaso-occlusive or hemolytic adverse events when administered to SCD patients. Larger, prospective studies using multiple gadolinium-based contrast materials would be useful to confirm the results of our investigation.

Neurocognitive deficits in children with sickle cell disease: a comprehensive profile

BACKGROUND

Sickle cell disease (SCD) can lead to profound cerebral damage, associated with neurocognitive deficits. The aim of the current study was to evaluate a broad range of neurocognitive functions in children with SCD compared to a SES-matched control group, in order to gain more insight into the specific deficits of these patients.

METHODS

Forty-one children with homozygous SCD (HbSS or HbS-β0-thalassemia) and 38 controls were assessed on a comprehensive set of well-defined and validated measures of neurocognitive functioning. Besides general intelligence, we evaluated executive functioning extensively (including response inhibition, sustained attention, planning, visuo-spatial working memory, and verbal working memory) as well as visuo-motor functioning.

RESULTS

SCD was clearly associated with lower IQ scores. More than one in three children with SCD had a Full-scale IQ below 75. Furthermore, children with SCD showed deficits in visuo-motor functioning. Some evidence was found for executive dysfunction: Children with SCD displayed poor visuo-spatial working memory, as well as subtle deficits in sustained attention and planning. No significant differences were found between children with SCD and controls in terms of response inhibition and verbal working memory.

CONCLUSIONS

Children with SCD are at increased risk of lower intelligence, visuo-motor impairments, and executive dysfunction. These neurocognitive deficits may underlie high rates of scholastic impairments in these children. The present findings further illuminate the importance of regular neurocognitive evaluations and future neurocognitive rehabilitation programs for children with SCD.

Neuropsychological dysfunction and neuroimaging abnormalities in neurologically intact adults with sickle cell anemia

CONTEXT

Sickle cell anemia (SCA) is a chronic illness causing progressive deterioration in quality of life. Brain dysfunction may be the most important and least studied problem affecting individuals with this disease.

OBJECTIVE

To measure neurocognitive dysfunction in neurologically asymptomatic adults with SCA vs healthy control individuals.

DESIGN, SETTING, AND PARTICIPANTS

Cross-sectional study comparing neuropsychological function and neuroimaging findings in neurologically asymptomatic adults with SCA and controls from 12 SCA centers, conducted between December 2004 and May 2008. Participants were patients with SCA (hemoglobin [Hb] SS and hemoglobin level < or = 10 mg/dL) aged 19 to 55 years and of African descent (n = 149) or community controls (Hb AA and normal hemoglobin level) (n = 47). Participants were stratified on age, sex, and education.

MAIN OUTCOME MEASURES

The primary outcome measure was nonverbal function assessed by the Wechsler Adult Intelligence Scale, third edition (WAIS-III) Performance IQ Index. Secondary exploratory outcomes included performance on neurocognitive tests of executive function, memory, attention, and language and magnetic resonance imaging measurement of total intracranial and hippocampal volume, cortical gray and white matter, and lacunae.

RESULTS

The mean WAIS-III Performance IQ score of patients with SCA was significantly lower than that of controls (adjusted mean, 86.69 for patients with SCA vs 95.19 for controls [mean difference, -5.50; 95% confidence interval {CI}, -9.55 to -1.44]; P = .008), with 33% performing more than 1 SD (<85) below the population mean. Among secondary measures, differences were observed in adjusted mean values for global cognitive function (full-scale IQ) (90.47 for patients with SCA vs 95.66 for controls [mean difference, -5.19; 95% CI, -9.24 to -1.13]; P = .01), working memory (90.75 vs 95.25 [mean difference, -4.50; 95% CI, -8.55 to -0.45]; P = .03), processing speed (86.50 vs 97.95 [mean difference, -11.46; 95% CI, -15.51 to -7.40]; P < .001), and measures of executive function. Anemia was associated with poorer neurocognitive function in older patients. No differences in total gray matter or hippocampal volume were observed. Lacunae were more frequent in patients with SCA but not independently related to neurocognitive function.

CONCLUSION

Compared with healthy controls, adults with SCA had poorer cognitive performance, which was associated with anemia and age.

Magnetic resonance imaging findings in children with a first recognized seizure

This study characterized structural abnormalities associated with onset of seizures in children, using magnetic resonance imaging and a standardized classification system in a large prospective cohort. Two hundred eighty-one children aged 6-14 years completed magnetic resonance imaging within 6 months of their first recognized seizure. Most examinations were performed with a standardized, dedicated seizure protocol; all were scored using a standard scoring system. At least one magnetic resonance imaging abnormality was identified in 87 of 281 (31%) children with a first recognized seizure. Two or more abnormalities were identified in 34 (12%). The commonest abnormalities were ventricular enlargement (51%), leukomalacia/gliosis (23%), gray-matter lesions such as heterotopias and cortical dysplasia (12%), volume loss (12%), other white-matter lesions (9%), and encephalomalacia (6%). Abnormalities defined as significant, or potentially related to seizures, occurred in 40 (14%). Temporal lobe and hippocampal abnormalities were detected at a higher frequency than in previous studies (13/87). Magnetic resonance imaging and a standardized, reliable, valid scoring system demonstrated a higher rate of abnormal findings than previously reported, including findings formerly considered incidental. Practice parameters may need revision, to expand the definition of significant abnormalities and support wider use of magnetic resonance imaging in children with newly diagnosed seizures.

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.

Neuropsychological assessment, neuroimaging, and neuropsychiatric evaluation in pediatric and adult patients with sickle cell disease (SCD)

Traditionally, neuropsychological deficits due to Sickle Cell Disease (SCD) have been understudied in adults. We have begun to suspect, however, that symptomatic and asymptomatic Cerebrovascular Events (CVE) may account for an alarming number of deficits in this population. In the current brief review, we critically evaluated the pediatric and adult literatures on the neurocognitive effects of SCD. We highlighted the studies that have been published on this topic and posit that early detection of CVE via neurocognitive testing, neuropsychiatric evaluations, and neuroimaging may significantly reduce adult cognitive and functional morbidities.

Cognitive visual impairment with good visual acuity in children with posterior periventricular white matter injury: a series of 7 cases

BACKGROUND

We describe a series of term and preterm children with occipito-parietal periventricular white matter abnormalities on magnetic resonance imaging (MRI) who manifest common clinical features of cognitive visual dysfunction. We also describe a strategy for taking clinical history that highlights the symptom complex and assists with management.

PATIENTS AND METHODS

A retrospective observational case series study of seven children with cognitive visual difficulties despite good (20/32 or better) visual acuities and MRI findings of periventricular white matter pathology in the territory subserving visual function. Structured history taking was used to identify and characterize the visual difficulties. Objective clinical findings (visual acuity, color vision, stereoacuity, visual fields, ocular motility, refraction, and fundoscopy) were recorded.

RESULTS

Seven children with visual acuities of 20/32 (0.200 logMAR) or better had symptoms of cognitive visual difficulties consistent with dorsal stream dysfunction. Four had strabismus of different types and were identified on the basis of parental concern expressed at the ocular motility clinic. The other three children presented to the general ophthalmology clinic. All seven children had various degrees of focal periventricular white matter pathology in a similar distribution on neuroimaging.

CONCLUSIONS

Children born prematurely are susceptible to periventricular white matter pathology. Such pathology can also occur in children born at term. This case series demonstrates that cognitive visual impairment due to periventricular white matter injury can occur despite good central visual function. A range of strategies to help affected children is described.

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.

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.

Pediatric Perfusion MR Imaging Using Arterial Spin Labeling

Cerebral blood flow (CBF, cerebral perfusion) mirrors cerebral metabolic demand and neuronal function, and therefore, is a vital parameter in the evaluation of pediatric brain injury and recovery. Until recently, measurement of CBF involved intravenous bolus injection of contrast agents or nuclear medicine methods that were technically difficult or ethically problematic in pediatrics. The development of arterial spin label (ASL) perfusion MR imaging as a noninvasive method for measuring CBF allows for the increased ability to measure this vital physiologic parameter in any age group. This article presents the technical aspects of performing ASL perfusion MR imaging in pediatrics, and discusses its current use in clinical studies and its potential for influencing important management strategies in specific disease entities.

MRI/MRA evaluation of sickle cell disease of the brain

Sickle cell disease is a major cause of pediatric stroke. Understanding the disease that affects the brain as infarctions, both clinically apparent and silent, requires an understanding of how the blood vessels are affected, the way in which both the brain and the blood vessels are imaged by MRI and MRA and the mechanism of injury.