Neuropsychologic performance in school-aged children with sickle cell disease: a report from the Cooperative Study of Sickle Cell Disease

Prevention and management of stroke in sickle cell anemia

As the overall health of patients with sickle cell anemia (SS) improves and diagnostic techniques become more sensitive, physicians are seeing patients with an increasingly wide range of subtle and not-so-subtle brain injury. The major breakthrough in the field of sickle-related brain injury has been the unprecedented success of transcranial Doppler ultrasonography (TCD) to identify asymptomatic patients at high risk of stroke, coupled with chronic transfusion therapy to prevent it. The evidence for TCD screening and preventive treatment is strong and compelling, but there are still important unanswered questions regarding the implications of "silent infarcts" found in the magnetic resonance images (MRIs) of asymptomatic individuals, and the growing awareness of the burden of neuropsychiatric dysfunction in otherwise apparently healthy individuals.

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.

Neurocognitive sequelae of sickle cell disease: current issues and future directions

Sickle cell disease is a genetic disorder with an autosomal recessive pattern of inheritance. This disease is most prevalent among those of African American and Mediterranean descent. Cerebral vascular accident (CVA) or stroke is one of the major complications of hemoglobin SS (Hgb SS) disease. CVA has implications for physical as well as neurocognitive function for children. Recent literature suggests that some children with sickle cell disease without overt signs of CVA may still have evidence of neurological deficit, both on magnetic resonance imaging and neurological examination. There is a growing body of knowledge that further aids in delineation of risk factors for CVA, silent infarct, and neurocognitive deficits in children with Hgb SS disease. More research is needed to continue to explore avenues for identification and intervention. The purpose of this article is to delineate areas of ongoing research in this important area.

Psychological complications in sickle cell disease

This review examines the evidence for some of the common psychological complications found across the life span of patients with sickle cell disease (SCD), which are likely to be encountered by haematologists responsible for their medical management. Electronic searches of medical and psychological databases were conducted with a focus on three main areas: psychological coping, quality of life and neuropsychology. Psychological complications were identified in both children and adults with SCD, and included inappropriate pain coping strategies; reduced quality of life owing to restrictions in daily functioning, anxiety and depression; and neurocognitive impairment. There were wide variations in design and consistency of the studies, therefore, some caution needs to be observed in the findings. Moreover, interventional studies were lacking in some areas such as neuropsychology. Utilization of psychological interventions including patient education, cognitive behavioural therapy, and special educational support to help improve the quality of life of patients are recommended.

Stroke in sickle cell disease in Africa: case report

Stroke, including asymptomatic cerebrovascular events, is a significant cause of morbidity and mortality in sickle cell disease, occurring with an incidence of 10 to 25%. Extensive research has established that cerebral stenosis, involving the circle of Willis, is the most common mechanism in children. We report a child with sickle cell disease who presented with cortical blindness and right-sided hemiplegia. Computerised tomography of the brain revealed an infarct involving the left parietal region and extending to the occipital region. Stroke in SCD is multifactorial, but high-risk individuals can be identified by simple well-established strategies such as transcranial doppler ultrasonography. There are approaches for both primary and secondary interventions, which have been shown to be effective and need to be incorporated into management guidelines for SCD patients. Before schemes are recommended into health care policies, research in the appropriate setting is required.

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.

Interactions of biomedical and environmental risk factors for cognitive development: a preliminary study of sickle cell disease

Sickle cell disease (SCD) is associated with a number of biopsychosocial risk factors for cognitive development. Understanding how these risk factors may interact is important for developing interventions for cognitive functioning. The authors assessed the cognitive abilities of children with SCD (n = 50) and related their performance to anemia severity, socioeconomic status (SES), and their interaction. Demographically matched peers without SCD (n = 36) served as a comparison group. Four areas of cognitive weakness were identified among children with SCD: general cognitive ability, crystallized ability, short-term memory, and processing speed. Anemia severity predicted general cognitive ability, crystallized ability, and processing speed. Interactions between anemia severity and SES were found for general cognitive ability and short-term memory. Disease effects in SCD appear to vary depending on the child's level of socioenvironmental risk. Biomedical interventions to benefit cognitive functioning may have different effects depending on whether additional socioenvironmental risk factors are present.

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.

Pseudotumor cerebri in children with sickle cell disease: a case series

Headache is a frequent symptom in sickle cell disease (SCD) that usually is attributable to anemia or cerebrovascular disease. We report 3 pediatric patients with SCD (1 patient with SCD-SC and 2 patients with SCD-SS) who presented with headache and were diagnosed with pseudotumor cerebri (PC). All 3 patients had elevated opening pressures during a lumbar puncture with normal cerebrospinal fluid studies. Magnetic resonance imaging revealed no evidence of hydrocephalus or arteriopathy in all 3 cases. Magnetic resonance venograms performed in 2 of the patients at diagnosis revealed no evidence of cerebral sinus thrombosis. Each patient received a thorough ophthalmologic examination. A diagnostic funduscopic examination revealed bilateral papilledema without signs of retinopathy in all 3 patients. There were no clinically significant changes in visual acuity or abnormalities of color vision in any patient. Goldmann or Humphrey visual-field assessment was abnormal only in patient 1, who demonstrated bilaterally enlarged blind spots at diagnosis and later developed reduced sensitivity in the inferomedial quadrant of the left eye in an arcuate pattern (which later resolved). The diagnosis of PC was made in all 3 patients, and acetazolamide treatment was started. Two of the patients' symptoms resolved completely with medical treatment, whereas the third patient's symptoms improved. None of these patients had permanent visual-field deficits as a result of their syndrome. PC has been reported in several other types of anemia including SCD-SC, but these cases are the first reported in conjunction with pediatric SCD. Early recognition of the signs and symptoms of PC in patients with SCD who present with headache can expedite proper diagnosis and treatment and prevent long-term ophthalmologic sequelae.

Silent Brain Infarcts in Patients With Manifest Vascular Disease

Background and Purpose— Silent infarcts are frequently found on MRIs of brains of healthy elderly persons (aged >60 years). The purpose of this study was to investigate the prevalence and determinants of silent infarcts in a population of patients with clinically manifest vascular disease.

Methods— To detect silent infarcts, MR images were made in 308 participants of the Second Manifestations of ARTerial disease (SMART) study (mean age, 58 years) without prior stroke or transient ischemic attack. These are patients referred to the University Medical Center Utrecht because of atherosclerotic vascular disease. Risk factors were assessed by questionnaire and by physical, ultrasonographic, and laboratory examinations.

Results— Silent infarcts were found in 51 patients (17%). Most infarcts (62%) were located in white matter, 20% in basal ganglia, 14% in brain stem and cerebellum, and 4% in cortical area. Categorical determinants for presence of silent infarct(s) that remained (borderline) significant after adjustment for age were hypertension (odds ratio [OR]=2.2; 95% CI, 1.2 to 4.2), abdominal aortic aneurysm (OR=2.4; 95% CI, 0.9 to 6.4), severe renal failure (OR=7.3; 95% CI, 2.1 to 25.2), and hyperhomocysteinemia (OR=2.6; 95% CI, 1.1 to 5.9).

Conclusions— Patients with manifest vascular disease are at risk for silent infarcts at a younger age. In particular, patients with the aforementioned risk factors should be considered for treatment or (secondary) prevention.

Prospective brain imaging evaluation of children with sickle cell trait: initial observations

PURPOSE

To determine whether sickle cell trait (hemoglobin AS) is associated with abnormalities in the brain of asymptomatic children.

MATERIALS AND METHODS

Magnetic resonance (MR) imaging and MR angiography were performed prospectively in 26 siblings (eight girls, 18 boys; mean age, 10.5 years) of patients with sickle cell disease. Two neuroradiologists, blinded as to whether a child had hemoglobin AS or AA, reviewed images obtained in siblings. With MR imaging, lacunae, loss of white matter volume, encephalomalacia, or leukoencephalopathy was identified. With MR angiography, arterial stenosis, occlusion, or tortuosity was identified. Images with definite or possible abnormalities were mixed with randomly selected images and were referred to a third neuroradiologist for a completely blinded review. In cases in which all neuroradiologists concurred, a score was assigned that indicated the sibling had an abnormality. MR angiographic findings were assigned a score for tortuosity with a new quantitative scale.

RESULTS

Among 26 siblings screened, 21 children had sickle cell trait. Among these 21 children, two had mild abnormalities at MR imaging (sample prevalence rate, 10% [95% CI: 1%, 29%]), and four had arterial tortuosity (sample prevalence rate, 19% [95% CI: 5%, 42%]). When children with sickle cell trait were compared with 31 control subjects without the trait, arterial tortuosity was significantly more common in children with sickle cell trait (P =.014). Among children with sickle cell trait, percentage of hemoglobin S was significantly greater in children who had tortuosity than percentage of hemoglobin S in children who had normal blood vessels at MR angiography (P <.03).

CONCLUSION

Findings suggest that greater percentage of hemoglobin S is associated with mild vasculopathy. This vasculopathy may explain some of the excess risk of stroke among African Americans.

Psychosocial and Neurocognitive Aspects of Sickle Cell Disease

Sickle cell disease (SCD) comprises a group of recessively inherited blood disorders and is the most common genetic disorder in the world (Embury et al., 1994). It is a chronic condition of variable severity that mainly affects people of African and African-Caribbean heritage. Over the last 20 years life expectancy has increased significantly, particularly for patients receiving western healthcare so that increasing attention has been directed to the psychosocial adaptation and neurocognitive profile of children and adolescents with SCD. Previously, research suggested that, like children with other chronic health conditions, children and adolescents with SCD were at increased risk for emotional and behavioural disorders. More recent research has not demonstrated increased rates of such difficulties. Increasing evidence suggests that children with severe disease are, however, at significantly increased risk for cerebro-vascular events and neurocognitive difficulties. This paper reviews the literature regarding the psychological and neurocognitive functioning of children with SCD and outlines a number of ways that psychological input may significantly contribute to more effective health care for these children and their families.

[Sickle cell anemia: experience in a center]

BACKGROUND

Sickle cell anemia is a structural hemoglobinopathy in which morphological and physical changes in erythrocytes cause vaso-occlusive episodes in various organs and tissues. The disease is common among blacks and the African population. As a result of the growing migratory flow, this is an emerging disease in Spain.

OBJECTIVE

To present the casuistics of a pediatric hospital: clinical onset, the most frequent features and complications, and treatment.

MATERIAL AND METHODS

We performed a retrospective study of 22 patients aged less than 18 years old diagnosed with sickle cell anemia between January 1985 and December 2001. Epidemiologic data, symptoms, complications, blood test results, treatment, and response were recorded.

RESULTS

The mean age of the patients was 39 months. In 54 %, diagnosis was established before the age of 2 years. No differences were found in sex. The countries of origin were Gambia in 32 %, Morocco in 23 %, and Senegal in 18 % as well as other African and Central America countries; 53 % of the children were born in Spain. The most common complaint was vaso-occlusive pain localized in the abdomen (45 %). The most frequent complications were infections and 13.7 % suffered stroke. Twenty-eight percent of the patients diagnosed before the age of 2 years presented complications. Eleven patients received hydroxyurea for recurrent vaso-occlusive crises with favorable results; one patient underwent splenectomy and another received an allogenic bone marrow transplant from an HLA-identical brother with excellent results.

CONCLUSIONS

This study reproduces the data described in the literature from countries with a high prevalence of the disease. Morbidity could be minimized by early diagnosis and preventive treatment and good healthcare. Given the increasing incidence of the disease, screening of black and African neonates and genetic counseling are recommended together with guidelines for prompt and appropriate treatment in primary health centers and emergency departments.

Sickle cell and the brain

Sickle cell disease affects many organ systems, but one of the major morbidities is brain disease, especially stroke. In this paper, the etiology, diagnosis, treatment, and prevention of clinical stroke, as well as so-called "silent stroke," are examined. Risk factors, diagnostic tools, and data from prevention and treatment studies as well as issues pertaining to neuropsychological function, especially in younger patients, are discussed and current best options for treatment considered.