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Saunthararajah Y, Vichinsky EP. Sickle Cell Disease. Hematology 2018. [DOI: 10.1016/b978-0-323-35762-3.00042-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
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Martins ACP, Silva GS, Adegoke SA, Rodrigues DLG, Braga JAP, Figueiredo MS. An unexpected full neurological recovery after cardiac arrest in a sickle cell anemia patient with bilateral cervical carotid artery disease. Rev Bras Hematol Hemoter 2015; 37:272-4. [PMID: 26190434 PMCID: PMC4519709 DOI: 10.1016/j.bjhh.2015.04.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2015] [Revised: 04/16/2015] [Accepted: 04/16/2015] [Indexed: 11/15/2022] Open
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Majumdar S, Webb S, Norcross E, Mannam V, Ahmad N, Lirette S, Iyer R. Stroke with intracranial stenosis is associated with increased platelet activation in sickle cell anemia. Pediatr Blood Cancer 2013; 60:1192-7. [PMID: 23509099 DOI: 10.1002/pbc.24473] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/01/2012] [Accepted: 12/17/2012] [Indexed: 12/21/2022]
Abstract
BACKGROUND Overt stroke in sickle cell anemia (SCA) is associated with intracranial stenosis and thrombus formation. Platelet activation is critical for thrombus formation. PROCEDURE Platelet activation studies were performed in 50 subjects: 18 SCA patients with history of stroke or abnormal transcranial Doppler (TCD) and intracranial stenosis seen by magnetic resonance angiogram (MRA), 7 SCA patients with history of stroke or abnormal TCD but no intracranial stenosis, 13 SCA patients with no history of stroke or abnormal TCD, and 12 healthy African-Americans. RESULTS Of the 18 patients with intracranial stenosis, 11 (61%) had evidence of the moyo-moya phenomenon on MRA. SCA children with intracranial stenosis had a significantly greater total white cell count compared to both healthy African-American controls and SCA patients in the steady-state (P < 0.001). In addition, SCA patients with history of stroke or abnormal TCD had a significantly higher platelet count compared to healthy African-American controls (P < 0.002). The percentage of platelet surface P-selectin expression was significantly greater in patients with intracranial stenosis compared to the other groups (P < 0.05), particularly in individuals that did not have the moya-moya phenomenon seen on MRA. CONCLUSION Stroke with intracranial stenosis is associated with increased platelet activation in sickle cell anemia, and further investigation is needed on the role of anti-platelet agents in this high-risk population.
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Affiliation(s)
- Suvankar Majumdar
- Department of Pediatrics, University of Mississippi Medical Center, Jackson, Mississippi 39216, USA.
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Lyle CA, Bernard TJ, Goldenberg NA. Childhood arterial ischemic stroke: a review of etiologies, antithrombotic treatments, prognostic factors, and priorities for future research. Semin Thromb Hemost 2011; 37:786-93. [PMID: 22187401 DOI: 10.1055/s-0031-1297169] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022]
Abstract
Childhood arterial ischemic stroke (AIS) is a rare, but serious, medical condition, which is fatal in approximately 3% and associated with both acute and long-term neurologic impairment in over 70% of cases. Common etiologies include sickle cell disease, congenital heart disease, arterial dissection, prothrombotic conditions, and preceding viral infections; however, one in four cases is considered idiopathic. To date, no randomized controlled clinical trials (RCTs) have been conducted to establish evidence for current therapeutic strategies outside of sickle cell disease, thus, treatment strategies are largely shaped by consensus-based guidelines, in which, beyond the acute period, aspirin is the mainstay of therapy and anticoagulation is reserved for select circumstances. In recent years, evidence on prognostic factors has accumulated, helping to inform the future design of prognostically stratified RCTs. In this narrative review, we discuss the current understanding of etiologies, consensus-based treatment recommendations, contemporary treatment data, and prognostic factors in childhood AIS. We also identify priorities for future research.
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Affiliation(s)
- Courtney A Lyle
- Division of Hematology/Oncology, Department of Pediatrics, University of California, San Diego, California, USA.
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Abstract
Cervical internal carotid artery (cICA) occlusion is a recognized cause of acute ischemic stroke (AIS) in sickle cell disease (SCD), but the associated clinical and radiologic features are not well described. We reviewed data on cervical magnetic resonance angiography (cMRA) performed prospectively in 67 patients (55 children) for indications including transcranial Doppler (TCD) abnormalities, AIS, or previous AIS. cICA lesions were seen in 10 (15%) patients, including 4 of 7 patients presenting with AIS, and appear to have been missed on first presentation in 4 of 10 patients with previous AIS. Radiologic features in 7 patients were consistent with dissection. In 2 patients, there was strong clinical and radiologic evidence for thromboembolic AIS, and this was also considered possible in 4 other patients. Three of the 4 AIS patients were anticoagulated acutely, and the nontreated patient had recurrent, probably thromboembolic, AIS. TCD findings were variable, but in 4 patients there were high velocities in the cerebral vessels contralateral to the cICA stenosis. We suggest that all patients with AIS should have cMRA during acute evaluation to identify cICA occlusions that may require anticoagulation. Routine screening of children with SCD should also include evaluation of neck vessels by carotid Doppler followed by cMRA if a cervical vascular lesion is suspected.
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Major artery occlusion: a rare complication of sickle cell disease. Mediterr J Hematol Infect Dis 2010; 2:e2010007. [PMID: 21415949 PMCID: PMC3033104 DOI: 10.4084/mjhid.2010.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2010] [Accepted: 04/27/2010] [Indexed: 11/12/2022] Open
Abstract
Sickle cell disease is hereditary hemoglobinopathy which causes haemolytic anemia, vaso-occlusive crisis, ischemic injuries and many other morbidities like cerebral infarction. In this report, we describe a case of a young patient with sickle cell disease presenting with right-sided weakness and slurring of speech with examination confirming right-sided hemiparesis with motor aphasia. On further investigation, she was found to have frontotemporal infarction. On magnetic resonance imaging with angiography, she was found to have absent circulation in left internal carotid artery probably secondary to sickle cell disease. Major vessel occlusion is rare complication of sickle cell disease that one must bear in mind.
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Amlie-Lefond C, Bernard TJ, Sébire G, Friedman NR, Heyer GL, Lerner NB, DeVeber G, Fullerton HJ. Predictors of cerebral arteriopathy in children with arterial ischemic stroke: results of the International Pediatric Stroke Study. Circulation 2009; 119:1417-23. [PMID: 19255344 DOI: 10.1161/circulationaha.108.806307] [Citation(s) in RCA: 236] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Cerebral arteriopathies, including an idiopathic focal cerebral arteriopathy of childhood (FCA), are common in children with arterial ischemic stroke and strongly predictive of recurrence. To better understand these lesions, we measured predictors of arteriopathy within a large international series of children with arterial ischemic stroke. METHODS AND RESULTS Between January 2003 and July 2007, 30 centers within the International Pediatric Stroke Study enrolled 667 children (age, 29 days to 19 years) with arterial ischemic stroke and abstracted clinical and radiographic data. Cerebral arteriopathy and its subtypes were defined using published definitions; FCA was defined as cerebral arterial stenosis not attributed to specific diagnoses such as moyamoya, arterial dissection, vasculitis, or postvaricella angiopathy. We used multivariate logistic regression techniques to determine predictors of arteriopathy and FCA among those subjects who received vascular imaging. Of 667 subjects, 525 had known vascular imaging results, and 53% of those (n=277) had an arteriopathy. The most common arteriopathies were FCA (n=69, 25%), moyamoya (n=61, 22%), and arterial dissection (n=56, 20%). Predictors of arteriopathy include early school age (5 to 9 years), recent upper respiratory infections, and sickle cell disease, whereas prior cardiac disease and sepsis reduced the risk of arteriopathy. The only predictor of FCA was recent upper respiratory infection. CONCLUSIONS Arteriopathy is prevalent among children with arterial ischemic stroke, particularly those presenting in early school age, and those with a history of sickle cell disease. Recent upper respiratory infection predicted cerebral arteriopathy and FCA in particular, suggesting a possible role for infection in the pathogenesis of these lesions.
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Affiliation(s)
- Catherine Amlie-Lefond
- Department of Neurology, Medical College of Wisconsin and Children's Hospital of Wisconsin, Milwaukee, USA
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Shet AS, Hoffmann TJ, Jirouskova M, Janczak CA, Stevens JRM, Adamson A, Mohandas N, Manci EA, Cynober T, Coller BS. Morphological and functional platelet abnormalities in Berkeley sickle cell mice. Blood Cells Mol Dis 2008; 41:109-18. [PMID: 18374611 DOI: 10.1016/j.bcmd.2008.01.008] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2008] [Accepted: 01/24/2008] [Indexed: 11/27/2022]
Abstract
Berkeley sickle cell mice are used as animal models of human sickle cell disease but there are no reports of platelet studies in this model. Since humans with sickle cell disease have platelet abnormalities, we studied platelet morphology and function in Berkeley mice (SS). We observed elevated mean platelet forward angle light scatter (FSC) values (an indirect measure of platelet volume) in SS compared to wild type (WT) (37+/-3.2 vs. 27+/-1.4, mean+/-SD; p<0.001), in association with moderate thrombocytopenia (505+/-49 x 10(3)/microl vs. 1151+/-162 x 10(3)/microl; p<0.001). Despite having marked splenomegaly, SS mice had elevated levels of Howell-Jolly bodies and "pocked" erythrocytes (p<0.001 for both) suggesting splenic dysfunction. SS mice also had elevated numbers of thiazole orange positive platelets (5+/-1% vs. 1+/-1%; p<0.001), normal to low plasma thrombopoietin levels, normal plasma glycocalicin levels, normal levels of platelet recovery, and near normal platelet life spans. Platelets from SS mice bound more fibrinogen and antibody to P-selectin following activation with a threshold concentration of a protease activated receptor (PAR)-4 peptide compared to WT mice. Enlarged platelets are associated with a predisposition to arterial thrombosis in humans and some humans with SCD have been reported to have large platelets. Thus, additional studies are needed to assess whether large platelets contribute either to pulmonary hypertension or the large vessel arterial occlusion that produces stroke in some children with sickle cell disease.
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Affiliation(s)
- Arun S Shet
- The Laboratory of Blood and Vascular Biology, Rockefeller University, 1230 York Avenue, New York, NY 10065, USA
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Kato GJ, Hsieh M, Machado R, Taylor J, Little J, Butman JA, Lehky T, Tisdale J, Gladwin MT. Cerebrovascular disease associated with sickle cell pulmonary hypertension. Am J Hematol 2006; 81:503-10. [PMID: 16755569 PMCID: PMC2206539 DOI: 10.1002/ajh.20642] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
In patients with sickle cell disease, anemia is a recognized risk factor for stroke, death, and the development of pulmonary hypertension. We have proposed that hemolytic anemia results in endothelial dysfunction and vascular instability and can ultimately lead to a proliferative vasculopathy leading to pulmonary hypertension. Consistent with this mechanism of disease, we now report a case series of six patients with obliterative central nervous system vasculopathy who also have pulmonary hypertension and high hemolytic rate. These patients, identified in the course of a prospective screening study for pulmonary hypertension, presented with neurological symptoms prompting neuroimaging studies. Compared to 164 other patients of similar age in the screened population, those with newly diagnosed or clinically active cerebrovascular disease have significantly lower hemoglobin levels and higher levels of lactate dehydrogenase. A review of the literature suggests that many clinical, epidemiological, and physiological features of the arteriopathy of pulmonary hypertension closely overlap with those of stroke in sickle cell disease, both known to involve proliferative vascular intimal and smooth muscle hypertrophy and thrombosis. These cases suggest that cerebrovascular disease and pulmonary hypertension in sickle cell disease share common mechanisms, in particular, reduced nitric oxide bioactivity associated with particularly high-grade hemolysis. Clinicians should suspect occult cerebrovascular disease in sickle cell patients with pulmonary hypertension.
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Affiliation(s)
- Gregory J Kato
- Vascular Medicine Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland 20892-1476, USA.
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Switzer JA, Hess DC, Nichols FT, Adams RJ. Pathophysiology and treatment of stroke in sickle-cell disease: present and future. Lancet Neurol 2006; 5:501-12. [PMID: 16713922 DOI: 10.1016/s1474-4422(06)70469-0] [Citation(s) in RCA: 165] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Sickle-cell anaemia is the most common cause of stroke in children, and stroke is one of the most devastating complications of sickle-cell disease. Overt strokes are typically due to large-artery vasculopathy affecting the intracranial internal carotid arteries and proximal middle cerebral arteries, whereas silent strokes typically occur in the territory of penetrating arteries. The sickled red blood cell can contribute to the pathogenesis of stroke via abnormal adherence to the vascular endothelium and by haemolysis, which results in endothelial cell activation, a hypercoaguable state, and alterations in vasomotor tone. Red-blood-cell transfusion, the most common preventive measure for stroke in sickle-cell disease, is associated with iron overload in chronic disease. Therefore, interventions directed towards the potential mechanisms that promote vasculopathy and occlusion in sickle-cell anaemia should be investigated. Here we review the epidemiology, clinical spectrum, and pathophysiology of stroke in sickle-cell disease to identify potential therapeutic targets.
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Affiliation(s)
- Jeffrey A Switzer
- Department of Neurology, Medical College of Georgia, Augusta, GA 30912, USA.
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Manci EA, Hillery CA, Bodian CA, Zhang ZG, Lutty GA, Coller BS. Pathology of Berkeley sickle cell mice: similarities and differences with human sickle cell disease. Blood 2005; 107:1651-8. [PMID: 16166585 PMCID: PMC1895417 DOI: 10.1182/blood-2005-07-2839] [Citation(s) in RCA: 112] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Because Berkeley sickle cell mice are used as an animal model for human sickle cell disease, we investigated the progression of the histopathology in these animals over 6 months and compared these findings to those published in humans with sickle cell disease. The murine study groups were composed of wild-type mixed C57Bl/6-SV129 (control) mice and sickle cell (SS) mice (alpha-/-, beta-/-, transgene +) of both sexes and between 1 and 6 months of age. SS mice were similar to humans with sickle cell disease in having erythrocytic sickling, vascular ectasia, intravascular hemolysis, exuberant hematopoiesis, cardiomegaly, glomerulosclerosis, visceral congestion, hemorrhages, multiorgan infarcts, pyknotic neurons, and progressive siderosis. Cerebral perfusion studies demonstrated increased blood-brain barrier permeability in SS mice. SS mice differed from humans with sickle cell disease in having splenomegaly, splenic hematopoiesis, more severe hepatic infarcts, less severe pulmonary manifestations, no significant vascular intimal hyperplasia, and only a trend toward vascular medial hypertrophy. Early retinal degeneration caused by a homozygous mutation (rd1) independent from that causing sickle hemoglobin was an incidental finding in some Berkeley mice. While our study reinforces the fundamental strength of this model, the notable differences warrant careful consideration when drawing parallels to human sickle cell disease.
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Affiliation(s)
- Elizabeth A Manci
- Department of Pathology, Centralized Pathology Unit for Sickle Cell Disease, University of South Alabama, Mobile, AL 36604, USA.
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Abstract
Sickle cell anaemia (SCA) is the most common cause of childhood stroke, occurring with the highest frequency before the age of 6 years. Despite the relative frequency of stroke in SCA, few predictors of risk exist. Anaemia, leucocytosis, hypertension, silent infarction, and history of acute chest syndrome are well-documented risk factors for ischaemic stroke in SCA. Recent data suggest that other environmental and genetic factors, many unrelated to SCA, influence the development of cerebrovascular disease. Non-invasive assessment of individual stroke risk using transcranial Doppler ultrasonography has provided a means of selecting and prophylactically treating SCA children at highest risk. With the ultimate goal of preventing stroke, the information gained from the studies reviewed here may lead to improved prediction of stroke so that clinical trials to assess risk-based therapy may be carried out on selected children with SCA.
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Affiliation(s)
- Carolyn Hoppe
- Department of Hematology/Oncology, Children's Hospital and Research Center at Oakland, Oakland, CA 94609, USA.
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Hoppe C, Klitz W, Cheng S, Apple R, Steiner L, Robles L, Girard T, Vichinsky E, Styles L. Gene interactions and stroke risk in children with sickle cell anemia. Blood 2004; 103:2391-6. [PMID: 14615367 DOI: 10.1182/blood-2003-09-3015] [Citation(s) in RCA: 135] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Abstract
Stroke is a devastating complication of sickle cell anemia (SCA), affecting up to 30% of children with the disease. Despite the relative frequency of stroke in SCA, few predictors of risk exist. Because stroke in SCA is likely a multifactorial disease, analysis of the combined effect of multiple genetic variants may prove more successful than evaluation of individual candidate genes. We genotyped 230 children with SCA for 104 polymorphisms among 65 candidate vascular genes to identify risk associations with stroke. Patients were phenotyped based on magnetic resonance imaging/angiography (MRI/MRA) findings into large-vessel (LV) versus small-vessel (SV) disease stroke subgroups. Specific polymorphisms in the IL4R 503, TNF (-308), and ADRB2 27 genes were independently associated with stroke susceptibility in the LV stroke subgroup, while variants in the VCAM1 (-1594) and LDLR NcoI genes were associated with SV stroke risk. The combination of TNF (-308)GG homozygosity and the IL4R 503P variant carrier status was associated with a particularly strong predisposition to LV stroke (odds ratio [OR] = 5.5; 95% confidence interval [CI] = 2.3-13.1). We show that several candidate genes may play a role in predisposition to specific stroke subtypes in children with SCA. If confirmed, these results provide a basis for population screening and targeted intervention to prevent stroke in SCA.
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Affiliation(s)
- Carolyn Hoppe
- Department of Hematology/Oncology, Children's Hospital and Research Center at Oakland, 747 52nd St, Oakland, CA 94609, USA.
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Steen RG, Xiong X, Langston JW, Helton KJ. Brain injury in children with sickle cell disease: Prevalence and etiology. Ann Neurol 2003; 54:564-72. [PMID: 14595645 DOI: 10.1002/ana.10727] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Our objective was to evaluate the relationship between brain injury by magnetic resonance imaging (MRI) and vasculopathy by magnetic resonance angiography (MRA) in children with hemoglobin SS, the most serious form of sickle cell disease. We reviewed imaging for all 146 SS patients imaged at St. Jude Children's Research Hospital since 1993. Standard MRI criteria were used to identify cystic infarction, leukoencephalopathy, encephalomalacia, or atrophy. Standard MRA criteria were used to identify arterial tortuousity (limited vasculopathy), and stenosis or occlusion (extensive vasculopathy). At an average age of 10 years, the estimated prevalence of infarction, ischemic damage, or atrophy in SS patients was 46%, and of vasculopathy was 64%. Only 28% of patients were normal by both modalities, and patients abnormal by MRA often were abnormal by MRI (p < 0.00001). Patients with cystic infarction had limited vasculopathy, whereas patients with encephalomalacia had stenosis or occlusion (p < 0.0001). Large arteries were affected in 31% of brain injury patients, whereas small arteries are inferred to be abnormal in up to 69% of patients with brain injury. The degree of vasculopathy is closely related to the degree of brain injury, implying that vasculopathy is prodromal to most forms of brain injury in hemoglobin SS.
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Affiliation(s)
- R Grant Steen
- Department of Diagnostic Imaging, St. Jude Children's Research Hospital, Memphis, TN, USA.
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Adams RJ, Ohene-Frempong K, Wang W. Sickle cell and the brain. HEMATOLOGY. AMERICAN SOCIETY OF HEMATOLOGY. EDUCATION PROGRAM 2002:31-46. [PMID: 11722977 DOI: 10.1182/asheducation-2001.1.31] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
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.
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Affiliation(s)
- R J Adams
- Department of Neurology, HB-2060, Medical College of Georgia, 1467 Harper Street, Augusta GA 30912-3200, USA
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Steen RG, Hu XJ, Elliott VE, Miles MA, Jones S, Wang WC. Kindergarten readiness skills in children with sickle cell disease: evidence of early neurocognitive damage? J Child Neurol 2002; 17:111-6. [PMID: 11952070 DOI: 10.1177/088307380201700204] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Young children with sickle cell disease are at risk of brain damage, including stroke. We tested the hypothesis that such patients are also at risk of cognitive impairment. We characterized the cognitive ability of kindergarten children to minimize the effect of disease-related school absence. The Memphis City Schools use the Developing Skills Checklist, a teacher-administered test given in the classroom, to assess kindergarten-appropriate skills. Data were obtained for 34 patients, who were matched to controls by gender, race, date of birth, school, and approximate income. Two controls were selected for each patient, and paired t-tests were used to compare patient's scores to composite control scores. Patients scored lower than controls in auditory discrimination (P < .01), and there was a trend (P < .10) toward lower patient scores in language. Deficits cannot be attributed to school absence and may predict academic problems for patients with sickle cell disease.
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Affiliation(s)
- R Grant Steen
- Department of Diagnostic Imaging, St Jude Children's Research Hospital, Memphis, TN 38105-2794, USA.
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Abstract
Thromboses are a serious complication in patients with sickle cell disease, paroxysmal nocturnal hemoglobinuria, beta-thalassemia major, or thalassemia intermedia. Despite prophylaxis, thrombotic events can continue and can result in severe physical or mental debilitation or death of the patient. The fact that thrombosis does not occur in all patients with hemolytic anemias suggests that multiple factors interact to cause the coagulation crisis. Genetic modifiers, associated diseases, nutritional status, infections, environment, and treatment modalities are variables implicated in thrombophilia. The complexity confounds attempts to identify single causative agents in humans with hemolytic anemias. In the past year, mutations in putative genetic modifiers of the coagulation response have been examined as risk factors in patients with a history of thromboses; red cell binding sites on endothelial cells have been identified; and mouse models of thrombogenesis that permit experimental manipulation of single factors on a defined genetic background have been described.
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Affiliation(s)
- J E Barker
- The Jackson Laboratory, Bar Harbor, ME 04609, USA
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