Stroke prevention and treatment in sickle cell disease

Brain perfusion changes in beta-thalassemia

BACKGROUND

Brain injury in hereditary hemoglobinopathies is commonly attributed to anemia-related relative hypoperfusion in terms of impaired oxygen blood supply. Supratentorial and infratentorial vascular watershed regions seem to be especially vulnerable, but data are very scarce.

AIMS

We investigated a large beta-thalassemia sample with arterial spin labeling in order to characterize regional perfusion changes and their correlation with phenotype and anemia severity.

METHODS

We performed a multicenter single-scanner cross-sectional 3T-MRI study analyzing non-invasively the brain perfusion in 54 transfusion-dependent thalassemia (TDT), 23 non-transfusion-dependent thalassemia (NTDT) patients and 56 Healthy Controls (HC). Age, hemoglobin levels, and cognitive functioning were recorded.

RESULTS

Both TDT and NTDT patients showed globally increased brain perfusion values compared to healthy controls, while no difference was found between patient subgroups. Using age and sex as covariates and scaling the perfusion maps for the global cerebral blood flow, beta-thalassemia patients showed relative hyperperfusion in supratentorial/infratentorial watershed regions. Perfusion changes correlated with hemoglobin levels (p = 0.013) and were not observed in the less severely anemic patients (hemoglobin level > 9.5 g/dL). In the hyperperfused regions, white matter density was significantly decreased (p = 0.0003) in both patient subgroups vs. HC. In NTDT, white matter density changes correlated inversely with full-scale Intelligence Quotient (p = 0.007) while in TDT no correlation was found.

CONCLUSION

Relative hyperperfusion of watershed territories represents a hemodynamic hallmark of beta-thalassemia anemia challenging previous hypotheses of brain injury in hereditary anemias. A careful management of anemia severity might be crucial for preventing structural white matter changes and subsequent long-term cognitive impairment.

Factors associated with young adult engagement with a web-based sickle cell reproductive health intervention

Objective

To determine the factors predicting the engagement of young adults who have sickle cell disease (SCD) or sickle cell trait (SCT) with an online reproductive health education intervention and engagement effects on knowledge.

Methods

The cross-sectional study included 167 participants who completed the web-based intervention either face-to-face (F2F) or online delivery (OL). Measures include: time used relative to length of the intervention narration and media (engagement) and the SCKnowIQ questionnaire. Ordinal regression was conducted.

Results

The sample mean age was 26-years (SD=5), 68% were female, 54% had SCD, and 68% were in the F2F group. Adjusting for age, partner sickle cell status, marital status, and education, participants who were female (p=.003), had SCD (p=.018), or had F2F delivery (p < .001) were more likely to spend more time on the intervention. Adjusting for baseline knowledge and modality, more time spent on the intervention was associated with higher posttest knowledge (p=.006).

Conclusions

Future studies are necessary to understand reasons underpinning engagement and to investigate other unmeasured factors, such as intervention interactivity elements, that could also be associated with engagement.

Innovation

This study of young adults with SCD or SCT provides much needed insight about their engagement with online reproductive health education.

Sickle Cell Disease: A Review

IMPORTANCE

Sickle cell disease (SCD) is an inherited disorder of hemoglobin, characterized by formation of long chains of hemoglobin when deoxygenated within capillary beds, resulting in sickle-shaped red blood cells, progressive multiorgan damage, and increased mortality. An estimated 300 000 infants are born annually worldwide with SCD. Most individuals with SCD live in sub-Saharan Africa, India, the Mediterranean, and Middle East; approximately 100 000 individuals with SCD live in the US.

OBSERVATIONS

SCD is diagnosed through newborn screening programs, where available, or when patients present with unexplained severe atraumatic pain or normocytic anemia. In SCD, sickling and hemolysis of red blood cells result in vaso-occlusion with associated ischemia. SCD is characterized by repeated episodes of severe acute pain and acute chest syndrome, and by other complications including stroke, chronic pain, nephropathy, retinopathy, avascular necrosis, priapism, and leg ulcers. In the US, nearly all children with SCD survive to adulthood, but average life expectancy remains 20 years less than the general population, with higher mortality as individuals transition from pediatric to adult-focused health care systems. Until 2017, hydroxyurea, which increases fetal hemoglobin and reduces red blood cell sickling, was the only disease-modifying therapy available for SCD and remains first-line therapy for most individuals with SCD. Three additional therapies, L-glutamine, crizanlizumab, and voxelotor, have been approved as adjunctive or second-line agents. In clinical trials, L-glutamine reduced hospitalization rates by 33% and mean length of stay from 11 to 7 days compared with placebo. Crizanlizumab reduced pain crises from 2.98 to 1.63 per year compared with placebo. Voxelotor increased hemoglobin by at least 1 g/dL, significantly more than placebo (51% vs 7%). Hematopoietic stem cell transplant is the only curative therapy, but it is limited by donor availability, with best results seen in children with a matched sibling donor. While SCD is characterized by acute and chronic pain, patients are not more likely to develop addiction to pain medications than the general population.

CONCLUSIONS AND RELEVANCE

In the US, approximately 100 000 people have SCD, which is characterized by hemolytic anemia, acute and chronic pain, acute chest syndrome; increased incidence of stroke, nephropathy, and retinopathy; and a life span that is 20 years shorter than the general population. While hydroxyurea is first-line therapy for SCD, L-glutamine, crizanlizumab, and voxelotor have been approved in the US since 2017 as adjunctive or second-line treatments, and hematopoietic stem cell transplant with a matched sibling donor is now standard care for severe disease.

Association of laboratory markers and cerebral blood flow among sickle cell anemia children

BACKGROUND

Stroke is one of the highest complications of sickle-cell anemia (SCA). The Transcranial Doppler (TCD) has been adopted worldwide as a gold standard method for detecting alterations in the blood velocity in cerebral arteries. In this study, we investigated the association between laboratory parameters and increased cerebral blood flow velocity in Brazilian SCA pediatric patients.

METHODS

The study included 159 pediatric patients with SCA, submitted to TCD velocity screening, and the time-averaged maximum mean velocity (TAMMV) was determined in the middle cerebral artery (MCA), anterior cerebral artery (ACA), and distal intracranial internal carotid artery (ICA). We compared cerebral blood flow in patients stratified by the following: TCD1-defined as normal, with TAMMV inferior to 170 cm/s; TCD2-conditional, with TAMMV above 170 cm/s, but less than 199 cm/s; TCD3-altered, with TAMMV greater than or equal to 200 cm/s.

RESULTS

TAMMV was negatively correlated with age and weight (p < 0.05). Moreover, TAMMV was associated or correlated with reductions in HbF, RBC, hemoglobin, hematocrit, HDL, and haptoglobin and, increases in MCV, MCH, RDW, reticulocytes, WBC, lymphocytes, monocytes, eosinophils, total and indirect bilirubin, LDH, AST, ALT, glucose, ferritin, and AAT (p < 0.05).

CONCLUSION

The current study highlights the importance of the investigation of hemolytic and inflammatory biomarkers for monitoring the clinical outcome of SCA pediatric patients, to avoid acute or chronic stroke. Moreover, glucose and HDL-C appear useful for predicting higher TAMMV.

Critical Role of Hemopexin Mediated Cytoprotection in the Pathophysiology of Sickle Cell Disease

Circulating hemopexin is the primary protein responsible for the clearance of heme; therefore, it is a systemic combatant against deleterious inflammation and oxidative stress induced by the presence of free heme. This role of hemopexin is critical in hemolytic pathophysiology. In this review, we outline the current research regarding how the dynamic activity of hemopexin is implicated in sickle cell disease, which is characterized by a pathological aggregation of red blood cells and excessive hemolysis. This pathophysiology leads to symptoms such as acute kidney injury, vaso-occlusion, ischemic stroke, pain crises, and pulmonary hypertension exacerbated by the presence of free heme and hemoglobin. This review includes in vivo studies in mouse, rat, and guinea pig models of sickle cell disease, as well as studies in human samples. In summary, the current research indicates that hemopexin is likely protective against these symptoms and that rectifying depleted hemopexin in patients with sickle cell disease could improve or prevent the symptoms. The data compiled in this review suggest that further preclinical and clinical research should be conducted to uncover pathways of hemopexin in pathological states to evaluate its potential clinical function as both a biomarker and therapy for sickle cell disease and related hemoglobinopathies.

[Rare causes of stroke-a frequent stroke etiology]

As a whole, rare stroke causes represent a frequent stroke etiology. Since rare stroke causes affect primarily young patients, early diagnosis and treatment are of high socioeconomic relevance. In our everyday clinical practice, cervical artery dissection, which is the most common stroke etiology among patients < 45 years, and vasculitis are particularly important. In the case of vasculitis, devastating disease courses and potentially harmful treatment options complicate clinical decision-making. Non-vasculitic vasculopathies, infections, hematological disorders, coagulation disorders, metabolic disorders and malignancies are further rare causes of stroke with variable clinical manifestations, thus impeding an early diagnosis. If eligible, patients with rare stroke causes should be considered for thrombectomy. Except for infective endocarditis, most rare stroke causes are not per se a contraindication to thrombolysis, so that eligible patients should also be considered for thrombolysis. Evidence based recommendations for the secondary prevention of most rare stroke causes are still missing. In many cases, treatment regimens are adapted to the patients' individual risk of stroke recurrence and bleeding complications.

Association Between Periodic Limb Movements in Sleep and Cerebrovascular Changes in Children With Sickle Cell Disease

STUDY OBJECTIVES

Periodic limb movements (PLMs) have been associated with increased risk of stroke, but there is currently scarce research exploring this relationship in the setting of sickle cell disease (SCD). The aim of this study was to explore whether increased PLMs in children with SCD are associated with increased risk of cerebrovascular disease and to determine if there are any clinical or laboratory differences between children with SCD with elevated periodic limb movement index (PLMI) versus those with normal PLMI.

METHODS

This study is a comprehensive review of medical records of 129 children with SCD (aged ≤ 18 years) who had undergone polysomnography for evaluation of sleep-disordered breathing.

RESULTS

Elevated PLMI (PLMI > 5 events/h) was present in 42% (54/129) of children with SCD. Children with elevated PLMI were found to have higher percentage of hemoglobin S, lower total iron, higher arousal index and tendency toward elevated transcranial Doppler velocity (P = .063, odds ratio = 3.9, 95% CI 0.93-16.22). While association between elevated PLMI and isolated cerebrovascular stenosis (P = .050, odds ratio 5.6, 95% CI 1.0-31.10) trended toward significance, there was significantly greater proportion of children with elevated PLMI who had cerebrovascular stenosis with Moyamoya disease (P = .046) as demonstrated by magnetic resonance imaging (MRI).

CONCLUSIONS

The prevalence of elevated PLMI in children with SCD was higher than in previously published data. Elevated PLMI was significantly associated with greater rates of cerebrovascular disease as detected by MRI.

Sickle cell disease: a malady beyond a hemoglobin defect in cerebrovascular disease

INTRODUCTION

Sickle cell disease (SCD) is a devastating monogenic disorder that presents as a multisystem illness and affects approximately 100,000 individuals in the United States alone. SCD management largely focuses on primary prevention, symptomatic treatment and targeting of hemoglobin polymerization and red blood cell sickling. Areas covered: This review will discuss the progress of SCD over the last few decades, highlighting some of the clinical (mainly cerebrovascular) and psychosocial challenges of SCD in the United States. In addition, focus will also be made on the evolving science and management of this inherited disease. Expert commentary: Until recently hydroxyurea (HU) has been the only FDA approved therapy for SCD. However, advancing understanding of SCD pathophysiology has led to multiple clinical trials targeting SCD related thrombo-inflammation, abnormal endothelial biology, increased oxidant stress and sickle cell mutation. Yet, despite advancing understanding, available therapies are limited. SCD also imposes great psychosocial challenges for the individual and the affected community, which has previously been under-recognized. This has created a pressing need for complementary adjuvant therapies with repurposed and novel drugs, in addition to the establishment of comprehensive clinics focusing on both the medical treatment and the psychosocial issues associated with SCD.

A reappraisal of the mechanisms underlying the cardiac complications of sickle cell anemia

Anemia, hemolysis-driven vasculopathy, and intrinsic myocardial injury have been proposed as predisposing factors to cardiac disease in sickle cell anemia (SCA). The individual impact of these mechanisms on the cardiac features of SCA and the way they influence complications such as sudden death and dysrhythmias have been unclear. Recent findings of an acquired restrictive SCA-related cardiomyopathy, driven by myocardial fibrosis, may explain some of these cardiac features. Given the complexity of cardiac pathology in SCA, using additional parameters to tricuspid regurgitant jet velocity (left atrial volume, diastolic parameters, NT-proBNP) may improve the accuracy of noninvasive screening for cardiopulmonary complications in SCA.

Patients with sickle cell disease are frequently excluded from the benefits of transcranial doppler screening for the risk of stroke despite extensive and compelling evidence

ABSTRACT Transcranial doppler (TCD) is a strategic component of primary stroke prevention in children with sickle cell disease (SCD). This study was conducted to examine the TCD characteristics of children with SCD in nine different medical centers in Brazil. Methods: Transcranial doppler was performed in accordance with the Stroke Prevention Trial in Sickle Cell Anemia Protocol. Results: Of the 396 patients, 69.5% had homozygous SS hemoglobin. The TCD result was abnormal in 4.8%, conditional in 12.6%, inadequate in 4.3% and abnormally low in 1% of patients. The highest mean flow velocities were 121±23.83cm/s and 124±27.21cm/s in the left and right middle cerebral artery respectively. A total of 28.8% patients (mean age 9.19±5.92 years) were evaluated with TCD for the first time. Conclusions: The SCD patients were evaluated with TCD at an older age, representing an important missed opportunity for stroke prevention. Since TCD screening in patients with SCD is important to detect those at high risk for stroke, it is recommended that this screening should be made more readily available.

Scientific Rationale for the Inclusion and Exclusion Criteria for Intravenous Alteplase in Acute Ischemic Stroke

Purpose—

To critically review and evaluate the science behind individual eligibility criteria (indication/inclusion and contraindications/exclusion criteria) for intravenous recombinant tissue-type plasminogen activator (alteplase) treatment in acute ischemic stroke. This will allow us to better inform stroke providers of quantitative and qualitative risks associated with alteplase administration under selected commonly and uncommonly encountered clinical circumstances and to identify future research priorities concerning these eligibility criteria, which could potentially expand the safe and judicious use of alteplase and improve outcomes after stroke.

Methods—

Writing group members were nominated by the committee chair on the basis of their previous work in relevant topic areas and were approved by the American Heart Association Stroke Council’s Scientific Statement Oversight Committee and the American Heart Association’s Manuscript Oversight Committee. The writers used systematic literature reviews, references to published clinical and epidemiology studies, morbidity and mortality reports, clinical and public health guidelines, authoritative statements, personal files, and expert opinion to summarize existing evidence and to indicate gaps in current knowledge and, when appropriate, formulated recommendations using standard American Heart Association criteria. All members of the writing group had the opportunity to comment on and approved the final version of this document. The document underwent extensive American Heart Association internal peer review, Stroke Council Leadership review, and Scientific Statements Oversight Committee review before consideration and approval by the American Heart Association Science Advisory and Coordinating Committee.

Results—

After a review of the current literature, it was clearly evident that the levels of evidence supporting individual exclusion criteria for intravenous alteplase vary widely. Several exclusionary criteria have already undergone extensive scientific study such as the clear benefit of alteplase treatment in elderly stroke patients, those with severe stroke, those with diabetes mellitus and hyperglycemia, and those with minor early ischemic changes evident on computed tomography. Some exclusions such as recent intracranial surgery are likely based on common sense and sound judgment and are unlikely to ever be subjected to a randomized, clinical trial to evaluate safety. Most other contraindications or warnings range somewhere in between. However, the differential impact of each exclusion criterion varies not only with the evidence base behind it but also with the frequency of the exclusion within the stroke population, the probability of coexistence of multiple exclusion factors in a single patient, and the variation in practice among treating clinicians.

Posterior Circulation Evaluation in Patients with Sickle Cell Anemia

BACKGROUND

The role of transcranial Doppler (TCD) ultrasonography in identifying children with sickle cell anemia (SCA) at risk for stroke is well known; however, the major studies that evaluated TCD velocities in children with SCA did not report posterior circulation evaluation data. The objective of our study was to describe the pattern of blood flow velocities in the posterior circulation of patients with SCA and to examine their relationship with findings on magnetic resonance imaging (MRI)/magnetic resonance angiography (MRA).

METHODS

All adult patients with SCA followed in the outpatient clinic of our hospital were evaluated with TCD and MRI/MRA. The highest velocities of the middle cerebral arteries or internal carotid arteries were taken as the time-averaged maximum mean (TAMM) velocity for each patient and the maximum mean flow velocities in the posterior circulation (TAMMpost) were recorded.

RESULTS

Fifty-six patients with SCA and 56 healthy nonanemic volunteers were evaluated. The mean TAMMpost in the basilar, vertebral, and posterior cerebral arteries (PCAs) were significantly higher among cases than controls (P < .01). In patients with SCA, the TAMMpost in all posterior circulation arteries had a positive correlation with TAMM. Only 1 patient with stenosis in the posterior circulation (right PCA) was identified.

CONCLUSION

We found a low frequency of stenosis but high blood flow velocities in the posterior circulation in patients with SCA. The role of increased TCD velocities in the posterior circulation upon stroke risk in patients with SCA should be further examined.

Can STOP Trial Velocity Criteria Be Applied to Iranian Children with Sickle Cell Disease?

Background and Purpose

Sickle cell disease (SCD) is strongly linked to stroke across all haplotypes in the pediatric population. Transcranial Doppler (TCD) ultrasound is known to identify the highest risk group in African-Americans who need to receive and stay on blood transfusions, but it is unclear if the same flow velocity cut-offs can be applied to the Iranian population. We aimed to evaluate baseline TCD findings in Iranian children with SCD and no prior strokes.

Methods

Children with genetically confirmed SCD (Arabian haplotype, homozygote) and without SCD (controls) were prospectively recruited from pediatric outpatient clinic over a period of 9 months. We performed TCD in both groups to determine flow velocities in the middle cerebral (MCA) and terminal internal carotid arteries (TICA).

Results

Of 74 screened children, 60 met the inclusion/exclusion criteria (62% female; mean age 10±4 years). Baseline characteristics did not differ between the cases and controls, except hemoglobin (Hb) which was significantly lower in the SCD group (P<0.001). The right MCA TAMM (Time Averaged Maximum Mean) was significantly higher than in controls (125+5.52 cm/s vs. 92.5+1.63 cm/s, P<0.001). Left MCA did not show differences. The TICA TAMM was also different between cases and controls (P<0.05).

Conclusions

Among Iranian children with asymptomatic SCD and without receiving recent transfusion TCD velocities are higher as compared to healthy controls but appear much lower than those observed in STOP (Stroke Prevention Trial in Sickle Cell Anemia) studies. We hypothesize that some children at high risk may be present with velocities lower than 170-200 cm/s thresholds. A prospective validation of ethnicity-specific prognostic criteria is warranted.

Treatment of acute ischemic stroke: beyond thrombolysis and supportive care

The initial therapeutic approach to acute ischemic stroke consists of thrombolytic therapy and early initiation of supportive care, usually commenced prior to the determination of the underlying stroke etiology. Varying stroke mechanisms may call for specific, etiology-based treatment. The majority of strokes result from cardioembolism, large-vessel atherothromboembolism, and small-vessel occlusive disease. There are scant data to support the use of acute anticoagulation therapy over anti-platelet therapy in cardioembolic stroke and large-vessel atherosclerosis, although it may be reasonable in a certain subset of patients. However, augmentation of blood flow with early surgery, stenting, or induced hypertension, may play a role in patients with large artery stenosis. The less commonly identified stroke mechanisms may warrant special consideration in treatment. Controversy remains regarding the optimal anti-thrombotic treatment of arterial dissection. Reversible cerebral vasoconstriction syndrome may benefit from therapy with calcium channel blockers, high-dose steroids, or magnesium, although spontaneous recovery may occur. Inflammatory vasculopathies, such as isolated angiitis of the central nervous system and temporal arteritis, require prompt diagnosis as the mainstay of therapy is immunosuppression. Cerebral venous thrombosis is a rare cause of stroke, but one that needs early identification and treatment with anticoagulation. Rapid determination of stroke mechanism is essential for making these critical early treatment decisions.

Results from transcranial Doppler examination on children and adolescents with sickle cell disease and correlation between the time-averaged maximum mean velocity and hematological characteristics: a cross-sectional analytical study

CONTEXT AND OBJECTIVE

Transcranial Doppler (TCD) detects stroke risk among children with sickle cell anemia (SCA). Our aim was to evaluate TCD findings in patients with different sickle cell disease (SCD) genotypes and correlate the time-averaged maximum mean (TAMM) velocity with hematological characteristics.

DESIGN AND SETTING

Cross-sectional analytical study in the Pediatric Hematology sector, Universidade Federal de São Paulo.

METHODS

85 SCD patients of both sexes, aged 2-18 years, were evaluated, divided into: group I (62 patients with SCA/Sß(0) thalassemia); and group II (23 patients with SC hemoglobinopathy/Sß(+) thalassemia). TCD was performed and reviewed by a single investigator using Doppler ultrasonography with a 2 MHz transducer, in accordance with the Stroke Prevention Trial in Sickle Cell Anemia (STOP) protocol. The hematological parameters evaluated were: hematocrit, hemoglobin, reticulocytes, leukocytes, platelets and fetal hemoglobin. Univariate analysis was performed and Pearson's coefficient was calculated for hematological parameters and TAMM velocities (P < 0.05).

RESULTS

TAMM velocities were 137 ± 28 and 103 ± 19 cm/s in groups I and II, respectively, and correlated negatively with hematocrit and hemoglobin in group I. There was one abnormal result (1.6%) and five conditional results (8.1%) in group I. All results were normal in group II. Middle cerebral arteries were the only vessels affected.

CONCLUSION

There was a low prevalence of abnormal Doppler results in patients with sickle-cell disease. Time-average maximum mean velocity was significantly different between the genotypes and correlated with hematological characteristics.

Diagnosis and management of pediatric arterial ischemic stroke

Pediatric stroke is among the top 10 causes of death in children and an important cause of chronic morbidity, with an incidence of 3.3/100,000 children/year. Risk factors associated with stroke in children include cardiac diseases, hematologic and vascular disorders, and infection. Clinical presentation varies depending on age, underlying cause, and stroke location. Antithrombotics and anticoagulants are used in the treatment of pediatric stroke; however, there are no established guidelines for the use of these agents in children. In this article we review the cause, pathophysiology, clinical presentation, diagnosis, acute management, secondary prevention, and outcome of children with stroke. The approach to patients with sickle cell disease and Moyamoya disease is also discussed. Up to date studies to determine the optimal acute treatment of childhood stroke and secondary prevention and risk factor modification are critically needed.

Silent Cerebral Infarct Transfusion (SIT) trial imaging core: application of novel imaging information technology for rapid and central review of MRI of the brain

The Silent Cerebral Infarct Multicenter Transfusion (SIT) Trial is a multi-institutional intervention trial in which children with silent cerebral infarcts are randomized to receive either blood transfusion therapy or observation (standard care) for 36 months. The SIT Trial is scheduled to enroll approximately 1,880 children with sickle cell disease from 29 clinical sites in the United States, Canada, UK, and France. Each child undergoes a screening magnetic resonance imaging (MRI) of the brain to detect the presence of silent cerebral infarct-like lesions, a pre-randomization (baseline) MRI and exit MRI to determine if there are new or enlarged cerebral infarcts, using a designated, prospective imaging protocol. The objective of this manuscript is to describe the innovative method used to process and adjudicate imaging studies for an international trial with a primary endpoint that includes neuroimaging. Institution investigators at each site were provided with computer hardware and software for transmission of MRI images that allow them to strip the scans of all personal information and add unique study identifiers. Three neuroradiologists at separate academic centers review MRI studies and determine the presence or absence of silent cerebral infarct-like lesions. Their findings are subsequently placed on web-based case report forms and sent to the Statistical Coordinating Center. The average time from imaging center receipt of the MRI study to the radiology committee report back to the local site is less than two working days. This novel strategy was designed to maximize efficiency and minimize cost of a complex large multicenter trial that depends heavily on neuroimaging for entry criteria and assessment for the primary outcome measures. The technology, process, and expertise used in the SIT Trial can be adapted to virtually any clinical research trial with digital imaging requirements.

Acute myocardial infarction in sickle cell disease: a systematic review

Myocardial infarction in young adults is, in practice, a diagnosis of exclusion. Given the fact that most of the patients with sickle cell disease are young and have predisposition to painful crisis, they are often overlooked for myocardial infarction. These patients often have few or no traditional risk factors for coronary artery disease, and risk stratification tools such as the Thrombolysis in Myocardial Infarction (TIMI) and Global Registry of Acute Coronary Events (GRACE) models place these patients at low risk. Nonspecific changes on electrocardiogram are of little diagnostic value. Myocardial infarction is very often a missed diagnosis in patients with sickle cell disease. Diagnostic criteria, potential mechanisms, and management for acute myocardial infarction in patients with sickle cell disease are discussed.

Erythrocytapheresis: Do Not Forget a Useful Therapy!

SUMMARY: In patients with pathologically altered erythrocytes, red blood cell exchange is a very efficient therapeutic measure without important side effects. With increasing migration more patients with e.g. severe malaria or sickle cell anemia have to be treated. In minor or bidirectional ABO-mismatched stem cell transplantations after reduced intensity conditioning, hemolysis can be prevented by prophylactic erythrocytapheresis. Other rare indications for red blood cell exchange are advanced erythropoietic protoporphyria and babesiosis. Sickle cell anemia can be treated with hydroxyurea. Transfusions are administered when necessary, but this results in iron overload in the long term. An expensive but safe and very efficient treatment alternative is red blood cell exchange. In cases with stroke, acute chest syndrome and other severe complications, erythrocytapheresis reproducibly breaks the vicious circle of sickling and increasing oxygen deficiency. At the same time one can aim at an exact end hematocrit. In severe malaria, erythrocytapheresis both reduces parasite load to the designated extent and reconstitutes reduced oxygen transport capacity without serious adverse effects. Here we describe our experience of erythrocytapheresis in long-term prophylaxis of complications in sickle cell anemia and sickle cell thalassemia patients. The documentation of improved iron balance was carried out by liver susceptometry.

Automated red cell exchange procedures in patients with sickle cell disease

In automated red cell exchange, about 60% of the patient's red blood cells are exchanged via apheresis for those of the donor. We report the outcome of 83 patients with sickle cell anemia (48 women and 35 men; age range, 17-49 years) who underwent a total of 196 apheresis procedures between December 2003 and October 2006 at our institution. We found that automated red cell exchange involving a reduced citrate infusion rate may provide benefit in the prevention or treatment of vaso-occlusive complications in patients with sickle cell disease and may be associated with protean effects on biochemical dynamics.

Overt and Incomplete (Silent) Cerebral Infarction in Sickle Cell Anemia: Diagnosis and Management

Cerebral vasculopathy in sickle cell anemia (HbSS) is manifest clinically as cerebral infarction and intracranial hemorrhage. The type of stroke, ischemic or hemorrhagic, is age specific with distinct differences in outcomes. Cerebral infarction with or without clinical stroke begins during early childhood and rarely causes death immediately.

Clinical response of patients with sickle cell anemia to cromolyn sodium nasal spray

Sickle cell anemia is the most common heritable hematological disease affecting humans. Although hydroxyurea is the most commonly used antisickling agent, several previous studies suggest that cromolyn sodium also prevents sickling when administered acutely. However, no previous studies have evaluated the safety or efficacy of prolonged administration of cromolyn to patients with sickle cell anemia. The purpose of this study, therefore, was to test the hypothesis that prolonged administration of cromolyn alone or in combination with hydroxyurea would decrease the incidence of pain crises and/or alter the chronic pain seen in patients with this disease. In this crossover, single-blind, in vivo and in vitro study, 17 patients with sickle cell disease were studied. Each patient had to fill out a standard pain chart. Every 3 months the patients' medications changed in the following manner: The first 3 months the patients used cromolyn sodium nasal spray; the second 3 months they received placebo nasal spray; the third 3 months they received cromolyn sodium nasal spray and hydroxyurea capsule; and the last 3 months they received hydroxyurea capsule and placebo nasal spray. The least pain was felt with the mixture of hydroxyurea capsule and cromolyn sodium nasal inhaler. Furthermore, with the other combinations of medications, there were no significant statistical changes in the number of sickled red blood cells. Every combination used in this survey had positive effects on decreasing the pain. cromolyn sodium nasal spray is significantly efficient in decreasing sickle cell crisis as well as pain intensity in patients with sickle cell anemia.

Treatment and prevention of stroke in children with sickle cell disease

Stroke is one of the major complications in children with sickle cell disease (SCD). Ischemic stroke is associated with small asymptomatic subcortical infarcts to large territorial lesions causing major disability. Intracranial hemorrhages may be caused by aneurysm rupture or by leakage from moyamoya vessels or venous sources. There have been no acute stroke treatment studies in SCD, but hydration and exchange transfusion are often recommended. However, there is an evidence base for primary and to some extent secondary stroke prevention. Primary prevention of stroke was demonstrated in the Stroke Prevention Trial in Sickle Cell Anemia (STOP), in which children with transcranial Doppler (TCD) mean blood flow velocities of 200 cm/second (previously shown to indicate high stroke risk) or higher were randomized to either regular blood transfusions or no transfusion. The study showed a very significant 90% reduction in first stroke with transfusion. In STOP2, discontinuing transfusions after 30 months or more (even with normal TCD) resulted in a high rate of reversion to abnormal TCD values and stroke. TCD screening of all children with SCD, and initiation and maintenance of chronic transfusion to maintain hemoglobin S below 30% in the high-risk group, is the only proven prevention strategy for stroke in SCD. Hydroxyurea is being studied as secondary stroke prevention at this time. No recommendation specific to SCD regarding the use of antiplatelet agents or anticoagulants in ischemic stroke can be made. Bone marrow transplantation can be curative for SCD, and limited data support its use to prevent stroke in SCD.

Treatment and prevention of cerebrovascular disorders in children

Cerebrovascular disorders are an important cause of mortality and chronic morbidity in children. Ischemic stroke is more common than cerebral venous thrombosis and hemorrhagic stroke in children. Several medical disorders have been associated with stroke in children, and a thorough evaluation of underlying causes is needed to determine the best treatment and prevention strategy. The treatment and prevention of stroke in children is not well studied, and current recommendations are based on adult studies, nonrandomized trials, or expert opinion. Children with stroke require immediate, special attention and if possible should be stabilized and transferred to an institution that can offer pediatric neurovascular expertise and care. All children with stroke should be referred to or have their care managed by a pediatric neurologist. The treatment of stroke in adults is well studied, and when applicable this evidence should be considered in the treatment of children with stroke. Data from animal and adult stroke studies have demonstrated a benefit for the aggressive treatment of infection, fever, blood pressure, hypo/hyperglycemia, intracranial pressure, and seizures, and should be applied to children with stroke. The use of thrombolytic, antithrombotic, and antiplatelet therapies is based on adult studies, cohort studies, and/or expert opinion. Two consensus guidelines regarding the treatment of arterial ischemic stroke and cerebral venous thrombosis were recently published and recommend the use of anticoagulants or antiplatelet agents in the acute setting, depending on the underlying cause of stroke. The evidence for the primary prevention of stroke in children is restricted to sickle cell disease (SCD) and derived from the Stroke Prevention in Sickle Cell Study Project studies. Long-term chronic transfusion therapy to maintain hemoglobin S levels below 30% is indicated in children with SCD and intracranial stenosis. It has also been recently determined that chronic transfusion therapy should not be stopped in children with SCD and an increased risk for stroke. The recurrence rate of arterial ischemic stroke (AIS) in children ranges from 6% to 30% and is highest among children with recurrent transient ischemic attack, cardiac disease, arteriopathies, and metabolic and coagulation abnormalities. Recommendations for secondary prevention are based on adult studies and the underlying pathophysiology of the stroke. Antiplatelet therapy (aspirin 1-5 mg/kg/day) is recommended in most children with a history of AIS. Although there is minimal evidence to support its use in children, anticoagulation may be indicated in AIS associated with extracranial arterial dissection, prothrombotic disorders, cardiac disease, severe intracranial stenosis, and recurrent AIS while on antiplatelet therapy.

Outcome of sickle cell anemia: a 4-decade observational study of 1056 patients

Based on a prospective cohort study of 1056 patients with sickle cell anemia (Hb SS) initiated in 1959, we investigated the influence of calendar era, age, sex, and prior medical conditions on the subsequent development of irreversible organ damage and survival using the Cox regression model with time-dependent covariates adjusting for all prior occurrences. We studied 30 acute clinical events, and focused on 8 prototypic forms of irreversible organ damage. Childhood survival to age 20 years has improved from 79% for those born before 1975 to 89% for children born in or after 1975. Bone infarction was a significant risk factor for avascular necrosis (p = 0.01), and infantile dactylitis was a significant risk factor for stroke (p = 0.01). Prior hospitalized vaso-occlusive sickle crisis in adults was significantly associated with the increased rate of avascular necrosis (p < 0.001), leg ulcers (p < 0.001), sickle chronic lung disease (p < 0.001), renal failure (p < 0.005), and early death (p < 0.001). The diagnosis of clearly evident clinical conditions such as leg ulcer, osteonecrosis, and retinopathy predicted an increased likelihood of developing a more lethal form of organ damage and earlier death: 77% of patients with chronic lung disease, 75% of those with renal insufficiency, and 51% of those with stroke had a prior chronic condition. Of the 232 patients who died, 73% had 1 or more clinically recognized forms of irreversible organ damage. By the fifth decade, nearly one-half of the surviving patients (48%) had documented irreversible organ damage. End-stage renal disease (glomerulosclerosis), chronic pulmonary disease with pulmonary hypertension, retinopathy, and cerebral microinfarctions are manifestations of arterial and capillary microcirculation obstructive vasculopathy. The current study underscores the need for preventive therapy to ameliorate the progression of the sickle vasculopathy.

Overt and Incomplete (Silent) Cerebral Infarction in Sickle Cell Anemia: Diagnosis and Management

Regional complete infarctions in children with sickle cell anemia (HbSS) are often associated with stenosis of the large intracranial arteries and result in lifetime disability. Incomplete infarction occurs more frequently than previously recognized and has far-reaching effects on neurocognitive development and the risk for overt secondary strokes into adulthood. Clinical and neuroimaging modalities have been highlighted in an algorithmic approach, with the studies giving the highest yield in results and most likely to be available listed in sequential order. The recognition of an emerging "second peak" incidence in the third decade of life is worrisome and warrants more intense scrutiny and diagnosis of subtle findings of stroke in this young adult population.

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.

Stroke in Latin America

Stroke is one of the leading causes of mortality in Latin America, with variable incidence and prevalence throughout the continent reflecting regional socioeconomic differences. In Latin America, uncontrolled hypertension is one of the major causes of stroke, but other modifiable risk factors also play a role, such as heavy alcohol consumption and smoking. Intracerebral hemorrhage and lacunar stroke are more frequent in Latin America than in North America and Europe. There are multiple causes of stroke that are endemic to Latin America, including neurocysticercosis, Chagas' disease, sickle cell anemia, malaria, hemorrhagic fever, and snake bites.

Transcranial Doppler Changes in Children With Sickle Cell Disease on Transfusion Therapy

Transcranial Doppler (TCD) is an effective method for screening patients with sickle cell disease (SCD) at risk for first stroke. Its usefulness in monitoring children with SCD receiving transfusions has not been established. The authors studied 17 children with SCD evaluated with TCDs and magnetic resonance angiograms (MRAs) while receiving transfusion therapy. Patients with normalized TCDs had normal MRAs that remained normal on transfusions. Patients with persistently abnormal TCDs had abnormal MRAs. In these children, TCD velocities decreased but rarely reverted to normal. Patients with low TCD velocities (<70 cm/s) had corresponding vasculopathy on MRA. Low velocities may be a risk factor for stroke and should be followed. Overall, there was good correlation between TCD velocity changes and MRA analysis.

Decreased cerebral perfusion correlates with increased BOLD hyperoxia response in transgenic mouse models of sickle cell disease

Neurological complications such as stroke are known consequences of sickle cell disease (SCD). In order to improve methods for the evaluation of stroke risk in SCD, MRI was used to evaluate cerebrovascular function in transgenic mouse models of human SCD. It is hypothesized that oxygen-sensitive imaging in the brain will reveal areas of excess deoxygenation that are either at risk of or the result of vaso-occlusion. Arterial spin labeling (ASL) perfusion was performed in order to correlate BOLD results with microvascular cerebral blood flow. Upon comparison with control animals, there was a relative increase in BOLD hyperoxia response of 42-67% (P < 0.001) in the transgenic mice while cerebral blood flow during normoxia was reduced by 30-40% (P < 0.02). Hyperoxia caused cerebral blood flow to decrease in control mice, whereas blood flow increased in the sickle transgenic mice. These results indicate impairment in brain autoregulation in the sickle cell transgenic mice leading to increased cerebral deoxyhemoglobin. Increased deoxyhemoglobin coupled with reduced perfusion may further increase the risk of vaso-occlusion and stroke. This may reflect polymer reduction or reduced cell adhesion during hyperoxia. The MRI protocol is noninvasive and thus directly applicable to a clinical population.

Declining stroke rates in Californian children with sickle cell disease

Although the Stroke Prevention Trial in Sickle Cell Anemia (STOP) demonstrated the efficacy of blood transfusions for primary stroke prevention in high-risk children with sickle cell disease (SCD) in 1998, the impact of this trial on public health has not been studied. Our objective was to determine whether stroke rates in Californian children with SCD have declined since 1998. Using a California-wide hospital discharge database, we identified all first admissions for stroke in children with SCD from 1991 through 2000. Annual stroke incidence rates were calculated as the number of admissions divided by the estimated population of Californian children with SCD in that year. For 1991-2000, 93 children with SCD were admitted to Californian hospitals with a first stroke during 12 030 person-years of follow-up; 92.5% were ischemic and 7.5% hemorrhagic. Overall, the rate of first stroke was 0.77/100 person-years. For the study years 1991-1998, the rate for first stroke was 0.88/100 person-years compared to 0.50 in 1999 and 0.17 in 2000 (P <.005 for trend). Since the publication of the STOP study in 1998, annual rates of admissions for first stroke for Californian children with SCD have declined.

Cerebrovascular disorders in children

Cerebrovascular disorders are an important cause of mortality and chronic morbidity in children. International incidence rates for childhood stroke (ie, from 30 days to 18 years of age) have ranged from 1.3 to 13 per 100,000 children. Ischemic stroke is probably more common than hemorrhagic stroke in children. The clinical presentation of stroke in children varies according to age and location of the stroke. Over 100 risk factors for stroke in children have been reported, but in up to one third of cases no cause is identified. The management and prevention of stroke in children is not well studied and current recommendations are based on adult studies, nonrandomized trials, or expert opinion. Over half of children with stroke will develop lifelong cognitive or motor disability and up to one third will have a recurrent stroke. This review briefly describes the epidemiology, risk factors, evaluation, treatment, and outcome of stroke in children.

Long-term therapeutic plasma exchange in the outpatient setting using an implantable central venous access device

We presented the results of our prospective trial of the Bard CathLink 20 in outpatient therapeutic plasma exchange in May 2000. Since the close of that study, three of the original subjects and one additional subject have received continuous outpatient treatment using the device. We report herein on its long-term use. Four patients with demyelinating polyneuropathy underwent outpatient plasma exchange of 1-1 1/4 plasma volumes using Bard CathLink 20 venous access devices for up to 2 1/2 years. Treatment schedules varied according to the status of the patient's neuropathy. Four men (age 59, 60, 76, 79) underwent 55, 56, 38, and 41 plasma exchanges over 18.5, 18, 20, and 38.5 months, respectively, all in the outpatient setting. Ninety-one percent were completed in <150 min (mean 120 +/- 28 min) with 3,783 +/- 314 ml of plasma removed. Mean access flow rates were approximately 70 +/- 11 ml/min. Plasma flow rates were approximately 38 +/- 6 ml/min. (During our original 6-month prospective trial, access and plasma flow rates were approximately 54 and 32 ml/min, respectively). There were no adverse effects resulting from use of the CathLink and no hospitalizations were needed for plasma exchange. Pressure alarms were infrequent. Access and plasma flow rates achieved with the CathLink 20 have increased by about 30 and 16%, respectively, with long-term use. The conclusion from our prospective trial of this device, that it could conveniently be used for long-term outpatient plasma exchange, is supported by our follow-up experience.