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

The association between preoperative lacunar infarcts and postoperative delirium in elderly patients undergoing major abdominal surgery: a prospective cohort study

OBJECTIVE

The primary goal was to investigate whether the presence of preoperative lacunar infarcts (LACI) was associated with postoperative delirium (POD) in elderly patients undergoing elective major abdominal surgery.

DESIGN

A prospective cohort study.

SETTING AND PARTICIPANTS

Patients aged ≥ 65 years from a tertiary level A hospital in China.

METHODS

The POD was assessed once daily within the first postoperative 3 days using the Confusion Assessment Method. Neurocognitive tests using the Mini-mental State Examination (MMSE) and the Beijing version of the Montreal Cognitive Assessment scales were carried out within 3 days before surgery and 4-7 days after surgery. Regional cerebral oxygen saturation (rScO2) was recorded in the operating room. Logistic regression analysis was used to evaluate the impact of preoperative LACI on POD and to explore the risk factors for POD.

RESULTS

A total of 369 participants were analyzed, 161 in the preoperative LACI-positive group (P group), and 208 in the preoperative LACI-negative group (N group), respectively. The incidence of POD was 32.7% in our study. The incidence of POD was significantly higher in the P group than in the N group (39.1 vs 27.9%, risk ratio, 1.66; 95% CI 1.07-2.58; P = 0.022). Furthermore, the P group exhibited lower mean rScO2 values during the procedure (P < 0.001). In exploratory analysis, the advanced age (P = 0.005), sex (P = 0.038), and lower preoperative MMSE score (P = 0.019) were independent risk factors for POD in patients undergoing major abdominal surgery.

CONCLUSIONS AND IMPLICATIONS

Preoperative LACI was common, and constituted a risk factor for POD in older patients undergoing abdominal surgery. Despite the frequent subclinical nature, the preoperative LACI led to lower mean rScO2 during the procedure. These findings could help early identification of high-risk POD patients.

Cerebral Hemodynamic Responses to Disease-Modifying and Curative Sickle Cell Disease Therapies

BACKGROUND AND OBJECTIVES

Sickle cell disease (SCD) is a hemoglobinopathy resulting in hemoglobin-S production, hemolytic anemia, and elevated stroke risk. Treatments include oral hydroxyurea, blood transfusions, and hematopoietic stem cell transplantation (HSCT). Our objective was to evaluate the neurologic relevance of these therapies by characterizing how treatment-induced changes in hemoglobin (Hb) affect brain health biomarkers.

METHODS

In this interventional study, adults with and without SCD underwent a 3T-MRI at Vanderbilt University Medical Center at 2 time points before and after clinically indicated transfusion or HSCT or at 2 time points without the introduction of a new Hb-altering therapy (adult controls and patients with SCD on hydroxyurea). Cerebral blood flow (CBF; mL/100 g/min) and cerebral venous blood relaxation rate (s-1; a marker of Hb and blood oxygen content) responses were assessed to understand how these markers of brain health vary with Hb modulation. CBF was assessed with arterial spin labeling MRI, and blood relaxation rate was assessed using T2 relaxation under spin tagging MRI. Measures were pairwise compared within each cohort using a 2-tailed Wilcoxon signed-rank test, and regression was applied to evaluate the parameter and Hb change relationships. The significance criterion was 2-sided p < 0.05.

RESULTS

Adults with (n = 43; age 28.7 ± 7.7 years; 42% male) and without (n = 13; age 33.5 ± 12.2 years; 46% male) SCD were evaluated. In adults receiving hydroxyurea (n = 10), neither Hb, CBF, nor venous relaxation rate changed between time 1 (Hb = 8.6 ± 1.2 g/dL) and time 2 (Hb = 9.0 ± 1.8 g/dL) (all p > 0.05). In transfusion patients (n = 19), Hb increased from 8.2 ± 1.4 g/dL to 9.3 ± 1.3 g/dL before vs after transfusion (p < 0.001), paralleling a CBF decrease of 14.2 mL/100 g/min (p < 0.001) toward control levels. The venous relaxation rate did not change after transfusion (p = 0.71). In HSCT patients (n = 14), Hb increased from 8.9 ± 1.9 g/dL to 12.9 ± 2.7 g/dL (p < 0.001) before vs after transplant, paralleling CBF decreases from 68.16 ± 20.24 to 47.43 ± 12.59 mL/100 g/min (p < 0.001) and increase in venous relaxation rate (p = 0.004). Across the Hb spectrum, a CBF decrease of 5.02 mL/100 g/min per g/dL increase in Hb was observed.

DISCUSSION

Findings demonstrate improvement in cerebral hemodynamics after transfusion and transplant therapies compared with hydroxyurea therapy; quantitative relationships should provide a framework for using these measures as trial end points to assess how new SCD therapies affect brain health.

Effect of voxelotor on cerebral perfusion and cerebral oxygen metabolism and cardiac stress in adult patients with sickle cell disease

Sickle cell disease (SCD) is complicated by silent cerebral infarcts (SCIs), for which anemia is an important risk factor. Despite normal oxygen delivery (OD), cerebral vascular reserve (CVR), and cerebral metabolic rate of oxygen (CMRO2) are diminished in SCD, possibly causing the formation of SCIs. Voxelotor inhibits polymerization by increasing the hemoglobin oxygen binding, ameliorating hemolytic anemia. Furthermore, anemia is related to cardiac complications. Our aims were to assess the effect of voxelotor on markers of cerebral perfusion, cerebral oxygen metabolism, and markers of cardiac stress in SCD patients. Cerebral hemodynamics and oxygen metabolism were measured with MRI before and after 3 months of voxelotor treatment (1500 mg/day) in 18 adults with SCD (HbSS/HbSβ0-thalassemia). Hemoglobin levels significantly increased (p = .001) and markers of hemolysis decreased (p < .05). OD increased from 6.5 (IQR, 6.0-7.1) mL O2/100 g/min to 8.1 (IQR, 7.2-8.7) mL O2/100 g/min (p = .001). CBF and CVR did not change. CMRO2 decreased from 2.0 (IQR, 1.9-2.1) mL O2/100 g/min to 1.9 (IQR, 1.6-2.1) mL O2/100 g/min (p = .03). N-terminal pro-B type natriuretic peptide (NT-proBNP) levels decreased (p = .048) and maximum tricuspid regurgitation flow velocity (TRVmax) normalized in all but one patient with increased TRVmax. Voxelotor treatment in patients with severe SCD did not decrease CBF despite increased Hb levels. Cerebral oxygen metabolism slightly decreased, despite raised OD, most likely due to drug-induced increase in oxygen binding. Nonetheless, voxelotor improved clinically validated markers of cardiac stress.

Macrovascular blood flow and microvascular cerebrovascular reactivity are regionally coupled in adolescence

Cerebrovascular imaging assessments are particularly challenging in adolescent cohorts, where not all modalities are appropriate, and rapid brain maturation alters hemodynamics at both macro- and microvascular scales. In a preliminary sample of healthy adolescents (n = 12, 8-25 years), we investigated relationships between 4D flow MRI-derived blood velocity and blood flow in bilateral anterior, middle, and posterior cerebral arteries and BOLD cerebrovascular reactivity (CVR) in associated vascular territories. As hypothesized, higher velocities in large arteries are associated with an earlier response to a vasodilatory stimulus (cerebrovascular reactivity delay) in the downstream territory. Higher blood flow through these arteries is associated with a larger BOLD response to a vasodilatory stimulus (cerebrovascular reactivity amplitude) in the associated territory. These trends are consistent in a case study of adult moyamoya disease. In our small adolescent cohort, macrovascular-microvascular relationships for velocity/delay and flow/CVR change with age, though underlying mechanisms are unclear. Our work emphasizes the need to better characterize this key stage of human brain development, when cerebrovascular hemodynamics are changing, and standard imaging methods offer limited insight into these processes. We provide important normative data for future comparisons in pathology, where combining macro- and microvascular assessments may better help us prevent, stratify, and treat cerebrovascular disease.

Macrovascular blood flow and microvascular cerebrovascular reactivity are regionally coupled in adolescence

Cerebrovascular imaging assessments are particularly challenging in adolescent cohorts, where not all modalities are appropriate, and rapid brain maturation alters hemodynamics at both macro- and microvascular scales. In a preliminary sample of healthy adolescents (n=12, 8-25 years), we investigated relationships between 4D flow MRI-derived blood velocity and blood flow in bilateral anterior, middle, and posterior cerebral arteries and BOLD cerebrovascular reactivity in associated vascular territories. As hypothesized, higher velocities in large arteries are associated with an earlier response to a vasodilatory stimulus (cerebrovascular reactivity delay) in the downstream territory. Higher blood flow through these arteries is associated with a larger BOLD response to a vasodilatory stimulus (cerebrovascular reactivity amplitude) in the associated territory. These trends are consistent in a case study of adult moyamoya disease. In our small adolescent cohort, macrovascular-microvascular relationships for velocity/delay and flow/CVR change with age, though underlying mechanisms are unclear. Our work emphasizes the need to better characterize this key stage of human brain development, when cerebrovascular hemodynamics are changing, and standard imaging methods offer limited insight into these processes. We provide important normative data for future comparisons in pathology, where combining macro- and microvascular assessments may better help us prevent, stratify, and treat cerebrovascular disease.

Children and Adolescents With Sickle Cell Disease and Skull Infarction: A Systematic Review

INTRODUCTION

Skull infarction is an uncommonly reported complication of sickle cell disease. We aimed to characterize the clinical and imaging features of skull infarction in pediatric patients with sickle cell disease.

METHODS

We searched the PubMed database for case reports on skull bone infarction in pediatric patients with sickle cell disease. Out of 67 records retrieved, 15 met inclusion criteria, and a 16th case reported by the senior author was included. We extracted and analyzed clinical and imaging data.

RESULTS

The most common symptom at onset was headache (88%). Bilateral skull infarction (50%) and parietal bone involvement (82%) were frequent imaging findings. Epidural hematoma developed in 65% of the cases, 30% of patients required drainage, and exchange infusion was reported in 18%. No fatal outcomes were reported.

CONCLUSIONS

Skull infarction is a potentially severe complication of sickle cell disease presenting unique clinical challenges. Acute headaches should raise suspicion for this condition and may require additional investigation.

Abnormal Neurologic Findings in Patients With Sickle Cell Disease Without a History of Major Neurologic Events

Background and Objectives

Patients with sickle cell disease (SCD) are prone to symptomatic neurologic complications. Previous studies reported accrual of neural injury starting at early age, even without having symptomatic neurologic events. The aim of this study was to assess the prevalence and risk factors of abnormal neurologic findings in patients with SCD with no history of major symptomatic neurologic events.

Methods

Our study extracted patients diagnosed with SCD from the Cooperative Study of Sickle Cell Disease. Patients who underwent a neurologic evaluation were included in our analysis. Patients with previous documented major symptomatic neurologic events were excluded. We compared patients with SCD with abnormal neurologic findings with those without in terms of clinical and laboratory parameters using multivariate binary logistic regression.

Results

A total of 3,573 patients with SCD were included (median age = 11 [IQR = 19] years, male = 1719 [48.1%]). 519 (14.5%) patients had at least one abnormal neurologic finding. The most common findings in descending order were abnormal reflexes, gait abnormalities, cerebellar dysfunction, language deficits, nystagmus, abnormal muscle tone and strength, Romberg sign, Horner syndrome, and intellectual impairment. History of eye disease (odds ratio [OR] = 2.76, 95% confidence interval [CI] = 1.63-4.68) and history of osteomyelitis (OR = 2.55, 95% CI 1.34-4.84) were the strongest predictors of abnormal neurologic findings, followed by smoking (OR = 1.59, 95% CI 1.08-2.33), aseptic necrosis (OR = 1.57, 95% CI 1.06-2.33), hand-foot syndrome (OR = 1.48, 95% CI 1.04-2.12), and male sex (OR = 1.42, 95% CI 1.01-2.02).

Discussion

Neurologic deficits are relatively common in patients with SCD, even without documented major neurologic insults. They range from peripheral and ophthalmic deficits to central and cognitive disabilities. Patients with SCD should have early regular neurologic evaluations and risk factor modification, particularly actively promoting smoking cessation.

Factors Associated with Overt Stroke in Children and Adolescents with Sickle Cell Disease: A Retrospective Cohort Study

Sickle cell disease (SCD) is associated with a high occurrence of complications due to vaso-occlusive phenomenon such as stroke. This retrospective cohort study aimed to examine the clinical and laboratory characteristics of 120 children and adolescents with SCD and analyze the factors associated with overt stroke incidence. All relevant data were obtained from patient medical records. Survival analysis was used to compare the demographic, clinical, and laboratory characteristics between patients with and those without overt stroke. The patients were 52.5% female with a mean (SD) age of 11.2 (4.3) years. The incidence of overt stroke in this cohort was nine out of 956.7 patient-years, resulting in an incidence density of 0.94 cases/100 patient-years. Reports of greater than or equal to two previous attacks of dactylitis and greater than or equal to three episodes of acute chest syndrome (ACS)/pneumonia were associated with overt stroke and an increase in reticulocyte count and red blood cell distribution width (RDW). In conclusion, a history of a high number of dactylitis, ACS/pneumonia, increased RDW, and reticulocytosis was associated with overt stroke occurrence in children and adolescents with SCD. Future studies with a higher stroke incidence in the evaluated sample are necessary to confirm this hypothesis.

Prevention of neurovascular complications in children with Sickle Cell Disease in the real-world setting: What adult medicine physicians should know

Neurovascular complications represent one of the most detrimental manifestations of Sickle Cell Disease (SCD), affecting many patients since infancy. They include overt stroke, silent cerebral infarcts and neurocognitive disorders. In fact, neurodevelopment can be impaired in children resulting in cognitive dysfunction in adults with SCD. This review is meant to resume the most recent guidelines about the prevention of SCD neurovascular complications and to highlight the open challenges in their implementation. Transcranial Doppler, Magnetic Resonance Imaging/Angiography and neurocognitive test are useful screening tools. Chronic transfusion regimen, hematopoietic stem cell transplantation and neurocognitive rehabilitation find indications in the context of primary and secondary prevention of neurovascular complications of SCD. However, international guidelines are often difficult to bring into the real world due to the lack of appropriate instruments and trained personnel. Many challenges have still to be faced to guarantee the best possible neurocognitive function to each child affected by SCD.

Neurofilament light chain: A potential biomarker for cerebrovascular disease in children with sickle cell anaemia

Cerebrovascular injury frequently occurs in children with sickle cell anaemia (SCA). Limited access to magnetic resonance imaging and angiography (MRI-MRA) in sub-Saharan Africa impedes detection of clinically unapparent cerebrovascular injury. Blood-based brain biomarkers of cerebral infarcts have been identified in non-SCA adults. Using plasma samples from a well-characterized cross-sectional sample of Ugandan children with SCA, we explored relationships between biomarker levels and MRI-detected cerebral infarcts and transcranial Doppler (TCD) arterial velocity. Testing was performed using a 4-plex panel of brain injury biomarkers, including neurofilament light chain (NfL), a central nervous system neuron-specific protein. Mean biomarker levels from the SCA group (n = 81) were similar to those from non-SCA sibling controls (n = 54). Within the SCA group, NfL levels were significantly higher in those with MRI-detected infarcts compared to no infarcts, and higher with elevated TCD velocity versus normal velocity. Elevated NfL remained strongly associated with MRI-detected infarcts after adjusting for sex and age. All non-SCA controls and SCA participants lacking MRI-detected infarcts had low NfL levels. These data suggest potential utility of plasma-based NfL levels to identify children with SCA cerebrovascular injury. Replication and prospective studies are needed to confirm these novel findings and the clinical utility of NfL versus MRI imaging.

Silent Cerebral Infarcts in Iraqi Patients with Sickle Cell Disease

Silent ischemic infarcts have been reported to be the most frequent neurological abnormalities in sickle cell disease (SCD) in several studies worldwide. However, no previous studies investigated this neurological disorder in Iraqi SCD patients. To address this issue, a total of 52 patients with a median age of 20 years (range 10-46) and including 46.2% males were enrolled. Patients were clinically evaluated and their records were reviewed. They had full blood and reticulocyte counts, hemoglobin F estimation, serum lactic dehydrogenase and bilirubin assayed, as well as brain magnetic resonance imaging (MRI) to screen for silent cerebral infarcts. Six out of the 52 patients (11.5%) had silent cerebral infarcts, all of which were in the deep white matter, ranging from 6 to 10 mm in their largest diameters. There were no significant differences in age, sex, or sickle cell genotype between those with silent cerebral infarcts and those without it. Those with silent cerebral infarcts had lower median hemoglobin, higher reticulocytes and lower pain frequencies than those without it, yet again this was not significant. Follow up MRI in four out of the six silent infarct patients showed no additional lesions and no increase in size of the original ones after six to eight months. In conclusion, it appears that the frequency of silent cerebral infarcts in Iraqi SCD patients is lower than the bulk of the literature from other populations. Further studies to screen for genetic polymorphisms that may explain this lower rate may be informative.

Prevalence and Risk Factors of Stroke Among Children With Sickle Cell Disease: A Retrospective Study at a Tertiary Care Center

Background Sickle cell disease (SCD) is a common autosomal recessive inherited hemoglobin disorder in many countries. Neurological complications are among the most disabling complications in SCD. Stroke and cerebral vasculopathy can lead to further neurological insult. Ischemic insults, stroke, and silent infarcts are preventable causes of morbidity and mortality in SCD patients. Understanding the epidemiology and characteristics of such patients will help to prevent complications.  Methodology This is a retrospective study conducted in a tertiary care center in Saudi Arabia. Cases of SCD admitted to the pediatric ward between the years 2019 to 2023 were included in the study. Demographic data, clinical diagnosis, and frequency of prior admissions were collected. Brain imaging results were reviewed and included. Furthermore, the study assessed common risk factors leading to developing a stroke in SCD pediatric patients. Risk factors and clinical outcomes after stroke were also included. Results Eighty-one patients were enrolled. The mean age of stroke patients was 8.21±3.50 years while the mean age of non-stroke patients was 6.24±3.76 years. More than half of the patients were females in both the stroke (61.50%) and non-stroke groups (52.90%). Thirteen SCD patients (16%) were diagnosed with stroke. Previous history of stroke, high mean corpuscular volume (MCV), and low red blood cells count (RBC) were statistically significant risk factors for stroke (p<0.0001), (p<0.0001), (p<0.03), respectively.  Conclusion Stroke is one of the most devastating complications of SCD. The prevalence of stroke among SCD patients in our study was 16%. Transcranial Doppler ultrasound screening is the most important predictor of stroke.

Cognitive-motor dual-task interference in adults with sickle cell disease

BACKGROUND

Sickle cell disease (SCD) is a genetic disorder that causes physical and cognitive impairment due to hemolysis, painful vaso-occlusion episodes, joint avascular necrosis, and strokes. As individuals with SCD age and develop conditions impacting their physical and cognitive function, their ability to multitask successfully and safely may decline. Cognitive-motor dual-task interference occurs when there is deterioration in one or both tasks while dual-tasking relative to single-tasking. Dual-task assessment (DTA) is a valuable measure of physical and cognitive function; however, there is limited data on DTA in adults with SCD.

RESEARCH QUESTION

Is DTA a feasible and safe method of measuring physical and cognitive function in adults with SCD? What patterns of cognitive-motor interference occur in adults with SCD?

METHODS

We enrolled 40 adults with SCD (mean age 44 years, range 20-71) in a single-center prospective cohort study. We used usual gait speed as the measure of motor performance and verbal fluency (F, A, and S) as the measure of cognitive performance. We measured feasibility as the proportion of consented participants able to complete the DTA. We calculated the relative dual-task effect (DTE %) for each task and identified patterns of dual-task interference.

RESULTS

Most consented participants completed the DTA (91%, 40/44) and there were no adverse events. There were 3 main dual-task interference patterns for the first trial using letter 'A': Motor Interference (53%, n = 21), Mutual Interference (23%, n = 9), and Cognitive-Priority Tradeoff (15%, n = 6). For the second trial using letter 'S', there were two main dual-task interference patterns: Cognitive-Priority Tradeoff (53%, n = 21) and Motor Interference (25%, n = 10).

STATEMENT OF SIGNIFICANCE

DTA was feasible and safe in adults with SCD. We identified specific patterns of cognitive-motor interference. This study supports further evaluation of DTA as a potentially useful tool to measure physical and cognitive function in ambulatory adults with SCD.

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

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

Does TGFBR3 Polymorphism Increase the Risk of Silent Cerebral Infarction in Egyptian Children with Sickle Cell Disease?

OBJECTIVES

To evaluate the relationship between TGFBR3 rs284875 single nucleotide polymorphism (SNP) state and silent cerebral infarction (SCI) in asymptomatic patients with sickle cell disease (SCD).

METHODS

A cross-sectional study was conducted on 50 children with SCD above 2 y of age followed up at the hematology outpatient clinic of Alexandria University Children's Hospital in Egypt. Twenty-four healthy children were included as a control group. All patients included in the study were subjected to complete history and clinical examination. Real-time polymerase chain reaction was performed on patients and controls for identification of SNP rs284875 of the TGFBR3 gene. A magnetic resonance imaging (MRI) of the brain were performed only on patients for detection of SCI.

RESULTS

Fifty SCD patients were enrolled (26 males and 24 females), with a median age of 10.9 y (2.3-17.8 y), and 24 children as healthy control for the studied SNP. Thirty-five (70%) patients had homozygous SCD, while 30% had sickle β-thalassemia. The brain MRI was normal in all the patients except for 2 patients who had features of SCI. The TGFBR3 rs284875 SNP was detected in 15 (30%) patients in the homozygous state (GG) versus only 1 (4.2%) child from the control group (p = 0.003). The prevalence of SCI was low in the study population and there was no statistically significant relationship between the TGFBR3 rs284875 SNP status and the presence of SCI in the brain MRI (p = 0.621).

CONCLUSIONS

This study confirmed a low prevalence of SCI in the SCD patient included in the study. The TGFBR3 rs284875 SNP did not significantly increase SCI among those patients.

Quantitative susceptibility mapping (QSM) and R2* of silent cerebral infarcts in sickle cell anemia

Silent cerebral infarction (SCI) is the most commonly reported radiological abnormality in patients with sickle cell anemia (SCA) and is associated with future clinical stroke risk. To date, there have been few histological and quantitative MRI studies of SCI and multiple radiological definitions exist. As a result, the tissue characteristics and composition of SCI remain elusive. The objective of this work was therefore to investigate the composition of segmented SCI lesions using quantitative MRI for R2 * and quantitative magnetic susceptibility mapping (QSM). 211 SCI lesions were segmented from 32 participants with SCA and 6 controls. SCI were segmented according to two definitions (FLAIR+/-T1w-based threshold) using a semi-automated pipeline. Magnetic susceptibility (χ) and R2 * maps were calculated from a multi-echo gradient echo sequence and mean SCI values were compared to an equivalent region of interest in normal appearing white matter (NAWM). SCI χ and R2 * were investigated as a function of SCI definition, patient demographics, anatomical location, and cognition. Compared to NAWM, SCI were significantly less diamagnetic (χ = -0.0067 ppm vs. -0.0153 ppm, p < 0.001) and had significantly lower R2 * (16.7 s-1 vs. 19.2 s-1, p < 0.001). SCI definition had a significant effect on the mean SCI χ and R2 * , with lesions becoming significantly less diamagnetic and having significantly lower R2 * after the application of a more stringent T1w-based threshold. SCI-NAWM R2 * decrease was significantly greater in patients with SCA compared with controls (-2.84 s-1 vs. -0.64 s-1, p < 0.0001). No significant association was observed between mean SCI-NAWM χ or R2* differences and subject age, lesion anatomical location, or cognition. The increased χ and decreased R2 * in SCI relative to NAWM observed in both patients and controls is indicative of lower myelin or increased water content within the segmented lesions. The significant SCI-NAWM R2 * differences observed between SCI in patients with SCA and controls suggests there may be differences in tissue composition relative to NAWM in SCI in the two populations. Quantitative MRI techniques such as QSM and R2 * mapping can be used to enhance our understanding of the pathophysiology and composition of SCI in patients with SCA as well as controls.

Effect of Blood Transfusion on Cerebral Hemodynamics and Vascular Topology Described by Computational Fluid Dynamics in Sickle Cell Disease Patients

The main objective of this study was to demonstrate that computational fluid dynamics (CFD) modeling can be used to study the contribution of covert and overt vascular architecture to the risk for cerebrovascular disease in sickle cell disease (SCD) and to determine the mechanisms of response to therapy such as chronic red blood cell (cRBC) transfusions. We analyzed baseline (screening), pre-randomization and study exit magnetic resonance angiogram (MRA) images from 10 (5 each from the transfusion and observation arms) pediatric sickle SCD participants in the silent cerebral infarct transfusion (SIT) trial using CFD modeling. We reconstructed the intracranial portion of the internal carotid artery and branches and extracted the geometry using 3D Slicer. We cut specific portions of the large intracranial artery to include segments of the internal carotid, middle, anterior, and posterior cerebral arteries such that the vessel segment analyzed extended from the intracranial beginning of the internal carotid artery up to immediately after (~0.25 inches) the middle cerebral artery branching point. Cut models were imported into Ansys 2021R2/2022R1 and laminar and time-dependent flow simulation was performed. Change in time averaged mean velocity, wall shear stress, and vessel tortuosity were compared between the observation and cRBC arms. We did not observe a correlation between time averaged mean velocity (TAMV) and mean transcranial Doppler (TCD) velocity at study entry. There was also no difference in change in time average mean velocity, wall shear stress (WSS), and vessel tortuosity between the observation and cRBC transfusion arms. WSS and TAMV were abnormal for 2 (developed TIA) out of the 3 participants (one participant had silent cerebral infarctions) that developed neurovascular outcomes. CFD approaches allow for the evaluation of vascular topology and hemodynamics in SCD using MRA images. In this proof of principle study, we show that CFD could be a useful tool and we intend to carry out future studies with a larger sample to enable more robust conclusions.

Assessment of cerebrovascular function in patients with sickle cell disease using transfer function analysis

In patients with sickle cell disease (SCD), the delivery of oxygen to the brain is compromised by anemia, abnormal rheology, and steno-occlusive vascular disease. Successful compensation depends on an increase in oxygen supply such as that provided by an increase in cerebral blood flow (CBF). We used magnetic resonance imaging to provide a high-resolution assessment of the ability of SCD patients to respond to a vasoactive stimulus in middle, anterior, and posterior cerebral artery territories for both white and gray matter. Cerebrovascular reactivity (CVR) was measured as the blood oxygen level dependent signal (a surrogate for CBF) response to an increase in the end tidal partial pressure of CO2 (PET CO2 ). The dynamic aspect of the response was measured as the time constant of the first order response kinetics (tau). To confirm and support these findings we used an alternative examination of the response, transfer function analysis (TFA), to measure the responsiveness (gain), the speed of response (phase), and the consistency of the response over time (coherence). We tested 34 patients with SCD and compared the results to those of 24 healthy controls participants. The results from a three-way ANOVA showed that patients with SCD have reduced CVR (p < 0.001) and lower coherence (p < 0.001) in gray matter and white matter and reduced gain in gray matter only (p < 0.001). In terms of the speed of the response to CO2 , tau (p < 0.001) and TFA phase (p < 0.001) were increased in SCD patients compared to healthy control subjects. These findings show that the cerebrovascular responsiveness to CO2 in patients with SCD is both decreased and slowed compared to healthy controls.

Sickle cell cerebrovascular reactivity to a CO2 stimulus: Too little, too slow

Background: Despite increased cerebral blood flow (CBF), cerebral infarcts occur in patients with sickle cell disease (SCD). This suggests increased CBF does not meet metabolic demand possibly due to compromised cerebral vasodilatory response. Hypothesis: In adult SCD patients, cerebrovascular reactivity (CVR) and speed of vasodilatory response (tau) to a standardized vasodilatory stimulus, are reduced compared to normal subjects.

Methods: Functional brain imaging performed as part of routine care in adult SCD patients without known large vessel cerebral vasculopathy was reviewed retrospectively. CVR was calculated as the change in CBF measured as the blood-oxygenation-level-dependent (BOLD)-magnetic resonance imaging signal, in response to a standard vasoactive stimulus of carbon dioxide (CO₂). The tau corresponding to the best fit between the convolved end-tidal partial pressures of CO₂ and BOLD signal was defined as the speed of vascular response. CVR and tau were normalized using a previously generated atlas of 42 healthy controls.

Results: Fifteen patients were included. CVR was reduced in grey and white matter (mean Z-score for CVR −0.5 [−1.8 to 0.3] and −0.6 [−2.3 to 0.7], respectively). Tau Z-scores were lengthened in grey and white matter (+0.9 [−0.5 to 3.3] and +0.8 [−0.7 to 2.7], respectively). Hematocrit was the only significant independent predictor of CVR on multivariable regression.

Conclusion: Both measures of cerebrovascular health (CVR and tau) in SCD patients were attenuated compared to normal controls. These findings show that CVR represents a promising tool to assess disease state, stroke risk, and therapeutic efficacy of treatments in SCD and merits further investigation.

Quantification of Silent Cerebral Infarction on High-Resolution FLAIR and Cognition in Sickle Cell Anemia

Research in sickle cell anemia (SCA) has used, with limited race-matched control data, binary categorization of patients according to the presence or absence of silent cerebral infarction (SCI). SCI have primarily been identified using low-resolution MRI, with radiological definitions varying in lesion length and the requirement for abnormality on both fluid attenuated inversion recovery (FLAIR) and T1-weighted images. We aimed to assess the effect of published SCI definitions on global, regional, and lobar lesion metrics and their value in predicting cognition. One hundred and six patients with SCA and 48 controls aged 8-30 years underwent 3T MRI with a high-resolution FLAIR sequence and Wechsler cognitive assessment. Prevalence, number, and volume of lesions were calculated using a semi-automated pipeline for SCI defined as: (1) Liberal: any length (L-SCI); (2) Traditional: >3 mm in greatest dimension (T-SCI); (3) Restrictive; >3 mm in greatest dimension with a corresponding T1-weighted hypo-intensity (R-SCI). Globally, as hypothesized, there were large effects of SCI definition on lesion metrics in patients and controls, with prevalence varying from 24-42% in patients, and 4-23% in controls. However, contrary to hypotheses, there was no effect of any global metric on cognition. Regionally, there was a consistent distribution of SCI in frontal and parietal deep and juxta-cortical regions across definitions and metrics in patients, but no consistent distribution in controls. Effects of regional SCI metrics on cognitive performance were of small magnitude; some were paradoxical. These findings expose the challenges associated with the widespread use of SCI presence as a biomarker of white-matter injury and cognitive dysfunction in cross-sectional high-resolution MRI studies in patients with SCA. The findings indicate that with high-resolution MRI: (1) radiological definitions have a large effect on resulting lesion groups, numbers, and volumes; (2) there is a non-negligible prevalence of lesions in young healthy controls; and (3) at the group-level, there is no cross-sectional association between global lesion metrics and general cognitive impairment irrespective of lesion definition and metric. With high-resolution multi-modal MRI, the dichotomy of presence or absence of SCI does not appear to be a sensitive biomarker for the detection of functionally significant pathology; the search for appropriate endpoints for clinical treatment trials should continue.

The Sickle Cell Disease Functional Assessment (SCD-FA) tool: a feasibility pilot study

Background

The life expectancy for individuals with sickle cell disease (SCD) has greatly increased over the last 50 years. Adults with SCD experience multiple complications such as cardiopulmonary disease, strokes, and avascular necrosis that lead to limitations that geriatric populations often experience. There are no dedicated instruments to measure functional decline and functional age to determine risk of future adverse outcomes in older adults with SCD. The objective of this study was to assess the feasibility of performing the Sickle Cell Disease Functional Assessment (SCD-FA).

Methods

We enrolled 40 adults with SCD (20 younger adults aged 18–49 years as a comparison group and 20 older adults aged 50 years and older) in a single-center prospective cohort study. Participants were recruited from a comprehensive sickle cell clinic in an academic center in the southeastern United States. We included measures validated in an oncology geriatric assessment enriched with additional physical performance measures: usual gait speed, seated grip strength, Timed Up and Go, six-minute walk test, and 30-second chair stand. We also included an additional cognitive measure, which was the Montreal Cognitive Assessment, and additional patient-reported measures at the intersection of sickle cell disease and geriatrics. The primary outcome was the proportion completing the assessment. Secondary outcomes were the proportion consenting, duration of the assessment, acceptability, and adverse events.

Results

Eighty percent (44/55) of individuals approached consented, 91% (40/44) completed the SCD-FA in its entirety, and the median duration was 89 min (IQR 80–98). There were no identified adverse events. On the acceptability survey, 95% (38/40) reported the length as appropriate, 2.5% (1/40) reported a question as upsetting, and 5% (2/40) reported portions as difficult. Exploratory analyses of physical function showed 63% (25/40) had a slow usual gait speed (< 1.2 m/s).

Conclusion

The SCD-FA is feasible, acceptable, and safe and physical performance tests identified functional impairments in adults with SCD. These findings will inform the next phase of the study where we will assess the validity of the SCD-FA to predict patient-important outcomes in a larger sample of adults with SCD.

Neurocognitive functioning in preschool children with sickle cell disease

BACKGROUND

Children with sickle cell disease (SCD) experience neurodevelopmental delays; however, there is limited research with preschool-age children. This study examined neurocognitive risk and protective factors in preschoolers with SCD.

PROCEDURE

Sixty-two patients with SCD (60% HbSS/HbSβ⁰ -thalassemia; 40% HbSC/HbSβ⁺ -thalassemia) between the ages of 3 and 6 years (mean = 4.77 years) received a neuropsychological evaluation as routine systematic surveillance. Patients were not selected for disease severity, prior central nervous system findings, or existing cognitive concerns. Thirty-four patients (82% HbSS/HbSβ⁰ -thalassemia) were prescribed hydroxyurea (HU) at the time of their neuropsychological evaluation. On average, these patients had been prescribed HU at 2.15 (standard deviation = 1.45) years of age. The average dose was 28.8 mg/kg/day. Besides genotype, there were no group differences in medical or demographic factors based on HU treatment status.

RESULTS

Patients with HbSS/HbSβ⁰ -thalassemia scored below normative expectations on measures of intelligence, verbal comprehension, and school readiness (false discovery rate-adjusted p-value [p_FDR ] < .05). Age, sickle genotype, and HU treatment exposure were not associated with measured neurocognitive outcomes (p_FDR  > .05). Greater social vulnerability at the community level was associated with poorer performance on measures of intellectual functioning, verbal comprehension, visuomotor control, and school readiness, as well as parent report of executive dysfunction (p_FDR  < .05). Greater household socioeconomic status was positively associated with academic readiness.

CONCLUSIONS

Preschoolers with severe SCD (HbSS/HbSβ⁰ -thalassemia) perform below age expectations on measures of intelligence and academic readiness. Sociodemographic factors were stronger drivers of neurocognitive performance than disease severity or disease-modifying treatment. Neurodevelopmental interventions targeting the home and broader community environment are needed.

EVALUATION OF MACULAR FLOW VOIDS ON OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY AS POTENTIAL BIOMARKERS FOR SILENT CEREBRAL INFARCTION IN SICKLE CELL DISEASE

PURPOSE

To determine the relationship between macular microvascular abnormalities on optical coherence tomography angiography and silent cerebral infarctions (SCIs) on cerebral magnetic resonance imaging in sickle cell disease.

METHODS

Patients (age <18 years old) from our previous pediatric sickle cell disease study cohort who had prior optical coherence tomography angiography and brain magnetic resonance imaging were identified. Brain magnetic resonance imaging images were compared with macular optical coherence tomography angiography scans to identify macular vascular density differences between patients with SCI and without SCI.

RESULTS

Sixty-eight eyes from 34 patients who underwent optical coherence tomography angiography were evaluated, of whom 28 eyes from 14 patients met the inclusion criteria for this study. Eight patients (57%) with SCI and 6 patients (43%) without SCI were identified. The mean age (17 years in SCI and 16.3 years in non-SCI) was comparable between groups. There was no statistically significant difference in systemic complications. Deep capillary plexus vessel density was lower in the temporal quadrant in patients with SCI (49.3% vs. 53.7%, P = 0.014).

CONCLUSION

Patients with SCI were found to have lower vessel density in the deep capillary plexus compared with those without SCI. This finding suggests that deep capillary plexus vessel density may have utility as an imaging biomarker to predict the presence of SCI.

Health-related quality of life in infants, toddlers and young children with sickle cell disease

BACKGROUND

Little is known about health-related quality of life (HRQoL) in young children with sickle cell disease living in a European country.

METHODS

A retrospective cross-sectional evaluation of TNO-AZL Preschool Children Quality of Life questionnaire (TAPQOL, 0-1 year) and Pediatric Quality of Life Inventory (PedsQL, 2-7 years) data was conducted. Study participants included caregivers of children with sickle cell disease aged 0-7 years attending the sickle cell centre at the Erasmus Medical Center or the Amsterdam University Medical Centers between April 2012 and October 2020. Comparisons were made with normative data on HRQoL in the general paediatric population.

RESULTS

The study enrolled 136 caregivers of 136 children. In children aged 0-5 years, no significant differences emerged between children with sickle cell disease and the general population. However, in children aged 5-7 years, children with sickle cell disease scored significantly lower on all subscales except for emotional functioning. Multiple regression models showed a negative association between age and HRQoL. No association was found between HRQoL and disease severity or sociodemographic characteristics.

CONCLUSIONS

This study demonstrates that HRQoL is negatively correlated with age in young children with sickle cell disease with a significantly lower HRQoL in 5- to 7-year-olds when compared to the general population. Our study underlines the importance of measuring HRQoL in young children to identify patients with impaired HRQoL early in life in order to be able to intervene accordingly. Future research should focus on deepening the knowledge of factors influencing HRQoL in children with sickle cell disease.

Navigating Ethical Challenges for Pediatric Sickle Cell Pain Management in the Context of the Opioid Epidemic

OBJECTIVES

The aim was to describe the impact of the opioid epidemic on pain management practices in pediatric sickle cell disease (SCD) and propose a conceptual framework for navigating ethical decision-making in pediatric sickle cell pain management.

METHODS

A review of the literature on ethical challenges in the management of sickle cell pain was conducted and considered in the context of the opioid epidemic and psychosocial factors affecting youth with SCD. The Integrated Ethical Framework for Pain Management (IEFPM) was applied to pediatric sickle cell pain management using a clinical case example.

RESULTS

Implicit bias, health-related stigma, and potential neurocognitive impairment all present unique challenges in ethical decision-making for youth with SCD. National guidelines for prescribing opioid medication may complicate providers' clinical decision-making and affect their sickle cell pain management practices. The IEFPM was found to be applicable to ethical decision-making for pediatric sickle cell pain and captures both patient-related and provider-related aspects of clinical pain management.

DISCUSSION

The opioid epidemic has exacerbated existing ethical challenges for pain management among youth with SCD. The IEFPM provides a conceptual model that can be integrated into health care settings to facilitate ethical decision-making and promote greater health equity in the clinical management of pediatric sickle cell pain.

Unusually High Prevalence of Stroke and Cerebral Vasculopathy in Hemoglobin SC Disease: A Retrospective Single Institution Study

INTRODUCTION

Unlike homozygous hemoglobin SS (HbSS) disease, stroke is a rare complication in hemoglobin SC (HbSC) disease. However, recent studies have demonstrated a high prevalence of silent stroke in HbSC disease. The factors associated with stroke and cerebral vasculopathy in the HbSC population are unknown.

METHODS

We conducted a retrospective study of all patients with sickle cell disease treated at the University of Missouri, Columbia, over an 18-year period (2000-2018). The goal of the study was to characterize the silent, overt stroke, and cerebral vasculopathy in HbSC patients and compare them to patients with HbSS and HbS/β thalassemia1 (thal) in this cohort. We also analyzed the laboratory and clinical factors associated with stroke and cerebral vasculopathy in the HbSC population.

RESULTS

Of the 34 HbSC individuals, we found that the overall prevalence of stroke and cerebral vasculopathy was 17.7%. Only females had evidence of stroke or cerebral vasculopathy in our HbSC cohort (33.3%, p = 0.019). Time-averaged means of maximum velocities were lower in the HbSC group than the HbSS group and did not correlate with stroke outcome. Among HbSC individuals, those with stroke and cerebral vasculopathy had a marginally higher serum creatinine than those without these complications (0.77 mg/dL vs. 0.88 mg/dL, p = 0.08). Stroke outcome was associated with recurrent vaso-occlusive pain crises (Rec VOCs) (75 vs. 25%, p = 0.003) in HbSC patients. The predominant cerebrovascular lesions in HbSC included microhemorrhages and leukoencephalopathy.

CONCLUSION

There is a distinct subset of individuals with HbSC who developed overt, silent stroke, and cerebral vasculopathy. A female predominance and association with Rec VOCs were identified in our cohort; however, larger clinical trials are needed to identify and confirm specific clinical and laboratory markers associated with stroke and vasculopathy in HbSC disease.

Correlates of gallbladder stones among patients with sickle cell disease: A meta-analysis

Sickle cell disorders are the most common hemoglobinopathies worldwide. Clinical variability of sickle cell disease (SCD) and susceptibility to its complications have been attributed to hematologic, genetic, and other influencing factors. This review aimed to provide further summary and analyses of the prevalence and factors associated with cholelithiasis among patients with SCD. A systematic database search was conducted in MEDLINE (PubMed), ScienceDirect, Google Scholar, World Health Organization Virtual Health Library, Cochrane Library databases, and System for Information on Gray Literature in Europe (SIGLE). Pooled prevalence, odds ratio (OR), and standardized mean difference (SMD) with the corresponding 95% confidence interval (CI) were calculated using Comprehensive Meta-Analysis Software version 3.3. A total of 34 studies that fulfilled the eligibility criteria were included in the analyses. The overall prevalence of cholelithiasis among SCD patients was 25.3% (95% CI 19.4-32.3%). The risk of developing cholelithiasis was significantly associated with lower total hemoglobin level (SMD = -0.45; P = 0.002), lower hemoglobin F (HbF) level (SMD = -0.85; P = 0.003), higher total serum bilirubin level (SMD = 1.15; P < 0.001), higher reticulocytes count (SMD = 0.44; P = 0.007), and UDP-glucuronosyltransferase-1A1 enzyme (UGT1A1) promoter polymorphism. This review provides a comprehensive view of the high rate of cholelithiasis and its associated factors in SCD patients.

Epidemiology of Stroke in Sickle Cell Disease

Sickle cell disease is the most common cause of stroke in childhood, both ischaemic and haemorrhagic, and it also affects adults with the condition. Without any screening or preventative treatment, the incidence appears to fall within the range 0.5 to 0.9 per 100 patient years of observation. Newborn screening with Penicillin prophylaxis and vaccination leading to reduced bacterial infection may have reduced the incidence, alongside increasing hydroxyurea prescription. Transcranial Doppler screening and prophylactic chronic transfusion for at least an initial year has reduced the incidence of stroke by up to 10-fold in children with time averaged mean of the maximum velocity >200 cm/s. Hydroxyurea also appears to reduce the incidence of first stroke to a similar extent in the same group but the optimal dose remains controversial. The prevention of haemorrhagic stroke at all ages and ischaemic stroke in adults has not yet received the same degree of attention. Although there are fewer studies, silent cerebral infarction on magnetic resonance imaging (MRI), and other neurological conditions, including headache, epilepsy and cognitive dysfunction, are also more prevalent in sickle cell disease compared with age matched controls. Clinical, neuropsychological and quantitative MRI screening may prove useful for understanding epidemiology and aetiology.

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.