Laboratory Biomarkers, Cerebral Blood Flow Velocity, and Intellectual Function in Children with Sickle Cell 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.

Prevalence and risk factors of cognitive impairment in children with sickle cell disease in Egypt

Little is known about cognitive impairment in patients with sickle cell disease in Africa. This study aimed to assess cognitive impairment and identify possible risk factors in patients with sickle cell disease in Egypt. This study was conducted at Cairo University Children Hospital. Patients with sickle cell disease, between ages of 6-20 years were enrolled. Cognitive ability was tested using the Stanford Binet intelligence quotient (IQ) test, fourth edition. Transcranial Doppler, magnetic resonance imaging and magnetic resonance angiography of the brain were performed within a week of the IQ test. Among the 40 enrolled patients, 55% had a Full Scale IQ at least 1 standard deviation below the mean, and 27.5% had an IQ 2 standard deviations below the mean. High lactate dehydrogenase was significantly associated with low IQ (p = 0.004). In univariate analyses, IQ was significantly correlated with older age (p = 0.025), high lactate dehydrogenase (p = 0.008) and older age at the start of hydroxyurea (p = 0.025). Impaired cognition is prevalent among sickle cell disease patients. Early initiation of hydroxyurea therapy, which should also reduce hemolysis and lactate dehydrogenase, may be a simple measure to preserve mental abilities in these patients.

Associations Between Transcranial Doppler Flow Velocities, Laboratory Parameters, and Clinical Features in Turkish Children With Sickle Cell Disease

OBJECTIVE

Stroke is one of the major complications of sickle cell disease (SCD). Stroke features either occlusion of, or stenosis at, the origin of one of the large intracerebral arteries, the internal carotid artery (ICA), and/or the middle cerebral artery (MCA).

PURPOSE

We sought correlations between cerebral blood flow velocities and the laboratory and clinical findings of patients with SCD.

MATERIALS AND METHODS

Fifty-three pediatric SCD patients (39 with HbSS, 14 with HbSβ0) were analyzed. The mean patient age was 12.9±3.9 years. The control group contained 24 healthy individuals. The time-averaged maximum mean velocity (TAMMV) and resistive index (RI) of the MCA, the TAMMVs of the ICA and vertebral artery (VA), and the diameter of the VA were estimated through transcranial Doppler ultrasonography using a 2.5 MHz transducer, in accordance with the Stroke Prevention Trial in Sickle Cell Anemia (STOP) protocol. We evaluated the relationships between the TAMMVs, laboratory parameters, and clinical findings.

RESULTS

The mean±SD MCA TAMMV was 161.2±35.4 cm/s in patients with HbSS and 185.8±62.9 cm/s in patients with HbSβ0. The mean MCA TAMMV, RI, ICA TAMMV, VA TAMMV, and VA diameter were 168.5±43.9 cm/s, 0.63±0.06, 116.8±25.5 cm/s, 69.2±18.5 cm/s, and 3.5±0.61 mm for all SCD patients, respectively. In the control group, the mean MCA TAMMV, RI, ICA TAMMV, VA TAMMV, and VA diameter were 103.8±28.8 cm/s, 0.53±0.04, 96.4±27.8 cm/s, 40.3±12.1 cm/s, and 3.4±0.6 mm, respectively. Although the differences were not significant, TAMMVs were higher in HbSβ0 patients taking hydroxyurea; those with hemoglobin levels <8 g/dL, ferritin levels >1000 ng/dL, mean platelet volume >12 fL, or red cell distribution width >18%; or required chelation, or were below the third percentiles of weight and height. The TAMMV was significantly higher only in SCD patients who complained of headache.

CONCLUSIONS

High ferritin and low hemoglobin levels, a high mean platelet volume, a high red cell distribution width, low weight (below the third percentile), and a short height (below the third percentile) may be associated with elevated cerebral blood flow velocities and an increased stroke risk in children with SCD. Children with such features should be closely followed-up through transcranial Doppler ultrasonography examination.

Effects of hydroxyurea on brain function in children with sickle cell anemia

INTRODUCTION

Sickle cell anemia (SCA) results in numerous adverse effects on the brain, including neurocognitive dysfunction. Hydroxyurea has been utilized extensively for management of SCA, but its effects on brain function have not been established.

METHODS

We examined prospectively the effects of 1 year of treatment with hydroxyurea on brain function in children with SCA (HbSS/HbSβ⁰ -thalassemia) by baseline and exit evaluations, including comprehensive neurocognitive testing, transcranial Doppler ultrasound (TCD), and brain MRI (silent cerebral infarcts [SCI], gray matter cerebral blood flow [GM-CBF], and blood oxygen level-dependent [BOLD] signal from visual stimulation).

RESULTS

Nineteen patients with SCA, mean age 12.4 years (range 7.2-17.8), were evaluated. At baseline, subjects had these mean values: full-scale IQ (FSIQ) 82.8, TCD velocity 133 cm/s, GM-CBF 64.4 ml/100 g/min, BOLD signal 2.34% increase, and frequency of SCI 47%. After 1 year of hydroxyurea, there were increases in FSIQ (+2, p = .059) and reading passage comprehension (+4, p = .033), a significant decrease in TCD velocity (-11 cm/s, p = .007), and no significant changes in GM-CBF, BOLD, or SCI frequency. Hemoglobin F (HbF) was associated with passage comprehension, hemoglobin with lower TCD velocity, and lower GM-CBF with greater working memory. Higher BOLD signal was associated with higher processing speed and lower TCD velocity with higher math fluency.

DISCUSSION

Improvements in neurocognition and decreased TCD velocity following 1 year of treatment support hydroxyurea use for improving neurocognitive outcomes in SCA. Understanding the mechanisms of benefit, as indicated by relationships of neurocognitive function with HbF, hemoglobin, and CBF, requires further evaluation.

Hydroxyurea Use Associated with Nonverbal and Executive Skills in Sickle Cell Anemia

OBJECTIVE

Hydroxyurea (HU) is used in children with sickle cell disease (SCD) to increase fetal hemoglobin (HF), contributing to a decrease in physical symptoms and potential protection against cerebral microvasculopathy. There has been minimal investigation into the association between HU use and cognition in this population. This study examined the relationship between HU status and cognition in children with SCD.

METHODS

Thirty-seven children with SCD HbSS or HbS/β0 thalassaemia (sickle cell anemia; SCA) ages 4:0-11 years with no history of overt stroke or chronic transfusion completed a neuropsychological test battery. Other medical, laboratory, and demographic data were obtained. Neuropsychological function across 3 domains (verbal, nonverbal, and attention/executive) was compared for children on HU (n = 9) to those not taking HU (n = 28).

RESULTS

Children on HU performed significantly better than children not taking HU on standardized measures of attention/executive functioning and nonverbal skills. Performance on verbal measures was similar between groups.

CONCLUSIONS

These results suggest that treatment with HU may not only reduce physical symptoms, but may also provide potential benefit to cognition in children with SCA, particularly in regard to attention/executive functioning and nonverbal skills. Replication with larger samples and longitudinal studies are warranted.