Visual cortex changes in children with sickle cell disease and normal visual acuity: a multimodal magnetic resonance imaging study

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.

Neurodevelopmental Outcomes in Preterm Children with Sickle Cell Disease

OBJECTIVES

To explore the combined effect of pediatric sickle cell disease (SCD) and preterm birth on cognitive functioning.

METHODS

Cognitive functioning was examined in children ages 6-8 with high risk SCD genotypes born preterm (n = 20) and full-term (n = 59) and lower risk SCD genotypes/no SCD born preterm (n = 11) and full-term (n = 99) using tests previously shown to be sensitive to SCD-related neurocognitive deficits. Factorial ANOVAs and log linear analyses were conducted to examine the relationship between SCD risk, preterm birth status, and cognitive outcomes. Continuous scores were examined for specific tests. Children were categorized as having an abnormal screening outcome if at least one cognitive score was ≥1.5 standard deviations below the population mean.

RESULTS

Children with elevated risk due to high risk SCD and preterm birth performed worse than other groups on a test of expressive language but not on tests that emphasize processing speed and working memory. There was a three-way interaction between preterm status, SCD risk, and abnormal screening outcome, which was largely driven by the increased likelihood of abnormal cognitive scores for children with high risk SCD born preterm.

CONCLUSIONS

The combination of SCD and preterm birth may confer increased risk for language deficits and elevated rates of abnormal cognitive screenings. This suggests that neurodevelopmental risk imparted by comorbid SCD and preterm birth may manifest as heterogenous, rather than specific, patterns of cognitive deficits. Future studies are needed to clarify the domains of cognitive functioning most susceptible to disease-related effects of comorbid SCD and preterm birth.

Chronic organ injuries in children with sickle cell disease

Median life expectancy of patients with sickle cell disease has increased to up to 55 years but there are still frequent cases of premature death, mostly in patients with pre-existing organ failure such as pulmonary hypertension, kidney injury, and cerebral vasculopathy. Most organ injuries remain asymptomatic for a long time and can only be detected through early systematic screening. Protocols combining assessment of velocities on transcranial Doppler and regular transfusions in patients with abnormal velocities have been demonstrated to dramatically reduce the risk of stroke. In contrast, no consensus has been reached on systematic screening or therapy for silent cerebral infarcts. The prognostic significance of increased tricuspid regurgitant jet velocity on echocardiography has not yet been identified in children, whereas increased albuminuria is a good predictor of kidney injury. Finally, screening for hip and eye disorder is recommended; however, different countries adopt different screening strategies. Hydroxyurea is probably of potential benefit in preventing chronic organ damage but this requires further study in order to be fully demonstrated. Efficacy and safety of the other new drugs available are also under investigation.

MRI detection of brain abnormality in sickle cell disease

Introduction: Over the past decades, neuroimaging studies have clarified that a significant proportion of patients with sickle cell disease (SCD) have functionally significant brain abnormalities. Clinically, structural magnetic resonance imaging (MRI) sequences (T2, FLAIR, diffusion-weighted imaging) have been used by radiologists to diagnose chronic and acute cerebral infarction (both overt and clinically silent), while magnetic resonance angiography and venography have been used to diagnose arteriopathy and venous thrombosis. In research settings, imaging scientists are increasingly applying quantitative techniques to shine further light on underlying mechanisms.Areas covered: From a June 2020 PubMed search of 'magnetic' or 'MRI' and 'sickle' over the previous 5 years, we selected manuscripts on T1-based morphometric analysis, diffusion tensor imaging, arterial spin labeling, T2-oximetry, quantitative susceptibility, and connectivity.Expert Opinion: Quantitative MRI techniques are identifying structural and hemodynamic biomarkers associated with risk of neurological and neurocognitive complications. A growing body of evidence suggests that these biomarkers are sensitive to change with treatments, such as blood transfusion and hydroxyurea, indicating that they may hold promise as endpoints in future randomized clinical trials of novel approaches including hemoglobin F upregulation, reduction of polymerization, and gene therapy. With further validation, such techniques may eventually also improve neurological and neurocognitive risk stratification in this vulnerable population.