Neuroimaging in Sickle Cell Disease: A Review

Imaging Review of Pediatric Monogenic CNS Vasculopathy with Genetic Correlation

Monogenic cerebral vasculopathy is a rare but progressively recognizable cause of pediatric cerebral vasculopathy manifesting as early as fetal life. These monogenic cerebral vasculopathies can be silent or manifest variably as fetal or neonatal distress, neurologic deficit, developmental delay, cerebral palsy, seizures, or stroke. The radiologic findings can be nonspecific, but the presence of disease-specific cerebral and extracerebral imaging features can point to a diagnosis and guide genetic testing, allowing targeted treatment. The authors review the existing literature describing the frequently encountered and rare monogenic cerebral vascular disorders affecting young patients and describe the relevant pathogenesis, with an attempt to categorize them based on the defective step in vascular homeostasis and/or signaling pathways and characteristic cerebrovascular imaging findings. The authors also highlight the role of imaging and a dedicated imaging protocol in identification of distinct cerebral and extracerebral findings crucial in the diagnostic algorithm and selection of genetic testing. Early and precise recognition of these entities allows timely intervention, preventing or delaying complications and thereby improving quality of life. It is also imperative to identify the specific pathogenic variant and pattern of inheritance for satisfactory genetic counseling and care of at-risk family members. Last, the authors present an image-based approach to these young-onset monogenic cerebral vasculopathies that is guided by the size and predominant radiologic characteristics of the affected vessel with reasonable overlap. ©RSNA, 2024 Test Your Knowledge questions for this article are available in the supplemental material.

Overview of the Association Between the Pathophysiology, Types, and Management of Sickle Cell Disease and Stroke

Sickle cell disease (SCD) is a genetic blood disorder that affects hemoglobin and increases stroke risk, particularly in childhood. This review examines the pathophysiological association between SCD and stroke, the classification of stroke types, risk factors, diagnosis, management, prevention, and prognosis. A comprehensive literature search was conducted via PubMed, Scopus, and Cochrane databases. Relevant studies on SCD and stroke pathophysiology, classification, epidemiology, diagnosis, treatment, and prevention were identified. Sickle cell disease causes red blood cells to become rigid and sickle-shaped, obstructing blood vessels. Recurrent sickling alters cerebral blood flow and damages vessel walls, often leading to ischemic or hemorrhagic strokes (HS). These occur most frequently in childhood, with ischemic strokes (IS) being more common. Key risk factors include a prior transient ischemic attack (TIA), low hemoglobin, and a high leukocyte count. Neuroimaging is essential for diagnosis and determining stroke type. Primary prevention centers on blood transfusions and hydroxyurea for those at high risk. Acute treatment involves promptly restoring blood flow and managing complications. However, significant knowledge gaps remain regarding stroke mechanisms, optimizing screening protocols, and improving long-term outcomes. This review synthesizes current evidence on SCD and stroke to highlight opportunities for further research and standardizing care protocols across institutions. Ultimately, a holistic perspective is critical for mitigating the high risk of debilitating strokes in this vulnerable patient population.

Preventive treatment of unruptured intracranial aneurysms in adult patients with sickle cell anemia: A cohort study

BACKGROUND AND PURPOSE

Intracranial aneurysms are frequent in patients with sickle cell anemia, while subarachnoid hemorrhage is a major cause of death and disability in young adult patients. Several characteristics, such as younger age and smaller size at rupture, may incline therapeutic decision towards exclusion treatments. Clinical guidelines on treatment of unruptured intracranial aneurysms in this population are still missing. We aimed to assess the safety and efficacy of the treatment of unruptured intracranial aneurysm in patients with sickle cell anemia, using an adapted hematological preparation regimen.

PATIENTS AND METHODS

Adult patients with sickle cell anemia and treated unruptured aneurysms by endovascular therapy or neurosurgery were included in this retrospective cohort study. Treatment decision was reached after multi-disciplinary assessment. A pre-operative blood transfusion protocol was undertaken targeting a HbS below 30%. Demographic data, hematological preparation parameters and clinical and radiological outcomes were documented.

RESULTS AND CONCLUSIONS

Twenty-five procedures were performed in 18 patients encompassing 19 aneurysms treated by embolization and 6 by surgery. Median age at treatment was 34 years-old and median aneurysm dome size was 4.4 mm. Immediate aneurysm exclusion rate was 85.7% after endovascular therapy and 100% after neurosurgery. Median follow-up was 6 months, with all patients being asymptomatic at last follow-up. Two transitory ischemic neurological deficits, as well as four cases of iodine-induced encephalopathy were identified after embolization. No complication occurred after surgery. Endovascular therapy by coiling and neurosurgical treatment of unruptured intracranial aneurysms appears to be safe in patients with sickle cell anemia and should be considered given the specific hemorrhagic risk observed in this population. A rigorous hematological preparation, associated with a dedicated peri‑operative protocol and an adequate therapeutic strategy are essential prerequisites.

Home Management and Prevention of Vaso-Occlusive Crisis of Sickle Cell Disease Knowledge among Nursing Students

Sickle cell crisis, or vaso-occlusive crisis, is a painful complication of sickle cell disease that occurs in adolescents and adults, which is considered the most common reason these patients seek medical attention in an emergency room. Despite the high prevalence of sickle cell disease in the Jazan region, Saudi Arabia, there hasn't been a study looking at nursing students' knowledge about sickle cell disease and home management and prevention of vaso-occlusive crises associated with sickle cell disease. Most of those focused on the investigation of the public, parents of children with sickle cell disease, school students, and patients with sickle cell disease. Therefore, this study aims to assess the level of knowledge about home management and prevention of vaso-occlusive crises among Saudi nursing students at the Aldayer University College, Jazan University, Kingdom of Saudi Arabia. A descriptive cross-sectional design was used in this study that involved 167 nursing students. The study revealed that Aldayer nursing students had adequate knowledge about the home management and prevention of sickle cell disease vaso-occlusive crises.

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.

A framework for advancing sustainable magnetic resonance imaging access in Africa

Magnetic resonance imaging (MRI) technology has profoundly transformed current healthcare systems globally, owing to advances in hardware and software research innovations. Despite these advances, MRI remains largely inaccessible to clinicians, patients, and researchers in low-resource areas, such as Africa. The rapidly growing burden of noncommunicable diseases in Africa underscores the importance of improving access to MRI equipment as well as training and research opportunities on the continent. The Consortium for Advancement of MRI Education and Research in Africa (CAMERA) is a network of African biomedical imaging experts and global partners, implementing novel strategies to advance MRI access and research in Africa. Upon its inception in 2019, CAMERA sets out to identify challenges to MRI usage and provide a framework for addressing MRI needs in the region. To this end, CAMERA conducted a needs assessment survey (NAS) and a series of symposia at international MRI society meetings over a 2-year period. The 68-question NAS was distributed to MRI users in Africa and was completed by 157 clinicians and scientists from across Sub-Saharan Africa (SSA). On average, the number of MRI scanners per million people remained at less than one, of which 39% were obsolete low-field systems but still in use to meet daily clinical needs. The feasibility of coupling stable energy supplies from various sources has contributed to the growing number of higher-field (1.5 T) MRI scanners in the region. However, these systems are underutilized, with only 8% of facilities reporting clinical scans of 15 or more patients per day, per scanner. The most frequently reported MRI scans were neurological and musculoskeletal. The CAMERA NAS combined with the World Health Organization and International Atomic Energy Agency data provides the most up-to-date data on MRI density in Africa and offers a unique insight into Africa's MRI needs. Reported gaps in training, maintenance, and research capacity indicate ongoing challenges in providing sustainable high-value MRI access in SSA. Findings from the NAS and focused discussions at international MRI society meetings provided the basis for the framework presented here for advancing MRI capacity in SSA. While these findings pertain to SSA, the framework provides a model for advancing imaging needs in other low-resource settings.

Should Magnetic Resonance Angiography Be Used for Screening of Intracranial Aneurysm in Adults with Sickle Cell Disease?

Magnetic resonance imaging (MRI) is used in patients with sickle cell disease (SCD) to detect silent cerebral infarcts. MR angiography (MRA) can identify arterial stenoses and intracranial aneurysms (ICANs) associated with SCD. In this study, we aimed to estimate the prevalence of ICANs in asymptomatic adult patients with SCD referred from the SCD clinic for routine screening by MRI/MRA using a 3T-MRI scanner. Findings were independently reviewed by two neuroradiologists. Between 2016 and 2020, 245 asymptomatic adults with SCD were stratified according to genotype (SS/S-β0thalassemia and SC/Sβ+). ICANs were found in 27 patients (11%; 0.95 CI: 8-16%). ICANs were more frequent in SS/S-β0thalassemia patients (20/118 or 17%; 0.95 CI: 11-25%) than in SC/βb+ patients (7/127 or 6%; 0.95 CI: 2-11%; p = 0.007). Individuals with SCD (particularly SS/S-β0thalassemia) have a higher prevalence of ICANs than the general population. We believe that MRA should be considered in the current American Society of Hematology guidelines, which already contain a recommendation for MRI at least once in adult SCD patients. However, the clinical significance of preventive treatment of unruptured aneurysms remains controversial.

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.

'Look into Their Hearts' 7-Year-Old Boy with Sickle Cell Disease, Fever, Left Sixth and Seventh Cranial Nerve Palsy and Left Hemiplegia

A 7-year-old Liberian boy presented with fever, severe headache, neck pain and 'not being able to walk'. In the emergency room, his sickle cell screen was positive, and his haemoglobin level was 7 g/dl. Initially, he was admitted to the ward with a diagnosis of sickle cell painful crisis and was treated with ceftrixone iv, and oral morphine and paracetamol. In a more complete physical examination, he had left peripheral seventh nerve palsy, left sixth nerve palsy and ipsilateral hemiplegia, also neck rigidity. In a bedside ultrasound scan, he had a large, mobile vegetation on the aortic leaflet of the mitral valve. The final diagnosis was acute infective endocarditis with multiple embolic strokes in a child with sickle cell disease. Headache and neck rigidity was most likely due to SAH or meningitis.