What is the relationship between Sickle Cell Disease (SCD) and cerebrovascular accident (CVA) or stroke?

From the Guidelines

Sickle cell disease significantly increases the risk of stroke, particularly in children, and regular blood transfusions are recommended to maintain normal hemoglobin levels and reduce the percentage of sickle cells in circulation for those with abnormal transcranial Doppler ultrasound results indicating high stroke risk. To prevent strokes, all children with sickle cell disease should be screened annually with transcranial Doppler ultrasound starting at age 2 1. For those with abnormal results, regular blood transfusions are recommended to maintain normal hemoglobin levels and reduce the percentage of sickle cells in circulation. Hydroxyurea (starting at 15-20 mg/kg/day) is another important medication that increases fetal hemoglobin production, reducing sickling and stroke risk 1. Key points to consider in the management of sickle cell disease and stroke prevention include:

• Annual screening with transcranial Doppler ultrasound starting at age 2
• Regular blood transfusions for those with abnormal results indicating high stroke risk
• Hydroxyurea therapy for primary stroke prevention
• Indefinite monthly blood transfusions for patients who have already experienced a stroke to maintain hemoglobin S levels below 30%
• Additional preventive measures such as maintaining good hydration, avoiding extreme temperatures, promptly treating infections, and ensuring adequate pain management during crises
• Regular follow-up with hematologists and neurologists is essential for monitoring and adjusting treatment as needed 1. The goal of these interventions is to reduce the viscosity of blood, improve circulation, and prevent the vaso-occlusive events that lead to strokes.

From the Research

Sickle Cell Disease and Stroke

• Sickle cell disease (SCD) is a significant risk factor for stroke, with approximately 10% of children with SCD experiencing a stroke by the age of 10-15 years 2.
• The risk of stroke in SCD patients can be estimated using transcranial Doppler ultrasound (TCD) to measure blood velocity through the middle cerebral artery (MCA) 2, 3.
• High MCA blood velocity is associated with increased stroke risk due to cerebral vasculopathy, and chronic blood transfusions have been used as a first-line treatment to prevent primary or recurrent strokes in high-risk children with SCD 2, 3.

Prevention and Treatment of Stroke in SCD

• Chronic blood transfusions have been shown to reduce the risk of stroke in SCD patients, with a reduction in risk of approximately 90% 2.
• Hydroxyurea (HU) treatment has also been shown to be effective in reducing stroke risk in SCD patients, and may be used as an alternative to chronic blood transfusions 4, 5, 3.
• Prophylactic HU treatment, started in infancy, may be associated with improved cerebral hemodynamics and reduced stroke risk in SCD patients 3.
• Exchange transfusions, rather than simple transfusions, may be more effective in improving oxygen transport efficiency in SCD patients, but are technically more demanding and require more blood units 6.

Risks and Benefits of Treatment

• Chronic blood transfusions are associated with risks such as alloimmunization and iron overload, which can limit their use in SCD patients 2, 6.
• HU treatment is generally well-tolerated, but may be associated with an increased risk of sickle cell disease-related events in some patients 5.
• The quality of evidence for the use of HU treatment in SCD patients is generally low to moderate, and further research is needed to fully understand its risks and benefits 5.