Stroke associated with sickle cell disease

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By Fenwick T Nichols III MD

In this clinical article, Dr. Nichols reviews the risk of stroke in children with sickle cell disease, which occurs in 11% of children with the disease by 20 years of age. The author reviews the pathophysiology of stroke in sickle cell disease and discusses ways to identify those at high risk for stroke. To date, blood flow velocity in the distal internal carotid (ICA) and proximal middle cerebral artery (MCA) as measured by transcranial Doppler (TCD) has proven to be the best predictor of stroke risk in this population. The author discusses the TCD technique used in the examination of children with sickle cell disease for both initial examination as well as follow-up examinations. He also reviews the effectiveness of transfusion therapy for prevention of stroke in this population and discusses possible alternative therapies, including hydroxyurea and bone marrow transplantation, for stroke prevention in this high-risk population. Finally, the author reviews recent publications on the risk associated with elevated anterior cerebral artery (ACA) velocities, reports on encephalo-arterio-duro-synangiosis (EDAS) in patients with homozygous sickle cell anemia (HbSS) with moyamoya, and reviews the parameters that affect TCD velocity and potentially impact stroke risk in this population.

Key points

  • Children with sickle cell disease have an 11% risk of developing stroke by age 20 years. Of these strokes, 75% occur in patients with severe stenosis of the terminal internal carotid artery or proximal middle and anterior carotid arteries.
  • Transcranial Doppler can identify those children at highest risk of developing stroke.
  • Prophylactic chronic transfusion to maintain HbS levels of less than 30% decreases stroke risk by 90%.
  • Because of the potential complications of long-term transfusion (risk of infection, alloimmunization, and iron overload), other therapies are currently being evaluated, but to date none have been as effective as transfusion.