Washington University School of Medicine reports
By American staff
A group of children who have sickle cell disease and who experience silent strokes showed some relief from the silent strokes with blood transfusion therapy, researchers at Washington University School of Medicine have found.
In a study of 10 children with sickle cell disease who also had multiple silent strokes (or cerebral infarcts), the blood transfusions helped to shrink the lesions on the brain caused by the strokes and eliminated one lesion completely, said Allison A. King, M.D., a pediatric hematologist at St. Louis Children’s Hospital.
Lesions are small areas of damaged tissue thought to be due to blockage of small arteries in the brain.
Silent strokes are strokes that don’t show the classic symptoms of clinical strokes, such as numbness, tingling, headache or slurred speech. Silent strokes can have an effect on memory and other brain functions. Blood transfusion has been shown to be effective in preventing clinical strokes in patients with sickle cell disease, but its effectiveness and the willingness of families to participate in long-term treatment to prevent silent strokes had not been tested.
Sickle cell disease is an inherited blood disorder affecting red blood cells that contain hemoglobin, a substance that carries oxygen from the air in the lungs to all parts of the body. In patients with this disease, red blood cells contain an abnormal type of hemoglobin that causes the normally round, flexible red blood cells to become sickle- or crescent-shaped. The sickle cells can’t pass through tiny blood vessels, preventing blood from reaching the body’s tissues, which can result in tissue and organ damage, pain and stroke.
Sickle cell disease affects about 70,000 people in the United States. It occurs in about 1 of every 500 African-American births and 1 of every 1,000 to 1,400 Hispanic-American births.
While there is no cure for the disease, blood transfusions and bone marrow transplants have been shown to be effective treatments by replacing short-lived sickle cells with longer-lived healthy red blood cells. Bone marrow transplants have a 10 percent mortality rate because of the possibility of rejecting the bone marrow, complications such as seizures and a high risk of infection.
In the study, brain lesions in six patients shrank after two years of regular blood transfusions, and no new silent strokes occurred. One patient had a lesion disappear. However, that patient did not continue with further blood transfusions, and the lesion returned at more than three times its original size, suggesting the need for prolonged transfusions. A lesion grew larger in the seventh patient.
Many of the lesions occur in the frontal lobe of the brain, which controls the cognitive function or problem-solving area, or in the occipital lobe, which controls the visual processing center, King said. Neuroradiologists can locate the lesions using magnetic resonance imaging (MRI).
“Because these lesions are usually in the frontal lobe, it is important to do cognitive testing on these children to determine any impairment,” King said. “We hope that by preventing further lesions through blood transfusions that we can preserve their ability to think and learn.”
King said the results of the trial were encouraging to health-care professionals treating children with sickle cell disease.
A larger study headed by Michael R. DeBaun, M.D., professor of pediatrics is evaluating 1,800 children in the United States, Canada and Europe to determine the effectiveness of blood transfusion therapy to prevent silent strokes in children with sickle cell disease.