Severely anemic children, especially those with sickle cell disease, are at a significantly higher risk for silent strokes, which carry no immediate symptoms but create long-term cognitive and learning deficiencies, according to research presented at the American Stroke Association’s International Stroke Conference 2011.

In fact, one-fourth to one-third of children with sickle cell disease have evidence of silent strokes in their brains, according to Michael M. Dowling, M.D., Ph.D., lead author of the study and assistant professor of pediatrics and neurology at the University of Texas Southwestern Medical Center in Dallas.

“These are 5- to 10-year-old children who have brains that look like the brains of 80-year-olds,” Dowling said. “These strokes are called ‘silent’ because they don’t cause you to be weak on one side or have any obvious neurologic symptoms. But they can lead to poor academic performance and severe cognitive impairments.”

Sickle cell disease is a blood disorder expressed by low levels of hemoglobin, the iron-containing, oxygen-carrying portion of red blood cells; having low hemoglobin causes anemia. In sickle cell disease, the blood cells are deformed (sickle-shaped) and may form dangerous clots or block blood vessels.

The researchers hypothesized that severe anemia triggers silent strokes and that magnetic resonance imaging (MRI) may be able to detect when this occurs.  They used MRI on the brains of 52 hospitalized children,  2 to 19 years old, with hemoglobin concentrations dropping below 5.5 g/dL. 

Some of these children had sickle cell disease and others did not, but still had these same low hemoglobin levels.  Children (without sickle cell disease) may develop anemia from  trauma, surgery, iron deficiency or cancer such as leukemia.

About 20 percent of the children with sickle cell disease who were experiencing acute anemia suffered from silent strokes. The researchers also found evidence of silent strokes, though not as often, in severely anemic children who did not have sickle cell disease.

“These are brain injuries that go unnoticed by doctors, unless the children have testing with a special MRI,” Dowling said.

“We looked at every child who went to the hospital for a 30-month period and identified about 400 children that came in with hemoglobin below 5.5 g/dL. That represented about 12 percent of the admissions for sickle cell disease and about 1 percent of the total admissions to Children’s Medical Center.”

The findings show that children with or without sickle cell disease who have severe anemia may be suffering from undetected brain damage. The researchers suggest that any child with severe anemia be carefully examined for evidence of a silent stroke.

According to the study, better recognition and timely transfusion to raise levels of hemoglobin may prevent permanent brain damage in children who experience silent strokes.

Future studies should examine larger groups of children for longer periods to get a better understanding of severe anemia in children, said Dowling.

Source:  American Heart Association