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Acute anemia in kids tied to 'silent' strokes.


LOS ANGELES - Acute anemic events were linked with significantly increased risk for "silent" strokes not only in children with sickle cell disease but also in those with acute anemia attributable to other causes, a controlled study of 52 patients found.

Prospective screening of all children admitted to one hospital during a 30-month period found that 398 were having acute anemic events - accounting for nearly 1% of all admissions and 12% of children admitted with sickle cell disease. Diffusion-weighted MRI in 52 of these children showed evidence of acute silent infarction in 4 (18%) of 22 patients with sickle cell disease and in 2 (7%) of 30 patients without sickle cell disease, Dr. Michael M. Dowling and his associates reported at the conference.

I didn't initially plan a controlled, study, "but funders insisted, and the comparison yielded unexpected information, said Dr. Dowling, a pediatric neurologist at the University of Texas Southwestern Medical Center, Dallas. "I didn't think these children [without sickle cell disease] would be having silent infarctions."

In addition, three patients with sickle cell disease showed evidence of what looked like remote silent infarctions on MRI (14%). Dr. Dowling said he was "fascinated" to also find evidence of remote silent infarctions in seven of the control patients (23%).

"These are not children with sickle cell disease. I'm worried that a lot of these children with acute anemic events were prone to recurrent anemic events from dysfunctional uterine bleeding, cancer, or repeat GI bleeds. I'm worried that at previous admissions they may have had an acute silent infarction in the setting of an acute anemic event that was missed," he said at the conference, which was sponsored by the American Heart Association.

Overall, 31% of all MRIs were abnormal.

"We can't simply look at a severely anemic child in an emergency room and say he's hemodynamically stable, because ... these kids are losing brain cells. We need to respond to them more quickly," he said, adding that he hopes a future study will monitor these kinds of children at home via a pulse oximeter so they can be brought in sooner for transfusion when hemoglobin levels fall. "We can prevent injury" he said.

Studies suggest that about 10% of children with sickle cell disease will have a clinically evident stroke unless they get prophylactic therapy and up to 35% will have silent infarctions. "It's a bad term because they're not silent," Dr. Dowling said. "They cause significant cognitive impairment," educational delays, and increased risk for new or progressive silent infarctions and overt stroke.

His definition of silent infarction is an MRI lesion consistent with infarction without a focal deficit lasting more than 24 hours. The study defined an acute anemic event as either a hemoglobin level no higher than 5,5 g/dL or, for children with sickle cell anemia whose "normal" hemoglobin level may be 6 g/dL, a decline of at least 30% from baseline hemoglobin level.

Follow-up imaging in four patients with acute silent infarctions showed signals consistent with permanent brain injury in three of them, but not in the fourth. "Some of these might be reversible," he said.

He estimated that the incidence of acute silent infarction during acute anemic events is 633 per 100 patient-years in children with sickle cell disease, and 243 per 100 patient-years in children without sickle cell disease, based on the study's findings. His estimates are much larger than are those from the SIT (Silent Infarct Transfusion) study, which suggested an incidence of 43 per 100 patient-years in children with sickle cell disease as a whole, he said.

"We have identified unsuspected silent infarctions occurring during acute anemic events in 18% of children with sickle cell disease and 7% of controls," he said, adding that children with acute anemia may need closer observation.

The etiologies of acute anemia were a bit surprising in both the sickle cell and control groups. There were more oncology patients than anticipated among the 294 children who were admitted without sickle cell disease, astic or hemolytic anemias were the leading etiology. Others included GI bleed or liver problems, leukemias, lymphomas, and other cancers. Among patients with sickle cell disease and acute anemia, fewer than expected had acute chest syndrome, aplastic crisis, or splenic sequestration, although these still accounted for the majority.


Major Finding: Diffusion-weighted MRI in children hospitalized with acute anemic events showed evidence of acute silent infarction in 4 of 22 patients with sickle cell disease (18%) and in 2 of 30 patients without sickle cell disease (7%).

Data Source: Prospective, controlled study of 52 children.

Disclosures: Dr. Dowling said he had no relevant conflicts of interest. He has received research support from First American Real Estate Services Inc. The Children's Medical Center, Dallas, funded the study.
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Author:Boschert, Sherry
Publication:Clinical Psychiatry News
Article Type:Clinical report
Date:Jun 1, 2011
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