Children under age 4 who get multiple courses of general anesthesia for surgery seem to be at greater risk of developing a learning disability later in childhood, compared with kids not exposed to the drugs, researchers report in the April Anesthesiology.
Despite this apparent danger, the researchers acknowledge that they don’t know whether the knock-out drugs are responsible for the risk or if children needing surgeries are just prone to developing learning disabilities.
“We feel strongly that this data is preliminary,” says study coauthor Randall Flick, a pediatrician and anesthesiologist at the Mayo Clinic in Rochester, Minn.
Flick and his colleagues consulted a medical registry of people born in Olmstead County, Minn., between 1976 and 1982 and identified 593 children who received anesthesia before reaching age 4 and 4,764 others who didn’t.
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The researchers also checked to see if school records designated any of the children as learning disabled, defined as scoring significantly below what their IQs would predict on reading, writing and math tests. The researchers excluded from the analysis any children who were severely mentally disabled or who had moved away before reaching age 5.
The analysis showed that children undergoing anesthesia just once were no more likely to be learning disabled than were kids who were never put under. But children getting anesthesia twice were 59 percent more likely to be learning disabled, and those getting anesthesia three times or more were more than twice as likely as were children who never got it.
By another measure, children anesthetized for more than two hours overall, faced the most significant risk of learning disability, the records show.
In making these calculations, the researchers accounted for differences between the groups in gender, birth weight and gestational age of the child at birth — the number of months the mother carried the fetus.
“This is indeed a very important and in many ways a thorough study,” says Tom Hansen, a pediatric anesthesiologist at Odense University Hospital in Denmark. “The results may at first glance be quite frightening.”
But Hansen notes that roughly one-third of the original children in the study moved away before age 5. While that might not matter in some studies, he says people whose children have greater medical needs might choose to remain near the Mayo Clinic, which would make these children overrepresented in the population. What’s more, children who need repeat surgeries might just be sicker than others and more prone to developing a learning disability.
Flick agrees that there is no way to know from these data whether the anesthesia poses the risk or if the need for surgery does. For the time being, he doesn’t want to scare parents away from necessary surgery for their children. “This information doesn’t affect my practice, nor would I suggest it should affect the practices of others,” he says.
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Studies in young animals have suggested that general anesthesia can impair learning. Hansen says this new report is part of ongoing research to determine whether these risks translate to humans — specifically whether anesthetic drugs contribute to the neurological impairment seen in some children after surgery. “But we will have to await other studies before definite answers can be made,” he says.