Mayo Clinic researchers have found that children who require multiple surgeries under anesthesia during their first three years of life are at higher risk of developing learning disabilities later.
Several studies have suggested that anesthetic drugs may cause abnormalities in the brains of young animals. This is the first study in humans to suggest that exposure of children to anesthesia may have similar consequences. The finding is reported in the current issue of the journal Anesthesiology.
Using data from the long-term Rochester Epidemiology Project, researchers studied the medical records of 5,357 children from Olmsted County who were born between 1976 and 1982.
The research team, led by Robert Wilder, M.D., Ph.D., a Mayo Clinic anesthesiologist, found that although one exposure to anesthesia was not harmful, more than one almost doubled the risk that a child would be identified as having a learning disability before age 19. The risk also increased with longer durations of anesthesia.
"It's very important for parents and families to understand that although we see a clear difference in the frequency of learning disabilities in children exposed to anesthesia, we don't know whether these differences are actually caused by anesthesia," says Randall Flick, M.D., a Mayo Clinic anesthesiologist and co-author of the study.
"The problem is that anyone who underwent an anesthetic also had surgery," says Dr. Wilder. "It's unclear whether it's the anesthetic, the physiological stress of surgery or perhaps the medical problems that made surgery necessary that are responsible for the learning disabilities."
Young children's brains are more vulnerable to a variety of problems because they are undergoing dynamic growth. The brain is rapidly forming connections between cells and trimming excess cells and connections, says Dr. Wilder.
The general anesthesia chemicals in use during the study period were primarily halothane and nitrous oxide (laughing gas). Although halothane is no longer used in the U.S., it has been replaced by newer agents that have similar effects on the brain. Nitrous oxide is widely used throughout the U.S. and the world.
Debate exists about the developmental correlation between the animal (rodent) and human studies. Some think that the related exposure period would be perinatal in humans (the last month of pregnancy and first six months after birth), so the researchers repeated their analysis, examining anesthetic exposure before age 2, and found similar results.