Children who have had multiple surgeries under general anesthesia by the age of 4 may be at a higher risk of developing learning disabilities, according to a new study by scientists at the Mayo Clinic in Rochester, Minn.
Dr. Robert Wilder, a Mayo Clinic anesthesiologist, says his study was motivated by recent research on baby rats and other young animals. Those studies, conducted in the last several years, show that exposure to anesthesia at a very young age can kill off brain cells. But results in rodents don't necessarily translate to humans.
"The initial reaction of the pediatric anesthesia community was, 'This must be wrong, we've been giving anesthetics to kids for years and we don't see a big problem,"' Wilder says. He, too, was skeptical.
The Mayo Clinic sits in Olmsted County. Both the research clinic and the county have kept precise records on the health care and hospitalization of its residents. Wilder sorted through the records of more than 5,000 children. About 600 of them had one or more surgeries with a general anesthesia, a class of drugs that enters the blood stream, reaches the brain and leaves a patient in a state of unconsciousness. Local anesthesia (like what's used by dentists when filling a cavity) and regional anesthesia (like an epidural that's common during childbirth) numb just a part of the body, but don't cause the patient to lose consciousness.
The surgeries ranged from those for serious problems, like open heart surgery, to more routine ones, like putting in ear tubes or removing adenoids and tonsils. Most of the kids in the study — about 80 percent — had surgeries for the small and common problems.
Wilder found that children who had undergone a single operation with a general anesthetic by the time they turned 4 were no more likely than other children to develop a learning disability.
But kids who had had two surgeries were one and a half times more at risk. And for children who had undergone three operations, the risk went up to two and a half times. Of the kids in Wilder's study who had had three or more operations, 50 percent of them later developed a learning disability.
Wilder speculates that anesthesia could cause learning problems in young children because it travels to the brain at a time when the brain is developing rapidly.
"If you're exposed to these drugs at just the right time in your life," he says, "you have a lot more cell death than you otherwise would — and some of that is in the hippocampus, which is part of the brain that is involved in learning new things and it, therefore, does not work as well throughout the rest of your life."
That makes sense to Amanda Rathbun, who lives outside Salt Lake City.
"I always thought that things like this ran in families, like if your dad has brown eyes, then you're more likely to have brown eyes. But there's not a history of this in our family," she says.
Rathbun has three very smart kids. Her 11-year-old daughter has no learning disabilities. But another daughter, who's 8, and her son, who's 13, have both been diagnosed with attention deficit disorder. Both kids had several surgeries soon after birth.
In addition, the son has struggled to write legibly. Fine motor skills are a problem for him, and Rathbun wonders if he could have gotten more attention for that sooner.
"If general anesthesia early in life can really cause these sorts of problems," she says, "I think it would be good to know that, because maybe we could start more early intervention services for these kids and maybe prevent some of these later problems."
The new research is published in the current issue of Anesthesiology, the journal of the American Society of Anesthesiologists. The co-authors write that more studies are needed to be certain it's the anesthesia that's causing the problem. It might be the illness that requires the surgery — although the researchers took the sickest children out of the study.
Wilder says parents shouldn't avoid surgery when kids younger than 4 need it.
"My advice is that if their child needs a surgical or diagnostic procedure that requires an anesthetic, then they should go ahead and have that surgical or diagnostic procedure with the anesthetic," he says.
Dr. Piyush Patel, who wrote an accompanying editorial in the same journal, agrees. He adds that parents can, however, ask their doctor if it's better to postpone a surgery until a child is older.
"Based on these data, the parents of children have to be comfortable that the surgery is absolutely needed and they have to balance the risk of waiting for the surgery to be done versus the complication that may arise," says Patel, a professor of anesthesiology at the University of California, San Diego. "This is a decision that is best made by the surgeon and the anesthesiologist."
Wilder's study, and others, have created a sense of urgency to answer questions about the effects of anesthesia on the brain development of infants and young children. Earlier this month, the federal Food and Drug Administration announced a collaboration with Mayo and other clinics to support further research.