For millions of infants and toddlers who get surgery every year, mounting concern about the risk of general anesthesia is leading more hospitals to consider an alternative: spinal anesthesia which leaves babies awake, immobilized and pain-free.

The spinal approach has been shown to have fewer breathing complications, quicker recoveries, and faster feeding, which enables families to take babies home sooner. It is used primarily for surgeries that last an hour and a half or less, and take place generally in the abdominal area and lower extremities.

Spinal anesthesia for infants was pioneered by the University of Vermont Children’s Hospital in Burlington, Vt., four decades ago, but it never caught on widely. Many surgeons and anesthesiologists were reluctant to change traditional practices, or deal with babies that might squirm or fuss during a procedure. But in recent years animal studies have increasingly shown that exposure to anesthetics can cause memory loss, learning difficulties and other harmful changes in developing brains of young lab rats and monkeys, so researchers have begun to tackle the question of whether the same risks apply to children.

Hospitals around the world are now participating in multiple studies to determine whether exposure to anesthesia is associated with cognitive problems later on. The largest of those, known as the GAS study, includes 28 hospitals in the U.S., Canada, Europe, Australia and New Zealand, and aims to measure intelligence at age 5 in 722 infants randomized to receive either general or spinal anesthesia for hernia repair surgeries.

An interim analysis, published online in October in the Lancet, found no difference in cognitive function at two years of age, which suggests a single short-duration exposure to general anesthesia may not be harmful. But lead investigator Andrew Davidson, medical director of the clinical trial center at Murdoch Children’s Research Institute in Melbourne, Australia, says that until the study has completed its evaluation of children at age 5, in 2017, there can be no definitive answer as “some aspects of neurodevelopment cannot be assessed at two years of age.”

The early results also don’t rule out the possibility that longer exposure or multiple exposures to anesthesia in early childhood can cause changes in the brain, Dr. Davidson says. A new study he is developing will compare a combination of a type of spinal and light anesthesia against longer use of general anesthesia in surgeries lasting longer than one hour.

The GAS study is partially funded by the U.S. Food and Drug Administration, which launched a partnership with the International Anesthesia Research Society in 2010 called SmartTots to coordinate and fund research on safer anesthesia for children. Last month, after the interim results were published, SmartTots issued a statement, endorsed by 19 health organizations, including the American Academy of Pediatrics, the American Society of Anesthesiologists, and the Society for Pediatric Anesthesia, which said while the early results are encouraging that a single short-duration exposure to general anesthesia “may not be harmful,” more questions remain.

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