Several studies have found evidence that children who undergo repeated surgical operations with general anesthesia before the age of 4 may be at an increased risk for learning disabilities. In the March issue of Anesthesiology, Massachusetts General Hospital (MGH) researchers report an animal study indicating that several factors - age, the specific anesthetic agent used and the number of doses - combine to induce impairments in learning and memory accompanied by the inflammation of brain tissue. An accompanying paper from the same team finds that the offspring of mice that received a specific anesthetic gas during pregnancy also showed the effects of neuroinflammation and impaired learning. Both articles have been released online.
"We found that different anesthetic drugs - sevoflurane but not desflurane - had different effects on neuroinflammation and on learning and memory function in young mice," says Zhongcong Xie, MD, PhD, corresponding author of both studies and director of the Geriatric Anesthesia Research Unit in the MGH Department of Anesthesia, Critical Care and Pain Medicine. "If they are confirmed by future studies in animals and humans, these findings would suggest that some anesthetics may be safer than others in young children and indicate ways to reduce risks."
In the first study - co-led by Xia Shen, MD, PhD, and Yuanlin Dong, MD, MS, both of MGH Anesthesia - the investigators treated two groups of 6-day-old mice with sevoflurane, the most commonly used general anesthetic. One group received a single two-hour dose of the drug, while the other received the same dose on three subsequent days. In a standardized assessment of learning and memory conducted 24 days later, the mice that had received three doses did significantly less well than a control group at learning the location of a platform in a shallow pool of water and then remembering where the platform had been after it was removed. Analysis of their brain tissue showed elevated levels of several markers of inflammation.
Mice that received only one dose of sevoflurane showed neither neuroinflammation nor cognitive impairment compared with the control group. No adverse effects were seen in either adult mice that received three doses of sevoflurane or in young mice that received three doses of desflurane, another commonly used anesthetic. Two strategies - preanesthesia treatment with an anti-inflammatory drug and placing the young animals in an enriched environment - cages that featured ladders, wheels and mazes - each appeared to reduce the negative effects of three doses of sevoflurane.