San Diego—Surgery with general anesthesia in young children may well lead to diminished language abilities and cognition, not to mention long-term regional volumetric alterations in brain structure, recent research suggests. Whether these findings are due to the anesthesia or some other mitigating factor, however, remains to be determined in a prospective trial.
Animal studies have shown that anesthetic exposure early in life leads to structural and functional abnormalities of the brain. But epidemiologic studies have been unable to determine whether this phenomenon also occurs in humans.
Andreas W. Loepke, MD, PhD, and his colleagues from Cincinnati Children’s Hospital Medical Center, compared children who were exposed to anesthesia before their fourth birthday (n=52) with those not exposed to the agents (n=52). Groups were matched for age, sex, handedness and family income. Neurocognitive assessments included tests of language skills and intelligence. Structural brain evaluations were performed using T1-weighted MRI scans.
“Most were [ear-nose-throat] procedures done under halothane or sevoflurane,” said Dr. Loepke, associate professor of anesthesiology at the University of Cincinnati, who presented the findings at the 2013 annual meeting of the International Anesthesia Research Society (IARS; abstract S-316). “The exposure was usually between the first and second years of life, and all of the patients were generally healthy.”
The researchers found that although average test scores for both groups were within population norms, the previously exposed children scored lower in all tests (Table 1). More specifically, exposed patients were statistically significantly worse with respect to listening comprehension, expressive language and measures of IQ.
“We then used an overlay of the patients’ MRIs to examine clusters of brain cells that were different between the exposed and unexposed cohorts,” Dr. Loepke said. The volume of gray matter was sporadically reduced in posterior brain regions of previously exposed children; lower IQ correlated with reduced gray matter volume in the precentral gyrus.
Although the findings seem to indicate that exposure to general anesthesia in early childhood leads to diminished language abilities and cognition, Dr. Loepke was uncomfortable making a causal relationship based on his group’s data.
“We still don’t know if these findings are due to anesthetic exposure, postoperative pain or the inflammatory response to the surgery,” he explained. “This is just a retrospective analysis, so we just have to take it as another piece in the puzzle.”
Dean B. Andropoulos, MD, chief of anesthesiology at Texas Children’s Hospital in Houston, cited yet another possible confounder. “There is a paper from the [ear-nose-throat] literature recently that says if a child suffers prolonged obstructive sleep apnea [OSA] during surgery, it has a detrimental effect on long-term neurodevelopmental outcomes,” Dr. Andropoulos said. “So we need to keep looking at confounding variables. Don’t leap to the conclusion that these results are purely due to the anesthetic agent itself. And obviously we know that a young child having a tonsillectomy will usually have a certain degree of OSA.”
If exposure to general anesthesia appears to raise a child’s risk for downstream cognitive problems, spinal anesthesia (SA) seems to be relatively benign, according to results from another study researchers presented at the IARS meeting (abstract S-319). A team from the University of Vermont found no evidence of learning difficulties or academic performance in 265 girls and boys in that state who had received SA for hernia repair, circumcision and other surgeries as infants (Table 2).
“This first examination of cognitive outcome after infant SA supports the long-term safety of infant SA and implies that cognitive dysfunction seen after exposure to [general anesthesia] in previous studies may be related to effects from anesthesia and not demographics of the patient population,” they wrote.