The relationship between neurocognitive development and anesthesia exposure in early life is a much discussed topic in the pediatric anesthesia literature. Preclinical studies have shown that exposure to common anesthetic agents in animals can lead to neuronal apoptosis or neural degeneration and measurable behavioral and functional deficits. Clinical literature thus far has been equivocal at best, partly due to the difficulty in separating out the effects of the anesthetic from other factors associated with the need for surgery.
Dr. Robert K. Williams, Department of Anesthesia, Vermont Children’s Hospital, University of Vermont, Burlington, Vermont, and colleagues endeavored to do just that. They constructed a combined medical and educational database to compare children receiving a single spinal anesthetic in their first year of life for inguinal hernia repair, circumcision, or pyloromyotomy (procedures not thought to be associated with later cognitive delay) to normative data for the population of Vermont. In doing so, they removed general anesthesia from the equation. The results of their study are published in this month’s issue of Anesthesia & Analgesia in the article titled “Cognitive Outcome After Spinal Anesthesia and Surgery During Infancy.”
This study uses a patient cohort similar to a recent study by Block et al. that compared children in Iowa that underwent general anesthesia for these same procedures in their first year of life to those that did not have any procedures, and showed that the duration of exposure to anesthesia and surgery correlated negatively with test score performance, as well as increased the chances of what they term “very poor academic performance,” defined as scoring below the fifth percentile on academic testing. In the study by Williams and colleagues, no link was found between surgical duration and academic achievement testing scores in grades 3, 4, and 5, which suggests that any difference in test scores shown by the Block study are likely due to general anesthesia and not to any factors related to the need for surgical intervention. Discovering what specific anesthetic agents this difference is attributable to will require further investigation.
Unfortunately, as with most currently available clinical data on this topic, the study is limited by its retrospective nature. There are currently two large-scale clinical trials underway: PANDA (Pediatric Anesthesia Neurodevelopment Assessment), a multicenter, sibling-matched cohort study examining ASA 1 and 2 patients with single exposure to GA for inguinal hernia repair, and GAS (General Anesthesia Spinal), which is an international randomized trial comparing sevoflurane general anesthesia with regional anesthesia for inguinal hernia repair.
In the accompanying editorial titled, “Cognitive Outcomes After Infant Spinal Anesthesia: The Other Side of the Coin,” Dr. Michael E. Nemergut, Departments of Anesthesiology and Pediatrics, Mayo College of Medicine, The Mayo Clinic, Rochester, Minnesota, and coauthors note that the combination of the Block et al. and Williams et al. studies “together loosely resemble a retrospective version of the GAS study now underway.” However, the editorial also points out that the Williams study is severely limited by its lack of a positive control and lack of statistical power to detect the small cognitive differences that prior research would predict. Although this is important preliminary data, the authors advise against changing current practice and increasing the use of regional anesthesia as an alternative to general anesthesia. Instead, the authors recommend that we wait for more definitive outcomes from more definitive studies before adjusting our practice.