HealthJune 01, 2020

The effect of anesthesia on the developing brain

By: Stacia Dearmin, MD

While the effect of anesthesia on the developing brain has been controversial, new research is reassuring.

It's a beautiful July afternoon when Alaya, a charming 12-year-old, presents to your emergency department. She and her cousins were swinging as high as they could go at a local park, each one's squeals livelier than the next, when Alaya bravely took a flying leap from the swingset.

The delicious aroma of burgers on the grill and the sunny sounds of reggae notwithstanding, Alaya's family reunion screeched to a halt thanks to the alarming deformity and rapidly increasing swelling now visible just above her left elbow. While Uncle James, a firefighter, adroitly fashioned a sling from Aunt Tonya's scarf, Alaya's parents pulled the car around. Having buckled her safely in, they brought her straight to you.

As someone experienced with emergencies in children, you take one look at her arm and know beyond a doubt that X-rays will reveal a significantly displaced supracondylar fracture of the humerus. After a little coaching and reassurance, Alaya accepts a "tiny little straw" in her other hand with stoicism on the promise that the pain medication will zoom straight to her left arm, making the added discomfort worthwhile.

Her X-rays confirm your initial suspicion that Alaya will require a trip to the operative suite for reduction and pinning of her humeral fracture. You sit with her parents to review the imaging studies and explain the next steps. Naturally, her parents have many questions.

They mention that several family members, including Alaya's older brother and an uncle, have significant dyslexia. They seem to recall hearing a story on NPR when Alaya was but a baby regarding the effect of anesthesia on the developing brain and linking anesthesia to learning disabilities. As a result, they've hoped to avoid anesthesia for their growing children ever since. Granted, Alaya's not a baby anymore, but her parents know that as an early adolescent, her brain is still rapidly changing, and they wonder whether anesthesia will harm their girl.

This question is one you hadn't heard before. You're open with Alaya's parents, indicating that you lack familiarity with the latest research in this domain and encouraging them to ask this question of the anesthesiologist prior to the procedure. You leave the room scratching your head, wondering what the latest research says about the effect of anesthesia on the developing brain.

Evolution of a controversy

In a 2018 article in Anesthesiology, Dr. Deborah Culley and Dr. Michael Avram relate that just over 25 years ago, "surgery was commonly performed on awake or paralyzed infants and children without the benefit of analgesics, sedatives, or anesthetics." Fears regarding the dangers of the medications together with a view that infants didn't feel pain underpinned this practice. When extensive data subsequently emerged indicating that insufficient anesthesia is associated with increased adverse surgical outcomes, practice shifted dramatically.

As Culley and Avram recount, the use of general anesthesia in children remained controversial nonetheless. Dr. John Olney, a leader in defining fetal alcohol syndrome, took up extensive animal research around the effect of anesthesia on the developing brain. His laboratory documented that repeated and prolonged exposure to anesthetic agents was linked to abnormal brain development in various mammalian species. In the same issue of Anesthesiology, Warner, Shi and Flick comment, "the answers are [still] not 'obvious" ... we grapple with the specific question of whether animal findings translate to children."

To listen to the full lecture, visit AudioDigest.

Unraveling the truth

In her lecture "Anesthesia and the Developing Brain," now available for CME credit through AudioDigest, Dr. Linda Mason provides a thorough and thoughtful critique of ten years' research addressing this question. After reviewing the 2016 U.S. Food and Drug Administration (FDA) statement regarding the use of anesthetic agents in children, she explores extensive scientific literature. In many studies suggesting a correlation between anesthesia and cognitive-behavioral concerns, she finds a failure to control for confounding factors such as prematurity or low birth weight. Other early studies demonstrate too great a variation in the type of surgery or duration of anesthesia, she indicates, and some incorporate data derived from children who received halothane, an anesthetic agent largely abandoned in the 1980s.

Mason goes on to describe exciting work underway thanks to SmartTots, a joint initiative of the FDA, the International Anesthesia Research Society and others aimed at funding research in pediatric anesthesia. She points her listener to excellent articles in the April 2018 issue of Anesthesia detailing the animal research and exploring clinical evidence for effects of anesthesia on human brain development.

Clearly, important questions remain regarding the potential impact of anesthetics on the developing human brain and the circumstances under which those impacts may be undesirable. Mason convincingly argues, however, that those impacts are certainly smaller than once suspected and in many infants and children, not present at all. It will be interesting to see how this body of research further unfolds.

Stacia Dearmin, MD

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