Anesthesia sends neurons in the wrong way in unborn infants

While we've been questioning for a long time about the harmful effects of anesthesia exposure on brain development, a new study from the Rush University Medical Center published in the newspaper Cerebral cortex describes how prenatal anesthesia in the rat appears to disrupt "accurately choreographed" and timed migration of neurons to the developing brain area where thought, memory, and language occur.

This discovery still feeds the debate about the safety of anesthesia during pregnancy for unborn babies. The researchers have suggested to approximately 75,000 women undergoing surgery during pregnancy to take a closer look at the timing of the surgery.

In a series of detailed experiments in in utero study, exposure to anesthetics alters the pattern of neuronal migration in cerebral cortex development and causes postnatal behavioral deficits in the rat, researchers have demonstrated how the exposure of pregnant rats to anesthetic affects neuronal migration, the process of mammals in which neurons migrate from their initial position deep within the brain to their final position on the outer edge, or cerebral cortex.

"The cerebral cortex, or gray matter, is the computer processor of the brain, where cognitive processes such as thought, memory, and language are directed, so that neurons never reach their own predetermined position in the brain. cortex can have a profound impact on brain function, "said the minister. Lead author of the study, anesthetist and neuroscientist, Dr. Vicko Gluncic, MD, Ph.D. Dr. Gluncic conducted the research at Rush and now practices at the Advocate Illinois Masonic Medical Center.

Anesthesia sends neurons in the wrong way

To test this hypothesis, researchers labeled migrating neurons in rat fetuses with a dye, and then anesthetized a group of pregnant rats during the precise period during which neuronal migration occurs is most active. This period of gestation is about the end of the second trimester in humans – when the motor areas of the brain are already well developed while the visual and somatosensory cortex is still developing. A control group was not anesthetized. Examinations of rats exposed to anesthetics showed that a significant number of neurons remained improperly dispersed in deeper layers of the cortex and that the longer rats were exposed to antenatal anesthesia, the more their neurons were dispersed. A second set of behavioral experiments showed that all littermates had consistent motor skills, but those exposed to anesthetics had significant behavioral and learning deficits.

Together, histological badysis of rat brain and behavioral tests demonstrate that in utero exposure to anesthesia has a negative impact on the formation of the most sensitive part of the brain by preventing the pattern migration of neurons. And despite these powerful and potentially disastrous alterations, the authors say that the effects of anesthetics on neuronal migration and development of cortical cortical organization had never been tested before.

Mario Moric, biostatistician of Rush 's Department of Anesthesiology, said that "there is a clear badociation between the type of anesthesia and the duration of anesthesia with neuronal migration and neurons. cognitive deficits at the drug levels used here (in rat fetuses), it is now necessary to validate the mechanisms involved and test various anesthetics and anesthetic protocols to badess the differential impact on cognitive functioning "

Researchers "do not want to push the panic button" but push for more discussion

The authors of the study pointed out that the results in rats could not directly affect pregnant women who canceled or delayed surgery, although these results should be taken into account in informal discussions between women and their counterparts. doctors.

"We do not want to press the panic button," says Dr. Gluncic. "It would be a mistake if women delay or stop having medically indicated surgeries during their pregnancy for this reason.However, elective surgeries during pregnancy are usually performed in the second trimester, after organogenesis, and when premature contractions and spontaneous abortion are less likely According to current data, the possibility that anesthesia affects brain development of the fetus should be seriously considered and disclosed in informed consent for the first time. second trimester anesthesia because the most active period of human fetal brain development actually occurs between the 12th and 24th week of pregnancy. "