Mouse studies detect altered brain connection after prolonged anesthesia

Chronic anesthesia, also known as medically induced coma, is a life-saving procedure performed worldwide on millions of patients in intensive care units each year.

But after prolonged anesthesia – which brings the brain to a state of deep anesthesia beyond short-term anesthesia for surgical procedures – it is common for family members to report that their loved ones were not after their hospital discharge.

“ICU survivors have long been known to suffer from brain impairment in terms of survival, such as depression and memory loss, which can go down for months and, in some cases, years,” he said. Michael Wenzel, MD, lead study author published in PNAS on this month which records changes associated with prolonged anesthesia in mouse brain.

Wenzel, a former postdoctoral researcher at Columbia University with experience as a physician in neuro-intensive care in Germany, said reports of post-hospital mental disorder are becoming more common due to the number Most coronavirus patients rely on ventilators that have taken days or weeks to wake up from a medically induced capacity.

To date, despite the body of evidence supporting the link between prolonged anesthesia and psychiatry, the direct effects on cloud connections have not been studied, said Rafael Yuste, professor of Bio Sciences at Columbia and senior author of the paper.

“This is because it is difficult to study a patient’s brain at a resolution high enough to monitor connections between individual neurons,” Yuste said.

To overcome the problem, Yuste and Wenzel developed an experimental platform in mice to study the connections between neurons, or synapses, and cognitive effects associated with continuous anesthesia.

Inspired by Wenzel’s experience in neuro-intensive care, the researchers set up a small ICU-like platform for mice. They performed continuous anesthesia for up to 40 hours, many times longer than the longest animal study to date (just six hours).

The researchers performed in vivo two-photon microscopy, a type of neuroimaging that pioneered Yuste and is capable of viewing living brain structures at micrometer resolution. The device allowed them to monitor cortical synapses in the sensory cortex, the area of ​​the brain responsible for processing bodily sensations, a technique they combined with re-assessment of behavior in the cortex.

Contrary to the notion that the connections between neurons in the adult brain remain stable during short-term anesthesia, the researchers found that prolonged anesthesia significantly alters the synaptic architecture of the brain no matter what. how old are they.

“Our results should ring a warning bell in the medical community, as they document a physical link between brain weakness and prolonged mental coma,” Wenzel said.

Since this study is only a pilot in mice, more research is needed, the researchers said. They said it will be important to test different, widely used anesthetics, as well as the combination of anesthetics given to patients. At present, anesthetics are not specifically made for patients in a systematic way.

“We are acutely aware that anesthesia is a life-saving method,” Wenzel said. “The reform of treatment plans for patients and the development of supportive therapies that keep the brain in shape during prolonged anesthesia would significantly improve clinical outcomes for those who have saved their lives, but who have compromised their quality of life. “