Scientists have discovered the brain mechanisms that allow the patient to lose consciousness during general anesthesia.
General anesthesia is a very mundane medical operation. Yet the neurological mechanism that causes the patient to lose consciousness has so far been a mystery to scientists. To pierce it, a team acquired images of the brain activity of macaques while awake or under general anesthesia with propofol, ketamine or sevoflurane. The data published in Anesthesiology were obtained by functional magnetic resonance imaging (fMRI) and electroencephalography (EEG).
General anesthesia stiffens the flow of information
Regardless of the drug used to put the monkeys to sleep, the researchers found a “universal brain signature” of general anesthesia within the brain. “To better understand the discovery, imagine that our brain is our planet earth and that the functional MRI is a satellite monitoring road axes. We have found that, in the conscious state, the road network is fluid and flexible: the axes Motorways and secondary roads see good traffic and good flexibility in the management of changes in the flow encountered by the network. On the other hand, in the event of general anesthesia, the network is confined to the motorway axes. It allows neither good flexibility nor a good distribution of the flow, generating in a way traffic jams “, describes Béchir Jarraya, professor of medicine at the University of Versailles-Paris-Saclay, neurosurgeon at the Foch hospital in Suresnes and researcher. at Neurospin in Saclay, who led this work with Lynn Uhrig, anesthesiologist, Hôpital Sainte-Anne Neuroscience researcher at CEA.
In other words, general anesthesia stiffens the flow of information through the brain. Only the activities of brain related to anatomical functions are maintained. This phenomenon explains the loss of consciousness induced by general anesthesia in a patient. “Regardless of the molecular mechanism, anesthesia has led to a massive reconfiguration of the repertoire of functional states of the brain which has become primarily shaped by the anatomy of the brain, giving rise to a well-defined cortical signature of induced loss of consciousness. by anesthesia “, conclude the authors of the study. The team brought together researchers from CEA, Inserm, the Universities of Versailles Saint-Quentin en Yvelines, Paris Sud / Paris Saclay, and Paris Descartes and the Foch hospital.
Develop new pharmacological products
This discovery could induce changes in the way of approaching general anesthesia and sedations in intensive care of patients. comatose patients. It could also make it possible to develop new, more selective pharmacological products.
In France, 9 million general anesthesias are performed each year. The mortality rate varies from 0.4 per 100,000 in the case of healthy patients to 55 per 100,000 for those with the most serious pathologies. “Having general anesthesia is more risky than traveling by train, but it’s safer than getting in your car”, sums up in The world André Lienhart, head of the anesthesia-intensive care unit at CHU Saint-Antoine in Paris.
.