How does general anesthesia work on the brain?

THE ESSENTIAL

• The process of general anesthesia would take place in 2 stages in the brain
• Understanding the mechanisms of anesthesia may lead to new discoveries in sleep biochemistry
• About 9 million general anesthesia are performed each year in France

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How does general anesthesia affect the human brain? How is it capable of making us lose consciousness? This is the question that researchers seem to have answered. Scripps Research Institute, an American biomedical research center, the work of which has been published in the journal PNAS.

A two-step process

The common use of general anesthesia has been introduced to medicine for about 175 years, during which time the scientific community, although satisfied with its effectiveness, never really understood its mechanisms. The debate was twofold: do the substances used to anesthetize a patient act on the ion channels on the cell membrane or on the membrane itself?

After five years of research, doctors Richard Lerner and Scott Hansen have finally solved the mystery and suggest that the anesthesia process would ultimately take place in 2 stages: the anesthetics would first disturb the lipid rafts, rigid structures present in the membrane cell, which would generate a succession of biological actions leading to loss of consciousness.

“We think there is no doubt that this new path is used for other brain functions beyond consciousness, which now allows us to eliminate other mysteries from the brain ”, detailed Doctor Lerner. This discovery could indeed allow researchers to better understand the mechanisms related to sleep biochemistry.

A little history

For hundreds of years, tooth pullers and surgeons have “treated” the human body on the spot, optimizing the speed of their gestures to make the medical procedure less painful. In 1846 finally, William Morton, surgeon at Boston hospital, removes a tooth from one of his patients anesthetized with ether.

Chloroform was then discovered and popularized the following year, but it was in 1860 that French doctor Claude Bernard proposed combined anesthesia associating morphine and chloroform. Other molecules, plant extracts and substances are then tested. Today, general anesthesia as we know it gathers three big families of drugs which can be associated: hypnotics, analgesics and curares.

Risks associated with general anesthesia

In France, around 9 million general anesthesia are performed each year. The mortality rate ranges from 0.4 per 100,000 in healthy patients to 55 per 100,000 for those with medical conditions. “Having general anesthesia is more risky than traveling by train, but safer than getting into your car ”, summarized in 2018 at World André Lienhart, head of the anesthesia-resuscitation department of the CHU Saint-Antoine in Paris.

In 2015, risks in children under 4 were reported as a decrease in gray matter density in the posterior regions of the brain. The previous year, a report from the Royal College of Anaesthesists and the Association of Anaesthesists of Great Britain and Ireland suggested that ane times every 19,000 operations, a patient woke up during his intervention, despite general anesthesia. A traumatic event inducing in some cases pain, paralysis and a feeling of panic.

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