How does general anesthesia affect the brain?

How does general anesthesia affect the human brain? How is she able to make us lose consciousness? This is the question to which researchers from the Scripps Research Institute, an American biomedical research center, and whose work has been published in the journal PNAS.

A two-step process

The common use of general anesthesia was introduced to medicine about 175 years ago, 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 in 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 argue that the anesthesia process would ultimately take place in 2 stages: the anesthetics would first disrupt the lipid rafts, rigid structures present in the membrane cellular, which would generate a succession of biological actions leading to loss of consciousness.

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

A little history

For hundreds of years, tooth pullers and surgeons have “treated” the raw human body, optimizing the speed of their movements to make the medical procedure less painful. Finally, in 1846, 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 the French doctor Claude Bernard proposed combined anesthesia combining morphine and chloroform. Other molecules, plant extracts and substances are then tested. Today, the general anesthesia that we know includes three main families of drugs that can be associated: hypnotics, analgesics and muscle relaxants.

The risks associated with general anesthesia

In France, approximately 9 million general anesthesias 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 pathology. “Having general anesthesia is more risky than traveling by train, but it’s safer than getting in your car”summarized in 2018 at World André Lienhart, head of the anesthesia-resuscitation service at 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 argued that an times in every 19,000 operations, a patient woke up during their procedure, despite general anesthesia. A traumatic event inducing in some cases pain, paralysis and a feeling of panic.