[LUM#3] Rethinking the Brain
What if the brain isn't what we thought it was? A true cartographer of the brain, Montpellier-based neurosurgeon Hugues Duffau has discovered the incredible plasticity of our gray matter—and changed the lives of thousands of patients.
The year is 1861. French physician Paul Broca encounters a rather unusual patient: although he understands everything that is said to him, he has become unable to utter a single intelligible word. A single syllable—"tan"—is all that features in his conversations, earning him the nickname "Tan." Tan is aphasic, and he will have a lasting impact on the history of neuroscience.
Upon Tan’s death, Paul Broca examined his brain thoroughly and noticed that a small area was damaged. He concluded that this specific region controls speech.“Based on accurate observations, he drew erroneous conclusions,” explains Hugues Duffau. The Montpellier-based neurosurgeon is categorical: the famous Broca’s area does not exist. He cites as proof the many patients in whom he has performed total ablation of this brain area and who nevertheless speak without any difficulty.
Broca's error
Beyond Broca’s area, it is the entire traditional conception of the brain that is open to question.“For 150 years, medicine has assumed that the brain is organized into distinct areas, each controlling specific functions. It is now proven that this ‘localizationist’ theory is false, and yet we continue to teach it,” laments the neurosurgeon, who has been waging a veritable crusade for the past 15 years to put an end to this deeply entrenched dogma.
So how does our brain really work?“It is organized into dynamic, interactive networks capable of constantly readjusting. Networks that differ from one person to another,” replies Hugues Duffau. This “connectionist” approach explains why some patients can lead perfectly normal lives despite having a tumor the size of an orange affecting areas previously considered crucial for brain function.
“Clearly, the brain can compensate for these lesions: its incredible plasticity allows it to reorganize itself to continue functioning normally. Take the Paris metro system—if you close a station, you’ll always find another route home,” the doctor illustrates. Provided, however, that the most important connections remain intact.“If you close Chatelet and Montparnasse, then you risk paralyzing traffic,” warns the recipient of the Herbert-Olivecrona Medal, the equivalent of the Nobel Prize in neurosurgery.
Wakeful Operations
This connectionist approach has revolutionized the care of patients with brain tumors.“As long as the tumor hasn’t caused any disability, we can remove most of it and treat the patient without routinely resorting to chemotherapy,” explains Hugues Duffau. But since every brain is different, how can we know where the ‘Chatelet station’ is located in the patient’s brain? There is only one solution: keeping the patient awake throughout the operation. A procedure that is unusual to say the least, but one that“allows us to verify the impact of surgical procedures in real time,” says Hugues Duffau.
In the operating room, “transient virtual lesions” are created in the brain using small electrical impulses delivered to very specific areas. Meanwhile, a neuropsychologist and a speech therapist ask the patient to follow instructions to test their ability to speak, move, or recognize an emotion. If they give the wrong answer, the surgeon knows which area to avoid, lest they disrupt an important neural network.“For example, if the patient says ‘a car’ instead of ‘a car,’ I mark the area with a small label to remind myself not to remove anything from that crucial spot”…Does it hurt? Not at all:“The brain has no pain receptors,” the neurosurgeon reassures us.
Preserving quality of life
Over the past 20 years, Hugues Duffau has operated on more than 650 patients, doubling or tripling their life expectancy. He treats dozens of men and women from all over the world who are suffering from brain tumors that his colleagues have deemed inoperable, for fear of excessive complications. ““By operating on awake patients, we can remove as much of the tumor as possible while significantly reducing the risk of complications, which has dropped from 20% to less than 0.5%. Our top priority is preserving patients’ quality of life—that’s crucial.” The first patients operated on in this manner by Hugues Duffau were treated 20 years ago. They are still here to attest to it.
For early detection
2,500 to 3,000. That is the number of new patients diagnosed with a glioma each year in France. “Often too late!” laments Hugues Duffau. “By offering routine screening MRIs, we could detect these tumors very early on and propose removing at least a large portion of them, ” suggests the man who revolutionized neuroscience. It’s an idea that is beginning to gain traction in the medical community.
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