Top Santé: You think that we made a mistake about the functioning of the brain … Explain to us why.
Prof. Hugues Duffau: A function like speech, for example, is not localized – as has been believed for 150 years and is still being taught – in a specific area called Broca’s area. Speech brings into play several areas of the brain far from each other, which will be connected simultaneously, thanks to the white matter beams. If certain areas are damaged, the brain can adapt as long as the main connections are not touched. This is called brain neuroplasticity. She explains why people with brain tumors in Broca’s area keep talking. But this potential for reorganization is not unlimited and depends on the state of the white fibers, which it is important to preserve. This is the goal of awake surgery.
TS What types of tumors do you operate on?
Pr HD Most of the brain tumors (gliomas) are operable, provided the patient has not already lost essential function. It is preventive surgery: it is necessary to intervene as long as the person is well, because when neurological disorders appear, it is most often not possible to restore them. On the other hand, as long as we have not reached the limits of cerebral plasticity, the situation is very likely not to worsen after the intervention: the brain is indeed capable of repairing itself. The first patient I operated on, in 1997, is leading a normal life.
TS How does an intervention take place when the patient is awake?
Pr HD Previously, I have a very long interview with him, because he must trust me, but also be motivated. In the operating room, we are a whole interactive team: anesthesiologist, speech therapist, neuropsychologist, nurses … After I open the cranial box, the anesthesiologist wakes up the patient (the brain does not feel the pain) and, for two hours, the speech-language pathologist conducts neuropsychological tests.
Meanwhile, with an electrical stimulation probe, I map the brain. Electrical stimulation deactivates the affected network. If the tasks performed by the patient are then disturbed, I will avoid intervening in this area. The goal is to preserve the maximum of cerebral functions and to generate the least possible sequelae. But the quality of life of patients is also taken into account. For example, a mathematician will need to retain all of his calculation skills but he may be less bothered by a bimanual coordination disorder, unlike a pianist. Each operation is unique, because each brain is different, even if there is a minimum common brain.
TS What other pathologies could benefit from your research?
Pr HD At the moment, we are still trying to understand. But we are beginning to better understand the networks that underlie emotions, which has enabled us to develop new cognitive models concerning affective aspects in individuals. Very useful advances in the knowledge of diseases such as autism. This pathology linked to communication disorders could be produced by a dissociation of networks linked to the recognition of emotions and the attribution of intentions. Other applications in epilepsy are also possible.
Broca’s mistake, Pr Hugues Duffau, ed. Michel Lafon.
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