Brain Mapping by Direct Electrostimulation: the Bilingualism

Objectives: The organization of the language in the brain of bilingual people is controversial since the description of dissociated aphasias after strokes. Since 1997, we have studied by electrostimulation the organization of the language areas of bilinguals operated on for various brain lesions.Methods: Forty bilingual patients were studied over 15 years in our department by electrostimulation during neurosurgical brain mappings. Different tasks were used: mainly naming and reading, but also in some cases writing and translating.Results: A majority of language areas are common in bilinguals and are mainly located in Broca's and Wernicke’s regions in small areas of cortex (<1cm2). However, we demonstrated that some areas involved in naming or reading tasks could be specific: 1) to a task and a language, 2) to a given task for two languages, 3) to a language but for two tasks.The initial surgical approach was changed according to these data in 18 cases over 40. Capacity of translation from one language to another would be more related with the deep brain structures. Conclusions: In practice during brain surgery in areas of language, when a brain mapping we needed, we recommend testing all languages spoken by bilingual patients.