Learning by Research

Thesis Title: HALF-BRAIN: Multimodal evaluation of neurocognitive functioning and anatomical cerebral reorganization after hemispherotomy in patients with Rasmussen’s encephalitis.

Rasmussen’s encephalitis (RE) is a very rare neurological disorder that generally affects children between the ages of 2 and 10. It leads to the progressive atrophy of one cerebral hemisphere, causing severe epileptic seizures, motor impairments, and significant cognitive decline. The only curative treatment is hemispherotomy, a neurosurgical procedure that fully disconnects the affected hemisphere. Following the operation, all cognitive functions must be supported by the remaining healthy hemisphere. But how can the brain function with only one hemisphere? This question is at the heart of this thesis, which investigates the cognitive outcomes and brain evolution of patients after hemispherotomy, aiming to understand better the mechanisms underpinning such extreme reorganization.
In this context, the thesis examines long-term cognitive and neural reorganization in adult patients who underwent hemispherotomy in childhood due to RE. We rely on a large and rare retrospective and prospective dataset of Rasmussen patients who all underwent the same surgical technique. We propose a multidisciplinary and individualized approach that combines cognitive, neuropsychological, neuroanatomical, and clinical assessments. From a clinical perspective, this work provides the first characterization of patients' recovery trajectories. From a fundamental perspective, it offers valuable insights into neurocognitive functioning in a context where only one cerebral hemisphere remains active (extreme “mono-hemispheric” condition).
Overall, our findings show that postoperative outcomes are not solely determined by the side of the surgery but are shaped by a complex interplay of clinical and cognitive factors. This doctoral work demonstrates that early surgical intervention is beneficial, even when the left hemisphere, specialized for language, is affected. Despite the complexity of the ensuing cognitive reorganization, functional improvements remain possible. These results underscore the importance of an integrative approach to understanding reorganization processes. It is essential to examine cognitive functions and their interactions with brain organization and clinical features. Adopting a multimodal perspective thus appears necessary to unveil the complexity of cognitive and cerebral reorganization in this rare mono-hemispheric context during development. The integration of the factors discussed is crucial for guiding surgical decision-making and determining the optimal timing for hemispherotomy, ultimately offering substantial benefits to patients, their families, and the medical community.

Key words:  Rasmussen Encephalitis, Hemispherotomy, Neurocognitive reorganization, Drug-resistant epilepsy, Cognitive profiles, Cognitive network

Doctoral School: ED ISCE - Health, cognition and environmental engineering
Research laboratory: Laboratoire de Psychologie et NeuroCognition (LPNC- CNRS/UGA/USMB)
Thesis supervision: Monica BACIU, Marcela PERRONE-BERTOLOTTI and Christine BULTEAU-PEYRIE

> Pour connaitre tous les prix de thèse 2025