Workshop on Brain Evoked Potentials in the context of Neurosurgery

In this workshop these new technique based on the electrophysiological potentials evoked (EP) by the direct electrical stimulation (DES) of the brain to recognize and localize the tumor and determine the anatomical connectivity on-line in order to guide the surgery in awake patients or under general anesthesia will be discussed. This need to go beyond the proof of concept already performed, and necessitate to address and solve some methodological challenges. In particular, it requires the improvement in spatial resolution both for stimulation and recording of the evoked response as well as the correct interpretation of the recorded evoked potentials. At a fundamental level, this will also help to better understand the electrophysiological effect of DES in order to optimize its use.

From this workshop the first guidelines for the recording and interpretation of brain EP in the clinical context of brain surgeries will emerge. Some possible innovations of this new technique in the arsenal of intraoperative neural monitoring (IONM) will be discussed.

In physiology, an evoked potential (EP) is defined as a change in the electrical activity of the nervous system in response to an external stimulus, whether visual, auditory, sensory or motor. The recording of evoked potentials provides information about the function of the stimulated pathway, i.e. the passage of the nerve impulse. The use of direct electrical stimulation is a new avenue of research for so-called 'awake' brain surgery. When removing brain tumours from awake patients, electrical stimulation is used to ensure in real time that essential functions such as speech and vision remain intact.

During the resection of brain tumors, the neurosurgeon has substantial imaging data allowing him/her to plan his gesture upstream. However, during the surgical act itself, this imaging becomes ineffective due to the deformation of the brain and because these imaging techniques give no information about the functional status of the brain tissue that are manipulated. It seems possible to use direct electrical stimulation (DES) of the brain in an awake patient who cooperates with the neurosurgeon to determine the connectivity on-line and functional areas.

François Bonnetblanc, Camin project-team

• François Bonnetblanc (Coordinator, PhD, Inria Camin Team)
• Prof. Hugues Duffau (MD, PhD, CHU Montpellier)
• Prof. Emmanuel Mandonnet (MD, PhD, CHU Lariboisière – APHP)
• Prof. Riki Matsumoto (Coordinator, MD PhD, Kobe University Hospital)
• Olivier Rossel (PhD, Inria Camin Team)
• Félix Schlosser-Perrin (MSc, Inria Camin Team)
• Clotilde Turpin (MSc, Inria Camin Team)
• “Brain & Electrophysiological Mapping”, France-Japan Inria Associate Team