Clinical Research Directory

Comparison of Modulations of Motor Brain Activity and SedLine After Median Nerve Stimulation in General Anesthesia

To this date, no monitoring device can reliably detect episodes of accidental awakening during general anesthesia. One promising approach is the use of electroencephalography (EEG) to detect movement attempts via a brain-computer interface (BCI). Previous work has shown that combining a BCI with painless median nerve stimulation can detect cerebral motor activity under light propofol sedation. However, clinical data are still lacking regarding the persistence or otherwise of a cerebral motor response (neural synchronization, or ERS) induced by this stimulation during general anesthesia. In this new study, the aim is to simultaneously record the EEG centered on the motor cortex and the signal from the SedLine Patient State Index (PSI) to better characterize the evolution of cerebral motor activity before, during general anesthesia, and up to awakening. This approach will allow us to explore the complementarity of the two signals for future automated detection of residual states of consciousness during surgery. Preliminary data from a previous protocol (STIM-MOTANA) allowed to develop an EEG classification algorithm based on Riemannian geometry, capable of inferring a patient's state of consciousness from cortical responses induced by median nerve stimulation. The objective of this new study is also to compare the sensitivity of this algorithm with that of PSI, in order to assess its potential as a complementary - or even alternative - indicator of the level of consciousness under general anesthesia. Investigators hypothesize that it is possible to detect, using EEG, specific brain signatures related to median nerve stimulation, including during propofol-induced general anesthesia. Specifically, neuronal desynchronization and resynchronization phases (ERD/ERS), well characterized in wakefulness or light sedation, could partially persist at higher propofol concentrations. Parallel PSI recording will allow analyzing to what extent these EEG modulations are related to classically measured levels of consciousness, and to validate the relevance of the new algorithm based on Riemannian geometry as a tool for detecting intra-operative arousals.

Prevalence of AAGA

Accidental Awareness During General Anesthesia (AAGA) is a condition where patients regain partial or full consciousness during anesthesia, unable to move or react. This can lead to distressing experiences such as pain, fear, or stress, and may cause long-term psychological effects like insomnia, nightmares, and post-traumatic stress disorder. Although AAGA prevalence is reported as 0.1% to 0.2% in Western studies, data specific to populations like Turkey are limited and lack large-scale research. This study aims to investigate the prevalence of AAGA in Turkey and identify associated risk factors, including patient characteristics (e.g., age, gender, comorbidities), surgical variables, and anesthesia techniques. By addressing these factors, the study seeks to enhance anesthesia safety standards and provide critical data for national health policies and practices.

Investigation of Cerebral Motor Activity Modulations Following Median Nerve Stimulation During General Anaesthesia

Accidental Awareness during General Anesthesia (AAGA) occurs in 1-2% of high-risk practice patients and is a cause of severe psychological trauma, termed post-traumatic stress disorder (PTSD). Actually, no monitoring techniques can accurately predict or detect an AAGA. Since the first reflex for a patient during an AAGA is to move, a brain-computer interface (BCI) based on the detection of an intention of movement would be conceivable to alert the anesthetist. The investigators previously showed that median nerve stimulation (MNS) could be the keystone of a BCI specialized in the detection of movement intention. Indeed, based on these previous results, the investigators can envisage a routine system where the patient would be stimulated at the median nerve position, while a BCI device would analyze the event-related desynchronization (ERD) and event-related synchronization (ERS) modulations in the motor cortex to check whether the patient is intending to move or not. According to the investigator's knowledge, no published studies have investigated the detection of EEG patterns in relation to peripheral nerve stimulation over the sensorimotor cortex during general anesthesia. The main objective of this study is to describe the changes in terms of ERD and ERS modulations, in the EEG signal over the motor cortex, during general anesthesia with propofol, while a median nerve stimulation is performed. STIM-MOTANA is an interventional and prospective study conducted in patients scheduled for surgery under general anesthesia, involving EEG measurements and median nerve stimulation. In this study, 30 patients will undergo surgery under total intravenous anesthesia using a propofol target-controlled infusion pump. The rest of the anesthetic protocol will be at the discretion of the anesthesiologist in charge. Changes in ERD and ERS during median nerve stimulation according to the various propofol concentrations will be continuously monitored by an EEG amplifier. Pre- and post-injection comparisons of propofol will be performed by paired series tests. After surgery, patients will have a gradual decrease of propofol at different effect-site concentrations (from 4.0 μg/ml to 2.0 μg/ml, in increments of 0.5 μg/ml).