A new study jointly conducted by the University of Liège (Belgium) and the Ecolenormal superieure - PSL (France) shows that heart-brain interactions, measured by electroencephalography (EEG), provide a new diagnostic path for patients with impaired consciousness .
In recent decades there have been many i improvements in the diagnosis of the functions of patients in coma and post coma. The great challenge, however, is still open: that of measuring the degree of self-awareness of people who cannot communicate. The scientific community already knew that the brain's response to heartbeat is related to body perception and self-awareness. Now a study shows that clinically meaningful information can also be obtained in patients with impaired consciousness.
Heartbeat study to reveal signs of consciousness on comatose patients
For their study, the researchers included 68 patients with a consciousness disorder. 55 suffered from a minimal state of consciousness, with fluctuating and consistent signs of consciousness but were unable to communicate. Thirteen patients were in a non-responsive waking state (formerly called a "vegetative state") showing no behavioral signs of awareness. These patients were diagnosed with a standardized clinical test to evaluate conscious behavior.
Because these patients have suffered from severe brain injuries, they may not be able to show behavioral signs of awareness. Therefore, we also based our diagnosis on brain metabolism. This is a state-of-the-art neuroimaging technique that can only be applied in specialized centers
Jitka Annen (GIGA Consciousness, ULiege)
The researchers recorded brain activity during the resting state. They selected EEG segments right after a heartbeat and EEG segments at random time points. They then used machine learning algorithms to classify (or diagnose) patients into the two diagnostic groups based on their brain's reaction to heartbeat.
The results
Our results indicate that the potential evoked by the heartbeat can give us additional evidence for the presence of consciousness
Diego Candia Rivera (Ecole normal superieure)
It is important to note that heartbeat-evoked responses were more in agreement with the diagnosis based on brain metabolism than the diagnosis based on behavioral assessment. It therefore appears that the response evoked by the heartbeat can be used to measure a perspective of self-awareness which is not successfully assessed using behavioral tools.
"The next challenge is to translate our findings into clinical applications. This way all patients with impaired consciousness will benefit from better diagnosis with widely available assessment technologies," he concludes. Steven laureys, head of the research unit GIGA Consciousness and Center du Cerveau (ULiege, CHU Liège).
