Detecting covert consciousness

Neurocritical patients that are clinically unresponsive can show a wide variety of covert consciousness. The terms minimal conscious state (MSC) and unresponsive wakefulness syndrome (UWS) were established to distinguish patients who still show signs of self or environmental awareness from patients showing no signs of awareness, respectively. Clinically determining these two states is a huge challenge and has an estimated error rate of about 30-40%. To address this problem, Giulio Bicciato (USZ) and colleagues tested a relatively new, non-invasive approach.

Using functional near-infrared spectroscopy (fNIRS), Giulio Bicciato and his team assessed the patients’ responses to music. The goal was to validate the feasibility of this method to evaluate the level of consciousness in neurocritical patients.

For the experiment the subjects were played their favorite music (or the music their relatives told the researchers to be their favorite). Before or/and after playing the music, there was a block without music to measure the baseline activity of the brain. During and after music exposure, the low-frequency oscillations (LFO) of the hemoglobin in the brain were measured by means of fNIRS. The measurements were compared with the level of consciousness of the patients and their clinical outcomes after 3 months.

The experiment showed a correlation between the LFO measurements during and after music exposure and the level of consciousness. Also, the outcome of the subjects after 3 months was correlated to these signals. These results suggest that measuring LFO through fNIRS may be a new marker for detecting covert consciousness. This approach is feasible in an actual intensive care set-up, and it provides physicians with a non-invasive method to assess their patients’ consciousness.

Reference: Giulio Bicciato,Gagan Narula, Giovanna Brandi, Amanda Eisele, Sven Schulthess, Susanne Friedl, Jan Folkard Willms, Laura Westphal, Emanuela Keller, Functional NIRS to detect covert consciousness in neurocritical patients, Clinical Neurophysiology, Volume 144, 2022, Pages 72-82,

Image: Adrian Korte, unsplash