1 Department of Algology-Palliative Care, University Hospital of Liège, University of Liège, Domaine Universitaire Du Sart Tilman B35, 4000, Liège, Belgium. avanhaudenhuyse@chu.ulg.ac.be.
2 Coma Science Group, Cyclotron Research Center, University of Liège, Allée Du 6 Août B30, 4000, Liège, Belgium.
3 Department of Algology-Palliative Care, University Hospital of Liège, University of Liège, Domaine Universitaire Du Sart Tilman B35, 4000, Liège, Belgium.