Background: Recent neuroimaging research has strikingly demonstrated the existence of covert awareness in some patients with disorders of consciousness (DoC). These findings have highlighted the potential for the development of simple brain-computer interfaces (BCI) for the significant minority of behaviourally unresponsive patients who display consistent signs of covert awareness.Objectives: In this article, we review current EEG-based BCIs that hold potential for assessing and eventually assisting patients with DoC. We highlight key areas for further development that might eventually make their application feasible in this challenging patient group.Methods: We consider the major types of BCIs proposed in the literature, namely those based on the P3 potential, sensorimotor rhythms, steady state oscillations, and slow cortical potentials. In each case, we provide a brief overview of the relevant literature, and then consider their relative merits for BCI applications in DoC.Results: Over the last few decades, a range of BCI designs have been proposed and tested for enabling communication in fully conscious, paralysed patients. Though many of these have potential applicability for patients with DoC, they share some key challenges that need to be overcome, including limitations of stimulation modality, feedback, user training and consistency.
Conclusion: Developing feasible BCIs for diagnostics and communication in DoCwill require parallel strands of enquiry. Preliminary exploratory research will need to specifically tailor cognitive tasks that can tap into the forms in which patients could potentially express volition. Alongside, future work will need to address the technical and practical challenges facing reliable implementation at the patient's bedside.