Although the use of Brain-Computer Interfaces (BCIs) in the arts originates in the 1960s, there is a limited number of known applications in the context of real-time audio-visual and mixed-media performances and accordingly the knowledge base of this area has not been developed sufficiently. Among the reasons are the difficulties and the unknown parameters involved in the design and implementation of the BCIs. However today, with the dissemination of the new wireless devices, the field is rapidly growing and changing. In this frame, we examine a selection of representative works and artists, in comparison to the current scientific evidence. We identify important performative and neuroscientific aspects, issues and challenges. A model of possible interactions between the performers and the audience is discussed and future trends regarding liveness and interconnectivity are suggested.