Acknowledgements: The authors wish to thank the National Institute for Health and Care Research Brain Injury MedTech Co-operative for support of this study and, in particular, Mita Brahmbhatt and Peter Jarritt. The authors also wish to thank Prof. David Menon, Prof. Peter Smielewski, and Prof. Paul White for their input and support. Finally, the authors wish to thank Enrico Giuliani for the technical support.