title: Detection of response to command using voluntary control of breathing in disorders of consciousness.
abstract: BACKGROUND
  Detecting signs of consciousness in patients in a vegetative state/unresponsive wakefulness syndrome (UWS/VS) or minimally conscious state (MCS) is known to be very challenging. Plotkin et al. (2010) recently showed the possibility of using a breathing-controlled communication device in patients with locked in syndrome. We here aim to test a breathing-based "sniff controller" that could be used as an alternative diagnostic tool to evaluate response to command in severely brain damaged patients with chronic disorders of consciousness (DOC).
  
  
  METHODS
  Twenty-five DOC patients were included. Patients' resting breathing-amplitude was measured during a 5 min resting condition. Next, they were instructed to end the presentation of a music sequence by sniffing vigorously. An automated detection of changes in breathing amplitude (i.e., >1.5 SD of resting) ended the music and hence provided positive feedback to the patient.
  
  
  RESULTS
  None of the 11 UWS/VS patients showed a sniff-based response to command. One out of 14 patients with MCS was able to willfully modulate his breathing pattern to answer the command on 16/19 trials (accuracy 84%). Interestingly, this patient failed to show any other motor response to command.
  
  
  CONCLUSIONS
  We here illustrate the possible interest of using breathing-dependent response to command in the detection of residual cognition in patients with DOC after severe brain injury.
authors.affiliation: Coma Science Group, Cyclotron Research Centre and Neurology Department, University of Liège and CHU Sart Tilman Hospital Liège, Belgium.
authors.forename: Vanessa
authors.initials: V
authors.lastname: Charland-Verville
authors.affiliation: Coma Science Group, Cyclotron Research Centre and Neurology Department, University of Liège and CHU Sart Tilman Hospital Liège, Belgium.
authors.forename: Damien
authors.initials: D
authors.lastname: Lesenfants
authors.affiliation: Department of Neurobiology, The Weizmann Institute of Science Rehovot, Israel.
authors.forename: Lee
authors.initials: L
authors.lastname: Sela
authors.affiliation: Coma Science Group, Cyclotron Research Centre and Neurology Department, University of Liège and CHU Sart Tilman Hospital Liège, Belgium ; Brain Innovation B.V., Maastricht Netherlands.
authors.forename: Quentin
authors.initials: Q
authors.lastname: Noirhomme
authors.affiliation: Cyclotron Research Centre, University of Liège Liège, Belgium.
authors.forename: Erik
authors.initials: E
authors.lastname: Ziegler
authors.affiliation: Coma Science Group, Cyclotron Research Centre and Neurology Department, University of Liège and CHU Sart Tilman Hospital Liège, Belgium ; Department of Physical Medicine and Rehabilitation, Spaulding Rehabilitation Hospital, Harvard Medical School Boston, MA, USA.
authors.forename: Camille
authors.initials: C
authors.lastname: Chatelle
authors.affiliation: Department of Neurobiology, The Weizmann Institute of Science Rehovot, Israel.
authors.forename: Anton
authors.initials: A
authors.lastname: Plotkin
authors.affiliation: Department of Neurobiology, The Weizmann Institute of Science Rehovot, Israel.
authors.forename: Noam
authors.initials: N
authors.lastname: Sobel
authors.affiliation: Coma Science Group, Cyclotron Research Centre and Neurology Department, University of Liège and CHU Sart Tilman Hospital Liège, Belgium.
authors.forename: Steven
authors.initials: S
authors.lastname: Laureys
keywords: brain-computer interface; breathing; diagnosis; disorders of consciousness; minimally conscious state; sniffing; unresponsive wakefulness syndrome; vegetative state