title: Transition from the locked in to the completely locked-in state: a physiological analysis.
abstract: OBJECTIVE
  To clarify the physiological and behavioral boundaries between locked-in (LIS) and the completely locked-in state (CLIS) (no voluntary eye movements, no communication possible) through electrophysiological data and to secure brain-computer-interface (BCI) communication.
  
  
  METHODS
  Electromyography from facial muscles, external anal sphincter (EAS), electrooculography and electrocorticographic data during different psychophysiological tests were acquired to define electrophysiological differences in an amyotrophic lateral sclerosis (ALS) patient with an intracranially implanted grid of 112 electrodes for nine months while the patient passed from the LIS to the CLIS.
  
  
  RESULTS
  At the very end of the LIS there was no facial muscle activity, nor external anal sphincter but eye control. Eye movements were slow and lasted for short periods only. During CLIS event related brain potentials (ERP) to passive limb movements and auditory stimuli were recorded, vibrotactile stimulation of different body parts resulted in no ERP response.
  
  
  CONCLUSIONS
  The results presented contradict the commonly accepted assumption that the EAS is the last remaining muscle under voluntary control and demonstrate complete loss of eye movements in CLIS. The eye muscle was shown to be the last muscle group under voluntary control. The findings suggest ALS as a multisystem disorder, even affecting afferent sensory pathways.
  
  
  CONCLUSIONS
  Auditory and proprioceptive brain-computer-interface (BCI) systems are the only remaining communication channels in CLIS.
authors.affiliation: Institute of Medical Psychology and Behavioral Neurobiology, MEG Center, University of Tübingen, Tübingen, Germany. aramos@fatronik.com
authors.forename: A Ramos
authors.initials: AR
authors.lastname: Murguialday
authors.forename: J
authors.initials: J
authors.lastname: Hill
authors.forename: M
authors.initials: M
authors.lastname: Bensch
authors.forename: S
authors.initials: S
authors.lastname: Martens
authors.forename: S
authors.initials: S
authors.lastname: Halder
authors.forename: F
authors.initials: F
authors.lastname: Nijboer
authors.forename: B
authors.initials: B
authors.lastname: Schoelkopf
authors.forename: N
authors.initials: N
authors.lastname: Birbaumer
authors.forename: A
authors.initials: A
authors.lastname: Gharabaghi
mesh_terms: D000328:Adult; D000690:Amyotrophic Lateral Sclerosis / Q000503:physiopathology*; D019540:Area Under Curve; D001921:Brain / Q000503:physiopathology*; D003143:Communication Devices for People with Disabilities; D018450:Disease Progression; D004569:Electroencephalography; D004576:Electromyography; D006801:Humans; D008297:Male; D012815:Signal Processing, Computer-Assisted; D014584:User-Computer Interface