Transition from the locked in to the completely locked-in state: a physiological analysis.

TitleTransition from the locked in to the completely locked-in state: a physiological analysis.
Publication TypeJournal Article
Year of Publication2011
AuthorsMurguialday, RA, Hill, N Jeremy, Bensch, M, Martens, SMM, Halder, S, Nijboer, F, Schoelkopf, B, Birbaumer, N, Gharabaghi, A
JournalClin Neurophysiol
Volume122
Issue5
Pagination925-33
Date Published06/2011
ISSN1872-8952
KeywordsAdult, Amyotrophic Lateral Sclerosis, Area Under Curve, Brain, Communication Aids for Disabled, Disease Progression, Electroencephalography, Electromyography, Humans, Male, Signal Processing, Computer-Assisted, User-Computer Interface
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. SIGNIFICANCE: Auditory and proprioceptive brain-computer-interface (BCI) systems are the only remaining communication channels in CLIS.
DOI10.1016/j.clinph.2010.08.019
Alternate JournalClin Neurophysiol
PubMed ID20888292
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