The first sign of loss of consciousness

The first clinically observable sign of an unconsciousness episode (UNCE) serves as the temporal sequence (kinetics) onset point for neurological events occurring during the loss of consciousness, unconsciousness and recovery of consciousness phases of the UNCE. The initial neurologic signs of 212 individuals exposed to gradual (N=114) and rapid (N=98) onset +Gz acceleration stress, inducing the ischemic LOC phase in 83.3±18.6s and 8.89±1.52s; p<0.001 respectively, were determined. The duration of the unconscious phase (considered absolute incapacitation) was 10.42±5.3s and 9.36±3.99s; p>0.1 for gradual and rapid onset +Gz-stress, respectively. Cerebral autoregulation may play a role in determination of ischemic UNCE induction and recovery. Five signs: loss of muscle control, eyelid closure, eye fixation, upward eye deviation, and muscular twitching occurred at LOC phase onset. The most frequent initial sign of LOC phase onset was loss of muscle control (84% of the episodes), followed by eye fixation (8.5%), and upward eye deviation (6.1%). Signs play a key role in differential diagnosis of syncopal, epileptic, psychogenic and other causes of UNCEs. Sign kinetics may provide insight into localization of the essential components and networks within the cephalic nervous system associated with UNCEs.