Application Of EEG Nonlinear Analysis In Monitoring The Degree Of Consciousness Disorder

Background: Consciousness disorder means brain dysfunction caused by extensive cerebral cortex and (or) brain stem ascending reticular activating system damage, the main clinical manifestations contain the conscious content and (or) arousal disorders, it's very common pathological state. The time of recovering from disorder of consciousness may be short or long; the degree of consciousness disorder maybe different with cortical function changing, and the changes could be obvious, or difficult to find by physical examination also. Nowadays, evaluating the different degree of consciousness disorder mainly depends on clinicians subjective, empirical judgments, there is no objective, systematic evaluation criteria, and therefore it is hard to give objective guidance to the clinical treatment, evaluation of consciousness disorder.Brain electrical activity is the sum of the cerebral cortex apical dendrites action potential, and the essence of EEG recorded form brain surface is also the aggregate of cerebral cortex apical dendrites action potential, which can reflect cortex function. In recent years, looking for an objective EEG analysis method to response the degree of consciousness disorder is one of the research focus, with the development of nonlinear science, the view of brain signals is non-linear signal has been widely accepted, our study was also carried out under this background.Objective : Dynamic monitoring of brain electrical activity in unconscious patients, applying the nonlinear methods to analyze the EEG characteristics to provide the electrophysiological objective basis for evaluation the degree and prognosis of consciousness disorder. And compare with both linear EEG analysis and results of consciousness scale score, to determine the advantages of EEG nonlinear analysis, and find the specific nonlinear parameters to accurately reflect the degree of consciousness disorder.Method:Collect 72 cases of unconscious patients, get the EEG original signal, record relating clinical information and the score of different consciousness scale, including Glasgow-Liege Coma Scale, Rappaport disability rating scale, Rappaport coma / near coma scale, The JFK coma recovery scale-revised scale. Using nonlinear and linear methods to analyze EEG original signal, and analyze the correlation of consciousness scale score and the degree of consciousness disorder.Results:There is no dynamic correlation between EEG linear grading and degree of consciousness disorder, and the constituent ratio of EEG linear grading of different degree of consciousness disorder subgroups also have no significant difference. The consciousness scale score could roughly reflect the overall trend of consciousness disorder's degree, but not the dynamic response of sequential changes in degree of consciousness disorder; EEG non-linear analysis can dynamic monitoring the change of the degree of consciousness disorder, and the three nonlinear parameters, contain complexity, approximate entropy and cross-approximate entropy linear correlated with the degree changing of consciousness disorder (P<0.05).Conclusion:Compare to the linear analysis of EEG, the nonlinear analysis of EEG and consciousness scale score are more more suitable for dynamic monitoring the brain function of patients with consciousness disorders, the nonlinear parameters such as complexity, approximate entropy and cross-approximate entropy are more sensitive than Correlation dimension, Point wise correlation dimension, Mutual dimension, Lyapunov exponent and Kolmogorov entropy, which could identify the different degree of consciousness disorder, it is suitable for dynamic monitoring the consciousness disorder, could response the degree changing of consciousness disorder objectively and quantitatively.