Prognostic Evaluation Of Patients With Vegetative State:an Electrophysiological Study

With the rapid development of treatment techniques, clinics and intensivecare technology, the mortality of emergency patients has decreased, but it alsobrings a new medical and social problem, that is, a large number of patients in avegetative state (VS). Objective and accurate evaluation of brain function playimportant role in the prognosis of patients with vegetative state. In this research,we intend to explore the value of the EEG reactivity, EEG sleep spindles andsomatosensory evoked potentials N20on the prognosis and treatment of patientswith vegetative state.ObjectiveThe purpose of this study is to explore the predicting role of the EEGreactivity, sleep spindle of EEG and somatosensory evoked potentials N20in therecovery of consciousness of thirty patients with vegetative state in theneurological intensive care unit (the NICU). ObjectSelect30patients who admitted to Xijing Hospital NICU from Jan,2010toJun,2011and diagnosed as VS:1. Unaware of self and environment;2. Nointeraction with others;3. No sustained, reproducible, or purposeful voluntarybehavioral response to visual, auditory, tactile, or noxious stimuli;4. Nolanguage comprehension or expression;5. No blink to visual threat;6. Presentsleep-wake cycles;7. Preserved autonomic and hypothalamic function tosurvive for long intervals with medical/nursing care;8. Preserved cranial nervereflexes;9. Bowel and bladder incontinence.Exclusion criteria:1. Patients in status epilepticus with epileptiformdischarges;2. Drugs such as Phenobarbital and Narcotics which can influencebrain function had been used nearly3days;3. Patients who had serious damagein the stimulation site;4. Patients with peripheral nerve injury which affect nerveconduction.There were30patients conform to the standards,25males and5females,aged from17to69years, with a median age of42. Among them, traumaticbrain injury in13cases, hypoxia ischemia encephalopathy aftercardiopulmonary resuscitation in9cases, CO poisoning in5cases, drowning in2cases, and brain stem hemorrhage in1cases. The first and the last VS scorewere evaluated when patients within24hours of admission and prior todischarge respectively. In order to observe the recovery of consciousness state,we performed VS scoring several times a day on the patients. Days of hospitalstay was from37to190, and average time of hospitalization was (83.8±7.74)days. Methods1.Indicators to determine recovery of consciousness: recovery ofconsciousness include minimally conscious state (MCS) and return to normalawareness； VS, coma and dead patients are considered not recover inconsciousness.When the patients showed a limited and definite evidence of theirperception of themselves and the surrounding environment, such as any one ofthe following performance is regarded as MCS:(1)Following simple commands;(2)Gestural or verbal responses to yes/no questions;(3)Intelligible verbalization;(4)Purposeful behavior: Patients may even make a purposeful action oremotional response to outside specific environmental stimuli.2. Patients admitted to hospital within24hours have been implementedmore than24hours of continuous EEG monitoring and judged of the EEGresponse and the sleep spindles.3. The judgment of EEG reactivity:(1) methods: Monitoring EEG when thepatient is quieter, with no agitation and the EEG is relatively stable; resort tovisual observation and computer quantitative analysis of the judgment of EEGreactivity. Select pain (oppression of the nail bed), olfactory (Essential Balm)and thermal stimulation (50degrees hot water) every five minutes. Any EEGchanges of such three kinds of stimuli are considered as the EEG reactivity.Criterion: In the visual group, we observed after stimulation, each stimuluswas repeated six times, with all leads of the EEG amplitude increase ordecrease, EEG frequency faster or slower, EEG background activity changedare indicating the EEG reactivity；In the quantitative analysis group, before andafter10seconds of stimulation test was used to analyze the changes of eachEEG frequency band. When the statistical probability P<0.05, showed that the EEG response.4. Judgment of sleep spindles: With long-range video surveillance andarchiving, the next day playback analysis appeared in the parietal, central orfrontal area of EEG, the duration is1.5-2s, the amplitude increased and thendecreased slowly, the frequency is10-14Hz, spindle-shaped wave is called"sleep spindles".5. The correlation between the EEG reactivity and sleep spindles and therecovery of consciousness was analyzed in patients with vegetative state.6. Somatosensory evoked potential N20were performed in all patientswithin48hours after admission. Analysis of the relationship between the aboveresults and the prognosis of patients proceeded then.Results1. Of30patients enrolled in the study,11of them regained consciousness,and19of them did not recover consciousness. EEG reactivity was elicited in11patients and8of them regained consciousness in the group of visual observation.While in the group of computer analysis, EEG reactivity was elicited in12patients and9of them regained consciousness. These data indicate that thepresence of EEG reactivity was a strong positive prognostic factor forconsciousness recovery. The sensitivity, specificity and accuracy of computeranalysis method were84.2％,81.8％,83.3％respectively, all of which werehigher than that of visual observation method (84.2％，72.7％，80％).2. Among12patients who have spindle waves,9cases with recovery ofconsciousness;16cases in other18patients did not. Our results havedemonstrated that sleep spindles of EEG is a good predictor of consciousnessrecovery in VS patients. It’s sensitivity, specificity and accuracy on the prognosis of patients were84.2％,81.8％,71.4％respectively.3. Somatosensory evoked potentials N20is correlation with patients’prognosis (P <0.05); The correlation coefficient r was0.725, p＜0.01. It’ssensitivity of judge VS patients’ awareness was100%, specificity63.6%, andaccuracy86.7%;Conclusions1. Continuous EEG monitoring (CEEG) has an important value on theassessment of prognosis in VS patients.2. The specificity and veracity of EEG reactivity of quantitative analysis ishigher than that of visual observations. Both of them are good positive factor forthe prognosis of recovery of consciousness in vegetative state patients.3. The sleep spindles of EEG and somatosensory evoked potential N20canbe served as a reference of consciousness recovery in VS patients withvegetative state.