The Correlation Between The Structural Changes Of Thalamic Connections And Disturbance Of Consciousness Following Coma Due To Brain Injury

Objective: Clinical Research: We use diffusion tensor imaging to assess the FA values andADC values which change in thalamus of coma patients caused by brain injuries. And thenwe assess the FA values and ADC values how to change when GCS scores changes inpatients with brain injuries. Experimental studies: We take the tract-tracing ways offluorescence immunohistochemical to explore the distribution of the tracer in whole brainwhich is injected in the subthalamic nucleus of rats in coma caused by brain injuries. Bythe two researches we can better understand the relationship between the thalamus anddisturbance of consciousness.Methods: Clinical study:6patients of coma following brain injury,9patients in thecontrol group. All the patients get the GCS scores before magnetic resonance diffusiontensor imaging scanning. Then we select the bilateral thalamus, medulla oblongata, pons,midbrain as a region of interest and achieved FA values and ADC values.After that we usestatistical methods to compare the differences of the FA values and ADC values in differentparts between the brain injury coma group and control group patients, we emphasis on theFA values and ADC values of the thalamus. Next we compare the differences of FA valuesand ADC values in various parts changing with the GCS scores reducing, we focus on FAvalues and ADC values of the bilateral thalamus how they change with the GCS scoresreduced.Experimental study: We adopt a straight-line acceleration brain injury coma rat model,with12coma rats,12normal control rats. All the rats are injected tracer--the cholera toxinβ subunit in subthalamic nucleus guided with the stereotaxic instrument.After two daystracer sites can be clearly demonstrated. Respectively in day1, day2and day3after comathe rats were sacrificed, parallel perfusion fixed, dehydrated. Then we take the mouse brainstained by fluorescent immunohistochemistry. The different parts of the brain tissue of ratswere observed under a fluorescence microscope and photographed. We use image analysissoftware to record the counts of the different parts of the phosphor particles. We take thestatistical method to analysis the differences of fluorescent particles distribution indifferent parts of the brain between the normal rats and the brain injury coma rats. Wecould evaluate the structural changes of thalamic connection and projection fibers in comafollowing brain injury with the two ways above.Results:1. Clinical research: The FA values in bilateral thalamus decline compared thebrain injury coma patients and the control group patients, there is a statistically significant difference (P <0.05). Because of the diversity of the ADC values, in the left thalamus theADC values of brain injury coma patients and the control group of patients are statisticallysignificant. The ADC values of patients with brain injury coma are greater. In rightthalamus ADC values of brain injury comatose patients and the control group of patientsare not significant difference. In the medulla oblongata, pons and midbrain, the FA valuesand the ADC values of brain injury coma patients and the control group patients are notstatistically different. FA values of left and right thalamus and GCS score are positivelycorrelated (P <0.05).About the ADC values, only the ADC values of right thalamus andGCS scores are negatively correlated (P <0.05),but ADC values of left thalamus and GCSscore was not statistically related. The FA or ADC values of the remaining parts and GCSscores are not statistically relevant, but from the scatter diagram, we could see that in themedulla oblongata, pons and midbrain FA values have a gradual downward trend with theGCS scores reducing. In medulla oblongata, pons and midbrain ADC values do not changeobviously with GCS score reducing.2. Experimental study: Rat brain tissue sections were immunofluorescence stained andobserved under the fluorescence microscope. The fluorescent particles in the location ofsubthalamic nucleus and needle tract can be clearly showed. Observing the brain tissuesections, we can see that the tracer with the shaftaxonal transport to the midbrain, thehippocampus and cortex site. In the midbrain, the hippocampus and cortex the distributionof fluorescent particles and the numbers are different between the normal control and comarats. We can see in the midbrain, the hippocampus and cortex fluorescent particles countbetween the normal control and coma rats in different times and in different parts of thefluorescence immunohistochemistry beam tracing result is not the same. In the subthalamicnucleus the normal group and injury group distribution was no significant different, but inthe midbrain, the hippocampus and cortex parts fluorescent particles distribution betweenthe normal group and one day of injury group, two days of injury group and one day ofinjury group,normal group and two days of injury groups all have statistically significantdifferences (P <0.05), and the distribution of one day of injury group in the hippocampus isthe least, but in the subthalamic nucleus is the most.Conclusion: The structural change of thalamic connections is one of the important reasonsthat lead to the disturbance of consciousness.