| Objective: the monitoring of intracranial pressure(ICP)plays an important role in guiding the postoperative management of patients with traumatic brain injury(TBI),improving their survival rate and prognosis.Clinical workers can not only directly judge the intracranial condition of patients by ICP value,but also indirectly get the CBF change by CBF formula,which provides great convenience for the follow-up diagnosis and treatment measures.However,in the CBF formula,the venous blood flow out of the cranial cavity is supposed to be constant,ignoring the participation of the cerebral venous system.Vein is the direct continuation of capillaries.At present,there are relatively few studies on the relationship between ICP and cerebral venous blood flow,especially in the field of animal experiments.There is not only short of specific description of cerebral vein anatomy,but also short of mature and stable animal model of acute intracranial hypertension.In view of this,the main purposes of this study are as follows: 1.Making the cerebral vascular specimen of Sprague Dawley(SD)rats by latex vascular perfusion,in order to clarify the anatomical characteristics of rat cerebral vessels and their corresponding relationship with human cerebral vessels;2.A novel model of acute extradural hematoma(AEDH)model was established by setting a controllable microsphere into the right frontal extradural cavity of SD rats.And verifying the stability and accuracy of this model;3.Based on the right frontal AEDH model in SD rats,CBF and ICP were monitored accurately in real time,so as to explore the changes of wide-area cerebral vein and microcirculation blood flow under the condition of local intracranial high pressure and its influence on secondary brain injury;4.A novel model of acute extradural hematoma(AEDH)model was established by setting a controllable microsphere into the right temporal extradural cavity of SD rats.And verifying the stability and accuracy of this model;5.Based on the right temporal AEDH model in SD rats,the pathological reasons of the aggravation of local brain injury by the persistent mechanical compression of hematoma were discussed.Methods: according to the research objectives,the methods adopted in this study include: 1.Dilute the latex with ammonia(the volume ratio of latex and ammonia is1:3),take two parts and add appropriate amount of water-soluble red and blue pigments respectively to prepare red and blue latex,so as to prepare the specimens of cerebral arteries and veins for SD rats.The perfusion channel was established under deep anesthesia and the whole body blood was then drained thoroughly.The prepared latex was used for perfusion,and the morphological characteristics of cerebral blood vessels were additionally observed by magnetic resonance angiography and laser speckle contrast imaging.2.The model of acute extradural hematoma was established by placing a controllable microsphere in the right frontal extradural cavity of SD rats.The size of the microcapsules was precisely adjusted to simulate different volumes of hematoma.16 adult male rats were randomly divided into 4 groups: sham group,25 ?L group,50 ?L group and 100 ?L group.3.Based on the successfully constructed right frontal AEDH model of SD rats.48 adult male rats were randomly divided into 4 groups according to the different volume of microsphere,12 rats in each group: sham group,25?L group,50 ?L group and 100 ?L group.CBF was observed in real time by laser speckle contrast imaging,and ICP was monitored simultaneously as well.At the end of the observation,the brain was taken for observation and the pathological changes were observed by hematoxylin eosin(HE)staining.4.The model of acute extradural hematoma was established by placing a controllable microsphere in the right temporal extradural cavity of SD rats.The size of the microsphere was precisely adjusted to simulate different volumes of hematoma.16 adult male rats were randomly divided into4 groups: sham group,25 ?L group,50 ?L group and 100 ?L group.The model was validated by MRI of small animals.5.Based on the successfully constructed right temporal AEDH model of SD rats.42 adult male SD rats were divided into groups according to the different volume and compression time of the microsphere.The changes of local CBF and ICP were monitored in real time during the modeling process.The effects of mechanical compression on local brain injury were explored by histopathology and serology.Results: according to the research purposes and methods,the results of this study are as follows: 1.The cerebral vascular specimens of SD rats were successfully perfused,the large and small vessels were full,and the blood vessels were filled with coagulated latex.The artery is red and the vein is blue,which can clearly distinguish the distribution of blood vessels.magnetic resonance angiography and laser speckle contrast imaging have successfully demonstrated the characteristics of cerebrovascular anatomy.2.MRI results showed that the microsphere was located in the right frontal epidural space of SD rats,and the occupying effect was more obvious with the increase of microsphere volume.3.Quantitative analysis of the blood flow obtained from the laser speckle contrast imaging showed that there was a significant negative correlation between the blood flow perfusion rate(BPR)and ICP in SD rats.The ipsilateral cerebral venous blood flow increased slightly when the microsphere was 25 ?L,and decreased significantly when the microsphere was 100 ?L.according to the general observation and pathological results,at this time,the brain tissue was most seriously damaged.The change trend of microcirculation blood flow around compression area is similar to that of ipsilateral cerebral vein blood flow.4.MRI results showed that the microsphere was located in the right temporal epidural space of SD rats,and the occupying effect was more obvious with the increase of microsphere volume.5.The increase of microsphere volume can lead to the increase of ICP,the decrease of blood flow of cerebral vein and microcirculation,the destruction of blood brain barrier(BBB)and hemorrhagic transformation.5.The increase of microcapsule volume can lead to the increase of ICP,the decrease of blood flow of cerebral vein and microcirculation,the destruction of blood brain barrier(BBB)and hemorrhagic transformation.With the increase of compression time,CBF decreased and thrombosis increased,BBB damage and hemorrhagic transformation were aggravated,and the closer the compression center was,the more serious the damage was.Taking out the microcapsule as early as possible can reduce the local brain injury.Conclusion: in this study,the cerebral vascular specimen of SD rat was successfully made by latex perfusion,and the anatomic characteristics of SD rat's cerebral surface vessels and their corresponding relationship with human cerebral vessels were clarified.In this study,we combined the anatomical characteristics of the cerebral vessels of SD rats with the purpose of the study,and placed a controllable microcapsule in the epidural space of the right forehead and right temporal of SD rats,and successfully established two new AEDH models with high accuracy and good repeatability,which can simulate different hematoma volumes by adjusting the size of the microcapsules,so as to provide high-quality model tools for the next study.Based on the right frontal AEDH model of SD rats,this study preliminarily described that the local intracranial hypertension of SD rats can cause the limitation of cerebral venous return and the disturbance of microcirculation.Based on the right temporal AEDH model of SD rats,it is proved that the continuous mechanical compression of hematoma can lead to local ischemic injury,and the central cortex of hematoma compression is the most serious.Early hematoma clearance can reduce the degree of ischemic injury. |
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