兔蛛网膜下腔出血早期脑损伤时脑微循环变化规律

Changes law of brain microcirculation during early brain injury induced by subarachnoid haemorrhage in rabbits

目的 探讨兔蛛网膜下腔出血(SAH)模型发生早期脑损伤(EBI)时不同脑叶、不同时间脑微循环的变化情况。方法 新西兰大白兔SAH造模后,进行全脑CT灌注成像,测量CBF、CBV、MTT和TTP,然后脑组织做病理切片进行常规HE染色。观察和记录结果,采用分组比较的研究方法进行分析。CBF、CBV、MTT、TTP测量结果采用定量分析统计方法。结果 CBV在手术组与假手术组间有差异(P<0.05);CBF值手术组低于对照组,6 h手术组较1 h组降低,在24 h达到最低值,72 h组CBF值上升高于24 h组;MTT各手术组与对照组比较具有明显统计学差异(P<0.05);手术组间比较,MTT在第1 h升高,第6、24 h达到顶峰,在第72 h减低;SAH后第6 h及24 h,颞叶、枕叶CBF值高于额、顶叶,病理上局部脑血管管壁增厚,周围可见明显炎性细胞浸润及出血坏死区。结论 CT灌注成像能够敏感而准确地反映蛛网膜下腔出血后早期脑微循环的改变;MTT及CBF能反映SAH后早期脑损伤的进展程度;蛛网膜下腔出血后早期脑损伤时各脑叶灌注情况存在差异,CBF可以提供一些依据及参考,对于临床治疗及预防脑缺血性改变具有一定价值。

Objective To observe changes law of the brain microcirculation in different brain lobes and at different time points in early brain injury(EBI)induced by subarachnoid haemorrhage(SAH)in a rabbit model.Methods A SAH model of New Zealand white rabbit was subjected to whole brain CT perfusion imaging.Measurement of cerebral blood flow(CBF),cerebral blood volume(CBV),mean transit time(MTT)and time to peak(TTP)was carried out.Brain tissue excision was prepared for pathological sectioning and HE staining.The results were observed and recorded,and then analyzed by group comparison methods.The CBF,CBV,MTT and TTP were quantitatively analyzed.Results There was a difference in the CBV between the operation group and the sham operation group(P<0.05).The CBF value in the operation group was lower than in the control group;in the operation group the CFB value at 6 h was decreased compared with that at 1 h,and reached the lowest value at 24th hour,and then turned to rise and the value at 72th hour was higher than that at 24th hour.The MTT of each operation group showed a significant difference compared with the control group(P<0.05).In the operation group,the MTT increased at the 1st hour,reached a peak at 6 and 24 hours,and decreased at hour 72.At 6 h and 24 h after SAH,CBF values in temporal and occipital lobes were higher than those in frontal and parietal lobes,and the local cerebral vascular wall was pathologically thickened,with obvious inflammatory cell infiltration and bleeding necrosis.Conclusions CT perfusion can sensitively and accurately reflect changes of brain microcirculation in the early stage after SAH.MTT and CBF can reflect the progression of EBI after SAH.Furthermore,there are differences in lobe perfusion in EBI after SAH.CBF can provide a basis and reference for evaluation.It has certain value for clinical treatment and prevention of cerebral ischemic changes.