兔脑激光间质热毁损及血脑屏障急性期改变

Observing thermal injury of rabbit brain in laser interstitial themotherapy and evaluating changed structure of blood brain barrier in acute stage

目的 观察激光间质加热（laser interstitial thermotherapy，LITT）后兔脑毁损组织与周边脑组织的超微病理改变，评估Lrrr后急性期的血脑屏障（blood brain barrier，BBB）开放性。方法浙江大学动物实验中心提供新西兰大门兔共70只，经随机筛选设LITTA组（2W，600S，20只）及B组（15W，100S，20只），应用直体定向技术插入半导体激光光纤，分别对兔右侧前脑实行立体定向间质加热，另随机设甘露醇灌注组和假手术对照组各15只。透射电镜下观察LITT后3h，6h，12h，24h的中心热毁损灶及靶周边脑组织BBB的超微形态学的改变；酶联免疫吸附法测定相应不同时间的S100B蛋白变化；另检测脑脊液白蛋白与血清白蛋白比值（BBB系数）。实验数据作单因素方差分析，组间均数比较用q检验。结果接触激光光纤前端成为加热毁损灶，以细胞坏死为主，细胞膜结构损伤，线粒体、内质网等细胞器膨胀，线粒体嵴消失，胞浆稀疏等。形态学改变明显于对照组。热能传导至周边，可见部分细胞发生不同时期的凋亡改变。急性期内可见内皮细胞肿胀、血管基膜模糊断裂、周围间隙增宽、缝隙结构破坏，且S100B蛋白及BBB系数在LITT组明显升高，BBB开放的时程较甘露醇灌注组长。但24h后LITT组开始恢复，S100B与BBB系数较LITT组的差异具有统计学意义（P=0．0087）。结论利用立体定向技术半导体激光加热兔脑组织的毁损灶，急性期内可导致明确的细胞组织损伤，BBB结构破坏，小功率加热组血脑屏障开放时程较大功率组缩短。提示利用小功率半导体激光可形成精确安全的脑毁损灶，为功能神经外科发展提供了新思路。

Objective To observe ultramicro pathologic change of rabbit brain central damaged tissue and peripheral tissue ＇after LITT, to evaluate the changed structure of blood brain barrier （BBB） of peripheral tissue in acute stage. Method Seventy Newzealand rabbits were randomly screened from Zhejiang University Animal Experiment Center. By stereotaxic technique, semiconductor surgica laser fibers were inserted into right frontal lobes and heat treated to randomly build LITT Group A （2W, 600 s, n = 20） and LITT Group B （15 W, 100 s, n = 20） brain damaged models successfully. Other 15 nomal rabbits were randomly distributed as mannitol perfusion group and fake operation group. The ultramicro structures in central theruaodamaged tissue were observed with transmission electro microscope ＇after LITT 3 h, 6 h, 12 h, 24 b. In peripheral tissue, ultramicro morphologie changes of brain vessels and BBB were evaluated. S100B protein in serum and BBB indexe were measured at different stages post LITT. Experimental data were treated as one-factor analysis of variance and q test. Results The brain damage center connected the tip of laser fiber and turn into thennodamage tissue. The main structure changes were cytoclasis, damnification of cell membrum, swelling of cell organelle such as mitochondrion, endoplasmicreticulum, disappearance of mitochondfion and sparseness of cytoplasm in local tissure. Heat energy conducted to damage peripheral tissue, some cells occured apoptosis in different stage. In aeute stage after LITT, contracted capillary, vessel, ancreted red cell, swell endothelium cell, broken base membrum, wide around clearance and destroyed aperture structure were identified. The levels of serum S100B and BBB indexe dramatically rised. The opening time of BBB in peripheral tissue was longer than mannital peffusion group. However at 24 h post LITT, they began to recover in Group A. The difference of serum S100B and BBB indexe between Group A and Group B has statistical significance （ P = 0. 0087）. Conclusions With semiconductor laser heat treatment and stereotaxic techniqe, definite ceils cytoclasis, cell membrance structures and chondriosome damage could be performed obviously in rabbit brain thermotherapy point. Apoptosis could be found in peripheral tissue, BBB could be opened in an acute stage. The opening time course of BBB was shortened in those LITT eases with small power. It shew us a new method to perform a safe and exact damage zone of brain for functional neurosurgery.