Diffuse axonal injury by assault

A case of diffuse axonal injury (DAI) by assault is reported. The majority of DAI cases documented have been due to traffic accidents and some due to falls from height. DAI is caused by angular or rotational acceleration of the victim's head. The condition is common and is the second most important head injury after subdural hematoma with regard to death. Its clinical picture is characterized by immediate and prolonged coma or demented state. Because of the subtle nature of histological changes in DAI, awareness and intentional search for the lesion is essential. The triad of DAI is as follows: focal lesions (hemorrhages and/or lacerations) in the corpus callosum and brain stem, and microscopic demonstration of axonal damage--retraction balls. The concept of DAI will elucidate and enhance the understanding of many head trauma cases.     

Diffuse axonal injury by simple fall.

Diffuse axonal injury (DAI) is the second most common lethal head trauma after subdural hematoma and probably the most frequent cause of traumatic coma in the absence of an expanding intracranial mass lesion. Though it occurs most often in traffic accidents, it may occasionally result from falls from a height. Previously, it has not been associated with a simple fall or a fall of a distance not more than the victim's own height. We report herein a case of DAI from a simple fall.     

Diffuse axonal injury in a rugby player

Sections of the cerebrum, cerebellum, and brain stem of a rugby player who died 15 hours after being tackled were stained using an immunoperoxidase technique to detect beta-amyloid protein. The sections of the pons showed axonal spheroids in the base, and those of the cerebellum showed axonal spheroids in deep white matter. The findings demonstrated axonal injury following a fall from the victim's height in a team sporting event.     

Diffuse vascular injury in fatal road traffic accident victims: its relationship to diffuse axonal injury

The authors have reported a macro- and microscopic study of brain lesions in 120 victims of fatal road traffic accidents, independent of the survival time. Diffuse vascular injury (DVI) was found in 14 patients (11.7%). All patients with DVI died within 24 h after the accident. The 14 patients with DVI also showed severe (Grade 2 or 3) diffuse axonal injury (DAI). Since DVI is restricted to road traffic accidents and incompatible with life, the high frequency observed in our series could be explained by the fact that all 120 patients were victims of road traffic accidents, and 69.2% had died within 24 h after the accident. The association between DVI and severe DAI (Grades 2 and 3) suggests that both lesions depend on the same mechanism, with the degree of axonal and vascular damage being determined by the intensity of the head acceleration. Our results show a relationship between DVI and DAI that suggest there may be a spectrum or at least a continuum between these entities as distinct from DVI being a separate entity.     

弥漫性轴索损伤的研究进展

弥漫性轴索损伤（diffuse axonal injury,DAI）以脑白质轴索弥漫性损伤为主要特征,迄今其形成机制尚未完全阐明,不同学科诊断标准迥异,是法医学和神经科学亟待解决的难题。磁共振弥散张量成像（diffusion tensor imaging,DTI）通过检测弥散参数及纤维束成像（fibre tracking,FT）可准确地反映轴索损伤部位及损伤程度,具有广泛的法医学应用前景。本文综述DAI发生机制及诊断方法的研究进展,尤其DTI技术在DAI诊断中的应用。     

大鼠弥漫性轴索损伤后NGF表达

目的研究大鼠弥漫性轴索损伤后神经生长因子（NGF）表达的时间变化规律及意义。方法采用SD雄性大鼠复制弥漫性轴索损伤（DAI）模型,分别于伤后1、3、6、12、24、48h和3、7d取脑组织,应用免疫组织化学法对DAI后不同时间段大脑皮层、丘脑、小脑和海马部位NGF的表达变化进行观察并与正常组、假手术组对照。结果正常及假手术组大鼠大脑皮层、丘脑、小脑、海马均有少量NGF的表达。打击后1hNGF表达增强,12h达高峰,3d开始下降,7d降至正常。结论NGF参与弥漫性轴索损伤后的修复：NGF的时序性变化有望成为法医学脑损伤时间推断的客观指标。     

The diagnosis of diffuse axonal injury in routine autopsy practice

A 40-year-old pedestrian was involved in a road traffic accident. He lost consciousness immediately and remained comatose for 6 months until he died of a bronchopneumonia. Examination of the fixed brain revealed the late results of diffuse axonal injury. Not all the features were readily visible macroscopically, but required a limited number of histological sections from readily predictable sites for demonstration. Special stains played only a confirmatory role. This case illustrates some of the problems in diagnosing one of the commoner patterns of brain damage in head injury, and shows how the problem may best be approached in practice.     

实验性脑弥漫性轴索损伤的组织病理学变化

目的探讨钝力致脑弥漫性轴索损伤(DAI)的法医病理学鉴定依据。方法采用液压冲击方法建立钝力致家猫脑DAI模型;通过H．E．、Bodian、Kluver-Barrera普通组织化学染色及NF免疫组化染色,观察致伤后不同时间脑实质内轴索及其髓鞘的变化,并通过图像分析系统对轴索内NF免疫组化染色阳性反应物面积进行定量检测,所得数据用SPSS 11．5 for Windows软件进行统计学分析。结果致伤后1-2h,猫大脑皮质下白质、胼胝体及脑干轴索轻度肿胀、弯曲;4h轴索肿胀、弯曲显著,呈断续状,且在胼胝体、丘脑及脑干出血区周围出现收缩球,髓鞘开始疏松崩解。随着观察时间的延长,收缩球进一步变大,中心空泡出现,髓鞘疏松、水肿、崩解。经对轴索内NF免疫组化染色阳性反应物的图像分析数据进行统计学分析,对比组间差别具有非常显著性差异意义(P<0．01)。结论脑轴索肿胀、弯曲、增粗、离断以及收缩球的形成,是DAI法医病理学鉴定的依据。     

实验性大鼠弥漫性轴索损伤的傅里叶红外光谱检测

目的探讨利用傅里叶红外光谱技术诊断弥漫性轴索损伤的可行性。方法利用HE染色、银染和β-APP免疫组化染色确认大鼠弥漫性轴索损伤模型,利用傅里叶变换显微红外光谱面扫描成像技术检测弥漫性轴索损伤区域酰胺Ⅱ带的光谱分布情况,得到弥漫性轴索损伤的红外光谱数据,绘制红外光谱病理图像。结果实验组与对照组的酰胺Ⅱ带红外光谱吸收度之间存在明显差异,红外光谱病理图像中酰胺Ⅱ带的高吸收区与弥漫性轴索损伤区符合。结论傅里叶红外光谱技术可对弥漫性轴索损伤进行病理形态学诊断。     

大鼠弥漫性轴索损伤后海马热休克蛋白质70mRNA表达

目的 研究大鼠弥漫性轴索损伤(diffuse axonal injury,DAI)后大脑海马中热休克蛋白质(heat-shockproteins,HSP)70 mRNA的表达变化.方法 采用RT-PCR扩增,扩增产物用琼脂糖凝胶电泳检验,观察DAI后大鼠海马中HSP70 mRNA的表达变化.结果 损伤后4h,大鼠海马中...     

弥漫性轴索损伤的扫描电镜观察

弥漫性轴索损伤是一种具有独特的临床、病理学特征的脑损伤，是重型脑损伤的主要死因之一，作者对６例脑外伤ＳＥＭ研究发现：大脑皮质挫伤远区可见神经细胞树实折断，轴索排列紊乱、断裂、粗细不等，有的断端球形扩大（ｒｅｔｒａｃｔｂａｌｌ）。髓鞘变性、表面粗糙、呈筛孔状，有的坏死脱落至轴索裸露，有的可见星形细胞附着在毛细血管壁的足板有断裂，毛细血管淤血、弯曲、破裂出血、出血区可见纤维蛋白网络红细胞。ＳＥＭ下上述病变观察清楚，立体感强，不失为一种先进的研究手段，脑外伤ＤＡＩ的研究中尚未见报告。     

大鼠弥漫性轴索损伤脑组织弥散张量成像与免疫组化染色观察

目的观察大鼠弥漫性轴索损伤(DAI)模型伤后不同时间大脑白质磁共振弥散张量成像(DTI)弥散参数和β-APP、NF68免疫组织化学染色的变化。方法建立SD大鼠Marmarou DAI模型,分别于伤后3、12、24、72 h行DTI扫描,获取大鼠胼胝体、内囊和外囊弥散参数;比较相应部位β-APP单位面积阳性轴索数及阳性染色面积百分比,NF68平均光密度的伤后变化。结果实验组胼胝体、内囊和外囊轴向弥散(AD)、各向异性分数(FA)伤后逐步下降;β-APP单位面积阳性轴索数量、阳性染色面积百分比及NF68平均光密度伤后逐步增加。相关分析证实AD、FA值与β-APP、NF68变化呈显著负相关。结论 DTI弥散参数可作为DAI早期诊断的生物标记物。     

CT、MRI在弥漫性轴索损伤法医学鉴定中应用价值分析

目的探讨CT和MRI检查方法在弥漫性轴索损伤(diffuse axonal injury,DAI)法医学鉴定中的应用价值。方法收集26例CT和MRI影像资料齐全的DAI鉴定资料进行回顾性分析,比较CT和MRI两种方法对DAI病灶检出率的差异,分析DAI病灶检出数量与法医学鉴定结果之间的关系。结果 26例经MRI检出DAI病灶787个,经CT检出DAI病灶32个,MRI对DAI病灶的敏感度显著高于CT(P0.01)具有统计学意义。26例DAI鉴定的伤残等级数值与影像学检查发现的病灶数量之间存在负相关(r=-0.908,P0.01)。结论 MRI检查对DAI病灶的检出率较CT检查具有明显优势,可为DAI诊断提供更为准确的依据,在法医临床学鉴定中具有重要的应用价值。     

大鼠DAI脑细胞凋亡与Phospho-Ser^727 Stat1表达的相关性

目的探讨Stat1是否参与弥漫性轴索损伤（diffuse axonal injury,DAI）后神经细胞凋亡的病理生理过程。方法应用自由落体撞击模型复制大鼠DAI模型,分为正常对照组、假手术组和打击后不同时间组（6、12、24、48、72h,5d和10d）。采用HE染色和镀银染色观察大鼠脑组织的病理改变,用流式细胞检测脑组织中脑细胞的凋亡率,RT-PCR法测定脑组织中bax和bcl-2的表达变化,免疫组织化学法测定脑组织中不同脑区727位丝氨酸磷酸化的信号转导与转录激活子1（Phospho-Ser727 Stat1）的表达情况。结果DAI后HE染色未见脑挫裂伤,镀银染色可见神经轴索扭曲肿胀,个别断端膨大形成轴缩球;损伤组脑细胞的凋亡率和脑组织中bax和bcl-2 cDNA扩增产物的比值24h达到最大值,随后下降;不同脑区Phospho-Ser727 Stat1表达升高,24h达峰后下降,至10d较对照组仍有显著差异;阳性细胞主要是神经元,在不同脑区也有一定量的神经胶质细胞阳性表达。脑组织中Phospho-Ser727 Stat1表达变化与bax和bcl-2的cDNA扩增产物比值的变化具有正相关性,相关系数r为0.921。结论大鼠DAI后Stat1的激活和损伤后脑细胞的凋亡有关,应与损伤后二次打击有关。     

Mechanism responsible for the formation of focal swellings on injured neuronal processes using a novel in vitro model of axonal injury

A novel in vitro model of axonal injury using PC12 cells was designed to introduce traumatic alterations on neuronal processes and to identify mechanisms responsible for the formation of focal swellings by observation with phase-contrast and transmission electron microscopes. The injury on the processes was developed by one-dimensional, horizontal oscillation. Phase-contrast microscopic observation on the injured processes showed their terminal increase in diameter. Long term observation of cellular responses to the mechanical insult disclosed that the terminal swelling coincided with the detachment of growth cones from the culture plate. The finding suggests that the detachment of the growth cone would destroy a cytoskeletal network, which determines and maintains the cell shapes, and then cause the spherical deformation of the processes. Ultramicroscopically, the processes with terminal swellings regenerated the growth cones by the cytoskeletal reconstruction.     

脑干轴索肿胀的半定量研究

目的 探讨轴索肿胀在鉴定脑干损伤中的意义。方法 取明确死于原发性脑干损伤(36例)和脑外疾病(28例)者共64例，分为损伤组(36例)和对照组(其中死于心血管疾病12例、非心血管疾病16例)，并将其死后24h和48h前、后做尸体解剖分为2组，通过对中脑、脑桥和延脑切片、镀银染色，在100倍光镜下采用显微测微器测量每片9条最粗的轴索横径，对所得数据作方差分析、t检验统计学处理。结果 损伤组与对照组(不包括心血管疾病死亡者)相比，中脑、延脑部的轴索肿胀程度有明显差异(P＜0.05)；死后48h内解剖的损伤组与对照组相比无差异(P＞0.05)，但超过48h解剖两组有明显差异(P＜0.05)。结论 中脑、延脑部轴索肿胀与外伤有明显的相关性。轴索肿胀对判断脑干损伤有意义。需排除心血管疾病致死。     

112例脑弥漫性轴索损伤分析

目的探讨脑弥漫性轴索损伤（diffuse axonal injury,DAI）与脑挫裂伤和原发性脑干损伤的关系。方法分析112例DAI伤者的法医临床学资料和影像学特点,对原发性脑损伤的特征进行比较。结果112例DAI伤者中70.5%为交通事故致伤,多次暴力致伤比较多见（60.7%）,伴脑挫裂伤者80例（71.4%）。CT或MRI发现出血灶者90例。结论DAI多伴有脑皮质挫裂伤和原发性脑损伤,CT或MRI有助于法医学死因分析和伤残程度鉴定。