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。     

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。     

磁敏感加权成像在出血性弥散性轴索损伤鉴定中的应用

目的探讨磁敏感加权成像(susceptibility weighted imaging,SWI)在出血性弥散性轴索损伤(diffuse axonal injury,DAI)法医学鉴定中的应用价值。方法对20例DAI的法医学鉴定资料进行回顾性分析,对其T1WI、T2WI、扩散加权成像(diffusion weighted imaging,DWI)、液体衰减反转恢复(fluid attenuated inversion recovery,FLAIR)、磁敏感加权成像(susceptibility weighted imaging,SWI)序列影像资料进行统计分析。结果 DAI出血灶多位于脑组织表浅区,SWI对出血性DAI的检出率最高,与其他序列成像之间的差异有统计学意义(P0.05)。结论 SWI在DAI法医学鉴定中具有重要的意义。     

大鼠弥散性轴索损伤后β-APP的表达

目的观察大鼠DAI损伤后β-APP表达和Gless神经纤维轴索染色在诊断DAI损伤及判断损伤时间的价值。方法按Marmarou法复制大鼠DAI损伤模型,脑组织常规取材后进行β-APP及Gless氏神经纤维轴索染色观察。结果β-APP及Gless氏染色法在大鼠DAI损伤后0.5h即可见神经轴索断裂、扭曲变形、增粗膨大,12h以后可见到轴索收缩球。二种方法均显示DAI损伤的病理形态学变化,伤后12h明显,1d达到高峰,3d后开始修复,10d后基本恢复正常。β-APP表达强度在实验组不同时间存在着明显的差异,即3h呈明显阳性表达,1d达到高峰,3d后逐渐减弱,10d基本恢复正常。结论β-APP免疫组织化学染色法及Gless氏神经纤维轴索染色法,对DAI的早期诊断具有重要应用价值,并能从病理形态学上反映DAI损伤的时序性。β-APP表达强度变化是推断早期DAI损伤时间的重要参考指标。     

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。     

Modification of the Marmarou and Foda model of diffuse axonal injury (DAI) improves percentage survival of rats at 24 h and increases the amount of DAI identified

More than two decades ago, Marmarou published a valid model for producing diffuse axonal injury (DAI) in rats. Since then, both mild and severe injuries have been obtained by researchers using the original method and a weight of 450 g. However, the diffuse brain injuries produced in rats were only similar to those seen in humans when the rats sustained severe brain injuries. In these cases, rat mortality in the original article was around 50%, and the cause of death was prolonged apnea post-impact. Rat survival after impact is critical for studying the progression of DAI. In order to explain the cause of death in human victims with cranial trauma who do not show gross brain injury, testing for the presence of DAI is essential. Thus, in order to minimize local and cervical injuries to increase rat survival, attention should be paid to the following aspects: a wider head protector disc should be used, the head of the rat should be elevated at the time of impact, and the foam bed should be soft enough to allow the movement caused by acceleration. With our modified method, rat survival increased by 30% compared to the original model (80% versus 50%). Moreover, 85.7% of rats demonstrated DAI after 24 h of survival. With these modifications, injuries appear in the same locations as in humans; thus, the method is suitable for the study of traumatic DAI in humans.     

Preliminary Study on Diffuse Axonal Injury by Fourier Transform Infrared Spectroscopy Histopathology Imaging

The objective of this study was to evaluate the application of Fourier transform infrared (FTIR) spectroscopy for detecting diffuse axonal injury (DAI) in a mouse model. Brain tissues from DAI mouse model were prepared with H&E, silver, and β‐amyloid precursor protein (β–APP) immunohistochemistry stains and were also studied with FTIR. The infrared spectrum images showed high absorption of amide II in the subcortical white matter of the experimental mouse brain, while there was no obvious expression of amide II in the control mouse brain. The areas with high absorption of amide II were in the same distribution as the DAI region confirmed by the silver and β‐APP studies. The result suggests that high absorption of amide II correlates with axonal injury. The use of FTIR imaging allows the biochemical changes associated with DAI pathologies to be detected in the tissues, thus providing an important adjunct method to the current conventional pathological diagnostic techniques.     

交通事故致弥漫性轴索损伤伤残等级鉴定89例分析

目的研究交通事故致弥漫性轴索损伤（diffuseaxonalinjury，DAI）的患者伤残等级鉴定结果，并探讨DAI对鉴定结果可能产生的影响。方法收集556例本鉴定中心2011年1月-2012年12月受理的交通事故致颅脑损伤案例，其中单纯性脑挫（裂）伤467例，临床诊断为DAI89例。再重新审阅被鉴定人颅脑CT及MRI检查结果，分为单纯DAI组、DAI合并脑挫（裂）伤组、无DAI脑挫（裂）伤组3组颅脑损伤，并对鉴定结果进行比较和统计学分析。结果单纯DAI组（20例）的伤残等级为7．72±1．09，DAI合并脑挫（裂）伤组（69例）的伤残等级为7．78±1．11，无DAI的脑挫（裂）伤组（467例）的伤残等级为8．86±0．66，前两组的伤残等级均高于无DAI的脑挫（裂）伤组（P〈0．05）。结论患有DAI的被鉴定人可能存在更为严重的脑功能损害．鉴定时应注意临床的漏诊和误诊，避免过于依赖CT、MRI等影像学表现。     

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.     

脑震荡后综合征及其客观评定技术的发展

脑震荡后综合征诊断具有很大的争议性。轻度创伤性脑损伤后脑震荡综合征的发病机制,涉及神经损伤和心理社会因素。迄今,已有大量的研究对现有的检查方法或工具(包括精神检查、常规CT和核磁共振、神经心理学测试和神经生化检查)的评定和诊断价值进行了分析。轻度创伤性脑损伤的受损部位主要分布在灰白质交界附近和大脑深部中线结构,由于大脑损伤的弥漫性,常规影像学检查无阳性发现。本文对脑震荡后综合征的流行病学研究、诊断现状及争议、常规诊断技术、新型核磁共振成像技术在脑震荡后综合征和轻度创伤性脑损伤诊断中的应用及展望进行了综述。现代大脑成像技术可无创定量评定大脑损伤,并可能成为脑震荡后综合征诊断及法医学鉴定更敏感和更有前途的评定工具。     

应用iTRAQ-LC-MS/MS方法筛选大鼠DAI后脑组织差异表达蛋白质

目的应用相对和绝对定量同位素标记结合液相色谱-串联质谱法(isobaric tag for relative and absolute quantification-liquid chromatograph-mass spectrometer/mass spectrometer,iTRAQ-LC-MS/MS)筛选SD大鼠弥漫性轴索损伤(diffuse axonal injury,DAI)后脑组织差异表达的蛋白质,寻找诊断DAI的潜在生物标志物。方法参照Marmarou法建立DAI动物模型,分为空白对照组(n=4)、假打击组(n=4)和打击致死组(n=4),采用iTRAQ-LC-MS/MS技术对大鼠脑组织蛋白质进行检测,并对检测结果进行生物信息学分析及验证,筛选出差异表达的蛋白质。结果定量检测出2016种蛋白质,生物信息学分析显示其在细胞中分布广泛、功能多样,并且参与了多种生物过程,16种蛋白质在打击致死组具有差异表达,包括1种表达上调蛋白质和15种下调蛋白质;Western印迹法验证了iTRAQ-LC-MS/MS的结果。结论 iTRAQ-LC-MS/MS的检测技术筛选出大鼠DAI后脑组织中多个差异表达的蛋白质,不仅为深入探讨DAI后轴索损伤的发病机制提供了研究方向,也为DAI的诊断提供了潜在生物标志物。     

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。     

IL-1β和TNF-α在大鼠弥漫性轴索损伤中的作用

目的观察大鼠弥漫性轴索损伤后IL-1β和TNF-α蛋白表达的时序性变化,探讨其在大鼠弥漫性轴索损伤（diffuse axonal injury,DAI）中的作用。方法 55只健康雄性SD大鼠,随机分为正常对照组、手术对照组和DAI组,采用HE、Gless氏嗜银染色和免疫组织化学（SP法）观察不同时间（30min～7d）脑干组织病理学改变及IL-1β和TNF-α蛋白的表达情况。结果 HE染色显示DIA大鼠脑干组织结构疏松、水肿,Gless氏嗜银染色可见轴索肿胀、扭曲、收缩球形成等改变,证明弥漫性轴索损伤模型成功;IL-1β和TNF-α在正常对照组与假手术组大鼠脑干神经元内有低表达,而在DAI后30min～6h大鼠脑干神经元和小胶质细胞内表达迅速增加,于6h达高峰。结论大鼠弥漫性轴索损伤后IL-1β和TNF-α蛋白在脑干内表达的增加,与轴索继发性损伤有关。     

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。     

脑外伤所致精神障碍司法鉴定400例分析

目的探讨精神疾病司法鉴定中颅脑损伤所致精神障碍的临床特征及相关因素。方法收集脑外伤后司法鉴定案例资料,按照神经外科GCS评分把脑损伤所致精神障碍鉴定案例分为重型(A组)、中型(B组)及轻型(C组)颅脑损伤;对案例的临床症状进行分析,根据中国精神障碍分类与诊断标准(第三版)(CCMD-3)进行精神障碍诊断,并探索临床症状与脑外伤程度之间的关系。结果轻、中度颅脑损伤所致精神障碍以器质性神经症样综合征最多见。重度颅脑损伤所致精神障碍中以智能损害综合征为多。三组间有显著性差异(P≤0.01)。结论在精神疾病司法鉴定中,不同严重程度的颅脑损伤所致的精神障碍有不同的临床特征。     

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.     

Delayed sudden death in an infant following an accidental fall: a case report with review of the literature

Several controversies exist regarding ultimately lethal head injuries in small children. Death from short falls, timing of head injury, lucid intervals, presence of diffuse axonal injury (DAI), and subdural hematoma (SDH) as marker of DAI are the most recent controversial topics of debate in this evolving field of study. In this area of debate, we present a case of delayed death from a witnessed fall backwards off a bed in a 9-month-old black male child who struck his head on a concrete floor and was independently witnessed as "healthy" postfall for 72 hours until he was discovered dead in bed. Grandmother, babysitter, and mother all independently corroborated under police investigation that the child "acted and behaved normally" after the fall until death. Autopsy showed a linear nondisplaced parietal skull fracture, diastasis of adjacent occipital suture, subgaleal hemorrhage with evidence of aging, small posterior clotting SDH, marked cerebral edema, and a small tear of the midsuperior body of the corpus callosum consistent with focal axonal injury (FAI). No DAI was seen, and there were no retinal hemorrhages. All other causes of death were excluded upon thorough police and medical examiner investigation. Although this seems to be a rare phenomenon, a delayed, seemingly symptom-free interval can occur between a clinically apparent mild head injury and accidental death in a young child.     

Neuroimaging in Mild Traumatic Brain Injury

Neuroimaging in mild traumatic brain injury (mTBI) is reviewed. While computed tomography remains the acute standard for neuroimaging of mTBI, it is only sensitive to gross abnormalities and is typically performed as a measure to rule out more serious and life-threatening injury. Magnetic resonance imaging (MRI), especially at field strength of 3.0 T, is the follow-up neuroimaging standard for assessing potential underlying structural injury to the brain. Several MRI sequences are particularly sensitive to subtle hemorrhagic lesions and signal abnormalities in white matter, sensitive enough to detect pathology when present in mTBI. Clinical correlation of neuropsychological outcome with neuroimaging findings is discussed along with the future potential for functional neuroimaging in evaluating the mTBI patient.     

Forensic medical differential diagnosis of craniocerebral trauma in children

It is emphasized that history, complaints, a comprehensive neurological examination, craniography are not often sufficient for differentiation between brain concussion and mild brain contusion in children because of specific characteristics of craniocerebral trauma (CCT) in such patients. To make an adequate forensic medical diagnosis of CCT in children, it is necessary to take into consideration anatomophysiological peculiarities of a child, biomechanical conditions of the brain injury, to apply modern methods of neurovisualization (ultrasonography, computed and MR imaging), to follow up brain function with quantitative electroencephalography. Improvement of differential forensic-medical assessment of CCT severity in childhood should be made according to the principles of evidence-based medicine.     

大鼠弥漫性脑损伤后c-jun和GFAP表达的研究

目的探讨即早基因c-jun和胶质纤维酸性蛋白（GFAP）在弥漫性脑损伤（DBI）中的表达规律。方法采用Marmarou方法制作大鼠DBI模型，将65只SD大鼠随机分为DBI组及对照组。用免疫组织化学技术（SABC）及图像分析方法观察大鼠DBI后15min、30min、1h、3h、6h、12h、24h、2d、3d、4d、6d脑组织内c-jun和GFAP表达规律，所得数据经SPSS10．0统计软件处理。结果对照组大鼠脑组织内未见c-jun阳性表达，可见少量GFAP表达。DBI15min即可在脑组织内观察到c-jun表达，而GFAP蛋白的表达则在DBI后6h增加。随着损伤经过时问的延长，c-jun与GFAP阳性细胞数及阳性表达范围逐渐扩大，c-jun表达在DBI后6h达高峰（P〈0．01），其后逐渐下降，伤后2d减退；GFAP阳性产物则在伤后4d左右达高峰（P〈0．01），其后呈下降的趋势。结论应用免疫组织化学方法检测c-jun与GFAP可作为诊断DBI的参考指标，二者在不同时段内表达所呈现出的时序性规律对损伤时间的推测也具有实际应用价值。