Correlation of survival time with size of axonal swellings in diffuse axonal injury

Widespread damage to axons in the white matter of the brain is a well-recognised consequence of non-missile head injury. This diffuse axonal injury is characterised by a gradual swelling of the axon associated with an accumulation of cellular organelles and proteins. We have investigated the relationship between the size of the swellings of the damaged axon with survival time in post-mortem brain tissue. Sixty-six cases of head injury with known length of post-traumatic survival were selected for study, and immunohistochemistry for β-amyloid precursor protein (βAPP) was carried out. The minimum diameter of the βAPP-immunolabelled damaged axons was measured in micrometers using the IBAS image analysis system. There was a strong, positive and significant relationship between the mean size of axonal swelling and survival time which plateaued at around 85 h post injury. With longer survival times the situation becomes more complex. βAPP immunolabelling of damaged axons can contribute evidence about trauma and post-injury survival time in the forensic setting but should always be assessed with other evidence. Received: 13 June 1996 / Revised: 18 July 1997, 20 October 1997, 4 November 1998 / Accepted: 5 January 1999     

The usefulness of diffusion tensor imaging in detection of diffuse axonal injury in a patient with head trauma

Diffuse axonal injury is the predominant mechanism of injuries in patients with traumatic brain injury. Neither conventional brain computed tomography nor magnetic resonance imaging has shown sufficient sensitivity in the diagnosis of diffuse axonal injury. In the current study, we attempted to demonstrate the usefulness of diffusion tensor imaging in the detection of lesion sites of diffuse axonal injury in a patient with head trauma who had been misdiagnosed as having a stroke. A 44-year-old man fell from a height of about 2 m. Brain magnetic resonance imaging (32 months after onset) showed leukomalactic lesions in the isthmus of the corpus callosum and the left temporal lobe. He presented with mild quadriparesis, intentional tremor of both hands, and trunkal ataxia. From diffusion tensor imaging results of 33 months after traumatic brain injury onset, we found diffuse axonal injury in the right corticospinal tract (centrum semiovale, pons), both fornices (columns and crus), and both inferior cerebellar peduncles (cerebellar portions). We think that diffusion tensor imaging could be a useful tool in the detection of lesion sites of diffuse axonal injury in patients with head trauma.     

Is β-APP a marker of axonal damage in short-surviving head injury?

β-Amyloid precursor protein (β-APP), a normal constituent of neurons which is conveyed by fast axonal transport, has been found to be a useful marker for axonal damage in cases of fatal head injury. Immunocytochemistry for β-APP is a more sensitive technique for identifying axonal injury than conventional silver impregnation. This study was designed to determine how quickly evidenc of axonal damage and bulb formation appears. Using this method a variety of brain areas were studied from 55 patients who died within 24 h of a head injury. Immunocytochemical evidence of axonal injury was first detected after 2 h survival, axonal bulbs were first identified after 3 h survival, and the amount of axonal damage and axonal bulb formation increased the longer the survival time. Received: 8 February 1996 / Revised, accepted: 13 May 1996     

Neuropathological investigation of cerebral white matter lesions caused by closed head injury

In order to ascertain whether there is widespread axonal disruption of cerebral white matter in the so‐called ‘diffuse axonal injury’ (DAI), a type of closed head injury, proposed by Adams et al. the author investigated his own cases clinicopathologically. Twenty‐six male autopsied cases of head injury, aged between 19 and 84, 15 of which had sustained road traffic accidents, were examined; the others were due to falling from heights and so on. The study group all belonged to non‐missile head injuries and included 12 cases of diffuse brain injury, as well as 14 cases of focal brain injury, according to the classification of Gennarelli et al. The survival time ranged from 2 h to 21 years. Formalin‐fixed brains were cut coronally so as to make paraffin‐embedded hemispheric sections. Then these sections were stained conventionally (HE, Bodian, Kluver‐Barrera and Holzer) and immunohistochemically (GFAP) to assess axonal decrease, myelin pallor and gliosis by the use of light microscopy. In the 13 chronic cases that died more than 1 month after the accidents, the intensities of gliosis, myelin pallor and axonal decrease tended to correlate with each other. In the 13 acute cases who died less than 1 month after their accident, the degree of axonal decrease in white matter seemed to correlate with the severity of myelin pallor. Regardless of types of trauma, however, axonal retraction balls, the so‐called hallmark of DAI, were found only with myelin pallor suggesting the presence of brain swelling after the injury. Therefore these findings indicate that it may be difficult to accept the notion of DAI, that is, the presence of axonal retraction balls without brain swelling. In addition, diffuse vascular injury (2 cases) as well as rarefaction of subcortical white matter (6 cases) were presented and their pathogenesis individually discussed based on a literature review.     

Ultrastructural evidence of axonal shearing as a result of lateral acceleration of the head in non-human primates

Summary The concept of shearing of axons at the time of non-impact injury to the head was first suggested in the middle of this century. However, no experimental model of diffuse axonal injury (DAI) has provided morphological confirmation of this concept. Evidence from experiments on invertebrate axons suggests that membrane resealing after axonal transection occurs between 5 and 30 min after injury. Thus, ultrastructural evidence in support of axonal shearing will probably only be obtained by examination of very short-term survival animal models. We have examined serial thin sections from the corpus callosum of non-human primates exposed to lateral acceleration of the head under conditions which induce DAI. Tearing or shearing of axons was obtained 20 and 35 min after injury, but not at 60 min. Axonal fragmentation occurred more frequently at the node/paranode but also in the internodal regions of axons. Fragmentation occurred most frequently in small axons. Axonal shearing was associated with dissolution of the cytoskeleton and the occurrence of individual, morphologically abnormal membranous organelles. There was no aggregation of membranous organelles at 20 and 35 min but small groups did occur in some axons at 60 minutes. We suggest that two different mechanisms of injury may be occurring in non-impact injury to the head. The first is shearing of axons and sealing of fragmented axonal membranes within 60 min. A second mechanism occurs in other fibres where pertubation of the axon results in axonal swelling and disconnection at a minimum of 2 h after injury.Supported by NIH grant number NS-08803-21, the Wellcome Trust, the Royal Society, London and the Institute of Neurological Sciences, University of Glasgow. Part of this work was presented at the Ist International Neurotrauma Symposium, Fukishima, Japan and the IVth European Meeting of Neuropathology, Berlin Dedication: The authors would like this work to be a tribute to Professor J. H. Adams upon his retiral. His research into diffuse axonal injury inspired the authors to undertake this study.     

弥漫性轴突损伤早期超微结构改变

目的通过观察弥漫性轴突损伤(DAI)患者伤后早期轴突的超微结构变化以探索DAI的发生机理.方法对12例DAI患者的14份活体脑组织标本进行透射电镜检查.结果 DAI患者在伤后早期可发生多方面的轴突改变,包括(1)轴突的细胞骨架破坏;(2)轴膜改变;(3)膜性细胞器的变化;(4)髓鞘的改变;(5)轴突出现肿胀和离断,轴突近侧断端呈现球状.结论在DAI的发生中,可能有多种机理参与.推测,在受到足够强的外力作用时,一些管径较细的轴突可能会立即断裂;其它受损轴突则会出现进行性的延迟性轴突断裂.在此演化过程中,细胞骨架破坏和轴膜受损继而通透性改变可能是造成轴突局灶性轴浆转运障碍最终离断的最重要的因素.     

Diffuse axonal injury without direct head trauma and with delayed onset of coma

A 16-year-old female was involved in a jet ski (water craft) accident resulting in bilateral lower extremity fractures but no loss of consciousness or any other evidence of head trauma. Thirty hours later she became comatose. Magnetic resonance imaging was consistent with diffuse axonal injury. She recovered after several weeks without any clinical sequelae. This patient demonstrates an unusual example of diffuse axonal injury without direct head trauma and with delayed onset of symptoms. The authors recommend that patients involved in high-velocity accidents, even without immediate evidence of head injury, be observed for signs of diffuse axonal injury.     

弥漫性轴突损伤胆碱能纤维改变的实验研究

目的通过大鼠弥漫性脑损伤模型观察海马及乳头体内的轴突损伤,了解轴突损伤后上述结构中胆碱酯酶纤维的变化,探讨轴突损伤与伤后记忆功能障碍的相关性.方法用Marmarou介绍的落体打击装置致伤动物,对海马和乳头体区脑组织进行胆碱酯酶(AChE)纤维染色.结果该模型较好地模拟了轴突损伤的表现,简便实用.在这个模型中轴突损伤的最常见部位为桥脑基底部和小脑上脚,其次为大脑半球白质、海马和乳头体.海马结构内含有大量胆碱酯酶阳性染色纤维.与对照组相比中,损伤10天海马CA1区,CA3区,齿状回分子层和乳头体内纤维密度明显低于对照组大鼠(P＜0.01).结论大鼠损伤后海马区和乳头体内胆碱酯酶阳性纤维明显减少,这可能是弥漫性轴突损伤病人记忆功能损害的原因.     

Time to Recover Consciousness in Patients with Diffuse Axonal Injury : Assessment with Reference to Magnetic Resonance Grading

Objective

This study was conducted to investigate the correlation between the degrees of injury on brain magnetic resonance imaging (MRI) and the time interval to recovery of consciousness in patients with diffuse axonal injury.

Methods

From January 2004 to December 2008, 25 patients with diffuse axonal injury were treated at our hospital. We retrospectively investigated the patients'' medical records and radiological findings. We divided the patients into three groups according to the grade of MRI finding : grade I, small scattered lesions on the white matter of the cerebral hemisphere; grade II, focal lesions on the corpus callosum; and grade III, additional focal lesions on the brain stem.

Result

Seven patients belonged to the grade I group; 10 to the grade II group; and 8 to the grade III group. The mean Glasgow Coma Scale (GCS) score of all patients at the time of admission was 7.28. Recovery of consciousness was observed in 23 of the 25 patients; the remaining two patients never regained consciousness. The time interval to recovery of consciousness (awake status) ranged from 1 day to 125 days (mean 22.1 days) : grade I group patients, within approximately 1 week (mean 3.7 days); grade II group patients, within approximately 2 weeks (mean 12.5 days); and grade III group patients, within approximately 2 months (mean 59.5 days).

Conclusion

Our study results suggest a correlation between the mean time interval to recovery of consciousness in patients with diffuse axonal injuries and the degrees of brain injuries seen on MRI. Patients with grade I and II diffuse axonal injuries recovered consciousness within 2 weeks, while patients with grade III injuries required approximately 2 months.     

Temporal characterisation of pro- and anti-apoptotic mechanisms following diffuse traumatic brain injury in rats.

Few studies have characterised apoptosis in a brain injury model that causes a significant degree of diffuse axonal injury. Such characterisation is essential from a clinical viewpoint since diffuse axonal injury is a major component of human head injury. The present study therefore, examines the expression of active and proactive caspase-3, and the bax, bcl-2 and bcl-x members of the bcl-2 family, to characterise the temporal profile of apoptosis in a model of traumatic brain injury in rats that produces significant diffuse axonal injury. Pentobarbital anaesthetised male Sprague-Dawley rats were injured using the 2m impact-acceleration model of diffuse traumatic brain injury. After injury, diffuse trauma resulted in an increased bax expression followed by induction of caspase-3. The increase in caspase-3 was simultaneous with an increase in anti-apoptotic bcl-2 expression. Bcl-x levels were increased after induction of caspase-3 and the increased levels of bcl-x were sustained to the end of the 5-day observation period. Increased active caspase-3 expression was associated with the appearance of TUNEL positive cells. These cells were detected in different brain regions at different times, with some regions showing no apoptotic cells until 3 days after injury. No TUNEL positive cells were detected at 7 and 14 days after injury. DNA electrophoresis confirmed that DNA fragmentation was maximal at 3 days after injury. Increased active caspase-3 levels were also significantly correlated with increased bcl-2 levels (r=0.80; P<0.001) suggesting that the apoptotic cascade after diffuse traumatic brain injury is a carefully controlled cellular homeostatic response. Pharmacological manipulation of this balance may offer a therapeutic approach for preventing cell death and improving outcome after diffuse traumatic brain injury.     

外伤性癫痫危险因素的临床分析

目的为外伤性癫痫的早期预防和治疗提供依据。方法回顾性分析356例颅脑损伤病人的临床资料,重点分析外伤性癫痫与颅脑损伤类型,患者年龄、性别以及颅脑损伤严重程度和损伤部位的关系。结果 16岁以下儿童和成人外伤性癫痫发生率分别为16.67%(9/54)和6.62%(20/302),两者相较相差显著(P0.01)。开放性颅脑损伤与闭合性颅脑损伤患者癫痫的发生率分别为29.73%(11/37)和5.64%(18/319),两者相较相差显著(P0.01);脑挫裂伤合并脑内血肿、弥漫性轴索损伤及凹陷性颅骨骨折患者的癫痫发生率分别为16.94%(21/124)、20.51%(8/39)和10.53%(4/38),明显高于CT检查未见颅内明显异常的98例颅脑损伤患者的癫痫发生率1.02%(P0.05)。结论开放性颅脑损伤、脑挫裂伤并脑内血肿、弥漫性轴索损伤、凹陷性颅骨骨折及年龄16岁以下可能是外伤性癫痫的危险因素。     

Diffuse axonal injury due to traumatic brain injury alters inhibition of imitative response tendencies

It is well known that traumatic brain injury particularly affects the frontal lobes. Consequently, patients often suffer from executive dysfunction and behavioral disturbances. Accordingly, our study aimed at investigating patients after traumatic brain injury with two tasks involving different functional processes and structural networks supported by the frontal lobes. Two paradigms were applied: the Stroop color-word task and a task in which subjects had to inhibit imitative response tendencies. We selected a patient group solely with diffuse axonal injury, as this type of injury is homogenous and is correlated with cognitive dysfunction more than focal contusions. To evaluate long-term effects most relevant for rehabilitation, we selected a patient group whose brain injuries dated back several years. Our results show that patients with diffuse axonal injury inhibited imitative responses more successfully than control subjects, whereas executive processes examined with the Stroop task were unaltered. Interestingly, impairments were tightly correlated both with the length of the post-traumatic amnesia predicting outcome in traumatic brain injury and with behavioral disturbances. Impairments in the imitation-inhibition task may indicate alterations in an anterior frontomedian neural network even years after traumatic brain injury.     

The cerebrovascular response to experimental lateral head acceleration

Summary A number of microvascular changes, such as the development of astrocyte lucency, increased endothelial pit/vesicle activity, development of crater like lesions, and endothelial microvilli have been reported after injury to the brain. Lateral head acceleration in the non-human primate, however, still provides the best experimental model for human diffuse axonal injury. No attempt has yet been made to document the spatial extent or time course of the microvascular response to acceleration injury to the head. We have examined the brains of baboons 1, 4, 6, and 12 h and 7 days after acceleration injury to the head to analyse the microvascular response. In the experimental animals there was a short-term rise in intracranial pressure followed by a long-term resolution, and a reduction in both mean arterial blood pressure and cerebral perfusion pressure which, however, never dropped below 75% of baseline for more than 5 min after injury in any animal. We found evidence for extravasation of blood in a small number of blood vessels in all parts of the brain. Interendothelial tight junctions are not disrupted. Pit/vesicle activity rises in the 1st h in the occipital cortex, but not until 4 h in the frontal cortex, and remains elevated for at least 7 days. There is little change in the thalamus. Development of microvilli is most rapid in the frontal cortex with peak values at 1 h, but slower in the thalamus and occipital cortex where peak values are only obtained at 6 h. Highest numbers of microvilli occur in parasagittal regions of the brain. Lucency of the foot processes of perivascular astrocytes develops throughout the diencephalon and telencephalon within 1 h of injury and is most marked in the frontal cortex 6 h after injury. Glycogen deposits occur in astrocytes throughout the brain and are maximal at 12 h. There is, therfore, a differential rate of response of endothelial and astrocyte changes in different parts of the brain after lateral had acceleration. We compare our findings with others in the literature dealing with brain injury. We postulate that lateral acceleration of the head results in widespread, nondisruptive mechanical stress and strain to the brain microvasculature, and suggest that a complex of pathophysiological changes acts throughout the whole brain.     

弥漫性轴突损伤形态学改变的实验研究

目的　观察弥漫性轴突损伤的常见部位， 病理改变过程， 以及其发生原因和机制。探讨其与临床的相关性。方法　用 Ｍａｒｍａｒｏｕ 的落体打击装置致伤动物， 大鼠脑组织标本在光镜和电镜下观察。结果　轴突回缩球密度在桥脑基底部和小脑上脚最高。伤后轴突内的微丝、微管结构紊乱， 轴突肿胀。伤后３ 天， 多数肿胀的轴突断裂， 形成轴突回缩球。１ 小时组轴突内钙颗粒数量是对照组的１７ 倍， 提示钙的内流。结论　本实验中弥漫性轴突损伤的最常见部位是桥脑基底部和小脑上脚。轴突损伤的过程为： 轴突内结构的紊乱， 轴突肿胀及断裂。轴突损伤的主要发生原因和机制可能是细胞外钙的内流。在伤后１２ 小时以内， 损伤轴突尚未断裂， 可能仍存在可逆性， 这可能是临床上有效治疗的最佳时机。     

Traumatic axonal damage in the brain can be detected using beta-APP immunohistochemistry within 35 min after head injury to human adults

Immunohistochemistry staining for beta-amyloid precursor protein (beta-APP) is a sensitive method to detect early axonal damage in traumatic brain injury, which was previously estimated to be of minimum 60-90 min after head injury. We present seven cases of well-documented posttraumatic survival of 35-60 min where beta-APP detects early axonal damage. Cases were selected from routine work where documentation about survival is judged to be accurate. These are divided into three groups: group 1: severe head injury (n = 7) with documented survival between 35 and 60 min. Group 2: severe head injury (n = 4) with documented survival of less than 30 min. Group 3: cases (n = 4) where death was not due to head injury but survival is documented between 45 and 109 min. The brains were fixed in formalin for 4 weeks and six regions (frontal lobe with anterior corpus callosum, parietal lobe with deep white matter, basal ganglia with posterior limb of internal capsule, cerebellum with white matter and middle cerebellar peduncle and pons with basis pontis and superior cerebellar peduncle) were sampled. All blocks were stained for haematoxylin and eosin and beta-APP and selected ones for CD68, using antigen retrieval method. In group 1 sections revealed beta-APP immunoreactivity in forms of small globules and granules and occasionally as thin and short filaments. These were detected in the pons, corpus callosum, internal capsule and cerebral white matter, with some variation in localization and intensity. In groups 2 and 3 all the sections were negative for beta-APP staining. None of the cases showed evidence of severe brain swelling, increased intracranial pressure, ischaemia or infection. Using the antigen retrieval method, beta-APP immunohistochemistry can detect axonal damage within 35 min after severe head injury. These results may have an implication in the consideration of minimal survival time after traumatic head injury in medico-legal practice.     

大鼠脑弥漫性轴索损伤不同轴索损伤类型的形态学观察

目的 观察脑弥漫性轴索损伤(DAI)急性期轴索损伤的类型和形态学改变,并探讨其相关机制. 方法 SD大鼠24只随机数字表法分为实验组(n=16)和对照组(n=8).实验组又按损伤后不同时间(6、24 h)分为2组,每组8只,运用自制联合损伤装置致实验组大鼠DAI模型,于损伤后急性期不同时间点行HE染色,免疫荧光染色检测脑组织轴浆运输障碍标志物β-淀粉样前体蛋白(β-APP)和神经微丝结构破坏标志物(NF-68)的表达,并在电镜下观察损伤轴索的超微结构变化.结果与对照组[(6.5±1.0)min]相比,实验组[(11.9±2.7)min]大鼠伤后出现昏迷时间延长,差异有统计学意义(P<0.05).β-APP免疫组化染色显示轴索肿胀扭曲、膨胀断裂及轴索球形成;NF-68免疫荧光染色显示轴索缩窄变细呈分割状.电镜下肿胀类型的轴索骨架溶解絮乱、细胞器聚集,而另一类损伤轴索骨架排列仍较清晰,但轴索内有较多空泡形成及神经微丝汇聚. 结论 DAI急性期损伤轴索存在着轴浆运输障碍和神经微丝结构破坏等病理生理过程,相应损伤轴索的形态不同.多种检测方法的使用能更全面地评估轴索损伤的严重程度及轴索对损伤的复杂反应.     

8-hydroxy-2-(di-n-propylamino)tetralin intervenes with neural cell apoptosis following diffuse axonal injury

Previous studies have reported a neuroprotective effect of 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT) against traumatic brain injury. In accordance with the Marmarou method, rat models of diffuse axonal injury were established. 8-OH-DPAT was intraperitoneally injected into model rats 8-OH-DPAT treated rats maintained at constant temperature served as normal temperature controls TUNEL results revealed that neural cell swelling, brain tissue necrosis and cell apoptosis occurred around the injured tissue. Moreover, the number of Bax-, Bcl-2- and caspase-3-positive cells increased at 6 hours after diffuse axonal injury, and peaked at 24 hours. However, brain injury was attenuated, the number of apoptotic cells reduced, Bax and caspase-3 expression decreased, and Bcl-2 expression increased at 6, 12, 24, 72 and 168 hours after diffuse axonal injury in normal temperature control and in 8-OH-DPAT-intervention rats. The difference was most significant at 24 hours. All indices in 8-OH-DPAT-intervention rats were better than those in the constant temperature group. These results suggest that 8-OH-DPAT inhibits Bax and caspase-3 expression, increases Bcl-2 expression, and reduces neural cell apoptosis, resulting in neuroprotection against diffuse axonal injury. This effect is associated with a decrease in brain temperature.     

CPG15在大鼠脑弥漫性轴索损伤中的表达及意义

目的探讨大鼠脑弥漫性轴索损伤（diffuse axonal injury，DAI）中不同时间点脑额叶皮层组织中候选可塑性相关基因15（candidate plasticity related gene 15，CPG15）的表达及意义。方法雄性SD大鼠54只，随机分为正常对照组18只和DAI组36只；采用头颅侧向旋转致伤方法制作DAI模型，并按伤后大鼠处死时间分为第1d、4d、7d、10d、14d、21d组，每组6只。用免疫组化方法检测大鼠脑额叶皮层CPG15的表达，并分析其表达变化特点。CPG阳性结果判断标准以细胞浆内出现棕黄染色颗粒为阳性，反之为阴性。结果正常对照大鼠额叶皮质中无CPG15的表达；DAI后，CPG15表达于神经元细胞的胞浆内。DAI后1d，大鼠大脑皮层仅见少量CPG15表达；DAI后4d、7d、10dCPG15表达逐渐增强，至14d达到峰值；损伤后第21d仍维持在较高水平。DAI后不同时间，神经元数量逐渐增多。结论DAI后，随着脑内CPG15表达增强，神经元数量也逐渐增多，提示二者存在正相关；本文对有关机理进行了讨论。     

脑中线区外伤性出血的治疗与预后

目的 探讨创伤性脑中线区出血的诊断、治疗和预后。方法 选择经CT证实脑中线区域有出血灶的重型颅脑损伤住院患12例。测算血肿体积和血肿距中线距离。急性期后隔日腰椎穿刺测CSF压力，计算平均CSF压力。采用Glasgow预后评定方法评估患预后。结果 预后不良4例(死亡1例、重残1例、中残2例)，恢复良好8例。平均腰椎穿刺CSF压力以及血肿体积在恢复良好和预后不良患组间无明显统计学差异，但预后不良组的血肿距中线距离则明显短于恢复良好组。结论 创伤性脑中线区域出血符合脑弥漫性轴索损伤(diffuse axonal injury，DAI)的病理改变，血肿距中线距离与患预后密切相关。