Diffuse axonal injury in infants with nonaccidental craniocerebral trauma: enhanced detection by beta-amyloid precursor protein immunohistochemical staining

OBJECTIVE: Accurate identification of diffuse axonal injury is important in the forensic investigation of infants who have died from traumatic brain injury. beta-Amyloid precursor protein (beta-APP) immunohistochemical staining is highly sensitive in identifying diffuse axonal injury. However, the effectiveness of this method in brain-injured infants has not been well established. The present study was undertaken to assess the utility of beta-APP immunohistochemistry in detecting diffuse axonal injury in infants with either shaken baby syndrome or blunt head trauma. MATERIALS AND METHODS: Archival formalin-fixed, paraffin-embedded blocks from infants (<1 year old) with shaken baby syndrome (7 cases) and blunt head trauma (3) and blocks from 7 control cases that included nontraumatic cerebral edema (1), acute hypoxic-ischemic encephalopathy (1), and normal brain (5) were immunostained for beta-APP. A semiquantitative assessment of the severity of axonal staining was made. Corresponding hematoxylin-eosin-stained sections were examined for the presence of axonal swellings. RESULTS: Immunostaining for beta-APP identified diffuse axonal injury in 5 of 7 infants with shaken baby syndrome and 2 of 3 infants with blunt head trauma. Immunoreactive axons were easily identified and were present in the majority of the sections examined. By contrast, hematoxylineosin staining revealed axonal swellings in only 3 of 7 infants with shaken baby syndrome and 1 of 3 infants with blunt head trauma. Most of these sections had few if any visible axonal swellings, which were often overlooked on initial review of the slides. No beta-APP immunoreactivity was observed in any of the 7 control cases. CONCLUSIONS: Immunostaining for beta-APP can easily and reliably identify diffuse axonal injury in infants younger than 1 year and is considerably more sensitive than routine hematoxylin-eosin staining. We recommend its use in the forensic evaluation of infants with fatal craniocerebral trauma.     

The possible role of hypoxia in the formation of axonal bulbs.

AIMS: To assess the possible role of hypoxia in the formation of axonal bulbs. METHODS: Study material comprised sections from 28 brains showing evidence of cerebral hypoxia with no history of head injury, four with a history of head trauma but no evidence of hypoxic change, eight with a history of head trauma and hypoxic change, and four from control brains originally described as "diffuse axonal injury." These were subjected to microwave antigen retrieval and immunohistochemistry using monoclonal antibodies to beta amyloid precursor protein (beta APP), glial fibrillary acid protein (GFAP), and CD68-PGM1. RESULTS: Positive staining for beta APP was seen in all four controls, all four cases of head injury only, seven of eight cases of head injury and hypoxic changes, and 12 of 28 cases of hypoxia without history of head injury; 22 of 25 cases who had been ventilated showed positive staining. The majority of cases showed evidence of cerebral swelling. CONCLUSIONS: Axonal bulbs staining positively for beta APP may occur in the presence of hypoxia and in the absence of head injury. The role of hypoxia, raised intracranial pressure, oedema, shift effects, and ventilatory support in the formation of axonal bulbs is discussed. The presence of axonal bulbs cannot necessarily be attributed to shearing forces alone.     

Anatomy of the shaken baby syndrome

Shaken baby syndrome refers to the constellation of nonaccidental injuries occurring in infants and young children as a consequence of violent shaking. The typical victim of shaken baby syndrome is a male infant younger than six months of age who is alone with the perpetrator at the time of injury. Occurrence of the syndrome is unrelated to race, gender, socioeconomic status, or education. The characteristic injuries observed in shaken baby syndrome include subdural hemorrhages, retinal hemorrhages, and fractures of the ribs or long bones. Although each of these injuries may result from violent shaking of the victim, the most severe brain injuries result from the addition of a forceful impact of the infant's or child's head against a firm surface. The unique anatomic features of the infant's head and skeletal system, which account for the type and pattern of injuries observed in shaken baby syndrome, are emphasized in this article. Anat. Rec. (New Anat.) 253:13–18, 1998. © 1998 Wiley-Liss, Inc.     

Experimental injury of the optic nerve with optic disc swelling.

An ultrastructural study utilizing horseradish peroxidase was performed to determine the mechanism and consequences of leakage of vascular protein following injury of the optic nerve. Unilateral optic nerve injuries were produced in four rhesus monkeys by making a cautery lesion on the retrobulbar portion of the optic nerve. Optic disc changes were followed with stereo fundus photography and fluorescein angiography. Three to 14 days after injury horseradish peroxidase was given intravenously and the tissue was prepared for electron microscopy, including serial sections of selected tissue blocks. Fundus photography and fluorescein angiography showed edema of the optic disc in two animals. There was leakage of horseradish peroxidase into the optic nerve head from the optic nerve lesion and the peripapillary choriocapillaris. Although the pathway of horseradish peroxidase leakage in the injured optic nerve was not entirely clear, serial sections indicated intraendothelial channels as one possible route. Alterations of the optic nerve head were confined to the axon segments anterior to the injury, and included aggregation of mitochondria, disruption of neurotubules, and swelling. These findings suggest that optic nerve injury produces damming of axoplasmic flow and that swelling of the optic nerve head is the result of axon enlargement.     

Primary brain trauma in non-accidental injury

The brains from 12 babies up to 21/2 years of age, who died after repeated non-accidental injury to the head, were subjected to detailed neuropathological examination. The nine brains from infants under 5 months showed contusional tears--slit like lesions in the white matter surrounded by astrocytes and associated with evidence of old and recent haemorrhage. The three brains from infants over 5 months showed white matter lesions similar to those seen in adults after closed head injury, including damage in the dorsolateral quadrant of the brain stem without axonal hemispheric damage, which may have been a result of whiplash injury after shaking. In addition, all the brains examined showed diffuse gliosis. This paper draws attention to contusional tears and other white matter lesions, which the authors believe are manifestations of mechanical damage produced by trauma. The long term neurological and intellectual defects observed in patients suffering non-accidental injury early in life are increasingly being recognised, although it is difficult to identify the extent to which these are due to social or neuropathological factors. We suggest that the white matter damage we describe has an important role.     

视神经磁共振成像方法研究

目的　探讨视神经磁共振 (MRI)成像最佳方法及正常视神经MRI征象 .方法　随机选择 4 0例进行头部检查 ,无眼部疾患或视力障碍患者作为正常视神经研究对象 .使用PhilipsACS -NT15 1.5T超导型磁共振成像仪及正交头线圈 .成像序列包括自旋回波T1加权成像 (SET1WI)及超快速自旋回波加或不加脂肪频谱饱和技术成像 (TSE±SPIRT2WI) .扫描方位包括与视神经平行轴位、斜矢状位及与视神经长轴垂直冠状位和标准冠状位 .结果　视神经眶内段、管内段及视束粗细均匀 .SET1WI显示视神经较周围的蛛网膜下腔信号强度稍高 ,T2WI显示视神经呈相对低信号 ,与脑髓质信号相等 ,周围包绕高信号脑脊液 .与视神经长轴平行的轴位及斜矢状位T1WI及T2WI均可显示视神经全貌 ,与视神经长轴垂直冠状位TSE +SPIRT2WI技术显示视神经信号均匀 .结论　MRI可以较好地显示视神经解剖 ,与视神经长轴垂直冠状位TSE +SPIRT2WI可以较好地显示信号特征 .     

Axonal injury in cerebral malaria

Impairment of consciousness and other signs of cerebral dysfunction are common complications of severe Plasmodium falciparum malaria. Although the majority of patients make a complete recovery a significant minority, particularly children, have sequelae. The pathological process by which P. falciparum malaria induces severe but usually reversible neurological complications has not been elucidated. Impairment of transport within nerve fibers could induce neurological dysfunction and may have the potential either to resolve or to progress to irreversible damage. Beta-amyloid precursor protein (beta-APP) immunocytochemistry, quantified using digital image analysis, was used to detect defects in axonal transport in brain sections from 54 Vietnamese cases with P. falciparum malaria. The frequency and extent of beta-APP staining were more severe in patients with cerebral malaria than in those with no clinical cerebral involvement. Beta-APP staining was often associated with hemorrhages and areas of demyelination, suggesting that multiple processes may be involved in neuronal injury. The age of focal axonal damage, as determined by the extent of the associated microglial response, varied considerably within tissue sections from individual patients. These findings suggest that axons are vulnerable to a broad range of cerebral insults that occur during P. falciparum malaria infection. Disruption in axonal transport may represent a final common pathway leading to neurological dysfunction in cerebral malaria.     

Intracranial diffuse axonal injury at autopsy

An illustrative case of diffuse axonal injury (DAI) emphasizes features that help to separate focal outer head trauma owing to blows and/or falls from angular acceleration head injuries associated with diffuse inner brain lesions. In the past, explaining significant neurological deficits and death as the result of diffuse closed head trauma received from high-speed automobile accidents has been difficult as well as confusing. The long-term consequences from such diffuse inner cerebral trauma are still poorly defined. Head injuries sustained in automobile accidents have been associated with diffuse brain damage characterized by axonal injury at the moment of impact. The reported victim of a motor vehicle accident showed post-mortem findings for both inner cerebral trauma and focal outer cerebral damage. The diffuse degeneration of cerebral white matter is associated with sagittal and lateral acceleration with centroaxial trauma and has a different pathogenesis from outer focal head trauma, typified by subdural hematomas and coup injuries. Unlike outer cerebral injury, over 50 percent of victims with diffuse axonal injury die within two weeks. These individuals characteristically have no lucid interval and remain unconscious, vegetative, or severely disabled until death. Compared to head trauma victims without diffuse axonal injury, there is a lower incidence of skull fractures, subdural hemorrhages, or other intracranial mass effect as well as outer brain contusions. Primary brainstem injuries often demonstrated at autopsy are seen in the reported victim. Diffuse axonal injury is produced by various angles of acceleration with prolonged acceleration/deceleration usually accompanying traffic accidents. Less severe diffuse axonal injury causes concussion.     

Delayed white matter injury in a murine model of shaken baby syndrome

Shaken baby syndrome, a rotational acceleration injury, is most common between 3 and 6 months of age and causes death in about 10 to 40% of cases and permanent neurological abnormalities in survivors. We developed a mouse model of shaken baby syndrome to investigate the pathophysiological mechanisms underlying the brain damage. Eight-day-old mouse pups were shaken for 15 seconds on a rotating shaker. Animals were sacrificed at different ages after shaking and brains were processed for histology. In 31-day-old pups, mortality was 27%, and 75% of survivors had focal brain lesions consisting of hemorrhagic or cystic lesions of the periventricular white matter, corpus callosum, and brainstem and cerebellar white matter. Hemorrhagic lesions were evident from postnatal day 13, and cysts developed gradually between days 15 and 31. All shaken animals, with or without focal lesions, had thinning of the hemispheric white matter, which was significant on day 31 but not earlier. Fragmented DNA labeling revealed a significant increase in cell death in the periventricular white matter, on days 9 and 13. White matter damage was reduced by pre-treatment with the NMDA receptor antagonist MK-801. This study showed that shaking immature mice produced white matter injury mimicking several aspects of human shaken baby syndrome and provided evidence that excess release of glutamate plays a role in the pathophysiology of the lesions.     

Diffuse axonal injury in early infancy.

Diffuse axonal injury typified by retraction balls and axonal swellings was identified in the brains of a series of infants, 5 months old and younger, who had suffered closed head injuries. These axonal discontinuities were shown by using Nauomenko and Feigin's silver method, which is particularly useful for showing fine axons such as those found in the developing brain. Diffuse axonal injury in early infancy may occur in the same way as that described in adults. The low incidence of intracerebral haematomata suggests that recurrent trauma to the head from a combination of direct contact and shaking results in axonal damage to the poorly myelinated axons and that blood vessels are rarely damaged.     

In-vivo high resolution imaging of optic nerve head drusen using spectral-domain Optical Coherence Tomography

Background  

Optic nerve head drusen (ONHD) are white calcareous deposits, seen either superficially on the optic nerve head or buried within it. Diagnosis of ONHD is made by one or more ways: clinical exam, autofluorescence, ultrasound of the optic nerve, CT scan and/or visual field examination. The present study describes features of ONHD based on another diagnostic modality, the spectral-domain OCT (Spectralis).     

Dimethylsulfoxide enhances CNS neuronal plasma membrane resealing after injury in low temperature or low calcium

The inability to repair the damaged membrane may be one of the key mechanisms underlying the severe neuronal degeneration and overall functional loss seen in in vivo spinal cord injury and traumatic axonal injury in blunt head trauma. Promoting membrane resealing following damage may therefore constitute a potential effective therapeutic intervention in treating head trauma and spinal cord injuries. In our previous studies, we have shown that the axolemma failed to reseal following transection in clinically related situations, such as low extracellular calcium and low temperature. Our current studies indicate that DMSO is capable of rendering significant improvement in guinea pig axonal membrane resealing following transection in both 0.5 mM [Ca(2+)](0) and 25 degrees C situations. This was demonstrated physiologically by monitoring membrane potential recovery and anatomically by conducting HRP-exclusion assays 60 minutes after injury. Further, we have shown that the addition of DMSO in normal Krebs' solution (2 mM [Ca(2+)](0) and 37 degrees C) resulted in a decrease in membrane repair following injury. This indicates that DMSO-mediated membrane repair is sensitive to temperature and calcium. This study suggests the role of DMSO in axonal membrane resealing in clinically relevant conditions and raises the possibility of using DMSO in combination with other more established therapies in spinal cord injury treatment.     

Computation of axonal elongation in head trauma finite element simulation

In the case of head trauma, elongation of axons is thought to result in brain damage and to lead to Diffuse Axonal Injuries (DAI). Mechanical parameters have been previously proposed as DAI metric. Typically, brain injury parameters are expressed in terms of pressure, shearing stresses or invariants of the strain tensor. Addressing axonal deformation within the brain during head impact can improve our understanding of DAI mechanisms. A new technique based on directional measurements of water diffusion in soft tissue using Magnetic Resonance Imaging (MRI), called Diffusion Tensor Imaging (DTI), provides information on axonal orientation within the brain. The present study aims at coupling axonal orientation from a 12-patient-based DTI 3D picture, called "DTI atlas", with the Strasbourg University Finite Element Head Model (SUFEHM). This information is then integrated in head trauma simulation by computing axonal elongation for each finite element of the brain model in a post-processing of classical simulation results. Axonal elongation was selected as computation endpoint for its strong potential as a parameter for DAI prediction and location. After detailing the coupling technique between DTI atlas and the head FE model, two head trauma cases presenting different DAI injury levels are reconstructed and analyzed with the developed methodology as an illustration of axonal elongation computation. Results show that anisotropic brain structures can be realistically implemented into an existing finite element model of the brain. The feasibility of integrating axon fiber direction information within a dedicated post-processor is also established in the context of the computation of axonal elongation. The accuracy obtained when estimating level and location of the computed axonal elongation indicates that coupling classical isotropic finite element simulation with axonal structural anisotropy is an efficient strategy. Using this method, tensile elongation of the axons can be directly invoked as a mechanism for Diffuse Axonal Injury.     

Posttraumatic torsional injury as an indirect cause of fibular intraneural ganglion cysts: case illustrations and potential mechanisms

Trauma has been loosely associated with the development of fibular intraneural ganglion cysts. Sporadic reports of direct trauma to the proximal lateral leg in the region of the superior tibiofibular joint (STFJ) capsule support the development of a capsular rent and the subsequent egress of joint fluid from the articular joint. This report provides evidence to suggest that indirect trauma from torsion can link concomitant ankle injury and fibular nerve palsy (foot drop) and fibular intraneural ganglion cysts. We present two cases to illustrate different potential mechanisms. One patient sustained an ankle ligamentous injury which was translated through the interosseous membrane (IOM) to the proximal leg region, affecting the STFJ and the fibular nerve (ascending pathway). The second patient had blunt injury to the popliteal fossa in combination with a twisting injury to the leg. In this latter case we offer two plausible explanations: (1) combined knee and ankle injury resulting in an ascending pathway mechanism; and (2) a knee injury which disrupted the STFJ, resulting in a translational force down the leg (descending pathway). We believe that fibular intraneural cysts from the STFJ result from direct and indirect trauma. Additional reports of similar cases and sophisticated biomechanical testing will allow us to delineate the exact mechanisms for these injury patterns.     

Beta electroencephalograph changes during passive movements: sensory afferences contribute to beta event-related desynchronization in humans

Limited optic nerve crush is a model of diffuse mechanical axon injury, the most prevalent cause of secondary neurodegeneration after closed head neurotrauma. In this report, a protocol is presented which allows for the rapid screening of differential gene expression in the inner retina, as well as the optic nerve, in response to partial nerve crush. To prove the reliability of the method, prototypically, the differential expression profiles of three candidate genes (kinesin light chain, ferritin, RYB-A) were verified. The method seems to be suitable to address the question of how differential gene expression contributes to degeneration, survival and axonal repair after partial nerve crush.     

Ultrastructural characterization of the optic pathway in a mouse model of neurofibromatosis-1 optic glioma

The purpose of this study was to investigate the progression of changes in retinal ganglion cells and optic nerve glia in neurofibromatosis-1 (NF1) genetically-engineered mice with optic glioma. Optic glioma tumors were generated in Nf1+/− mice lacking Nf1 expression in GFAP+ cells (astrocytes). Standard immunohistochemistry methods were employed to identify astrocytes (GFAP, S100β), proliferating progenitor cells (sox2, nestin), microglia (Iba1), endothelial cells (CD31) and retinal ganglion cell (RGC) axons (Neurofilament 68k) in Nf1+/−, Nf1^GFAPCKO (wild-type mice with Nf1 loss in glial cells), and Nf1+/−^GFAPCKO (Nf1+/− mice with Nf1 loss in glial cells) mice. Ultrastructural changes in the optic chiasm and nerve were assessed by electron microscopy (EM). RGC were counted in whole retina preparations using high-resolution, mosaic confocal microscopy following their delineation by retrograde FluoroGold labeling. We found that only Nf1+/−^GFAPCKO mice exhibited gross pre-chiasmatic optic nerve and chiasm enlargements containing aggregated GFAP+/nestin+ and S100β+/sox2+ cells (neoplastic glia) as well as increased numbers of blood vessels and microglia. Optic gliomas in Nf1+/−^GFAPCKO mice contained axon fiber irregularities and multilamellar bodies of degenerated myelin. EM and EM tomographic analyses showed increased glial disorganization, disoriented axonal projections, profiles of degenerating myelin and structural alterations at nodes of Ranvier. Lastly, we found reduced RGC numbers in Nf1+/−^GFAPCKO mice, supporting a model in which the combination of optic nerve Nf1 heterozygosity and glial cell Nf1 loss results in disrupted axonal-glial relationships, subsequently culminating in the degeneration of optic nerve axons and loss of their parent RGC neurons.     

Early decompression of the injured optic nerve reduces axonal degeneration and improves functional outcome in the adult rat

The putative beneficial role of an early decompression of injured CNS tissue following trauma remains controversial. In this study, we approach this scientific query using a standardized injury of the optic nerve in adult rats. Adult Sprague–Dawley rats were subjected to a standardized optic nerve constriction injury by applying a loose ligature around the nerve for 5 min, 1, 6 or 24 h. All animals were sacrificed at 28 dpi. Viable axons distal to the injury were quantified using semithin sections, and regenerative fibers were studied using antisera to neurofilament and GAP43. Axonal degeneration and glial scar development were analyzed using Fluoro-Jade staining and anti-GFAP, respectively. Visual function was studied with visual evoked potentials (VEP). No significant differences were observed between 1 and 6 h of optic nerve compression. However, the number of viable axons analyzed with neurofilament and on semithin sections, decreased significantly between 6 and 24 h, paralleled by an increase in Fluoro-Jade labeled axonal debris (P < 0.001). GFAP-IR density was significantly higher (P < 0.001) in the 24 h compression group in comparison to 6 h. VEP showed preserved, but impaired visual function in animals subjected to compression up to 6 h, compared to an abolished cortical response at 24 h. Regenerative GAP43-positive sprouts were occasionally found distal to the lesion in animals subjected to compression up to 6 h, but not at 24 h. These findings suggest that early optic nerve decompression within hours after the initial trauma is beneficial for functional outcome. Funding: Grants from Swedish Medical Research Council and Karolinska Institutet. Disclosure statement: No disclosure to be stated for the two authors.     

Death-scene investigation in sudden infant death

We conducted death-scene investigations in 26 consecutive cases in which a presumptive diagnosis of sudden infant death syndrome (SIDS) was made and the infants were brought to the emergency room of the Kings County Hospital Center between October 1983 and January 1985. In six cases, we observed strong circumstantial evidence of accidental death. In 18 other cases, we discovered various possible causes of death other than SIDS, including accidental asphyxiation by an object in the crib or bassinet, smothering by overlying while sharing a bed, hyperthermia, and shaken baby syndrome. This study suggests that many sudden deaths of infants have a definable cause that can be revealed by careful investigation of the death scene and that the extremely high rate of SIDS (4.2 per 1000 live births) reported in the population of low socioeconomic status served by Kings County Hospital Center should be questioned.     

大鼠受损视神经中神经前体细胞的变化及预变性腓总神经的调节

为了研究大鼠受损视神经内神经前体细胞的变化及调节,本研究建立了成年雄性大鼠视神经损伤及自体腓总神经移植模型,分正常组、损伤组和移植组,体外培养视神经的神经前体细胞,在相差显微镜下观测各组神经前体细胞神经球的形态和数目,以免疫荧光细胞化学方法对神经球细胞进行鉴定。结果显示:正常组神经球较小、较少,多数细胞表达nestin、GFAP或半乳糖脑苷脂(GC);视神经损伤后神经球的总数有所增加,但大神经球数明显减少,nestin、GFAP或GC阳性细胞也明显减少;神经移植后增加了各类神经球数,nestin、GFAP或GC阳性细胞也明显增加。本研究提示成年大鼠视神经内神经前体细胞较少,增殖能力较弱;视神经损伤也伤及其神经前体细胞并抑制其增殖;自体神经移植能保护神经前体细胞并促进其增殖。     

Myelin repair by Schwann cells in the regenerating goldfish visual pathway: regional patterns revealed by X-irradiation

Summary In the regenerating goldfish optic nerves, Schwann cells of unknown origin reliably infiltrate the lesion site forming a band of peripheral-type myelinating tissue by 1–2 months, sharply demarcated from the adjacent new CNS myelin. To investigate this effect, we have interfered with cell proliferation by locally X-irradiating the fish visual pathway 24 h after the lesion. As assayed by immunohistochemistry and EM, irradiation retards until 6 months formation of new myelin by Schwann cells at the lesion site, and virtually abolishes oligodendrocyte myelination distally, but has little or no effect on nerve fibre regrowth. Optic nerve astrocyte processes normally fail to re-infiltrate the lesion, but re-occupy it after irradiation, suggesting that they are normally excluded by early cell proliferation at this site. Moreover, scattered myelinating Schwann cells also appear in the oligodendrocyte-depleted distal optic nerve after irradiation, although only as far as the optic tract. Optic nerve reticular astrocytes differ in various ways from radial glia elsewhere in the fish CNS, and our observations suggest that they may be more permissive to Schwann cell invasion of CNS tissue.