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PubMed1989

[A clinical and pathological study of diffuse axonal injury].

There is increasing evidence from human and experimental studies that the most important factor governing the outcome in head injury is the severity of diffuse axonal injuries. The authors have experienced 18 cases of severe diffuse axonal injury which showed post-traumatic coma for more than 24 hours and CT findings resembling those of shearing injuries of the cerebral white matter such as have been presented by Zimmerman et al. (1978). The consciousness levels on admission were 6 or less on the Glasgow Coma Scale and all cases were shown clinically to have primary brain stem injury. The main type of head trauma resulted from road traffic accidents (83%). Skull fractures were found in only 5 cases (28%). These findings suggested that acceleration/deceleration injury produce in the patients severe diffuse axonal injury. Initial ICP was below 20 mmHg in 11 cases out of 13 (85%). Parenchymal small hemorrhagic lesions of initial CT were basal ganglia (7 cases), corpus callosum (4 cases), pons (4 cases), midbrain (3 cases) and thalamus (2 cases). Extraparenchymal hemorrhagic lesions included intraventricular hemorrhage (6 cases) and subarachnoid hemorrhage (6 cases). Two autopsied cases of severe diffuse axonal injury (acute case and chronic case) showed remarkable congestion and edema in the deep part of the frontal white matter. Microscopic examination revealed marked axonal degeneration including axonal retraction ball in the corpus callosum, in the internal capsule and in the white matter of the brain stem. Glasgow Outcome Scale of the 18 patients at 3 months after the trauma made us concerned that no patients indicated good recovery or even only moderate disability.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1992

Coexisting diffuse axonal injury (DAI) and outcome of severe head injury.

The importance of coexisting diffuse axonal injury (DAI) and outcome were studied in 107 patients with diffuse and focal brain injury. Comprehensive neuropathological study was undertaken in 26 fatal patients. There was a clear rank order of the mortality rate in the lesion type. The rank order of good recovery and moderate disability was also similar to the inverse of the mortality ranking. The pathological "marker" of DAI, macroscopic lesions in the corpus callosum and dorsolateral quadrant of the upper brainstem and histological evidence of axonal retraction balls, were commonly found not only in patients with diffuse brain injury but also in focal brain injury. The type of intracranial lesion in severe head injury is thus an important factor in determining outcomes and DAI of varying severity is the common subjacent lesion in the fatal patients.

Adolescent↗
PubMedDate not supplied

Diffuse axonal injury associated with chronic traumatic brain injury: evidence from T2*-weighted gradient-echo imaging at 3 T.

BACKGROUND AND PURPOSE: Diffuse axonal injury is frequently accompanied by tissue tear hemorrhages. We examined whether high field strength T2*-weighted gradient-echo imaging performed during the chronic stage of traumatic brain injury may have advantages in the evaluation of diffuse axonal injury as compared with T1- and T2-weighted MR imaging. METHODS: Prospective MR imaging of 66 patients (age range, 17-57 years) was performed using a 3-T system 3 to 292 months (median, 23.5 months) after traumatic brain injury. T1-, T2-, T2*-hypointense and T2-hyperintense foci of 1- to 15-mm diameter were registered in 10 brain regions by two readers separately. Foci that appeared hypointense both on the T1- and T2- and/or on the T2*-weighted images were defined as traumatic microbleeds. RESULTS: For 46 (69.7%) of the patients, T2*-weighted gradient-echo imaging revealed traumatic microbleeds. Hyperintense foci were observed on the T2-weighted images of only 15 (22.7%) patients. T2*-weighted imaging showed significantly more traumatic microbleeds (P =.000) than did T1- and T2-weighted imaging. Interobserver agreement was strong (kappa = 0.79, tau = 0.749, P =.000). For 14 (21.2%) of the patients, T2*-weighted gradient-echo imaging revealed traumatic microbleeds in the corpus callosum, whereas for only two (3%), hyperintense callosal lesions were seen on the T2-weighted images. Although a significant correlation existed between the total amount and callosal appearance of traumatic microbleeds and Glasgow Coma Scale scores (P =.000), no correlation existed with extended Glasgow Outcome Scale scores. CONCLUSION: T2*-weighted gradient-echo imaging at high field strength is a useful tool for the evaluation of diffuse axonal injury during the chronic stage of traumatic brain injury. Diffuse axonal injury-related brain lesions are mainly hemorrhagic. The relevance of diffuse axonal injury for long-term clinical outcome is uncertain.

Adolescent↗
PubMed2001

Outcome after mild-to-moderate blunt head injury: effects of focal lesions and diffuse axonal injury.

PRIMARY OBJECTIVE: A comparison of the effects of focal and diffuse axonal injury in mild-to-moderate traumatic brain injury (TBI). RESEARCH DESIGN: In a prospective longitudinal study of 138 consecutive patients suffering from TBI who were admitted to the Magdeburg University Hospital, 60 could be assessed neuropsychologically 8--31 days after trauma and 18--45 weeks later. METHODS AND PROCEDURES: GCS, CT-analysis, comprehensive neuropsychological assessment. MAIN RESULTS: The initial GCS-score was significantly correlated with outcome impairments of semantic fluency and memory in the Wechsler Similarities and in two clinical scales (Neurobehavioural Rating Scale, Frontal Lobe Score). The presence of CT-signs of DAI corresponded with deficits in tasks of response selection and suppression, the presence of focal contusions with results in the clinical scales, reaching significance for behavioural deficits with frontal contusions. Improvements between first and second assessments were pronounced in patients with signs of DAI. CONCLUSIONS: The data indicate that traumatic DAI results in mainly transient neuropsychological deficits. Focal frontal contusions result in more relevant deficits at outcome that affect behaviour and, thus, impair rehabilitation prognosis. It is concluded that even in clinically 'mild' TBI, prognosis and rehabilitation requirements should be established by early imaging and post-acute neuropsychological assessment.

Adolescent↗
PubMed2005

Brain MR diffusion tensor imaging and fibre tracking to differentiate between two diffuse axonal injuries.

We report here two cases of diffuse axonal injury (DAI) studied by MR diffusion tensor imaging (DTI) and fibre tracking (FT) focused on the corpus callosum. In one case, DTI and FT pattern matched the diagnosis of broken white matter tracts. In the other case there was a discrepancy between DTI and FT data that showed unaltered white matter tracts with the presence of intra-cellular oedema. These data suggested that DTI and FT are able to differentiate between traumatic cytotoxic oedema and broken fibres in the case of DAI.

Adult↗
PubMed1994

Severe diffuse axonal injury in adults and children.

Diffuse axonal injury (DAI) occurs in 30% of all fatal head injuries. DAI is identified on autopsy as microscopic lesions that commonly appear in the splenium of the corpus callosum, rostral brainstem and frontal and temporal lobes of the cerebrum. Clinical presentation of severe DAI includes patients with no lucid interval and decorticate or decerebrate posturing. Diagnostic studies describe concurrent pathologic anatomy associated with DAI. The most common mechanism for DAI is motor vehicle accidents. The neuroscience nurse needs to have an understanding of DAI anatomy and physiology, including the differences and similarities in the clinical presentation and neurologic functional outcome in both adult and pediatric populations.

Accidents, Traffic↗
PubMed2005

Proton MR spectroscopic imaging depicts diffuse axonal injury in children with traumatic brain injury.

BACKGROUND AND PURPOSE: Diffuse axonal injury (DAI) after traumatic brain injury (TBI) is important in patient assessment and prognosis, yet they are underestimated with conventional imaging techniques. We used MR spectroscopic imaging (MRSI) to detect DAI and determine whether metabolite ratios are accurate in predicting long-term outcomes and to examine regional differences in injury between children with TBI and control subjects. METHODS: Forty children with TBI underwent transverse proton MRSI through the level of the corpus callosum within 1-16 days after injury. T2-weighted, fluid-attenuated inversion recovery, and susceptibility-weighted MR imaging was used to identify voxels as normal-appearing or as nonhemorrhagic or hemorrhagic injury. Neurologic outcome was evaluated at 6-12 months after injury. Metabolite ratios for total (all voxels), normal-appearing, and hemorrhagic brain were compared and used in a logistic regression model to predict long-term outcome. Total and regional metabolite ratios were compared with control data. RESULTS: A significant decrease in N-acetylaspartate (NAA)/creatine (Cr) and increase in choline (Cho)/Cr (evidence of DAI) was observed in normal-appearing (P < .05) and visibly injured (hemorrhagic) brain (P < .001) compared with controls. In normal-appearing brain NAA/Cr decreased more in patients with poor outcomes (1.32 +/- 0.54) than in those with good outcomes (1.61 +/- 0.50, P = .01) or control subjects (1.86 +/- 0.1, P = .00). In visibly injured brains, ratios were similarly altered in all patients. In predicting outcomes, ratios from normal-appearing and visibly-injured brain were 85% and 67% accurate, respectively. CONCLUSION: MRSI can depict injury in brain that appears normal on imaging and is useful for predicting long-term outcomes.

Adolescent↗
PubMed1991

Diffuse axonal injury and early intracranial sequelae in severe head injury.

The importance of diffuse axonal injury (DAI) and early intracranial sequelae was studied in 107 patients with diffuse and focal brain injuries. Comprehensive neuropathological study was also undertaken in 24 fatal patients. The mortality rate was clearly the highest in traumatic subarachnoid hemorrhage, followed by acute subdural hematoma, cerebral contusion with delayed hematoma formation, traumatic intracerebral hematoma, diffuse cerebral swelling, DAI with classical features, and finally nearly normal on computed tomographic scans. The mean flow velocities in the middle cerebral artery recorded by transcranial Doppler ultrasound were variable in diffuse brain injury, but commonly decreased on the hematoma side depending on increased intracranial pressure and decreased cerebral perfusion pressure in focal brain injury. Deep-seated hemorrhagic lesions did not expand in diffuse brain injury, but sizable hematoma developed within 24 hours in focal brain injury. The platelet count was significantly lower in patients with poor outcomes in focal brain injury. Histological evidence of classical DAI was found in eight (50%) of 16 cases with focal brain injury. DAI of varying severity is the common subjacent lesion in patients with severe head injury, but the final outcome varies greatly with different lesion types.

Axons↗
PubMed2004

Diffuse axonal injury in children: clinical correlation with hemorrhagic lesions.

An inception cohort of 40 children and adolescents with traumatic brain injury and suspected diffuse axonal injury were studied using a new high-resolution magnetic resonance imaging susceptibility-weighted technique that is very sensitive for hemorrhage. A blinded comparison was performed between the extent of parenchymal hemorrhage and initial clinical variables as well as outcomes measured at 6 to 12 months after injury. Children with lower Glasgow Coma Scale scores (< or =8, n = 30) or prolonged coma (>4 days, n = 20) had a greater average number (p = 0.007) and volume (p = 0.008) of hemorrhagic lesions. Children with normal outcomes or mild disability (n = 30) at 6 to 12 months had, on average, fewer hemorrhagic lesions (p = 0.003) and lower volume (p = 0.003) of lesions than those who were moderately or severely disabled or in a vegetative state. Significant differences also were observed when comparing regional injury to clinical variables. Because susceptibility-weighted imaging is much more sensitive than conventional T2*-weighted gradient-echo sequences in detecting hemorrhagic diffuse axonal injury, more accurate and objective assessment of injury can be obtained early after insult, and may provide better prognostic information regarding duration of coma as well as long-term outcome.

Adolescent↗
PubMed1990

Diffuse axonal injury: analysis of 100 patients with radiological signs.

One hundred patients with head injuries who showed diffuse axonal injury on computed tomographic scans are reported. Evaluation of the Glasgow Coma Score, pupillary signs, and computed tomographic findings on admission led to an improved ability to forecast outcomes. Our relatively good results as compared with other series, can be explained by the high proportion of children and by the liberal use of computed tomography to evaluate head injuries, thus revealing that concussion may sometimes be regarded as an early form of diffuse axonal injury.

Adult↗
PubMed1999

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 beta-amyloid precursor protein (betaAPP) was carried out. The minimum diameter of the betaAPP-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. betaAPP 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.

Adolescent↗
PubMed1994

Distribution of forebrain diffuse axonal injury following inertial closed head injury in miniature swine.

Diffuse axonal injury (DAI) is one of the most frequently encountered types of brain damage resulting from closed head injury. This study was designed to verify whether DAI could be produced in miniature swine by rapid acceleration and deceleration of the head in the coronal plane. Hanford miniature swine (16-19 kg) were anesthetized with 3% isoflurane and their heads accelerated rapidly once through a 60-105 degrees arc in the coronal plane, producing only transient post-traumatic unconsciousness without prolonged coma. All animals made a good recovery and were sacrificed between 6 h and 10 days after injury. The response of forebrain projection systems to this injury was studied using neurofilament immunohistochemistry with antisera to nonphosphorylated (SMI-32) and phosphorylated (SMI-31) epitopes common to heavy (200 kDa) and medium (160 kDa) neurofilament proteins. In 9 of 12 animals, lesions characterized by foci of SMI-32 positive axonal retraction balls were present at the white matter/gray matter junction at the crests of gyri in the dorsolateral regions of the frontal, parietal, and temporal cortices and along margins of the lateral ventricles. A high density of pyramidal neuron perikarya in layers III and V within cortical gyri associated with subcortical DAI were intensely positive for SMI-31 immunohistochemistry. These results validate the use of miniature swine in studies of axonal injury and demonstrate that axonal injury analogous to that seen in the mildest form of DAI (grade I) can be produced in these animals without producing prolonged coma.

Animals↗
PubMed2002

Semiquantitative analysis of corpus callosum injury using magnetic resonance imaging indicates clinical severity in patients with diffuse axonal injury.

OBJECTIVE: To evaluate the hypothesis that the extent of corpus callosum injury indicates the depth of shearing lesions in the central brain structure and therefore relates to the clinical severity of diffuse axonal injury. METHODS: A simple and objective procedure for semiquantitative analysis of magnetic resonance images (MRI)-the maximum signal intensity ratio (MSIR)-was employed prospectively in 21 patients with diffuse axonal injury but without apparent injury to the ventral pons. All were diagnosed using serial combination MRI scans of fluid attenuated inversion recovery (FLAIR) and T2* weighted gradient echo imaging during the initial two weeks after the injury. The signal intensity ratio between the two regions of interest-the corpus callosum and the normal appearing ventral pons-was calculated serially in mid-sagittal and parasagittal FLAIR image sections in each patient. The MSIR during the study period was determined as a semiquantitative index of corpus callosum injury in each patient. The correlations between MSIR and the duration of unconsciousness, Glasgow outcome scale at six months, and the presence of apparent midbrain injury were investigated. RESULTS: The mean (SD) MSIR value was 1.12 (0.18) at 7.4 (3.1) days after the injury (n = 21). MSIR correlated strongly with the duration of unconsciousness (n = 19, R(2) = 0.74, p < 0.0001), and was higher in patients with both an unfavourable GOS outcome (p = 0.020) and apparent midbrain injury (p < 0.001). CONCLUSIONS: MSIR, which is a simple and objective procedure for semiquantitative analysis of corpus callosum damage in diffuse axonal injury, correlated with clinical severity. A high MSIR value may indicate the presence of concomitant midbrain injury.

Adolescent↗
PubMedDate not supplied

Diffusion-weighted imaging for the evaluation of diffuse axonal injury in closed head injury.

PURPOSE: The purpose of this work was to compare diffusion-weighted imaging (DWI) with conventional MRI in the detection of shearing injuries in acute closed head injuries. METHOD: Twenty-five patients (19 male, 6 female) were examined within 48 h of trauma. Conventional MRI included T2-weighted fast spin echo, fluid-attenuated inversion recovery (FLAIR), and T2*-weighted gradient echo sequences. Full tensor DWI with calculation of apparent diffusion coefficient (ADC) maps was also performed. Lesions were identified and compared on all sequences. RESULTS: Four hundred twenty-seven lesions were counted by the combined use of all sequences. DWI identified 70 lesions not seen on conventional MRI. DWI identified 310 shearing injuries, followed by T2/FLAIR (n = 248) and T2* (n = 202). The majority of DWI-positive lesions showed decreased diffusion (65%). CONCLUSION: DWI is valuable in closed head injury because it identifies additional shearing injuries not visible on T2/FLAIR or T2* sequences. Furthermore, DWI/ADC maps differentiate between lesions with decreased or increased diffusion. DWI is less sensitive than T2* imaging for detecting hemorrhagic lesions.

Adolescent↗
PubMed2000

[The role of diffuse axonal injury in psychiatric assessment of brain-head trauma].

The concept of diffuse axonal injury is presented and the relevance in medicolegal assessment of brain injured patients is discussed. The lesion pattern of diffuse axonal injury not only plays a significant role in the acute management and rehabilitation of brain injured patients but also in issues of litigation. Brain imaging techniques are most important in the evaluation of structural damage to the brain and play a pivotal role in the detection of diffuse axonal injury. While computer-tomography follow-up studies may be valuable for the detection of diffuse axonal injury, magnetic resonance imaging is superior due to better sensitivity and contrast-resolution. The article presents selected case studies and illustrates the different lesion patterns.

Axons↗
PubMed2001

Clinical features of diffuse axonal injury.

OBJECTIVE: To analyze the mechanism of diffuse axonal injury (DAI) and study the relationship between DAI and brain concussion, brain contusion, and primary brain stem injury. METHODS: The clinical data and iconographic characteristics of 56 patients with DAI were analyzed retrospectively. RESULTS: Traffic accidents were the main cause of DAI. Among t he 56 cases, 34 were injured for at least twice, and 71.43% of the patients were complicated with contusion. CONCLUSIONS: It is considered that DAI is a common pattern of primary brain injury, which is often underestimated. And DAI includes cerebral concussion and primary brain injury, and is often complicated by cerebral cortex contusion. Therefore, it is very simple and practical to divide primary brain injuries into local and diffuse injuries.

Adolescent↗
PubMed2004

Effects of diffuse axonal injury on speed of information processing following severe traumatic brain injury.

To test the hypothesis that slowed information processing in traumatic brain injury is related to diffuse axonal injury (DAI), the authors compared 10 patients with predominant DAI (diffuse group) and minimal DAI (mixed injury group) on the Symbol Digit Modalities Test, simple and choice reaction time, Trail Making Tests A and B, and the Stroop Neuropsychological Screening Test. The diffuse group was slower than the mixed injury and control groups on basic speed of processing tasks. This difference was not apparent on complex speeded tasks once basic speed of processing was controlled for. The diffuse group's slower speed of processing was not accounted for by differences in injury severity, age, or time postinjury. The diffuse group showed greater recovery over time.

Adolescent↗