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PubMed2005

Conspicuity of diffuse axonal injury lesions on diffusion-weighted MR imaging.

OBJECTIVE: (1) To detect diffuse axonal injury (DAI) lesions by diffusion-weighted imaging (DWI), as compared with fluid-attenuated inversion recovery (FLAIR) imaging and (2) to evaluate hemorrhagic DAI lesions by b0 images obtained from DWI, as compared with gradient-echo (GRE) imaging. METHODS: We reviewed MR images of 36 patients with a diagnosis of DAI. MR imaging was performed 20 h to 14 days (mean, 3.7 days) after traumatic brain injury. We evaluated: (1) conspicuity of lesions on DWI and FLAIR and (2) conspicuity of hemorrhage in DAI lesions on b0 images and GRE imaging. RESULTS: DWI clearly depicted high-signal DAI lesions. The sensitivity of DWI to lesional conspicuity in DAI lesions was almost equal to that of FLAIR. The sensitivity of b0 images to identification of hemorrhagic DAI lesions was inferior to that of GRE. CONCLUSION: DWI is as useful as FLAIR in detecting DAI lesions. GRE imaging is still the superior tool for the evaluation of hemorrhagic DAI.

Adolescent↗
PubMed2002

Diffusion-weighted MRI in diffuse axonal injury of the brain.

The goal of this study was to identify and describe the different types and patterns of tissue injury which are encountered by diffusion-weighted imaging (DWI) in diffuse axonal injury (DAI) of the brain. The DWI data sets of 98 patients who suffered from a closed-head injury were retrospectively evaluated. Medical records were reviewed to rule out pre-existing neurological diseases. Lesions were studied for their DWI signal characteristics and lesion size or extension. Traumatic lesions were classified into three categories depending on their signal characteristica on DWI and apparent diffusion coefficient (ADC) maps: type 1, DWI- and ADC-hyperintense most likely representing lesions with vasogenic edema; type 2, DWI-hyperintense, ADC-hypointense indicating cytotoxic edema; type 3, central hemorrhagic lesion surrounded by an area of increased diffusion. According to the size and extent of lesions, injury was classified into three groups: group A, focal injury; group B, regional/confluent injury; and group C, extensive/diffuse injury. Our study showed that diffusion-weighted imaging differentiates between lesions with decreased and increased diffusion in patients with DAI. Different degrees of tissue injury extent were noticed. Future prospective studies should study if this additional information can be used as a predictor of injury reversibility, final outcome and prognosis.

Adolescent↗
PubMed1987

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.

Axons↗
PubMed1996

[Clinical analysis of diffuse axonal injury].

Sixty cases of diffuse axonal injury were analysed in this paper. All cases were caused by traffic accident; the mortality was 53.12%. Clinical manifestations were post-traumatic immediate and continuous coma with severe dysfunction of brain stem. MRI is helpful for clinical diagnosis. Pathological findings include the diffuse axonal injury of cortical while matter, corpus callosum, brain stem, and focal hemorrhage and infarction. The early use of hyperbaric oxygen combined with neuro-growth factor as an effective therapy is recommended.

Accidents, Traffic↗
PubMed1999

1H spectroscopic imaging of acute head injury--evidence of diffuse axonal injury.

Using single slice two-dimensional spectroscopic imaging (SI), nine acute head injury patients and six controls have been successfully scanned. The problems presented by the need for ITU monitoring of these patients during MR scanning was overcome using MR compatible monitoring equipment. In previous studies of head injury which used proton spectroscopy, single voxel localisation procedures have meant that the spatial extent of the spectral data has been limited. With spectral data from a whole axial slice, we have been able to identify NAA abnormalities in regions remote to any T2 visible lesions. This suggests that SI (of NAA in particular) will be useful for the diagnosis of diffuse axonal injury.

Adult↗
PubMed2002

Diffusion tensor MR imaging in diffuse axonal injury.

BACKGROUND AND PURPOSE: Disruption of the cytoskeletal network and axonal membranes characterizes diffuse axonal injury (DAI) in the first few hours after traumatic brain injury. Histologic abnormalities seen in DAI hypothetically decrease the diffusion along axons and increase the diffusion in directions perpendicular to them. DAI therefore is hypothetically associated in the short term with decreased diffusion anisotropy. We tested this hypothesis by measuring the diffusion characteristics of traumatized brain tissue with use of diffusion tensor MR imaging. METHODS: Five patients with mild traumatic brain injuries and 10 control subjects were studied with CT, conventional MR imaging, and diffusion tensor imaging. All patients were examined within 24 hours of injury. In each participant, diffusion tensor indices from homologous normal-appearing white matter regions of both hemispheres were compared. These indices were also compared between homologous regions of each patient and the control group. In two patients, diffusion tensor images from the immediate post-trauma period were compared with those at 1 month follow-up. RESULTS: Patients displayed significant reduction of diffusion anisotropy in several regions compared with the homologous ones in the contralateral hemisphere. Such differences were not observed in the control subjects. Significant reduction of diffusion anisotropy was also detected when diffusion tensor results from the patients were compared with those of the controls. This reduction was often less evident 1 month after injury. CONCLUSION: White matter regions with reduced anisotropy are detected in the first 24 hours after traumatic brain injury. Therefore, diffusion tensor imaging may be a powerful technique for in vivo detection of DAI.

Adult↗
PubMed1994

[Parasagittal white matter shearing injury (so-called gliding contusion): possible radiological evidence of spastic hemiplegia in diffuse axonal injury].

Severe head injury or diffuse axonal injury is frequently associated with spastic hemiplegia/paraplegia. However, the causative lesion has not been well elucidated. Especially, the relationship between the gliding contusion and spastic hemiplegia has not been inferred yet. We have analyzed 6 brain concussion cases and 19 cases of diffuse axonal injury. None of the concussion cases experienced hemiplegia in their courses. Among the 19 cases, 10 were left with persistent and disabling hemiplegia/quadriplegia, whereas 5 showed persistent but mild hemiplegia. Among the 10 cases, one was incapacitated by a brainstem hemorrhage. The remaining 9 cases exhibited, in the parasagittal white matter, small hemorrhagic spots in the acute phase CT, low-density areas in the chronic phase CT, and/or T2 high and T1 low signal lesions in the MRI. In 8 cases, the lesion was in accord with the hemiplegic side, but in one case the low density area was on the ipsilateral side. Two of the 3 cases showing quadriplegia exhibited bilateral parasagittal lesions. None of the 5 mild hemiplegia cases and 10 nonhemiplegia cases showed such abnormality. Superficial brain contusions were found in 17 cases altogether, but they were not at all correlated with the occurrence of hemiplegia. Thus, it was concluded that parasagittal white matter shearing injury or so called gliding contusion could be the manifestation of injury to the corticospinal tract in the corona radiata.

Adolescent↗
PubMed2002

Diffuse axonal injury: detection of changes in anisotropy of water diffusion by diffusion-weighted imaging.

Myelinated axons of white matter demonstrate prominent directional differences in water diffusion. We performed diffusion-weighted imaging on ten patients with head injury to explore the feasibility of using water diffusion anisotropy for quantitating diffuse axonal injury. We showed significant decrease in diffusion anisotropy indices in areas with or without signal abnormality on T2 and T2*-weighted images. We conclude that the water diffusion anisotropy index a potentially useful, sensitive and quantitative way of diagnosing and assessing patients with diffuse axonal injury.

Adult↗
PubMed1989

Diffuse axonal injury in head injury: definition, diagnosis and grading.

Diffuse axonal injury is one of the most important types of brain damage that can occur as a result of non-missile head injury, and it may be very difficult to diagnose post mortem unless the pathologist knows precisely what he is looking for. Increasing experience with fatal non-missile head injury in man has allowed the identification of three grades of diffuse axonal injury. In grade 1 there is histological evidence of axonal injury in the white matter of the cerebral hemispheres, the corpus callosum, the brain stem and, less commonly, the cerebellum; in grade 2 there is also a focal lesion in the corpus callosum; and in grade 3 there is in addition a focal lesion in the dorsolateral quadrant or quadrants of the rostral brain stem. The focal lesions can often only be identified microscopically. Diffuse axonal injury was identified in 122 of a series of 434 fatal non-missile head injuries--10 grade 1, 29 grade 2 and 83 grade 3. In 24 of these cases the diagnosis could not have been made without microscopical examination, while in a further 31 microscopical examination was required to establish its severity.

Adolescent↗
PubMed2006

[Diffuse axonal injury in traumatic brain injury].

BACKGROUND: Head trauma of varying severity may induce diffuse axonal injury. More attention is now given to this important type of injury, as examinations of head-injured patients with MRI have given us more knowledge. MATERIAL AND METHODS: We present a review of diffuse axonal injury with the main focus on clinical presentation and radiology, based on a Pubmed search and own experience. RESULTS AND INTERPRETATION: Axons seldom rupture at the moment of injury. It is more common that it takes hours or a few days until the axons are detached. Areas most commonly affected are white matter in the hemispheres, corpus callosum and the brain stem. Half of the patients with severe head injury have diffuse axonal injury, but this type of injury also occurs in patients with moderate and mild head injury. The clinical presentation and prognosis will therefore vary. Diffuse axonal injury can present with typical signs revealed by CT, but the CT scan may also be normal, especially when there is no bleeding. New MRI techniques are more sensitive and show that diffuse axonal injury occurs more often than previously assumed. MRI is therefore necessary to give the patients correct diagnoses and adequate rehabilitation and follow-up.

Brain Injuries↗
PubMed1989

Diffuse axonal injury in head trauma.

Diffuse axonal injury (DAI) as defined by detailed microscopic examination was found in 34 of 80 consecutive cases of head trauma surviving for a sufficient length of time to be clinically assessed by the Royal Adelaide Hospital Neurosurgery Unit. The findings indicate that there is a spectrum of axonal injury and that one third of cases of DAI recovered sufficiently to talk between the initial head injury producing coma and subsequent death. The macroscopic "marker" lesions in the corpus callosum and dorsolateral quadrants of the brainstem were present in only 15/34 of the cases and represented the most severe end of the spectrum of DAI.

Axons↗
PubMed1992

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.

Accidental Falls↗
PubMed1996

Diffuse axonal injury: its mechanism in an assault case.

Diffuse axonal injury is caused by irreparable shearing of the axons. A case of diffuse axonal injury by a well-witnessed assault is reported. The victim survived for 13 days after the assault. The mode of assault was numerous kicks to the head of the victim lying on the ground. The kicking motion was sideways across the long axis of the body. Thus, on each impact, the victim's head moved with relative freedom or was tossed violently side to side or in a lateral, even angular or rotational, manner. This resulted in a low acceleration/deceleration rate. Grossly, the brain showed no lesions; however, a microscopic lytic lesion was present in the corpus callosum. These injuries were consistent with a grade-2 diffuse axonal injury (Adams classification).

Axons↗
PubMed1984

Diffuse axonal injury in head injuries caused by a fall.

82 cases of diffuse axonal injury were found at necropsy in 635 patients with fatal nonmissile head injuries. 13 of these injuries were attributable to falls, and in all the patients fell from a considerable height. Diffuse axonal injury was not found in those with head injuries caused by a simple fall--ie, a fall from not more than the person's own height--but there was a statistically significant association between the presence of diffuse axonal injury and falls from a considerable height. These results indicate that diffuse axonal injury rarely, if ever, occurs as a result of a fall unless the patient has fallen some distance.

Accidents↗
PubMedDate not supplied

Diffuse axonal injury in head trauma.

BACKGROUND: Diffuse axonal injury (DAI) is one of the most common and important pathologic features of traumatic brain injury (TBI). The susceptibility of axons to mechanical injury appears to be due to both their viscoelastic properties and their high organization in white matter tracts. Although axons are supple under normal conditions, they become brittle when exposed to rapid deformations associated with brain trauma. Accordingly, rapid stretch of axons can damage the axonal cytoskeleton resulting in a loss of elasticity and impairment of axoplasmic transport. Subsequent swelling of the axon occurs in discrete bulb formations or in elongated varicosities that accumulate transported proteins. Calcium entry into damaged axons is thought to initiate further damage by the activation of proteases. Ultimately, swollen axons may become disconnected and contribute to additional neuropathologic changes in brain tissue. DAI may largely account for the clinical manifestations of brain trauma. However, DAI is extremely difficult to detect noninvasively and is poorly defined as clinical syndrome. CONCLUSIONS: Future advancements in the diagnosis and treatment of DAI will be dependent on our collective understanding of injury biomechanics, temporal axonal pathophysiology, and its role in patient outcome.

Alzheimer Disease↗
PubMedDate not supplied

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.

Adolescent↗
PubMed2002

Diffuse axonal injuries: pathophysiology and imaging.

Diffuse axonal shear injury is a common traumatic brain injury, with significant neurologic and behavioral impact on patients. Radiologic recognition of this entity and understanding of its sequelae can be of utmost importance in the prediction of outcome and planning for rehabilitation. MRI has proven to be the optimal means of detection and characterization of DAI lesions, with GRE and FLAIR sequences being particularly helpful, and more advanced techniques such as MRS show preliminary evidence of some utility in determining outcome.

Brain↗
PubMed2006

Cognitive sequelae of diffuse axonal injury.

BACKGROUND: The results of recent studies on cognitive disability after traumatic brain injury-associated diffuse axonal injury (DAI) are inconsistent. In these studies, the diagnosis of DAI relied on cranial computed tomography. OBJECTIVE: To further clarify the extent and severity of a possibly DAI-associated cognitive impairment by the use of magnetic resonance imaging (MRI) and detailed neuropsychological testing. DESIGN AND PARTICIPANTS: From a databank of 299 patients with traumatic brain injury, 18 patients (age range, 17-50 years; median initial Glasgow Coma Scale score, 5) who showed an MRI lesion pattern compatible with pure DAI were identified. All of the patients had undergone MRI on a 3-T system. Pure DAI was defined by the findings of traumatic microbleeds on T2*-weighted gradient-echo images in the absence of otherwise traumatic or nontraumatic MRI abnormalities. MAIN OUTCOME MEASURES: Neuropsychological performance in the categories of attention and psychomotor speed, executive functions, spans, learning and memory, and intelligence 4 to 55 months (median, 9 months) after traumatic brain injury. RESULTS: All of the patients showed impairments of 1 or more cognitive subfunctions, and no cognitive domain was fundamentally spared. Memory and executive dysfunctions were most frequent, the former reaching a moderate to severe degree in half of the patients. In comparison, deficits of attention, executive functions, and short-term memory were mostly mild. Correlations between the amount of traumatic microbleeds and specific or global cognitive performance were absent. CONCLUSIONS: An MRI lesion pattern compatible with isolated DAI is associated with persistent cognitive impairment. The traumatic microbleed load is no sufficient parameter for the assessment of DAI severity or functional outcome.

Adolescent↗