Type Of Traumatic Brain Injury Research Articles

Global/local head models to analyse cerebral blood vessel rupture leading to ASDH and SAH

Blunt and rotational head impacts due to vehicular collisions, falls and contact sports cause relative motion between the brain and skull. This increases the normal and shear stresses in the (skull/brain) interface region consisting of cerebrospinal fluid (CSF) and subarachnoid space (SAS) trabeculae. The relative motion between the brain and skull can explain many types of traumatic brain injuries (TBI) including acute subdural hematomas (ASDH) and subarachnoid hemorrhage (SAH) which is caused by the rupture of bridging veins that transverse from the deep brain tissue to the superficial meningeal coverings. The complicated geometry of the SAS trabeculae makes it impossible to model all the details of the region. Investigators have compromised this layer with solid elements, which may lead to inaccurate results. In this paper, the failure of the cerebral blood vessels due to the head impacts have been investigated. This is accomplished through a global/local modelling approach. Two global models, namely a global solid model (GSM) of the skull/brain and a global fluid model (GFM) of the SAS/CSF, were constructed and were validated. The global models were subjected to two sets of impact loads (head injury criterion, HIC = 740 and 1044). The relative displacements between the brain and skull were determined from GSM. The CSF equivalent fluid pressure due to the impact loads were determined by the GFM. To locally study the mechanism of the injury, the relative displacement between the brain and skull along with the equivalent fluid pressure were implemented into a new local solid model (LSM). The strains of the cerebral blood vessels were determined from LSM. These values were compared with their relevant experimental ultimate strain values. The results showed an agreement with the experimental values indicating that the second impact (HIC = 1044) was strong enough to lead to severe injury. The global/local approach provides a reliable tool to study the cerebral blood vessel ruptures leading to ASDH and/or SAH.

New Methods for Detecting and Deciphering Types of Traumatic Brain Injury

New Methods for Detecting and Deciphering Types of Traumatic Brain Injury

Predicting brain injury under impact with a strain measure from analytical models

Caused by strain deformation in brain tissue, diffuse axonal injury (DAI) is one of the most devastating types of traumatic brain injury; it frequently occurs in automobile crashes. Although offering detailed anatomical structures, finite-element human head models require complete knowledge of material properties of the head and need high computational capacity. Similar to a brain injury model developed in the sagittal plane in an earlier work, an analytical model in the coronal plane is developed for brain injury study. A measure of strain for DAI prediction is presented on the basis of the two planar models. With the maximum shear strain selected as the injury indicator of DAI, the strain measure was applied to frontal and side impact tests conducted by the National Highway Traffic Safety Administration. The results of the crash reconstructions from the planar models were compared with the injury predictions using the head injury criterion and the SIMon finite-element head model. It shows that the simple measure of strain has the capability to predict brain injuries from automobile crashes. The maximum shear strain from the planar models can be used as a critical element to predict DAI.

Early diagnosis of diffuse brain damage resulting from a blunt head injury

Diffuse types of traumatic brain injury (TBI) are more difficult to diagnose than focal types in forensic postmortem examination, since macroscopic abnormalities may be minimal. In addition, most microscopic findings are not specific to TBI and are sometimes not obvious in cases when the survival period is short. Therefore, early diagnosis of diffuse TBI is most difficult. Histopathological and immunohistochemical examinations of various elements including axons, nerve cells, and glial cells in a sufficient number of blocks are indispensable. Mapping of changes in these elements with complicated focal lesions, even if the lesions are trivial, on anatomical diagrams would be useful. The combination of histopathological and immunohistochemical examinations as well as analysis of the exact history of the trauma, if possible, and elimination of other causes of death would lead to accurate diagnosis of diffuse types of TBI in cases when the survival period is brief.

Age-Dependent Cerebral Hemodynamic Effects of Traumatic Brain Injury in Newborn and Juvenile Pigs

Traumatic brain injury is one of the major causes of morbidity, mortality, and pediatric intensive care unit admissions of children. Although the effects of traumatic brain injury have been well described for adult animal models, few have investigated these effects in the newborn or have characterized such effects as a function of age using a single model of injury. Using a piglet model of brain injury, recent studies have shown that the cerebral hemodynamic effects and the corresponding mechanisms for such effects of injury vary as a functional of age. This review discusses the types of traumatic brain injury, their models, and the role of species in such model choice. This review also describes the effects of brain injury on cerebral blood flow, metabolism, and cerebrovascular regulation as a function of age. Finally, this review presents evidence for potential mechanisms that may contribute to age-dependent impaired cerebral hemodynamics following brain injury.

Cognitive dysfunction and histological findings in rats with chronic-stage contusion and diffuse axonal injury

The Morris water maze (MWM) technique is well known as a prominent method of evaluating learning acquisition and memory retention impairments in rats. We previously reported on a modified fluid percussion device that is able to consistently produce experimental cortical contusion (CC) and diffuse axonal injury (DAI) in separate groups of rats. The purpose of the present protocol is to evaluate the differences in learning acquisition and memory retention impairments between these two types of injured rats in the chronic stage using the MWM technique. CC and DAI rats are respectively induced by lateral and midline fluid percussion. We also compare the histological differences between these two different types of traumatic brain injury. The results show statistically significant differences in learning acquisition impairment between the sham and CC rats and between the sham and DAI rats. However, a difference in memory retention impairment was expected to be seen only between the sham and DAI rats. Histologically, the loss of CA3 pyramidal cells in the hippocampus was observed ipsilaterally in the CC and bilaterally in DAI. Neuronal cell loss was observed in bilaterally in layer II of the entorhinal cortex in DAI, but not in CC. Themes: Neural basis of behavior Topics: Learning and memory: systems and functions

Traumatic brain injury in children in Denmark: a national 15-year study.

Demographic trends are reported concerning three types of traumatic brain injury (concussions, cranial fractures, and intracranial contusions/haemorrhages) among children in Denmark of ages up to and including 14 years, for a fifteen year period from 1979 through 1993. The data were derived from a national computer-based hospitalization register and include 49,594 children, of whom 60% were boys and 89% had suffered a concussion. Virtually all injuries were the result of accidents. A major finding was that there has been a general decline in the incidence of traumatic brain injuries, especially for boys from 5 to 14 years old, suggesting a degree of success in preventive measures, particularly regarding road safety. The incidence of fatal cases of intracranial contusions/haemorrhages approximately halved over the 15 year period. However, as a proportion of all diagnosed cases, mortality from intracranial contusions/haemorrhages remained fairly constant at about 22%, perhaps because there have been no markedly successful innovations in acute care. Among children surviving a intracranial contusions/haemorrhages, rather considerable numbers were found to have been awarded disability pension at ages under 30.

Evaluation of learning and memory dysfunction and histological findings in rats with chronic stage contusion and diffuse axonal injury

We previously reported a modified fluid percussion device capable of consistently producing experimental cortical contusion (CC) and diffuse axonal injury (DAI) in separate groups of rats by lateral and midline fluid percussion, respectively. The purpose of the present study was to compare the differences in learning acquisition and memory retention impairments between these two types of injured rats in the chronic stage using the Morris water maze technique. We also compared the histological differences between these two different types of traumatic brain injury. The results showed a statistically significant difference in learning acquisition impairment between the sham and CC rats and also between the sham and DAI rats. However, a significant difference in memory retention impairment was observed only between the sham and DAI rats. Histologically, the neuronal cell loss of CA3 pyramidal cells in the hippocampus was observed on the ipsilateral side in the CC and bilaterally in DAI. The neuronal cell loss was seen in bilateral entorhinal cortex layer II in DAI, but it was not seen in CC. From these results, we speculate that the marked cell loss in the hippocampus CA3 region in both CC and DAI rats was related to the impairment of spatial learning acquisition. The marked cell loss in entorhinal cortex layer II in DAI rats may be one of the important factors in the impairment of spatial memory retention.

Head injury mechanisms and the concept of preventive management: a review and critical synthesis.

Recent advances in head injury research have produced a plethora of useful data coupled with a paucity of conceptual integration across the four ways in which this research is pursued. These research orientations are the epidemiological, biomechanical, basic neuroscientific, and clinicopathologic/therapeutic (including rehabilitation). This overview of the history and current state of the art assumes that biomechanics is the basic science of causation in head injury research and when fully integrated with its counterparts, physiology and pathology, it can serve to overcome our conceptual handicaps. A paradigm integrating biomechanics; into the sequence of preventive, protective, acute therapeutic, and rehabilitative interventions will be described as the concept of preventive management. From this we derive the hypothesized claim that the exact biomechanics and the physiopathologic response at the time of injury (at the macroscopic and microscopic levels) determine the sequence of so-called secondary effects that are conceived as the inexorable delayed manifestations of the primary events and concomitant boundary conditions. Knowledge of these events will enable accurate predictions of the natural history and outcome of head injuries from observations carried out in the early acute phase. Examples to test this claim will be given with particular reference to the two types of traumatic brain injury (TBI) phenomenologically associated with disturbances of consciousness, the onset of which can be either immediate or delayed. The current economics and availability of computational power provide a significant opportunity for the development of selected experimental, physical, and simulated models of head injury on the basis of which the complex neurovascular and nonneural cellular and fluid elements of the nervous system may be accurately modeled. This approach will significantly improve the efficiency and quality of the essential biological and clinical observations and model experiments required to validate the theoretical methods and their predictions.

Types of Traumatic Brain Injury and Regional Cerebral Blood Flow Assessed by <SUP>99m</SUP>Tc-HMPAO SPECT

To investigate the relationship between focal and diffuse traumatic brain injury (TBI) and regional cerebral blood flow (rCBF), rCBF changes in the first 24 hours post-trauma were studied in 12 severe head trauma patients using single photon emission computed tomography (SPECT) with 99mtechnetium-hexamethyl propyleneamine oxime. Patients were classified as focal or diffuse TBI based on x-ray computed tomographic (X-CT) findings and neurological signs. In six patients with focal damage, SPECT demonstrated 1) perfusion defect (focal severe ischemia) in the brain region larger than the brain contusion by X-CT, 2) hypoperfusion (focal CBF reduction) in the brain region without abnormality by X-CT, and 3) localized hyperperfusion (focal CBF increase) in the surgically decompressed brain after decompressive craniectomy. Focal damage may be associated with a heterogeneous CBF change by causing various focal CBF derangements. In six patients with diffuse damage, SPECT revealed hypoperfusion in only one patient. Diffuse damage may be associated with a homogeneous CBF change by rarely causing focal CBF derangements. The type of TBI, focal or diffuse, determines the type of CBF change, heterogeneous or homogeneous, in the acute severe head trauma patient.

Acute regional cerebral blood flow changes caused by severe head injuries

To evaluate the changes in cerebral blood flow (CBF) that occur immediately after head injury and the effects of different posttraumatic lesions on CBF, 61 CBF studies were obtained using the xenon-computerized tomography method in 32 severely head-injured adults (Glasgow Coma Scale score (GCS) less than or equal to 7). The measurements were made within 7 days after injury, 43% in the first 24 hours. During the 1st day, patients with an initial GCS score of 3 or 4 and no surgical mass had significantly lower flows than did those with a higher GCS score or mass lesions (p less than 0.05): in the first 1 to 4 hours, those without surgical mass lesions had a mean CBF of 27 cc/100 gm/min, which rose to 44 cc/100 gm/min by 24 hours. Patients without surgical mass lesions who died tended to have a lower global CBF than did those with better outcomes. Mass lesions were associated with a high global CBF and bihemispheric contusions with the lowest flows. By 24 hours after injury, global blood flow increased in groups that originally had low flows and decreased in those with very high initial flows, such that by 36 to 48 hours, most patients had CBF values between 32 and 55 cc/100 gm/min. Lobar, basal ganglion, and brain-stem blood flow values frequently differed by 25% or more from global averages. Brain-stem CBF varied the most but did not correlate with clinical signs of brain-stem dysfunction. Double studies were performed at two different pCO2 values in 10 patients with various posttraumatic lesions, and the CO2 vasoresponsivity was calculated. Abnormal CO2 vasoresponsivity was found with acute subdural hematomas and defuse cerebral swelling but not with epidural hematomas. In patients without surgical mass lesions, the findings suggest that CBF in the first few hours after injury is often low, followed by a hyperemic phase that peaks at 24 hours. Global CBF values vary widely depending on the type of traumatic brain injury, and brain-stem flow is often not accurately reflected by global CBF values. These findings underscore the need to define regional CBF abnormalities in victims of severe head injury if treatment is intended to prevent regional ischemia.