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| 2. |
- Hamberger, Anders, 1937, et al.
(författare)
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Concussion in Professional Football: Morphology of Brain Injuries in the Nfl Concussion Model-Part 16
- 2009
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Ingår i: Neurosurgery. - 0148-396X. ; 64:6, s. 1174-1182
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: An animal model of concussions in National Football League players has been described in a previous study. It involves a freely moving 300-g Wistar rat impacted on the side of the head at velocities of 7.4 to 11.2 m/s with a 50-g impactor. The impact causes a 6% to 28% incidence of meningeal hemorrhages and 0.1- to 0.3-mm focal petechiae depending on the impact velocity. This study addresses the immunohistochemical responses of the brain. METHODS: Twenty-seven tests were conducted with a 50-g impactor and velocities of 7.4, 9.3, or 11.2 m/s. The left temporal region of the helmet-protected head was hit 1 or 3 times. Thirty-one additional tests were conducted with a 100-g impactor. Diffuse axonal injury in distant regions of the brain was assessed with immunohistochemistry for NF-200, the heaviest neurofilament subunit, and glial fibrillary acidic protein, an intermediate filament protein in astrocytes. Hemorrhages were analyzed by unspecific peroxidase. There were 10 controls. RESULTS: A single impact at 7.4 and 9.3 m/s velocity with the 50-g impactor causes minimal neuronal injury and astrocytosis. Repeat impacts with 11.2 m/s velocity and more than 9.3-m/s impacts with 100 g cause diffuse axonal injury and distant injury bilaterally in the cerebral cortex, the subcortical, the white matter, the hippocampus CA1, the corpus callosum, and the striatum, as indicated by NF-200 accumulation in neuronal perikarya 10 days after impact. It also causes reactive astrocytosis in the midline regions of the cerebral cortex and periventricularly. Regions with erythrocyte-loaded blood capillaries indicated brain edema in regions of the cerebral cortex, the brainstem, and the cerebellum. CONCLUSION: When the immunohistochemical results are extrapolated to professional football players, concussions result in no or minimal brain injury. Repeat impacts at higher velocity or with a heavier mass impactor cause extensive and distant diffuse axonal injury. Based on this model, the threshold for diffuse axonal injury is above even the most severe conditions for National Football League concussion. Copyright (C) by the Congress of Neurological Surgeons
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| 3. |
- Linder, Astrid, et al.
(författare)
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Evaluation of the BioRID P3 and the Hybrid III in pendulum impacts to the back : a comparison to human subject test data
- 2000
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Ingår i: Annual proceedings / Association for the Advancement of Automotive Medicine. Association for the Advancement of Automotive Medicine. - : Association for the Advancement of Automotive Medicine. - 1540-0360. ; 44, s. 283-297
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Tidskriftsartikel (refereegranskat)abstract
- The BioRID P3 (Biofidelic Rear Impact Dummy) and the Hybrid III were evaluated in pendulum impacts to the back and compared to data from previous cadaver tests. The test setup impacting seated cadavers was reproduced with a pendulum impacting seated dummies at the level of T6 (6th thoracic vertebra). The pendulum mass was 23 kg and the impact velocity 4.6 m/s. The results showed that the BioRID P3 was more biofidelic than the Hybrid III in terms of the peak responses and the temporal window of the head and head relative to T1 horizontal, vertical, and angular displacement. This study is an evaluation of both the BioRID P3 and the Hybrid III against a recently available set of human subject data. The study meets the need for validation of the BioRID P3 at a higher impact severity than has been previously accomplished.
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| 4. |
- Linder, Astrid, et al.
(författare)
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Evaluation of the BioRID P3 and the hybrid III in pendulum impacts to the back : A comparison with human subject test data
- 2002
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Ingår i: Traffic Injury Prevention. - : Informa UK Limited. - 1538-9588 .- 1538-957X. ; 3:2, s. 159-166
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Tidskriftsartikel (refereegranskat)abstract
- Crash test dummies able to mimic the motion of a human are needed to assess the protective performance of seats and head restraints in crash tests. This study evaluates both a newly developed dummy for rear impacts (BioRID P3) and the Hybrid III dummy by means of a recently available set of human subject data. The study also meets the need for validation of the BioRID P3 at a higher impact severity than that previously achieved. The BioRID P3 and the Hybrid III were evaluated by means of pendulum impacts to the back and compared with data from previously run cadaver tests. Seated dummies were struck with a pendulum with a mass of 23 kg and an impact velocity of 4.6 m/s at the level of the 6th thoracic vertebra. The results showed that peak values and temporal responses of the BioRID P3 was closer to that of the corridor of the cadavers than the Hybrid III in terms of horizontal, vertical, and angular displacement of the head and of the head relative to T1.
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| 5. |
- Linder, Astrid, 1959, et al.
(författare)
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Evaluation of the BioRID P3 and the Hybrid III in Pendulum Impacts to the Back: A Comparison with Human Subject Test Data
- 2002
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Ingår i: Traffic Injury Prevention. ; 3, s. 159-166
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Tidskriftsartikel (refereegranskat)abstract
- Crash test dummies able to mimic the motion of a human are needed to assess theprotective performance of seats and head restraints in crash tests. This study evaluatesboth a newly developed dummy for rear impacts (BioRID P3) and the Hybrid III dummyby means of a recently available set of human subject data. The study also meets the needfor validation of the BioRID P3 at a higher impact severity than that previously achieved.The BioRID P3 and the Hybrid III were evaluated by means of pendulum impacts to theback and compared with data from previously run cadaver tests. Seated dummies werestruck with a pendulum with a mass of 23kg and an impact velocity of 4.6m/s at the levelof the 6th thoracic vertebra. The results showed that peak values and temporal responsesof the BioRID P3 was closer to that of the corridor of the cadavers than the Hybrid III interms of horizontal, vertical, and angular displacement of the head and of the headrelative to T1.
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| 6. |
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| 7. |
- Viano, David
(författare)
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Brain injury biomechanics in closed-head impact : studies on injury epidemiology, tolerance criteria, biomechanics and traffic injury prevention
- 1997
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Permanent disability from traumatic brain injury is a devastating consequence of traffic crashes. Injury prevention is a fruitful approach to reduce the incidence and severity of disabling brain injury. However, the development of effective prevention techniques requires better knowledge on the mechanisms and biomechanics of brain injury in closed-head impact. The overall aim of this study is focused on brain injury mechanisms, biomechanics, and tolerances in closed-head impact. The research was multifaceted. It assessed the importance of traffic-related causes for disabling brain injury, determined brain injury biomechanics, criteria, and tolerances, analyzed a physical model of brain impact responses, developed a mathematical model of brain displacement and deformation during head impact, and linked brain motion and deformation to clinical patterns of traumatic brain injury. Karolinska hospital records were analyzed for traffic accident victims admitted to the Department of Neurosurgery. 32.5% of the patients experienced severe cognitive disability (GOS <4) at discharge. A Prevention Priority Index (PPI) was developed and combines injury incidence and disability outcome. PPI was 40.7% for car occupants (27.0% drivers and 13.7% passengers) and 44.7% for other road users (33.6% pedestrians, 10.2% bicyclists, and 0.9% mopedists). Anesthetized animal tests showed that brain injury is primarily caused by rate-dependent tissue deformation measured by the viscous response (VC). VC is the time-varying product of tissue deformation velocity (V) and compression (C). Compression is another mechanism. Locally, VC is the product of strain and strain-rate, e~de/dt, and C is strain, e. Statistical analysis gave proposed tolerance levels of VC = 0.7 m/s, e*de/dt = 45 s-1, C = 25%, and E = 0.25 for traumatic brain injury. Physical and mathematical models demonstrated that brain responses depend on the translational and rotational acceleration of the head. In severe head impacts, brain displacement < 25 mm at the vertex and compressive strain e < 0.30 at the base of the skull, brainstem, and occiput were observed during rotational head acceleration. Different response patterns were observed for translational head acceleration. The observed responses are consistent with published literature. Analysis showed that cortical contusion is primarily related to translational head acceleration that rapidly displaces the skull and deforms the brain along the axis of impact. Bridging vein rupture is related to both translational and rotational head acceleration that causes slip between the skull and brain, and stretches bridging veins in the cortical region. Diffuse axonal injury (DAI), coma, and concussion are related to high, strain-rate deformation of the brain. Analysis of impact biomechanics shows that the brain is naturally protected by a low-friction CSF layer, smooth intracranial surface at the vertex, and compliant bridging veins that allows non-injurious cortical motion of 10-15 mm. An important teleologic role for the lateral ventricles was identified since the fluid inclusions relieve strain in brain tissue during cortical motion. This allows the lower regions of the brain to remain fixed, while the cortex displaces without high internal strain that would otherwise occur if the brain were continuous. New information is provided on brain injury mechanisms, tolerance criteria, and impact biomechanics that is useful to the evaluation of occupant protection systems for brain injury prevention. The research improves the understanding of brain injury biomechanics in closed-head impact.
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| 8. |
- Viano, David C, et al.
(författare)
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Concussion in professional football: animal model of brain injury--part 15.
- 2009
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Ingår i: Neurosurgery. - 1524-4040. ; 64:6
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: A concussion model was developed to study injury mechanisms, functional effects, treatment, and recovery. Concussions in National Football League football involve high-impact velocity (7.4-11.2 m/s) and rapid change in head velocity (DeltaV) (5.4-9.0 m/s). Current animal models do not simulate these head impact conditions. METHODS: One hundred eight adult male Wistar rats weighing 280 to 350 g were used in ballistic impacts simulating 3 collision severities causing National Football League-type concussion. Pneumatic pressure accelerated a 50 g impactor to velocities of 7.4, 9.3, and 11.2 m/s at the left side of the helmet-protected head. A thin layer of padding on the helmet controlled head acceleration, which was measured on the opposite side of the head, in line with the impact. Peak head acceleration, DeltaV, impact duration, and energy transfer were determined. Fifty-four animals were exposed to single impact, with 18 each having 1, 4, or 10 days of survival. Similar tests were conducted on another 54 animals, which received 3 impacts at 6-hour intervals. An additional 72 animals were tested with a 100g impactor to study more serious brain injuries. Brains were perfused, and surface injuries were identified. RESULTS: The 50 g impactor matches concussion conditions scaled to the rat. Impact velocity and head DeltaV were within 1% and 3% of targets on average. Head acceleration reached 450 g to 1750 g without skull fracture. The test is repeatable and robust. Gross pathology was observed in 11%, 28%, and 33% of animals in the 7.4-, 9.3-, and 11.2-m/s single impacts, respectively. At 7.4 m/s, a single diameter area of less than 0.5 mm of fine petechial hemorrhage occurred on the brain surface in the parenchyma and meninges nearest the point of impact. At higher velocities, there were larger areas of bleeding, sometimes with subdural hemorrhage. When the 50 g impactor tests were examined by logistic regression, greater energy transfer increased the probability of injury (odds ratio, 5.83; P = 0.01), as did 3 repeat impacts (odds ratio, 4.72; P = 0.002). The number of survival days decreased the probability of observing injury (odds ratio, 0.25 and 0.11 for 4 and 10 days, respectively, compared with 1 day). The 100g impactor produced more severe brain injuries. CONCLUSION: A concussion model was developed to simulate the high velocity of impact and rapid head DeltaV of concussions in National Football League players. The new procedure can be used to evaluate immediate and latent effects of concussion and more severe injury with greater impact mass.
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| 9. |
- Viano, David C, et al.
(författare)
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Evaluation of three animal models for concussion and serious brain injury.
- 2012
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Ingår i: Annals of biomedical engineering. - : Springer Science and Business Media LLC. - 1573-9686 .- 0090-6964. ; 40:1, s. 213-26
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Tidskriftsartikel (refereegranskat)abstract
- Three animal models were evaluated in this study involving head impacts of the rat, including the Marmarou drop-weight and two momentum-exchange techniques. In series 1, 36 Wistar rats were hit on the side of the free-moving head using Marmarou's 450 g impact mass at 4.4, 5.4, and 6.3 m/s. Head acceleration was measured and injuries were observed. The 6.3-m/s side impact resulted in no deaths, no skull fractures, infrequent contusions, and some injuries consistent with diffuse axonal injury. In series 2, 57 Marmarou drop-weight tests were conducted to study head biomechanical responses. Marmarou's technique involves a head impact followed by prolonged loading into a foam pad under the animal. Based on the literature, the 2 m (6.3 m/s) Marmarou drop causes death, skull fracture, brain and spinal cord contusions, and diffuse axonal injury. These injuries are more severe than that occurring with impact of similar mass and velocity to the free-moving head. Impacts to the free-moving head provide more realistic animal models to study concussion and severe brain injury.
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