Journal of neurotrauma
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Journal of neurotrauma · Oct 2016
Minor Functional Deficits in Basic Response Patterns for Reinforcement following Frontal Traumatic Brain Injury in Rats.
Traumatic brain injury (TBI) is a major contributor to numerous psychiatric conditions and chronic behavioral dysfunction. Recent studies in experimental brain injury have begun to adopt operant methodologies to assess these deficits, all of which rely on the process of reinforcement. No studies have directly examined how reinforced behaviors are affected by TBI, however. ⋯ Further, injured rats were specifically impaired at lower response requirements on the progressive ratio. Taken together, these findings indicate that simple reinforced behaviors are mostly unaffected after TBI, except in the case of variable ratio schedules, but the altered performance on the higher-order progressive ratio schedule suggests changes involving motivation or potentially perseveration. These findings validate operant measures of more complex behaviors for brain injury, all of which rely on reinforcement and can be taken into consideration when adapting and developing novel functional assessments.
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Journal of neurotrauma · Oct 2016
Excitotoxicity and Metabolic Crisis Are Associated with Spreading Depolarizations in Severe Traumatic Brain Injury Patients.
Cerebral microdialysis has enabled the clinical characterization of excitotoxicity (glutamate >10 μM) and non-ischemic metabolic crisis (lactate/pyruvate ratio [LPR] >40) as important components of secondary damage in severe traumatic brain injury (TBI). Spreading depolarizations (SD) are pathological waves that occur in many patients in the days following TBI and, in animal models, cause elevations in extracellular glutamate, increased anaerobic metabolism, and energy substrate depletion. Here, we examined the association of SD with changes in cerebral neurochemistry by placing a microdialysis probe alongside a subdural electrode strip in peri-lesional cortex of 16 TBI patients requiring neurosurgery. ⋯ In patients with SD, both glutamate and LPR increased in a dose-dependent manner with the number of SDs in the microdialysis sampling period (0, 1, ≥2 SD) [glutamate: 2.1→7.0→52.3 μmol/L; LPR: 27.8→29.9→45.0, p values <0.05]. In these patients, there was a 10% probability of SD occurring when glutamate and LPR were in normal ranges, but a 60% probability when both variables were abnormal (>10 μmol/L and >40 μmol/L, respectively). Taken together with previous studies, these preliminary clinical results suggest SDs are a key pathophysiological process of secondary brain injury associated with non-ischemic glutamate excitotoxicity and severe metabolic crisis in severe TBI patients.
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Journal of neurotrauma · Oct 2016
Serum Neurofilament Light in American Football Athletes Over the Course of a Season.
Despite being underreported, American football boasts the highest incidence of concussion among all team sports, likely due to exposure to head impacts that vary in number and magnitude over the season. This study compared a biological marker of head trauma in American football athletes with non-contact sport athletes and examined changes over the course of a season. Baseline serum neurofilament light polypeptide (NFL) was measured after 9 weeks of no contact and compared with a non-contact sport. ⋯ Over the course of the season, an increase (effect size [ES] = 1.8; p < 0.001) was observed post-camp relative to baseline (1.52 ± 1.18 pg•mL-1), which remained elevated until conference play, when a second increase was observed (ES = 2.6; p = 0.008) over baseline (4.82 ± 2.64 pg•mL-1). A lack of change in non-starters resulted in substantial differences between starters and non-starters over the course of the season. These data suggest that a season of collegiate American football is associated with elevations in serum NFL, which is indicative of axonal injury, as a result of head impacts.
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Journal of neurotrauma · Oct 2016
Mechanisms of Head and Neck Injuries Sustained by Helmeted Motorcyclists in Fatal Real-World Crashes: Analysis of 47 In-Depth Cases.
Despite an improved understanding of traumatic head and neck injury mechanisms, the impact tests required by major motorcycle helmet standards have remained unchanged for decades. Development of new test methods must reflect the specific impact loads causing injury in real crashes as well as test criteria appropriate for the observed injury profiles. This study analysed a collection of in-depth crash investigations of fatally injured helmeted riders in the Adelaide metropolitan region between 1983 and 1994 inclusive to review the head and neck injury patterns that resulted from specific types of impact. ⋯ Motorcycle helmets are effective for preventing local skull fractures in impacts for which they are designed, whereas other serious injuries such as basilar skull fracture (BSF) and inertial brain injury persist despite helmet protection. Further impact test procedures should be developed for injurious impact types not currently assessed by major helmet standards, in particular facial impacts, and using test criteria based on commonly observed injuries. This study provides the necessary link, from impact load to injury, for guiding impact test development.
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Journal of neurotrauma · Oct 2016
Reliability and Validity of the Therapy Intensity Level Scale: Analysis of Clinimetric Properties of a Novel Approach to Assess Management of Intracranial Pressure in Traumatic Brain Injury.
We aimed to assess the reliability and validity of the Therapy Intensity Level scale (TIL) for intracranial pressure (ICP) management. We reviewed the medical records of 31 patients with traumatic brain injury (TBI) in two European intensive care units (ICUs). The ICP TIL was derived over a 4-day period for 4-h (TIL4) and 24-h epochs (TIL24). ⋯ The results were consistent with the expected direction. A linear mixed effect analysis, accounting for within-subjects repeated measures, showed strong correlation between TIL4 and 4-h ICP (p < 0.0000005). The TIL scale is a reliable measurement instrument with a high degree of validity for assessing the therapeutic intensity level of ICP management in patients with TBI.