Journal of neurotrauma
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Journal of neurotrauma · May 2016
Nodal versus Total Axonal Strain and the Role of Cholesterol in Traumatic Brain Injury.
Traumatic brain injury (TBI) is a health threat that affects every year millions of people involved in motor vehicle and sporting accidents, and thousands of soldiers in battlefields. Diffuse axonal injury (DAI) is one of the most frequent types of TBI leading to death. In DAI, the initial traumatic event is followed by a cascade of biochemical changes that take time to develop in full, so that symptoms may not become apparent until days or weeks after the original injury. ⋯ Here, we present preliminary evidence from micro-finite element (FE) simulations that the mechanical response of central nervous system myelinated fibers is dependent on the axonal diameter, the ratio between axon diameter and fiber diameter (g-ratio), the microtubules density, and the cholesterol concentration in the axolemma and myelin. A key outcome of the simulations is that there is a significant difference between the overall level of strain in a given axonal segment and the level of local strain in the Ranvier nodes contained in that segment, with the nodal strain being much larger than the total strain. We suggest that the acquisition of this geometric and biochemical information by means of already available high resolution magnetic resonance imaging techniques, and its incorporation in current FE models of the brain will enhance the models capacity to predict the site and magnitude of primary axonal damage upon TBI.
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Journal of neurotrauma · May 2016
Suppression of Serum Prolactin Levels after Sports Concussion with Prompt Resolution upon Independent Clinical Assessment to Permit Return-to-Play.
A significant outflow of neurotransmitters and metabolites with associated enhanced cortical excitation occurs after concussive head trauma. Cellular changes in the acute post-injury period cannot be observed directly in humans, and as such, require indirect evidence from systems sufficiently sensitive to central neuronal cellular excitation. Dopamine is a neurotransmitter with numerous targets in the central and peripheral nervous system. ⋯ These serum PRL changes accompanied the resolution of symptoms and the clinical decision to permit return-to-play. It may be postulated that transient augmentation of central dopaminergic tone resulted in inhibition of PRL secretion early after concussion and that disinhibition of PRL release occurred when central dopaminergic tone subsequently returned to baseline levels. This novel observation provides evidence for dopaminergic dysfunction after concussion that may be tracked by determination of serum PRL levels.
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Journal of neurotrauma · May 2016
Neuroimaging biomarkers of a history of concussion observed in asymptomatic young athletes.
Participation in contact sports places athletes at elevated risk for repeated head injuries and is associated with negative mental health outcomes later in life. The current study identified changes observable on neuroimaging that persisted beyond the apparent resolution of acute symptoms of concussion. Sixteen young adult ice hockey players with a remote history of concussion but no subjective complaints were compared against 13 of their teammates with no history of concussion. ⋯ Athletes with concussion history also showed significant differences in the organization of the default mode network (DMN) characterized by stronger temporal coherence in posterior DMN, decreased temporal coherence in anterior DMN, and increased functional connectivity outside the DMN. In the absence of deficits on detailed phenotypic assessment, athletes with a history of concussion displayed changes to the microstructural architecture of the cerebral white matter and to the functional connectivity of the brain at rest. Some of these changes are consistent with those previously associated with persisting deficits and complaints, but we also report novel, complementary changes that possibly represent compensatory mechanisms.
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Journal of neurotrauma · May 2016
Performance of male and female C57BL/6J mice on motor and cognitive tasks commonly used in pre-clinical traumatic brain injury research.
To date, clinical trials have failed to find an effective therapy for victims of traumatic brain injury (TBI) who live with motor, cognitive, and psychiatric complaints. Pre-clinical investigators are now encouraged to include male and female subjects in all translational research, which is of particular interest in the field of neurotrauma given that circulating female hormones (progesterone and estrogen) have been demonstrated to exert neuroprotective effects. To determine whether behavior of male and female C57BL6/J mice is differentially impaired by TBI, male and cycling female mice were injured by controlled cortical impact and tested for several weeks with functional assessments commonly employed in pre-clinical research. ⋯ Female mice were generally more active, as evidenced by greater distance traveled in the first exposure to the open field, greater distance in the y-maze, and faster swimming speeds in the MWM. Statistical analysis showed that variability in all behavioral data was no greater in cycling female mice than it was in male mice. These data all suggest that with careful selection of tests, procedures, and measurements, both sexes can be included in translational TBI research without concern for effect of hormones on functional impairments or behavioral variability.
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Journal of neurotrauma · Apr 2016
Recovery from Mild Traumatic Brain Injury in Previously Healthy Adults.
This prospective longitudinal study reports recovery from mild traumatic brain injury (MTBI) across multiple domains in a carefully selected consecutive sample of 74 previously healthy adults. The patients with MTBI and 40 orthopedic controls (i.e., ankle injuries) completed assessments at 1, 6, and 12 months after injury. Outcome measures included cognition, post-concussion symptoms, depression, traumatic stress, quality of life, satisfaction with life, resilience, and return to work. ⋯ A large percentage of the subgroup who had persistent symptoms had a modifiable psychological risk factor at 1 month (i.e., depression, traumatic stress, and/or low resilience), and at 6 months, they had greater post-concussion symptoms, fatigue, insomnia, traumatic stress, and depression, and worse quality of life. All of the control subjects who had mild post-concussion-like symptoms at 12 months also had a mental health problem (i.e., depression, traumatic stress, or both). This illustrates the importance of providing evidence-supported treatment and rehabilitation services early in the recovery period.