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
Ventilator Associated Pneumonia in Pediatric Traumatic Brain Injury.
Ventilator-associated pneumonia (VAP) is a common occurrence among intubated pediatric traumatic brain injury (TBI) patients. However, little is known about the epidemiology, risk factors, and microbiology of VAP in pediatric TBI. We reviewed a cohort of 119 pediatric moderate-to-severe TBI patients and identified 42 with VAP by positive protected bronchial brush specimens. ⋯ Methicillin-sensitive Staphylococcus aureus (34%), Haemophilus influenzae (22%), and Streptococcus pneumoniae (15%) were the most common organisms, comprising 71% of isolated pathogens (36% of infections were polymicrobial). Patients with VAP had significantly longer intensive care unit and hospital stays, as well as increased risk of chronic care needs after discharge, but not mortality. VAP is a common occurrence in pediatric TBI patients, and early empiric therapy for patients requiring barbiturate infusion, NMBA, or use of a cooling blanket could mitigate morbidity.
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Journal of neurotrauma · May 2016
Vagus nerve stimulation delivered with motor training enhances recovery of function after traumatic brain injury.
Traumatic Brain Injury (TBI) is one of the largest health problems in the United States, and affects nearly 2 million people every year. The effects of TBI, including weakness and loss of coordination, can be debilitating and last years after the initial injury. Recovery of motor function is often incomplete. ⋯ VNS paired with rehabilitative therapy over a period of 5 weeks significantly increased recovery of both forelimb strength and success rate on the isometric pull task compared with rehabilitative training without VNS. No significant improvement was observed in the Rehab group. Our findings indicate that VNS paired with rehabilitative therapy enhances functional motor recovery after TBI.
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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.