Journal of neurotrauma
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Journal of neurotrauma · Oct 2017
Functional and molecular correlates following single and repeated rat closed-head concussion; indices of vulnerability following brain injury.
Closed-head concussive injury is one of the most common causes of traumatic brain injury (TBI). Isolated concussions frequently produce acute neurological impairments, and individuals typically recover spontaneously within a short time frame. In contrast, brain injuries resulting from multiple concussions can result in cumulative damage and elevated risk of developing chronic brain pathologies. ⋯ Acute changes in molecular signatures correlated with behavioral impairments, whereas increased times to regaining consciousness and balance impairments were associated with higher GFAP and neuroinflammation. Overall, behavioral consequences of either single or repeated concussive impact injuries appeared to resolve more quickly than the underlying molecular, metabolic, and neuropathological abnormalities. This observation, which is supported by similar studies in other mTBI models, underscores the critical need to develop more objective prognostic measures for guiding return-to-play decisions.
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Journal of neurotrauma · Oct 2017
Early asymmetric cardio-cerebral causality and outcome after severe traumatic brain injury.
The brain and heart are two vital systems in health and disease, increasingly recognized as a complex, interdependent network with constant information flow in both directions. After severe traumatic brain injury (TBI), the causal, directed interactions between the brain, heart, and autonomic nervous system have not been well established. Novel methods are needed to probe unmeasured, potentially prognostic information in complex biological networks that are not revealed by traditional means. ⋯ Those who died had significantly lower GC for ICP causing MAP and HR causing ICP (p = 0.006 and p = 0.004, respectively) and were predictors of mortality independent of age, sex, and traditional intracranial variables (ICP, cerebral perfusion pressure, GCS, and pressure reactivity index). Examining the brain and heart with GC-based features for the first time in severe TBI patients has confirmed strong interdependence and reveals a significant relationship between select causality pairs and mortality. These results support the notion that impaired causal information flow between the cerebrovascular, autonomic, and cardiovascular systems are of central importance in severe TBI.
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Journal of neurotrauma · Oct 2017
The Relationship between Cerebral Vasoreactivity and Post-Concussive Symptom Severity.
While pathophysiology underlying post-concussion symptom burden is unknown, data suggest that cerebrovascular dysfunction may be among the culprits. We sought to determine whether the degree of impairment in the ability of cerebrovasculature to buffer against changes in arterial gases (vasoreactivity) is associated with concussion symptoms. In 15 participants (19 ± 5 years, 1 week to 1 year post-injury) diagnosed with concussion, we assessed vasoreactivity from the slope of the linear relationship of beat-by-beat middle cerebral artery blood flow velocity (transcranial Doppler ultrasound) to end-tidal CO2 during progressive increases in end-tidal CO2 (air rebreathing). ⋯ Higher vasoreactivity was strongly associated with more severe headaches (R2 = 0.57; p < 0.01) and worse cognitive symptoms (R2 = 0.71; p < 0.01). Thus, cerebral vasoreactivity relates strongly to post-concussive headache and cognitive symptom burden. This has significant implications for understanding the pathophysiology underlying post-concussive symptom burden and for devising effective treatment options.
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Journal of neurotrauma · Oct 2017
Does normobaric hyperoxia cause oxidative stress in the injured brain? A microdialysis study using 8-iso-PGF2α as a biomarker.
Significant controversy exists regarding the potential clinical benefit of normobaric hyperoxia (NBO) in patients with traumatic brain injury (TBI). This study consisted of two aims: 1) to assess whether NBO improves brain oxygenation and metabolism and 2) to determine whether this therapy may increase the risk of oxidative stress (OxS), using 8-iso-Prostaglandin F2α (PGF2α) as a biomarker. Thirty-one patients with a median admission Glasgow Coma Scale score of 4 (min: 3, max: 12) were monitored with cerebral microdialysis and brain tissue oxygen sensors and treated with fraction of inspired oxygen (FiO2) of 1.0 for 4 h. ⋯ In the five patients with brain lactate concentration ([Lac]brain) > 3.5 mmol/L at baseline, NBO induced a marked reduction in both [Lac]brain and lactate-to-pyruvate ratio. Although these differences were not statistically significant, together with the results of our previous study, they suggest that TBI patients would benefit from receiving NBO when they show indications of disturbed brain metabolism. These findings, in combination with increasing evidence that TBI metabolic crises are common without brain ischemia, open new possibilities for the use of this accessible therapeutic strategy in TBI patients.
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Journal of neurotrauma · Oct 2017
Focal electroencephalographic changes index post-traumatic confusion and outcome.
While the duration and severity of post-traumatic confusional state (PTCS) after traumatic brain injury have well-established implications for long-term outcomes, little is known about the underlying pathophysiology and their role in functional outcomes. Here, we analyzed the delta-to-alpha frequency band power ratios (DAR) from localized scalp areas derived from standard resting electroencephalographic (EEG) data recorded during eyes closed state in 49 patients diagnosed with PTCS. Higher global, occipital, parietal, and temporal DARs were significantly associated with the severity of PTCS, as assessed by the Confusion Assessment Protocol (CAP) observed on the same day, after controlling for injury severity. ⋯ Our finding that posterior DAR is a marker of PTCS and functional recovery post-injury, likely reflects functional de-afferentation of the posterior medial complex (PMC) in PTCS. Altered function of the PMC is proposed as a unifying physiological mechanism underlying both acute and chronic confusional states. We discuss the relationship of these findings to electrophysiological markers associated with disorders of consciousness.