Traumatic Brain Injury

Mild traumatic brain injury from primary blast vs. blunt forces: Post-concussion consequences and functional neuroimaging

Authors: Mendez MF, Owens EM, Reza Berenji G, Peppers DC, Liang LJ, Licht EA.

INTRODUCTION: Primary blast forces may cause dysfunction from mild traumatic brain injury (mTBI).
OBJECTIVE: To investigate the effects of primary blast forces, independent of associated blunt trauma and post-traumatic stress disorder, on sensitive post-concussive measures.
METHODS: This study investigated post-concussive symptoms, functional health and well-being, cognition, and positron emission tomography (PET) neuroimaging among 12 Iraq or Afghanistan war veterans who sustained pure blast-force mTBI, compared to 12 who sustained pure blunt-force mTBI.
RESULTS: Both groups had significantly lower scores than published norms on the Rivermead Post-Concussion Questionnaire (RPQ) and the SF36-V Health Survey. Compared to the Blunt Group, the Blast Group had poorer scores on the Paced Auditory Serial Addition Test (PASAT) and greater PET hypometabolism in the right superior parietal region. Only the Blast Group had significant correlations of their RPQ, SF36-V Mental Composite Score, and PASAT scores with specific regional metabolic changes.
CONCLUSION: This pilot study suggests that pure blast force mTBI may have greater post-concussive sequelae including deficits in attentional control and regional brain metabolism, compared to blunt mTBI. A disturbance of a right parietal-frontal attentional network is one potential explanation for these findings.

Pediatric traumatic brain injury in 2012: the year with new guidelines and common data elements

Authors: Bell MJ, Kochanek PM.

Traumatic brain injury (TBI) remains the leading cause of death of children in the developing world. In 2012, several international efforts were completed to aid clinicians and researchers in advancing the field of pediatric TBI. The second edition of the Guidelines for the Medical Management of Traumatic Brain Injury in Infants, Children and Adolescents updated those published in 2003. This article highlights the processes involved in developing the Guidelines, contrasts the new guidelines with the previous edition, and delineates new research efforts needed to advance knowledge. The impact of common data elements within these potential new research fields is reviewed.

Postconcussion Syndrome After Mild Traumatic Brain Injury in Children and Adolescents Requires Further Detailed Study

Author: Butler IJ.

OBJECTIVE:  To determine the acute predictors associated with the development of postconcussion syndrome (PCS) in children and adolescents after mild traumatic brain injury. DESIGN:  Retrospective analysis of a prospective observational study. SETTING:  Pediatric emergency department (ED) in a children's hospital. PARTICIPANTS:  Four hundred six children and adolescents aged 5 to 18 years. MAIN EXPOSURE:  Closed head trauma. MAIN OUTCOME MEASURES:  The Rivermead Post Concussion Symptoms Questionnaire administered 3 months after the injury. RESULTS:  Of the patients presenting to the ED with mild traumatic brain injury, 29.3% developed PCS. The most frequent PCS symptom was headache. Predictors of PCS, while controlling for other factors, were being of adolescent age, headache on presentation to the ED, and admission to the hospital. Patients who developed PCS missed a mean (SD) of 7.4 (13.9) days of school. CONCLUSIONS:  Adolescents who have headache on ED presentation and require hospital admission at the ED encounter are at elevated risk for PCS after mild traumatic brain injury. Interventions to identify this population and begin early treatment may improve outcomes and reduce the burden of disease.

A prospective, randomized Phase II clinical trial to evaluate the effect of combined hyperbaric and normobaric hyperoxia on cerebral metabolism, intracranial pressure, oxygen toxicity, and clinical outcome in severe traumatic brain injury

Authors: Rockswold SB, Rockswold GL, Zaun DA, Liu J.

Object: Preclinical and clinical investigations indicate that the positive effect of hyperbaric oxygen (HBO2) for severe traumatic brain injury (TBI) occurs after rather than during treatment. The brain appears better able to use baseline O2 levels following HBO2 treatments. In this study, the authors evaluate the combination of HBO2 and normobaric hyperoxia (NBH) as a single treatment.

Methods: Forty-two patients who sustained severe TBI (mean Glasgow Coma Scale score 5.7) were prospectively randomized within 24 hours of injury to either: 1) combined HBO2/NBH (60 minutes of HBO2 at 1.5 atmospheres absolute followed by NBH, 3 hours of 100% fraction of inspired oxygen at 1.0 ATA) or 2) control, standard care. Treatments occurred once every 24 hours for 3 consecutive days. Intracranial pressure, surrogate markers for cerebral metabolism, and O2 toxicity were monitored. Clinical outcome was assessed at 6 months using the sliding dichotomized Glasgow Outcome Scale (GOS) score. Mixed-effects linear modeling was used to statistically test differences between the treatment and control groups. Functional outcome and mortality rates were compared using chi-square tests. 

Consequences of the dynamic triple peak impact factor in Traumatic Brain Injury as Measured with Numerical Simulation

Authors: von Holst H, Li X.

There is a lack of knowledge about the direct neuromechanical consequences in traumatic brain injury (TBI) at the scene of accident. In this study we use a finite element model of the human head to study the dynamic response of the brain during the first milliseconds after the impact with velocities of 10, 6, and 2 meters/second (m/s), respectively. The numerical simulation was focused on the external kinetic energy transfer, intracranial pressure (ICP), strain energy density and first principal strain level, and their respective impacts to the brain tissue. We show that the oblique impacts of 10 and 6 m/s resulted in substantial high peaks for the ICP, strain energy density, and first principal strain levels, however, with different patterns and time frames. Also, the 2 m/s impact showed almost no increase in the above mentioned investigated parameters. More importantly, we show that there clearly exists a dynamic triple peak impact factor to the brain tissue immediately after the impact regardless of injury severity associated with different impact velocities. The dynamic triple peak impacts occurred in a sequential manner first showing strain energy density and ICP and then followed by first principal strain. This should open up a new dimension to better understand the complex mechanisms underlying TBI. Thus, it is suggested that the combination of the dynamic triple peak impacts to the brain tissue may interfere with the cerebral metabolism relative to the impact severity thereby having the potential to differentiate between severe and moderate TBI from mild TBI.

Timing of Intracranial Hypertension Following Severe Traumatic Brain Injury

Authors: Stein DM, Brenner M, Hu PF, Yang S, Hall EC, Stansbury LG, Menaker J, Scalea TM.

BACKGROUND: We asked whether continuous intracranial pressure (ICP) monitoring data could provide objective measures of the degree and timing of intracranial hypertension (ICH) in the first week of neurotrauma critical care and whether such data could be linked to outcome.
METHODS: We enrolled adult (>17 years old) patients admitted to our Level I trauma center within 6 h of severe TBI. ICP data were automatically captured and ICP 5-minute means were grouped into 12-hour time periods from admission (hour 0) to >7 days (hour 180). Means, maximum, percent time (% time), and pressure-times-time dose (PTD, mmHg h) of ICP >20 mmHg and >30 mmHg were calculated for each time period.
RESULTS: From 2008 to 2010, we enrolled 191 patients. Only 2.1 % had no episodes of ICH. The timing of maximum PTD20 was relatively equally distributed across the 15 time periods. Median ICP, PTD20, %time20, and %time30 were all significantly higher in the 84-180 h time period than the 0-84 h time period. Stratified by functional outcome, those with poor functional outcome had significantly more ICH in hours 84-180. Multivariate analysis revealed that, after 84 h of monitoring, every 5 % increase in PTD20 was independently associated with 21 % higher odds of having a poor functional outcome (adjusted odds ratio = 1.21, 95 % CI 1.02-1.42, p = 0.03).
CONCLUSIONS: Although early elevations in ICP occur, ICPs are the highest later in the hospital course than previously understood, and temporal patterns of ICP elevation are associated with functional outcome. Understanding this temporal nature of secondary insults has significant implications for management.

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