Journal of neurotrauma
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Journal of neurotrauma · Oct 2008
Brain tissue oxygen pressure monitoring in awake patients during functional neurosurgery: the assessment of normal values.
Local brain tissue oxygen (ptiO2) monitoring is frequently applied in patients at risk for cerebral ischemia. To identify ischemic thresholds, the normal range of local brain tissue oxygen pressure (ptiO2) values needs to be established. Ideally, such normal values are determined in healthy and awake subjects, so as to eliminate the possible influences of anesthetics on cerebral physiology or ptiO2. ⋯ No iatrogenic complications occurred. In conclusion, the normal ptiO2 of cerebral white matter is most likely lower than previously assumed. Further, the long adaptation time renders this widely applied monitoring instrument unreliable in detecting ischemia early after insertion and limits its usefulness for intraoperative monitoring.
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Journal of neurotrauma · Oct 2008
Computer-aided assessment of head computed tomography (CT) studies in patients with suspected traumatic brain injury.
In this study, we sought to determine the accuracy of a computer algorithm that automatically assesses head computed tomography (CT) studies in patients with suspected traumatic brain injury (TBI) for features of intracranial hemorrhage and mass effect, employing a neuroradiologist's interpretation as the gold standard. To this end, we designed a suite of computer algorithms that evaluates in a fully automated fashion the presence of intracranial blood and/or mass effect based on the following CT findings: (1) presence or absence of a subdural or epidural hematoma, (2) presence or absence of subarachnoid hemorrhage, (3) presence or absence of an intraparenchymal hematoma, (4) presence or absence of clinically significant midline shift (>or=5 mm), and (5) normal, partly effaced, or completely effaced basal cisterns. The algorithm displays abnormal findings as color overlays on the original head CT images, and calculates the volume of each type of blood collection, the midline shift, and the volume of the basal cisterns, based on the above-described features. ⋯ The software was excellent at detecting the presence of mass effect and intracranial hemorrhage, but showed some disagreements with the neuroradiologist in quantifying the degree of mass effect and characterizing the type of intracranial hemorrhage. In summary, we have developed a fully automated computer algorithm that demonstrated excellent sensitivity for acute intracranial hemorrhage and clinically significant midline shift, while maintaining intermediate specificity. Further studies are required to evaluate the potential favorable impact of this software on facilitating workflow and improving diagnostic accuracy when used as a screening aid by physicians with different levels of experience.
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Journal of neurotrauma · Oct 2008
CYP4Fs expression in rat brain correlates with changes in LTB4 levels after traumatic brain injury.
Cytochrome P450 (CYP) 4Fs constitute a subgroup of the cytochrome P450 superfamily and are involved in cellular protection and metabolism of numerous molecules, including drugs, toxins, and eicosanoids. CYP4Fs are widely distributed in rat brain with each isoform having a unique distribution pattern throughout different brain regions. The present study shows that traumatic brain injury (TBI) triggers inflammation and elicits changes in mRNA expression of CYP4Fs in the frontal and occipital lobes and the hippocampus. ⋯ These changes in CYP4F levels inversely correlate with levels of leukotriene B4 (LTB4) levels in the brain following injury at the same time points. TBI also causes changes in CYP4F protein expression and localization around the injury site. CYP4F1 and CYP4F6 immunoreactivity increases in surrounding astrocytes, while CYP4F4 immunoreactivity shifts from endothelia of cerebral vessels to astrocytes.
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Journal of neurotrauma · Sep 2008
Comparative StudyFocal lesions in acute mild traumatic brain injury and neurocognitive outcome: CT versus 3T MRI.
Mild traumatic brain injury (mTBI) is associated with long-term cognitive deficits. This study compared the detection rate of acute post-traumatic focal lesions on computed tomography (CT) and 3T (Tesla) magnetic resonance (MR) imaging with neurocognitive outcomes. Adults (n = 36; age range, 19-52 years) with a single episode of mTBI (Glasgow Coma Scale 13-15, as well as loss of consciousness and post-traumatic amnesia) were prospectively enrolled and had CT within 24 h of injury and 3T MR within 2 weeks of injury. ⋯ Mild TBI patients had significantly worse performance on working memory tasks than matched controls at the acute time point (<2 weeks), and at 1 month and at 1 year post-injury; yet there was no significant correlation of imaging findings with working memory impairment. In conclusion, 3T MR detected parenchymal lesions in 75% of this mTBI cohort with loss of consciousness and post-traumatic amnesia, a much higher rate than CT. However, the CT and 3T MR imaging findings did not account for cognitive impairment, suggesting that newer imaging techniques such as diffusion tensor imaging are needed to provide biomarkers for neurocognitive and functional outcome in mTBI.
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Journal of neurotrauma · Sep 2008
Simple dual tasking recruits prefrontal cortices in chronic severe traumatic brain injury patients, but not in controls.
The ability to carry out two tasks simultaneously, dual tasking, is specifically impaired after traumatic brain injury (TBI). The aim of the present study was to investigate the neuronal correlates to this increased dual cost in chronic severe TBI patients (n = 10) compared to healthy controls (n = 11) using functional magnetic resonance imaging (fMRI) at 3 Tesla (T). The tasks were a visual search and a simple two-fingers button press motor task. ⋯ This finding points to substitution, functional reorganization within the primary network subserving the task, following TBI, and demonstrates more effortful processing. Recruitment of these additional prefrontal resources may be connected to serial rather than parallel processing in low level dual tasking in TBI. Thus, in severe TBI, low level dual task performance depends on increased attentional and executive guidance.