Journal of neurotrauma
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Journal of neurotrauma · Aug 2015
Multicenter StudyAbnormal white matter BOLD signals in chronic mild traumatic brain injury.
Concussion, or mild traumatic brain injury (mTBI), can cause persistent behavioral symptoms and cognitive impairment, but it is unclear if this condition is associated with detectable structural or functional brain changes. At two sites, chronic mTBI human subjects with persistent post-concussive symptoms (three months to five years after injury) and age- and education-matched healthy human control subjects underwent extensive neuropsychological and visual tracking eye movement tests. At one site, patients and controls also performed the visual tracking tasks while blood-oxygen-level-dependent (BOLD) signals were measured with functional magnetic resonance imaging. ⋯ In contrast, BOLD signals were normal in cortical regions, such as the frontal eye field and intraparietal sulcus, that mediate oculomotor and attention functions necessary for visual tracking. The abnormal BOLD signals accurately differentiated chronic mTBI patients from healthy controls at the single-subject level, although they did not correlate with symptoms or neuropsychological performance. We conclude that subjects with persistent post-concussive symptoms can be identified years after their TBI using fMRI and an eye movement task despite showing normal structural MRI and DTI.
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Journal of neurotrauma · Aug 2015
Mortality following traumatic brain injury inpatient rehabilitation.
The aim of this study was to examine the rate and causes of mortality following mild to severe traumatic brain injury (TBI) rehabilitation and to develop a multivariate prognostic model of mortality. We conducted a cohort study of 3341 individuals with mild to severe TBI followed-up from a post-acute inpatient rehabilitation center. Rate of death and survival between one and 26 years following injury were examined using standardized mortality ratios (SMRs) and prognostic models developed using Cox regression. ⋯ Premorbid lifestyle factors exerted a greater influence on mortality following TBI, compared with injury-related factors. This risk was especially prominent for younger individuals, who died primarily due to external causes. These findings highlight the need for interventions that address premorbid issues, such as substance abuse and mental health issues.
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Journal of neurotrauma · Aug 2015
Procedures for the comparative testing of noninvasive neuroassessment devices.
A sequential process for comparison testing of noninvasive neuroassessment devices is presented. Comparison testing of devices in a clinical population should be preceded by computational research and reliability testing with healthy populations, as opposed to proceeding immediately to testing with clinical participants. A five-step process is outlined as follows: 1. Complete a preliminary literature review identifying candidate measures. 2. Conduct systematic simulation studies to determine the computational properties and data requirements of candidate measures. 3. Establish the test-retest reliability of each measure in a healthy comparison population and the clinical population of interest. 4. Investigate the clinical validity of reliable measures in appropriately defined clinical populations. 5. Complete device usability assessment (weight, simplicity of use, cost effectiveness, ruggedness) only for devices and measures that are promising after steps 1 through 4 are completed. Usability may be considered throughout the device evaluation process but such considerations are subordinate to the higher priorities addressed in steps 1 through 4.
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Journal of neurotrauma · Aug 2015
Neurotransmitter systems in a mild blast traumatic brain injury model: catecholamines and serotonin.
Exposure to improvised explosive devices can result in a unique form of traumatic brain injury--blast-induced traumatic brain injury (bTBI). At the mild end of the spectrum (mild bTBI [mbTBI]), there are cognitive and mood disturbances. Similar symptoms have been observed in post-traumatic stress disorder caused by exposure to extreme psychological stress without physical injury. ⋯ Using in situ hybridization, we found elevated messenger ribonucleic acid levels of both tyrosine hydroxylase and tryptophan hydroxylase 2 in the locus coeruleus and the dorsal raphe nucleus, respectively, as early as 2 h post-exposure. High-performance liquid chromatography analysis 1 d post-exposure primarily showed elevated noradrenaline levels in several forebrain regions. Taken together, we report that exposure to mild blast results in transient changes in both anxiety-like behavior and brain region-specific molecular changes, implicating the monoaminergic system in the pathobiology of mbTBI.
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Journal of neurotrauma · Aug 2015
Acute Temporal Profiles of serum levels of UCH-L1 and GFAP and Relationships to Neuronal and Astroglial Pathology Following Traumatic Brain Injury in Rats.
A number of potential traumatic brain injury (TBI) biomarkers have been proposed and evaluated in the laboratory and clinic. This study investigated the temporal profile of circulating biomarkers of astrocytic and neuronal injury over the first 24 h and relevant histopathological changes after experimental moderate TBI. Twenty male rats were randomly assigned to either moderate parasagittal fluid percussion or sham injury. ⋯ Histology revealed characteristic acute neuronal degeneration in the ipsilateral hippocampus and parietal cortex and reduction in GFAP immunostaining in areas of neuronal cell loss. The data provide evidence of a causal relationship between TBI-induced acute brain pathology and circulating neuronal and glial markers, further demonstrating their role as candidate markers for TBI. Studies of relative changes in biomarker levels in CSF and serum suggest that different mechanisms may underlie the transport and/or clearance of UCH-L1 and GFAP in these two compartments.