Journal of neurotrauma
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Journal of neurotrauma · Jan 2014
Randomized Controlled TrialInvestigating the Properties of the Hemodynamic Response Function Following Mild Traumatic Brain Injury.
Abstract Although several functional magnetic resonance imaging (fMRI) studies have been conducted in human models of mild traumatic brain injury (mTBI), to date no studies have explicitly examined how injury may differentially affect both the positive phase of the hemodynamic response function (HRF) as well as the post-stimulus undershoot (PSU). Animal models suggest that the acute and semi-acute stages of mTBI are associated with significant disruptions in metabolism and to the microvasculature, both of which could impact on the HRF. Therefore, fMRI data were collected on a cohort of 30 semi-acute patients with mTBI (16 males; 27.83±9.97 years old; 13.00±2.18 years of education) and 30 carefully matched healthy controls (HC; 16 males; 27.17±10.08 years old; 13.37±2.31 years of education) during a simple sensory-motor task. ⋯ The interaction was the result of an earlier time-to-peak and positive magnitude shift throughout the estimated HRF in patients with mTBI relative to HC. This difference in HRF shape combined with the greater volume of activated tissue may be indicative of a potential compensatory mechanism to injury. The current study demonstrates that direct examination and modeling of HRF characteristics beyond magnitude may provide additional information about underlying neuropathology that is not available with more standard fMRI analyses.
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Journal of neurotrauma · Jan 2014
Comparative StudyTo Exclude or Not to Exclude: Further Examination of the Influence of White Matter Hyperintensities in Diffusion Tensor Imaging Research.
White matter hyperintensities (WMHIs) visible on magnetic resonance imaging (MRI) are common in both healthy adults and in those with medical or psychiatric problems. A practical methodological issue for diffusion tensor imaging (DTI) researchers is whether to include, or exclude, participants from a control group who have WMHIs. The aim of this study was to compare the influence of WMHIs on whole-brain DTI in trauma control subjects. ⋯ In the entire sample, the 2+WMHI group had a greater number of abnormal FA, MD, and RD scores, compared to the no-WMHI group (p<0.015 and Cohen's d >0.82, indicating large to very large effect sizes, for all comparisons). When controlling for the effects of age using a matched-groups design, the 2+WMHI group still had a significantly greater number of abnormal FA, MD, and RD scores, compared to the no-WMHI group (all p<0.012, all d >0.89, large to very large effect sizes). Researchers should be aware that the inclusion or exclusion of subjects with incidental WMHIs will influence the results of DTI studies.
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Journal of neurotrauma · Jan 2014
Comparative StudyInfluences of developmental age on the resolution of diffuse traumatic intracranial hemorrhage and axonal injury.
This study investigated the age-dependent injury response of diffuse traumatic axonal injury (TAI) and regional subdural and subarachnoid intracranial hemorrhage (ICH) in two pediatric age groups using a porcine head injury model. Fifty-five 5-day-old and 40 four-week-old piglets-which developmentally correspond to infants and toddlers, respectively-underwent either a sham injury or a single rapid non-impact rotational injury in the sagittal plane and were grouped by post-TBI survival time (sham, 3-8 h, one day, 3-4 days, and 5-6 days). Both age groups exhibited similar initial levels of ICH and a significant reduction of ICH over time (p<0.0001). ⋯ Both ages also exhibited similar resolution of axonal injury with a peak in TAI at one day post-injury (p<0.03) and significantly elevated levels even at 5-6 days after the injury (p<0.008), which suggests a window of vulnerability to a second insult at one day post-injury that may extend for a prolonged period of time. However, five-day-old piglets had significantly more TAI than four-week-olds overall (p=0.016), which presents some evidence for an increased vulnerability to brain injury in this age group. These results provide insight into an optimal window for clinical intervention, the period of increased susceptibility to a second injury, and an age dependency in brain injury tolerance within the pediatric population.
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Journal of neurotrauma · Jan 2014
ReviewA Systematic Review of Proton Magnetic Resonance Spectroscopy in Sport-Related Concussion.
Traditional structural neuroimaging techniques are normal in athletes who sustain sport-related concussions and are only considered to be clinically helpful in ruling out a more serious brain injury. There is a clinical need for more sophisticated, non-invasive imaging techniques capable of detecting changes in neurophysiology after injury. Concussion is associated with neurometabolic changes including neuronal depolarization, release of excitatory neurotransmitters, ionic shifts, changes in glucose metabolism, altered cerebral blood flow, and impaired axonal function. ⋯ Nine of 11 studies reported a MRS abnormality consistent with an alteration in neurochemistry. The results support the use of MRS as a research tool for identifying altered neurophysiology and monitoring recovery in adult athletes, even beyond the resolution of post-concussive symptoms and other investigation techniques returning to normative levels. Larger cross-sectional, prospective, and longitudinal studies are needed to understand the sensitivity and prognostic value of MRS within the field of sport-related concussion.
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Journal of neurotrauma · Jan 2014
Longitudinal follow-up of patients with traumatic brain injury: Outcome at 2, 5, and 10-years post-injury.
The deleterious consequences of traumatic brain injury (TBI) impair capacity to return to many avenues of pre-morbid life. However, there has been limited longitudinal research examining outcome beyond five years post-injury. The aim of this study was to examine aspects of function, previously shown to be affected following TBI, over a span of 10 years. ⋯ Older age at injury did not substantially alter the pattern of changes over time, except in employment. Overall, problems that were evident at two years post-injury persisted until 10 years post-injury. The importance of these findings is discussed with reference to rehabilitation programs.