Journal of neurotrauma
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Journal of neurotrauma · Jun 2016
Environmental Enrichment Attenuates Traumatic Brain Injury-Induced Neuronal Hyperexcitability in Supragranular Layers of Sensory Cortex.
We have previously demonstrated that traumatic brain injury (TBI) induces significant long-term neuronal hyperexcitability in supragranular layers of sensory cortex, coupled with persistent sensory deficits. Hence, we aimed to investigate whether brain plasticity induced by environmental enrichment (EE) could attenuate abnormal neuronal and sensory function post-TBI. TBI (n = 22) and sham control (n = 21) animals were randomly assigned housing in either single or enriched conditions for 7-9 weeks. ⋯ However, single-cell responses demonstrated EE-induced hypoexcitation in L4 post-TBI. EE was also able to fully ameliorate sensory hypersensitivity post-TBI, although it was not found to improve motor function. Long-term enrichment post-TBI induces changes at both the population and single-cell level in the sensory cortex, where EE may act to restore the excitation/inhibition balance in supragranular cortical layers.
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Journal of neurotrauma · May 2016
Multidimensional Analysis of MRI Predicts Early Impairment in Thoracic and Thoracolumbar Spinal Cord Injury.
Literature examining magnetic resonance imaging (MRI) in acute spinal cord injury (SCI) has focused on cervical SCI. Reproducible systems have been developed for MRI-based grading; however, it is unclear how they apply to thoracic SCI. Our hypothesis is that MRI measures will group as coherent multivariate principal component (PC) ensembles, and that distinct PCs and individual variables will show discriminant validity for predicting early impairment in thoracic SCI. ⋯ Variables of signal abnormality were all negatively correlated with AIS at discharge with the highest level of correlation for axial grade as assessed with the Brain and Spinal Injury Center (BASIC) score. A multiple variable model identified BASIC as the only statistically significant predictor of AIS at discharge, signifying that BASIC best captured the variance in AIS within our study population. Our study provides evidence of convergent validity, construct validity, and clinical predictive validity for the sampled MRI measures of SCI when applied in acute thoracic and thoracolumbar SCI.
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Journal of neurotrauma · May 2016
Defining the Pathway to Definitive Care and Surgical Decompression after Traumatic Spinal Cord Injury: Results of a Canadian Population Based Cohort Study.
Early access to specialized care after acute traumatic spinal cord injury (SCI) is associated with improved outcomes. However, many SCI patients do not receive timely access to such care. To characterize and quantify patients' pathway to definitive care and surgery post SCI, and to identify factors that may delay expeditious care, a population based cohort study was performed in Ontario. ⋯ Older age (IRR = 1.01; 95% CI: 1.01, 1.02), increased number of stops at intermediate health care centers (IRR = 7.70; 95% CI: 7.54, 7.86), higher comorbidity index (IRR = 1.43; 95% CI: 1.14, 1.72) and fall related SCI etiology (IRR = 1.16; 95% CI: 1.02, 1.29) were associated with increased time to arrival at definitive care. For surgery, increased age (OR = 1.02; 95% CI: 1.01, 1.03) and stops at intermediate health centers (OR = 2.48; 95% CI: 1.35, 4.56) were associated with a greater odds of undergoing late surgery (>24hrs). These results can inform policy decisions and facilitate creation of a streamlined path to specialized care for patients with acute SCI.
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Journal of neurotrauma · May 2016
Diffusion Weighted MRI Characterization of White Matter Injury Produced by Axon-sparing Demyelination and Severe Contusion Spinal Cord Injury in Rats.
Alterations in magnetic resonance imaging (MRI)-derived measurements of water diffusion parallel (D∥) and perpendicular (D⊥) to white matter tracts have been specifically attributed to pathology of axons and myelin, respectively. We test the hypothesis that directional diffusion measurements can distinguish between axon-sparing chemical demyelination and severe contusion spinal cord white matter injury. Adult rats received either unilateral ethidium bromide (EB) microinjections (chemical demyelination) into the lateral funiculus of the spinal cord at C5 or were subjected to unilateral severe contusion spinal cord injury (SCI). ⋯ In the early setting, directional diffusion measurements at the injury epicenter associated with chemical demyelination are indistinguishable from those seen with severe contusive SCI, despite dramatic pathologic differences between injury models. Caution is advised in interpretation of diffusion metrics with respect to specific white matter structural alterations. Diffusion analysis should not be limited to the epicenter of focal spinal lesions as alterations marginal to the epicenter are useful for assessing the nature of focal white matter injury.
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Journal of neurotrauma · May 2016
Serial Diffusion Tensor imaging In Vivo Predicts Long-Term Functional Recovery in Rats Following Spinal Cord Injury.
The current study demonstrates the feasibility of using serial magnetic resonance imaging (MRI) and diffusion tensor imaging (DTI) in vivo to quantify temporally spinal cord injury (SCI) pathology in adult female Sprague-Dawley rats that were scanned prior to a moderate or severe upper lumbar contusion SCI. Injured rats were behaviorally tested for hind limb locomotion (Basso, Beattie, Bresnahan [BBB] scores) weekly for 4 weeks and scanned immediately after each session, ending with terminal gait analyses prior to euthanasia. As a measure of tissue integrity, fractional anisotropy (FA) values were significantly lower throughout the spinal cord in both injury cohorts at all time-points examined versus pre-injury. ⋯ Critically, quantified FA values at subacute (24 h) and all subsequent time-points were highly predictive of terminal behavior, reflected in significant correlations with both weekly BBB scores and terminal gait parameters. Critically, the finding that clinically relevant subacute (24 h) FA values accurately predict long-term functional recovery may obviate long-term studies to assess the efficacy of therapeutics tested experimentally or clinically. In summary, this study demonstrates a reproducible serial MRI procedure to predict the long-term impact of contusion SCI on both behavior and histopathology using subacute DTI metrics obtained in vivo to accurately predict multiple terminal outcome measures, which can be particularly valuable when comparing experimental interventions.