Journal of neurotrauma
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Journal of neurotrauma · Jun 2016
Using post-traumatic amnesia to predict outcome following traumatic brain injury.
Duration of post-traumatic amnesia (PTA) has emerged as a strong measure of injury severity after traumatic brain injury (TBI). Despite the growing international adoption of this measure, there remains a lack of consistency in the way in which PTA duration is used to classify severity of injury. This study aimed to establish the classification of PTA that would best predict functional or productivity outcomes. ⋯ This finding indicates that the greatest accuracy in prognosis is likely to be achieved using PTA as a continuous variable. This enables the probability of productive outcomes to be estimated with far greater precision than that possible using a classification system. Categorizing PTA to classify severity of injury may be reducing the precision with which clinicians can plan the treatment of patients after TBI.
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Journal of neurotrauma · Jun 2016
Neuroprotective effects of the glutamate transporter activator, MS-153, following traumatic brain injury in the adult rat.
Traumatic brain injury (TBI) in humans and in animals leads to an acute and sustained increase in tissue glutamate concentrations within the brain, triggering glutamate-mediated excitotoxicity. Excitatory amino acid transporters (EAATs) are responsible for maintaining extracellular central nervous system glutamate concentrations below neurotoxic levels. Our results demonstrate that as early as 5 min and up to 2 h following brain trauma in brain-injured rats, the activity (Vmax) of EAAT2 in the cortex and the hippocampus was significantly decreased, compared with sham-injured animals. ⋯ Administration of (R)-(-)-5-methyl-1-nicotinoyl-2-pyrazoline (MS-153), a GLT-1 activator, beginning immediately after injury and continuing for 24 h, significantly decreased neurodegeneration, loss of microtubule-associated protein 2 and NeuN (+) immunoreactivities, and attenuated calpain activation in both the cortex and the hippocampus at 24 h after the injury; the reduction in neurodegeneration remained evident up to 14 days post-injury. In synaptosomal uptake assays, MS-153 up-regulated GLT-1 activity in the naïve rat brain but did not reverse the reduced activity of GLT-1 in traumatically-injured brains. This study demonstrates that administration of MS-153 in the acute post-traumatic period provides acute and long-term neuroprotection for TBI and suggests that the neuroprotective effects of MS-153 are related to mechanisms other than GLT-1 activation, such as the inhibition of voltage-gated calcium channels.
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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 · Jun 2016
Clinical application of a novel clinical scale for the pre-operative risk evaluation of cerebral herniation from traumatic epidural hematoma.
Secondary massive cerebral infarction (MCI) is the predominant prognostic factor for cerebral herniation from epidural hematoma (EDH) and determines the need for decompressive craniectomy. In this study, we tested the clinical feasibility and reliability of a novel pre-operative risk scoring system, the EDH-MCI scale, to guide surgical decision making. It is comprised of six risk factors, including hematoma location and volume, duration and extent of cerebral herniation, Glasgow Coma Scale score, and presence of preoperative shock, with a total score ranging from 0 to 18 points. ⋯ Results suggested that simple hematoma evacuation craniotomy was sufficient for patients with low risk scores (≤9 points), whereas decompressive craniectomy in combination with duraplasty were necessary only for those with high risk scores (≥13 points). In patients with borderline risk scores (10-12 points), those having unstable vital signs, coexistence of severe secondary brainstem injury, and unresponsive dilated pupils after emergent burr hole hematoma drainage had a significantly increased incidence of post-traumatic MCI and necessity of radical surgical treatments. In conclusion, the novel pre-operative risk EDH-MCI evaluation scale has a satisfactory predictive and discriminative performance for patients who are at risk for the development of secondary MCI and therefore require decompressive craniectomy.
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Journal of neurotrauma · Jun 2016
"Is traumatic brain injury associated with reduced inter-hemispheric functional connectivity? A study of large-scale resting state networks following traumatic brain injury"
Traumatic brain injury (TBI) often has long-term debilitating sequelae in cognitive and behavioral domains. Understanding how TBI impacts functional integrity of brain networks that underlie these domains is key to guiding future approaches to TBI rehabilitation. In the current study, we investigated the differences in inter-hemispheric functional connectivity (FC) of resting state networks (RSNs) between chronic mild-to-severe TBI patients and normal comparisons (NC), focusing on two externally oriented networks (i.e., the fronto-parietal network [FPN] and the executive control network [ECN]), one internally oriented network (i.e., the default mode network [DMN]), and one somato-motor network (SMN). ⋯ Region of interest correlation analyses confirmed the presence of significantly higher inter-hemispheric FC in NC for the FPN (p < 0.01), and ECN (p < 0.05), but not for the DMN (p > 0.05) or SMN (p > 0.05). Further analysis revealed that performance on a neuropsychological test measuring organizational skills and visuo-spatial abilities administered to the TBI group, the Rey-Osterrieth Complex Figure Test, positively correlated with FC between the right FPN and homologous regions. Our findings suggest that distinct RSNs display specific patterns of aberrant FC following TBI; this represents a step forward in the search for biomarkers useful for early diagnosis and treatment of TBI-related cognitive impairment.