The structural basis of moderate disability after traumatic brain damage

Comparative study of brain damage and oxidative stress using two animal models of the shaken baby syndrome

The objective was compare the morphological damages in brain and to evaluate the participation of oxidative stress, using two animal models of shaken baby syndrome (SBS). Five-day-old Wistar rats were used to develop two models of SBS as follows: Gyrotwister (GT) group was subjected to low intensity, high duration rotating movements and Ratshaker (RS) group made to undergo high intensity, low duration anteroposterior movements. Both groups presented respiratory distress, weight loss and shorter stature compared with the control group. In addition, involuntary movements occurred in both experimental models. Hemorrhage was observed in 10 % of the GT group and in 40 % of the RS group. This last group experienced lesser weight gain at 30 days. Glutathione decreased by 25.7 % (GT) and 59.96 (RT). Cell data analysis revealed the presence of crenate and pyknotic cells, characterized by apparent absence of nucleus and nucleolus as well as vacuolation in the GT group. In the RS group, there were a high number of angular, pyknotic and shrunken cells, and a lot of vacuolization. The severity of the brain damage can be related to the magnitude of biochemical modifications, specifically, those related to the production of reactive oxygen or nitrogen species, oxidative stress, oxidative damage.

Treatment of Swine Closed Head Injury with Perfluorocarbon NVX-428

Pre-hospital treatment of traumatic brain injury (TBI) with co-existing polytrauma is complicated by requirements for intravenous fluid volume vs. hypotensive resuscitation. A low volume, small particle-size-oxygen-carrier perfluorocarbon emulsion NVX-428 (dodecafluoropentane emulsion; 2% w/v) could improve brain tissue with minimal additional fluid volume. This study examined whether the oxygen-carrier NVX-428 shows safety and efficacy for pre-hospital treatment of TBI. Anesthetized swine underwent fluid percussion injury TBI and received 1 mL/kg IV NVX-428 (TBI-NVX) at 15 min (T15) or normal saline (no-treatment) (TBI-NON). Similarly, uninjured swine received NVX-428 (SHAM-NVX) or normal saline (SHAM-NON). Animals were monitored and measurements were taken for physiological and neurological parameters before euthanasia at the six-hour mark (T360). Histopathological analysis was performed on paraffin embedded tissues. Physiological, biochemical and blood gas parameters were not different, with the exception of a significant but transient increase in mean pulmonary artery pressure observed in the TBI-experimental group immediately after drug administration. There were no initial differences in brain oxygenation at baseline, but over time oxygen decreased ~50% in both TBI groups. Histological brain injury scores were similar between TBI-NVX and TBI-NON, although a number of subcategories (spongiosis-ischemic/dead neurons-hemorrhage-edema) in TBI-NVX had a tendency for lower scores. The cerebellum showed significantly lower spongiosis and ischemic/dead neuron injury scores and a lower number of Fluoro-Jade-B-positive cerebellar-Purkinje-cells after NVX-428 treatment compared to controls. NVX-428 may assist in mitigating secondary cellular brain damage.

Interhemispherical Anatomical Disconnection in Disorders of Consciousness Patients

In patients with disorder of consciousness (DOC), the corpus callosum (CC) and subcortical white matter (SWM) integrity were shown to discriminate between diagnostic categories. The aims of the study were: (1) to clarify the link between the integrity of CC and of SWM and the clinical status in DOC patients, disentangling the role played by the different brain injuries (traumatic or hemorrhagic brain injury); (2) to investigate the relationship between the CC integrity and the brain metabolism. We assessed the diagnostic accuracy of the CC and SWM integrity, using diffusion tensor imaging (DTI) and structural magnetic resonance imaging (sMRI), in a sample of DOC individuals, well balanced for diagnosis and etiology. The CC DTI-derived measures were correlated with the brain metabolism, computed with fluorodeoxyglucose positron emission tomography. Our results showed that the CC macrostructural DTI-derived measures discriminate between diagnosis and correlate with the clinical status of DOC patients irrespective of the etiology. Moreover, the CC DTI-derived measures strongly correlate with the metabolism of the right hemisphere. No significant diagnostic accuracy emerged for the CC sMRI evaluation and the SWM measures. Our results indicate that: (1) the degree of the interhemispherical anatomical disconnection is a marker of the level of consciousness independent from the type of brain injury; (2) CC alterations might be the consequence of the reduced brain metabolism. Remarkably, our results suggest that the functional interplay between the two hemispheres is linked tightly to the level of consciousness.

White matter correlates of different aspects of facial affect recognition impairment following traumatic brain injury

Although facial affect recognition deficits are well documented in individuals with moderate-to-severe traumatic brain injury (TBI), little research has examined the neural mechanisms underlying these impairments. Here, we use diffusion tensor imaging (DTI), specifically the scalars fractional anisotropy (FA), mean diffusivity (MD), and radial diffusivity (RD), to examine relationships between regional white-matter integrity and two facial affect sub-skills: perceptual affect recognition abilities (measured by an affect matching task) and verbal categorization of facial affect (measured by an affect labeling task). Our results showed that, within the TBI group, higher levels of white-matter integrity in tracts involved in affect recognition (inferior fronto-occipital, inferior longitudinal, and uncinate fasciculi) were associated with better performance on both tasks. Verbal categorization skills were specifically and positively correlated with integrity of the left uncinate fasciculus. Moreover, we observed a striking lateralization effect, with perceptual abilities having an almost exclusive relationship with integrity of right hemisphere tracts, while verbal abilities were associated with both left and right hemisphere integrity. The findings advance our understanding of the neurobiological mechanisms that underlie subcomponents of facial affect recognition and lead to different patterns of facial affect recognition impairment in adults with TBI.

Traumatic axonal injury, a clinical-pathological correlation

Traumatic axonal injury (TAI) is a distinct clinicopathological entity that can cause serious impairment of the brain function and can sometimes be found as a concrete cause of death. It has been discussed from the perspective of its biomechanical importance, and also from the standpoint of certain criteria for the pathological diagnosis of TAI. However, since the time when DAI (diffuse axonal injury) was initially described, there have been few, if any, discussions about the clinical-pathological correlation in TAI. This paper is an attempt to address this issue. For the purpose of certain pathological diagnoses of TAI, 63 cases with closed head injuries have been subjected to the complete forensic-neuropathological examination, involving immunohistochemistry with antibody against β-APP. In the diagnosis of TAI strict criteria have been followed. Then, retrograde analysis of the clinical parameters has been performed in order to determine some clinical-pathological correlation. The following two most reliable parameters of the impairment of the brain function have been analyzed: the impairment of the consciousness and the time of survival. Comparing the two groups, the one with TAI and the other without TAI, and using appropriate statistical evaluation, our results show that TAI is not a significant contributing factor to the lethal outcome in the early post injury period (24 h), but it is undoubtedly a contributing factor for the severe impairment of the brain function indicated through the status of the consciousness.

The Glasgow Coma Scale: History and current practice

The Glasgow Coma Scale (GCS) was devised to assess injury severity in a multi-centre study of outcome after severe brain damage. It uses unambiguous terms that are readily understood by a wide range of observers. Giving numbers to responses makes communication and display of responsiveness easy and the overall score allows classifi cation of overall severity of brain injury for triage and for epidemiological studies. The total score involves some loss of predictive information. Outcome correlates well with the early GCS both in head injuries and other intensive care patients. When early sedation and ventilation after head injury makes GCS assessment difficult, the motor score is often available and is a useful index of injury severity. The GCS also facilitates monitoring in the early stages after injury, allowing rapid detection of complications. Even among mild injuries (GCS 13- 15) the scale can discriminate between those more or less likely to have detectable brain damage and to be at risk of complications.

Frontal and Temporal Structural Connectivity Is Associated with Social Communication Impairment Following Traumatic Brain Injury

OBJECTIVES

Although it has been well documented that traumatic brain injury (TBI) can result in communication impairment, little work to date has examined the relationship between social communication skills and structural brain integrity in patients with TBI. The aim of the current study was to investigate the association between self- and other-perceived communication problems and white matter integrity in patients with mild to severe TBI.

METHODS

Forty-four individuals (TBI=24) and people with whom they frequently communicate, as well as demographically matched normal healthy comparisons (NC) and their frequent communication partners, were administered, respectively, the La-Trobe Communication Questionnaire Self form (LCQ-SELF) and Other form (LCQ-OTHER). In addition, diffusion tensor imaging data were collected, and fractional anisotropy (FA) measures were extracted for each lobe in both hemispheres.

RESULTS

Within the TBI group, but not within the NC group, participants who were perceived by their close others as having more communication problems had lower FA in the left frontal and temporal lobes (p<.01), but not in other brain regions.

CONCLUSIONS

Frontotemporal white matter microstructural integrity is associated with social communication abilities in adults with TBI. This finding contributes to our understanding of the mechanisms leading to communication impairment following TBI and can inform the development of new neuromodulation therapies as well as diagnostic tools. (JINS, 2016, 22, 705-716).

Diffuse Axonal Injury-A Distinct Clinicopathological Entity in Closed Head Injuries

The knowledge about the diffuse axonal injury (DAI) as a clinicopathological entity has matured in the last 30 years. It has been defined clinically (immediate and prolonged unconsciousness leading to death or severe disability) and pathologically (the triad of DAI specific changes). In terms of its biomechanics, DAI is occurring as a result of acceleration forces of longer duration and has been fully reproduced experimentally.In the process of diagnosing DAI, the performance of a complete forensic neuropathological examination is essential and the immunohistochemistry method using antibodies against β-amyloid precursor protein (β-APP) has been proved to be highly sensitive and specific, selectively targeting the damaged axons.In this review, we are pointing to the significant characteristics of DAI as a distinct clinicopathological entity that can cause severe impairment of the brain function, and in the forensic medicine setting, it can be found as the concrete cause of death. We are discussing not only its pathological feature, its mechanism of occurrence, and the events on a cellular level but also the dilemmas about DAI that still exist in science: (1) regarding the strict criteria for its diagnosis and (2) regarding its biomechanical significance, which can be of a big medicolegal importance.

Early metabolic crisis-related brain atrophy and cognition in traumatic brain injury

Traumatic brain injury often results in acute metabolic crisis. We recently demonstrated that this is associated with chronic brain atrophy, which is most prominent in the frontal and temporal lobes. Interestingly, the neuropsychological profile of traumatic brain injury is often characterized as 'frontal-temporal' in nature, suggesting a possible link between acute metabolic crisis-related brain atrophy and neurocognitive impairment in this population. While focal lesions and diffuse axonal injury have a well-established role in the neuropsychological deficits observed following traumatic brain injury, no studies to date have examined the possible contribution of acute metabolic crisis-related atrophy in the neuropsychological sequelae of traumatic brain injury. In the current study we employed positron emission tomography, magnetic resonance imaging, and neuropsychological assessments to ascertain the relationship between acute metabolic crisis-related brain atrophy and neurocognitive outcome in a sample of 14 right-handed traumatic brain injury survivors. We found that acute metabolic crisis-related atrophy in the frontal and temporal lobes was associated with poorer attention, executive functioning, and psychomotor abilities at 12 months post-injury. Furthermore, participants with gross frontal and/or temporal lobe atrophy exhibited numerous clinically significant neuropsychological deficits in contrast to participants with other patterns of brain atrophy. Our findings suggest that interventions that reduce acute metabolic crisis may lead to improved functional outcomes for traumatic brain injury survivors.

Spectrum of surgical trauma and associated head injuries at a university hospital in eastern Nepal

Background:

Trauma is one of the common surgical emergencies presenting at B. P. Koirala Institute of Health Sciences (BPKIHS), Nepal, a tertiary referral center catering to the needs of the population of Eastern Nepal and nearby districts of India.

Objective:

The objective of this study is to analyze the magnitude, epidemiological, clinical profile and outcome of trauma at B P Koirala Institute of Health Sciences.

Materials and Methods:

This descriptive case series study includes all patients with history of trauma coming to BPKIHS emergency and referred to the surgery department. We noted the detailed clinical history and examination, demographics, mechanism of injury, nature of injury, time of reporting in emergency, treatment offered (operative or non operative management) and analyzed details of operative procedure (i.e. laparotomy, thoracotomy, craniotomy etc.), average length of hospital stay, morbidity and outcome (according to Glasgow outcome scale). Collected data were analyzed using EpiInfo 2000 statistical software.

Results:

There were 1848 patients eligible to be included in the study. The mean age of the patients was 28.9 ± 19.3 years. Majority of the patients (38%) belonged to the age group of 21 - 40 years and the male to female ratio was 2.7:1. Most of the trauma victims were students (30%) followed by laborers (27%) and farmers (22%) respectively. The commonest causes of injury were fall from height (39%), road traffic accident (38%) and physical assault (18%); 78% of the patients were managed conservatively and 22% underwent operative management. Postoperative complications were seen in 18%. Wound infection 7.5%, neurological deficit including cerebrospinal fluid (CSF) otrorrhea was seen in 2.2% patients. Good recovery was seen in 84%, moderate disability in 5.2% patients and severe disability in 1.4% patients. The mortally was 6.3% and most of the deaths were related to traumatic brain injuries.

Conclusions:

In Nepal, trauma-related injury contributes significantly to morbidity and mortality and is the third leading cause of death. There are very few studies on trauma from this country and hence this study will help in understanding the etiology and outcome particularly in the Eastern region of Nepal.

The impact of verbal memory encoding and consolidation deficits during recovery from moderate-to-severe traumatic brain injury

OBJECTIVE

Encoding and consolidation deficits appear to account for verbal memory impairment following traumatic brain injury (TBI). It is unknown whether these abilities vary during TBI recovery. We sought to determine the pattern and impact of verbal encoding and consolidation deficits following TBI.

METHODS

Twenty-three participants with moderate-to-severe TBI and 25 age- and education-matched control participants' verbal memory abilities were assessed at 2 time points approximately 1 year apart; assessments occurred at acute and chronic visits for TBI survivors.

MAIN OUTCOME MEASURES

Rey Auditory Verbal Learning Test and Item Specific Deficit Approach indices of encoding, consolidation, and retrieval deficits.

RESULTS

In contrast to the controls, participants with TBI showed impaired verbal memory characterized by encoding and consolidation deficits at both time points. The TBI group's short-delayed recall and consolidation scores improved between the acute and chronic assessments. Encoding (primary) and consolidation (secondary) deficits emerged as predictors of acute and chronic recall in the TBI group. Also, acute visit encoding deficits predicted chronic visit delayed recall in TBI survivors, but acute consolidation deficits did not.

CONCLUSIONS

These findings suggest that memory rehabilitation efforts focused on improving encoding of verbal material may be useful during both the acute and chronic phases of recovery following TBI.

Neuropathological findings in disabled survivors of a head injury

We investigated how the occurrence and severity of the main neuropathological types of traumatic brain injury (TBI) influenced the severity of disability after a head injury. Eighty-five victims, each of whom had lived at least a month after a head injury but then died, were studied. Judged by the Glasgow Outcome Scale (GOS), before death 35 were vegetative, 30 were severely and 20 were moderately disabled. Neuropathological assessment showed that 71 (84%) victims had sustained cerebral contusions, 49 (58%) had diffuse axonal injury (DAI), 57 (67%), had ischemic brain damage (IBD), 58 (68%) had symmetrical ventricular enlargement, and in 47 (55%) intracranial pressure (ICP) had been increased. Thirty-five (41%) had undergone evacuation of an intracranial hematoma. Brainstem damage was seen in only 11 (13%). Analysis (χ(2) test for trends) of the relationship between these features and outcome showed that findings of DAI, raised ICP, thalamic damage, or ventricular enlargement (all p<0.005), and IBD (p=0.04) were associated with an increasingly worse outcome. Conversely, moderate or severe contusions (p=0.001) were increasingly associated with better outcomes, and evacuation of a hematoma was associated (p=0.001) with outcomes likely to be better than vegetative. We conclude that diffuse or multifocal neuropathological patterns of TBI from primary axonal injury or secondary ischemic damage are most likely to be associated with the most severely impaired outcomes after a head injury.

Neuronal and glial markers are differently associated with computed tomography findings and outcome in patients with severe traumatic brain injury: a case control study

INTRODUCTION

Authors of several studies have studied biomarkers and computed tomography (CT) findings in the acute phase after severe traumatic brain injury (TBI). However, the correlation between structural damage as assessed by neuroimaging and biomarkers has not been elucidated. The aim of this study was to investigate the relationships among neuronal (Ubiquitin carboxy-terminal hydrolase L1 [UCH-L1]) and glial (glial fibrillary acidic protein [GFAP]) biomarker levels in serum, neuroradiological findings and outcomes after severe TBI.

METHODS

The study recruited patients from four neurotrauma centers. Serum samples for UCH-L1 and GFAP were obtained at the time of hospital admission and every 6 hours thereafter. CT scans of the brain were obtained within 24hrs of injury. Outcome was assessed by Glasgow Outcome Scale (GOS) at discharge and at 6 months.

RESULTS

81 severe TBI patients and 167 controls were enrolled. The mean serum levels of UCH-L1 and GFAP were higher (p < 0.001) in TBI patients compared to controls. UCH-L1 and GFAP serum levels correlated significantly with Glasgow Coma Scale (GCS) and CT findings. GFAP levels were higher in patients with mass lesions than in those with diffuse injury (2.95 ± 0.48 ng/ml versus 0.74 ± 0.11 ng/ml) while UCH-L1 levels were higher in patients with diffuse injury (1.55 ± 0.18 ng/ml versus 1.21 ± 0.15 ng/ml, p = 0.0031 and 0.0103, respectively). A multivariate logistic regression showed that UCH-L1 was the only independent predictor of death at discharge [adjusted odds ratios 2.95; 95% confidence interval, 1.46-5.97], but both UCH-L1 and GFAP levels strongly predicted death 6 months post-injury.

CONCLUSIONS

Relationships between structural changes detected by neuroimaging and biomarkers indicate each biomarker may reflect a different injury pathway. These results suggest that protein biomarkers could provide better characterization of subjects at risk for specific types of cellular damage than that obtained with neuroimaging alone, as well as provide valuable information about injury severity and outcome after severe TBI.

Association of chronic vascular changes with functional outcome after traumatic brain injury in rats

We tested the hypothesis that vascular remodeling in the cortex, hippocampus, and thalamus is associated with long-term functional recovery after traumatic brain injury (TBI). We induced TBI with lateral fluid-percussion (LFP) injury in adult rats. Animals were followed-up for 9 months, during which we tested motor performance using a neuroscore test, spatial learning and memory with a Morris water maze, and seizure susceptibility with a pentylenetetrazol (PTZ) test. At 8 months, they underwent structural MRI, and cerebral blood flow (CBF) was assessed by arterial spin labeling (ASL) MRI. Then, rats were perfused for histology to assess the density of blood vessels. In the perilesional cortex, the CBF decreased by 56% (p < 0.01 compared to controls), and vessel density increased by 28% (p < 0.01). There was a negative correlation between CBF in the perilesional cortex and vessel density (r = -0.75, p < 0.01). However, in the hippocampus, we found a 13% decrease in CBF ipsilaterally (p < 0.05) and 20% contralaterally (p < 0.01), and no change in vessel number. In the ipsilateral thalamus, the increase in CBF (34%, p < 0.01) was associated with a remarkable increase in vessel density (78%, p < 0.01). Animals showed motor impairment that was not associated with vascular changes. Instead, poor performance in the Morris water maze correlated with enhanced thalamic vessel density (r = -0.81, p < 0.01). Finally, enhanced seizure susceptibility was associated with reduced CBF in the ipsilateral hippocampus (r = 0.78, p < 0.05) and increased vascular density in the thalamus (r = 0.69, p < 0.05). There was little interaction between the behavioral measures. The present study demonstrates that each of the investigated brain areas has a unique pattern of vascular abnormalities. Chronic alterations in CBF could not be attributed to changes in vascular density. Association of thalamic hypervascularity to epileptogenesis warrants further studies. Finally, hippocampal hypoperfusion may predict later seizure susceptibility in the LFP injury model of TBI, which could be of value for pre-clinical antiepileptogenesis trials.

Verbal memory impairment in severe closed head injury: the role of encoding and consolidation

We applied the item-specific deficit approach (ISDA) to California Verbal Learning Test data obtained from 56 severe, acceleration-deceleration closed head injury (CHI) participants and 62 controls. The CHI group demonstrated deficits on all ISDA indices in comparison to controls. Regression analyses indicated that encoding deficits, followed by consolidation deficits, accounted for most of the variance in delayed recall. Additionally, level of acquisition played a partial role in CHI-associated consolidation difficulties. Finally, CHI encoding deficits were largely driven by low semantic clustering during list learning. These results suggest that encoding (primary) and consolidation (secondary) deficits account for CHI-associated verbal memory impairment.

Stereology of cerebral cortex after traumatic brain injury matched to the Glasgow outcome score

Magnetic resonance imaging provides evidence for loss of both white and grey matter, in terms of tissue volume, from the cerebral hemispheres after traumatic brain injury. However, quantitative histopathological data are lacking. From the archive of the Department of Neuropathology at Glasgow, the cerebral cortex of 48 patients was investigated using stereology. Patients had survived 3 months after traumatic brain injury and were classified using the Glasgow Outcome Scale as follows: moderately disabled (n = 13), severely disabled (n = 12) and vegetative state (n = 12); and controls. Some patients from the archive were diagnosed with diffuse axonal injury post-mortem. Comparisons of changes in cortical neuron population across Glasgow Outcome Scale groups between diffuse axonal injury and non-diffuse axonal injury patients were undertaken using effect size analyses. The hypotheses tested were that (i) thinning of the cerebral cortex occurred after traumatic brain injury; (ii) changes in thickness of cortical layers in Brodmann areas 11, 10, 24a and 4 differed; and (iii) different changes occurred for neuronal number, their size and nearest neighbour index across Glasgow Outcome Scale groups. There was a greater loss of large pyramidal and large non-pyramidal neurons with a more severe score on the Glasgow Outcome Scale from all four cortical regions, with the greatest loss of neurons from the prefrontal cortex of patients with diffuse axonal injury. There were differences in the changes of number of medium and small pyramidal and non-pyramidal neurons between different cortical regions, and between patients with and without diffuse axonal injury. Generally, a decrease in the somatic diameter of pyramidal and non-pyramidal neurons was associated with a more severe clinical outcome. However, in the motor cortex a more severe Glasgow Outcome Scale was associated with an increased diameter of medium pyramidal neurons and small non-pyramidal cells. Pyramidal and non-pyramidal neurons did not follow a Poisson distribution within the neuropil of control patients. Pyramidal neurons were usually scattered while medium and small non-pyramidal neurons were clustered. An increased spacing between remaining neurons usually occurred across Glasgow Outcome Scale groups. It is concluded that loss of neurons resulted in reduced executive and integrative capability in patients after traumatic head injury.

Monitoring of brain interstitial total tau and beta amyloid proteins by microdialysis in patients with traumatic brain injury

OBJECT

Damage to axons contributes to postinjury disabilities and is commonly observed following traumatic brain injury (TBI). Traumatic brain injury is an important environmental risk factor for the development of Alzheimer disease (AD). In the present feasibility study, the aim was to use intracerebral microdialysis catheters with a high molecular cutoff membrane (100 kD) to harvest interstitial total tau (T-tau) and amyloid beta 1-42 (Abeta42) proteins, which are important biomarkers for axonal injury and for AD, following moderate-to-severe TBI.

METHODS

Eight patients (5 men and 3 women) were included in the study; 5 of the patients had a focal/mixed TBI and 3 had a diffuse axonal injury (DAI). Following the bedside analysis of the routinely measured energy metabolic markers (that is, glucose, lactate/pyruvate ratio, glycerol, and glutamate), the remaining dialysate was pooled and two 12-hour samples per day were used to analyze T-tau and Abeta42 by enzyme-linked immunosorbent assay from Day 1 up to 8 days postinjury.

RESULTS

The results show high levels of interstitial T-tau and Abeta42 postinjury. Patients with a predominantly focal lesion had higher interstitial T-tau levels than in the DAI group from Days 1 to 3 postinjury (p < 0.05). In contrast, patients with DAI had consistently higher Abeta42 levels when compared with patients with focal injury.

CONCLUSIONS

These results suggest that monitoring of interstitial T-tau and Abeta42 by using microdialysis may be an important tool when evaluating the presence and role of axonal injury following TBI.

Analysis of acute traumatic axonal injury using diffusion tensor imaging

Traumatic axonal injury (TAI) contributes significantly to mortality and morbidity following traumatic brain injury (TBI), but is poorly characterized by conventional imaging techniques. Diffusion tensor imaging (DTI) may provide better detection as well as insights into the mechanisms of white matter injury. DTI data from 33 patients with moderate-to-severe TBI, acquired at a median of 32 h postinjury, were compared with data from 28 age-matched controls. The global burden of whole brain white matter injury (GB(WMI)) was quantified by measuring the proportion of voxels that lay below a critical fractional anisotropy (FA) threshold, identified from control data. Mechanisms of change in FA maps were explored using an Eigenvalue analysis of the diffusion tensor. When compared with controls, patients showed significantly reduced mean FA (p < 0.001) and increased apparent diffusion coefficient (ADC; p = 0.017). GB(WMI) was significantly greater in patients than in controls (p < 0.01), but did not distinguish patients with obvious white matter lesions seen on structural imaging. It predicted classification of DTI images as head injury with a high degree of accuracy. Eigenvalue analysis showed that reductions in FA were predominantly the result of increases in radial diffusivity (p < 0.001). DTI may help quantify the overall burden of white matter injury in TBI and provide insights into underlying pathophysiology. Eigenvalue analysis suggests that the early imaging changes seen in white matter are consistent with axonal swelling rather than axonal truncation. This technique holds promise for examining disease progression, and may help define therapeutic windows for the treatment of diffuse brain injury.

Functional outcome is impaired following traumatic brain injury in aging Nogo-A/B-deficient mice

Increasing age is associated with a poor prognosis following traumatic brain injury (TBI). CNS axons may recover poorly following TBI due to expression of myelin-derived inhibitors to axonal outgrowth such as Nogo-A. To study the role of Nogo-A/B in the pathophysiological response of the elderly to TBI, 1-year-old mice deficient in Nogo-A/B (Nogo-A/B homozygous(-/-) mice), Nogo-A/B heterozygous(-/+) mice, and age-matched wild-type (WT) littermate controls were subjected to a controlled cortical impact (CCI) TBI. Sham-injured WT mice (7 months old) and 12 month old naïve Nogo-A/B(-/-) and Nogo-A/B(-/+) served as controls. Neurological motor function was evaluated up to 3 weeks, and cognitive function, hemispheric tissue loss, myelin staining and hippocampal beta-amyloid (A beta) immunohistochemistry were evaluated at 4 weeks post-injury. In WT littermates, TBI significantly impaired learning ability at 4 weeks and neurological motor function up to 2 weeks post-injury and caused a significant loss of hemispheric tissue. Following TBI, Nogo-A/B(-/-) mice showed significantly less recovery from neurological motor and cognitive deficits compared to brain-injured WT mice. Naïve Nogo-A/B(-/-) and Nogo-A/B(-/+) mice quickly learned the MWM task in contrast to brain-injured Nogo-A/B(-/-) mice who failed to learn the MWM task at 4 weeks post-injury. Hemispheric tissue loss and cortical lesion volume were similar among the brain-injured genotypes. Neither TBI nor the absence of NogoA/B caused an increased A beta expression. Myelin staining showed a reduced area and density in the corpus callosum in brain-injured Nogo-A/B(-/-) animals compared to their littermate controls. These novel and unexpected behavioral results demonstrate that the absence of Nogo-A/B may negatively influence outcome, possibly related to hypomyelination, following TBI in mice and suggest a complex role for this myelin-associated axonal growth inhibitor following TBI.

Emotion perception deficits following traumatic brain injury: a review of the evidence and rationale for intervention

While the cognitive disturbances that frequently follow severe traumatic brain injury (TBI) are relatively well understood, the ways in which these affect the psychosocial functioning of people with TBI are yet to be determined and have thus received little attention in treatment research. Growing evidence indicates that a significant proportion of individuals with TBI demonstrate an inability to recognize affective information from the face, voice, bodily movement, and posture. Because accurate interpretation of emotion in others is critical for the successful negotiation of social interactions, effective treatments are necessary. Until recently, however, there have been no rehabilitation efforts in this area. The present review examines the literature on emotion perception deficits in TBI and presents a theoretical rationale for targeted intervention. Several lines of research relevant to the remediation of emotion perception in people with TBI are considered. These include work on emotion perception remediation with other cognitively impaired populations, current neuropsychological models of emotion perception and underlying neural systems, and recent conceptualizations of remediation processes. The article concludes with a discussion of the importance of carrying out efforts to improve emotion perception within a contextualized framework in which the day-to-day relevance of training is clear to all recipients.

A lack of amyloid beta plaques despite persistent accumulation of amyloid beta in axons of long-term survivors of traumatic brain injury

Traumatic brain injury (TBI) is a risk factor for developing Alzheimer's disease (AD). Additionally, TBI induces AD-like amyloid beta (Abeta) plaque pathology within days of injury potentially resulting from massive accumulation of amyloid precursor protein (APP) in damaged axons. Here, progression of Abeta accumulation was examined using brain tissue from 23 cases with post-TBI survival of up to 3 years. Even years after injury, widespread axonal pathology was consistently observed and was accompanied by intra-axonal co-accumulations of APP with its cleavage enzymes, beta-site APP cleaving enzyme and presenilin-1 and their product, Abeta. However, in marked contrast to the plaque pathology noted in short-term cases post TBI, virtually no Abeta plaques were found in long-term survivors. A potential mechanism for Abeta plaque regression was suggested by the post-injury accumulation of an Abeta degrading enzyme, neprilysin. These findings fail to support the premise that progressive plaque pathology after TBI ultimately results in AD.

Perisomatic Thalamic Axotomy After Diffuse Traumatic Brain Injury Is Associated With Atrophy Rather Than Cell Death

Morbidity and mortality associated with traumatic brain injury (TBI) stem from diffuse axonal injury (DAI) throughout subcortical and brainstem white matter and subcortical nuclei. After midline fluid percussion brain injury, DAI in the thalamus includes perisomatic axotomy and resembles human post-traumatic pathology where the degree of morbidity correlates with thalamic damage. After axotomy, acute somatic perturbations resolve and appear compatible with cell survival; however, the long-term fate of neurons in an area with perisomatic axotomy is unknown. From brain-injured and uninjured rats at 1, 7 and 28 days after injury (injury, n = 5/group; sham, n = 4), alternate sections were immunostained for amyloid precursor protein (APP) to detect perisomatic axotomy or Giemsa stained for quantification of neuronal number, neuronal density, regional volume, and neuronal nuclear volume using design-based stereology. One day postinjury, APP-immunoreactive axons were identified consistently within the perisomatic domains of thalamic neurons of the ventral basal complex. Bilateral systematic-random quantification of the ventral basal complex indicated a significant reduction in neuronal density (number per mm, but not number alone) at 1 week after injury, compared with sham and 1 day postinjury. Furthermore, by 1 day and persisting through 1 week after injury, the mean neuronal nuclear volume was atrophied significantly compared with sham. Therefore, diffuse TBI results in early perisomatic axonal injury followed by neuronal atrophy in the ventral basal complex, without gross degeneration. Enduring atrophy in thalamic relays could underlie circuit disruption responsible for post-traumatic morbidity.

Tissue sparing and functional recovery following experimental traumatic brain injury is provided by treatment with an anti-myelin-associated glycoprotein antibody

Axonal injury is a hallmark of traumatic brain injury (TBI) and is associated with a poor clinical outcome. Following central nervous system injury, axons regenerate poorly, in part due to the presence of molecules associated with myelin that inhibit axonal outgrowth, including myelin-associated glycoprotein (MAG). The involvement of MAG in neurobehavioral deficits and tissue loss following experimental TBI remains unexplored and was evaluated in the current study using an MAG-specific monoclonal antibody (mAb). Anesthetized rats (n=102) were subjected to either lateral fluid percussion brain injury (n=59) or sham injury (n=43). In surviving animals, beginning at 1 h post-injury, 8.64 microg anti-MAG mAb (n=33 injured, n=21 sham) or control IgG (n=26 injured, n=22 sham) was infused intracerebroventricularly for 72 h. One group of these rats (n=14 sham, n=11 injured) was killed at 72 h post-injury for verification of drug diffusion and MAG immunohistochemistry. All other animals were evaluated up to 8 weeks post-injury using tests for neurologic motor, sensory and cognitive function. Hemispheric tissue loss was also evaluated at 8 weeks post-injury. At 72 h post-injury, increased immunoreactivity for MAG was seen in the ipsilateral cortex, thalamus and hippocampus of brain-injured animals, and anti-MAG mAb was detectable in the hippocampus, fimbria and ventricles. Brain-injured animals receiving anti-MAG mAb showed significantly improved recovery of sensorimotor function at 6 and 8 weeks (P<0.01) post-injury when compared with brain-injured IgG-treated animals. Additionally, at 8 weeks post-injury, the anti-MAG mAb-treated brain-injured animals demonstrated significantly improved cognitive function and reduced hemispheric tissue loss (P<0.05) when compared with their brain-injured controls. These results indicate that MAG may contribute to the pathophysiology of experimental TBI and treatment strategies that target MAG may be suitable for further evaluation.

Changes in white matter late after severe traumatic brain injury in childhood

Severe traumatic brain injury in childhood, particularly that complicated by raised intracranial pressure, has significant long-term effects on the brain. Since magnetic resonance imaging provides a means of visualizing neuroanatomic structure in exquisite detail, the scope of this review is to revisit the pathology of traumatic brain injury described in recent clinical imaging studies. Acute imaging provides insight into the acute mechanism of focal and diffuse injury. There is some reduction in threshold for white matter pathology in the hemisphere ipsilateral to injury. After injury, there may be long-term effects on white matter architecture and the potential for brain growth. In this context, the pattern of hippocampal rather than parahippocampal gyrus tissue loss provides insight into the likely cause of white matter injury being cerebral hypoperfusion.

Animal models of post-traumatic epilepsy

Epilepsy is a major unfavorable long-term consequence of traumatic brain injury (TBI). Moreover, TBI is one of the most important predisposing factors for the development of epilepsy, particularly in young adults. Understanding the molecular and cellular cascades that lead to the development of post-traumatic epilepsy (PTE) is key for preventing its development or modifying the disease process in such a way that epilepsy, if it develops, is milder and easier-to-treat. Tissue from TBI patients undergoing epileptogenesis is not available for such studies, which underscores the importance of developing clinically relevant animal models of PTE. The goal of this review is to (1) provide a description of PTE in humans, which is critical for the development of clinically relevant models of PTE, (2) review the characteristics of currently available PTE models, and (3) provide suggestions for the development of future models of PTE based on our current understanding of the mechanisms of TBI and epilepsy. The development of clinically relevant models of PTE is critical to advance our understanding of the mechanisms of post-traumatic epileptogenesis and epilepsy, as well as for producing breakthroughs in the development and testing of novel antiepileptogenic treatments.

Thalamic nuclei after human blunt head injury

Paraffin-embedded blocks from the thalamus of 9 control patients, 9 moderately disabled, 12 severely disabled, and 10 vegetative head-injured patients assessed using the Glasgow Outcome Scale and identified from the Department of Neuropathology archive. Neurons, astrocytes, macrophages, and activated microglia were differentiated by Luxol fast blue/cresyl violet, GFAP, CD68, and CR3/43 staining and stereological techniques used to estimate cell number in a 28-microm-thick coronal section. Counts were made in subnuclei of the mediodorsal, lateral posterior, and ventral posterior nuclei, the intralaminar nuclei, and the related internal lamina. Neuronal loss occurred from mediodorsal parvocellularis, rostral center medial, central lateral and paracentral nuclei in moderately disabled patients; and from mediodorsal magnocellularis, caudal center medial, rhomboid, and parafascicular nuclei in severely disabled patients; and all of the above and the centre median nucleus in vegetative patients. Neuronal loss occurred primarily from cognitive and executive function nuclei, a lesser loss from somatosensory nuclei and the least loss from limbic motor nuclei. There was an increase in the number of reactive astrocytes, activated microglia, and macrophages with increasing severity of injury. The study provides novel quantitative evidence for differential neuronal loss, with survival after human head injury, from thalamic nuclei associated with different aspects of cortical activation.

Diffusion tensor imaging in chronic head injury survivors: correlations with learning and memory indices

Diffusion tensor imaging (DTI) provides a unique insight into the cellular integrity of the brain. While conventional magnetic resonance imaging underestimates the extent of pathology following closed head injury, diffusion-weighted imaging has been shown to more accurately delineate the extent of cerebral damage. There have only been a few case studies of DTI in chronic head injury survivors. This study used DTI to investigate changes in anisotropy and diffusivity in survivors of head injury at least 6 months after their injury. The relationship between cognition and diffusion abnormality was also investigated. The voxel-based analysis revealed significant bilateral decreases in anisotropy, in major white matter tracts and association fibers in the temporal, frontal, parietal and occipital lobes. Statistically significant increases in diffusivity were also found in widespread areas of the cortex. A significant positive correlation was found between diffusivity and impairment of learning and memory in the left posterior cingulate, left hippocampal formation and left temporal, frontal and occipital cortex. The common pattern of abnormality despite heterogeneous injury mechanism and lesion location in the group suggests that these cellular changes reflect secondary insults. The importance of diffusion abnormalities in head injury outcome is emphasized by the significant correlation between a learning and memory index and diffusivity in areas known to subserve this cognitive function.

Predicting posttraumatic epilepsy with MRI: prospective longitudinal morphologic study in adults

PURPOSE

Evaluation of morphologic risk factors for posttraumatic epilepsy (PTE) by using brain magnetic resonance imaging (MRI) in serial assessments <or=2 years after traumatic brain injury (TBI).

METHODS

Brain MRI hyperintense (gliosis) or hypointense (hemosiderin) areas or both were assessed in the images of 135 adult TBI inpatients who completed a 2-year clinical, EEG, and MRI study protocol. Overall clinical follow-up for the development of PTE was 5-10 years (median, 102 months). Morphologic risk factors for PTE were evaluated by using Kaplan-Meier curves and Cox regression analysis.

RESULTS

In 20 patients, PTE developed. Kaplan-Meier curves showed that gliomesenchymal sequelae of focal brain lesions (subdural hematomas/contusions) that required surgical treatment (sSDH-C) were a PTE risk factor (p<0.001), as were sequelae of nonsurgical hemorrhagic contusions with gliosis wall incompletely surrounding hemosiderin dregs (IW) (p=0.039) and mainly those with time-related changes from incomplete to complete gliosis wall around hemosiderin (I/CW) (p=0.005); those with early hemosiderin completely surrounded by gliosis (CW) were not (p=0.821). Cox regression analysis showed that for patients with sequelae of sSDH-C, the PTE risk was 4.38 (p=0.023) times higher than for those who did not require surgical treatment or underwent surgery because of purely extradural hematoma; for those with IW and I/CW lesions, considered pooled, it was 6.61 times higher (p=0.014) than for those with CW lesions.

CONCLUSIONS

MRI follow-up examination in the early chronic stage can differentiate among low-, intermediate-, and high-risk sequelae of TBI. These findings yield new evidence for, but do not resolve, the debate on posttraumatic epileptogenesis.

Diffuse axonal injury in mild traumatic brain injury: a diffusion tensor imaging study

OBJECT

Diffuse axonal injury (DAI) is a major complication of traumatic brain injury (TBI) that leads to functional and psychological deficits. Although DAI is frequently underdiagnosed by conventional imaging modalities, it can be demonstrated using diffusion tensor imaging. The aim of this study was to assess the presence and extent of DAI in patients with mild TBI.

METHODS

Forty-six patients with mild TBI and 29 healthy volunteers underwent a magnetic resonance (MR) imaging protocol including: dual-spin echo, fluid-attenuated inversion recovery, T2-weighted gradient echo, and diffusion tensor imaging sequences. In 20 of the patients, MR imaging was performed at a mean of 4.05 days after injury. In the remaining 26, MR imaging was performed at a mean of 5.7 years after injury. In each case, mean diffusivity and fractional anisotropy were measured using both whole-brain histograms and regions of interest analysis. No differences in any of the histogram-derived measures were found between patients and control volunteers. Compared with controls, a significant reduction of fractional anisotropy was observed in patients' corpus callosum, internal capsule, and centrum semiovale, and there were significant increases of mean diffusivity in the corpus callosum and internal capsule. Neither histogram-derived nor regional diffusion tensor imaging metrics differed between the two groups.

CONCLUSIONS

Although mean diffusivity and fractional anisotropy abnormalities in these patients with TBI were too subtle to be detected with the whole-brain histogram analysis, they are present in brain areas that are frequent sites of DAI. Because diffusion tensor imaging changes are present at both early and late time points following injury, they may represent an early indicator and a prognostic measure of subsequent brain damage.

Late mortality after head injury

OBJECTIVES

To investigate mortality trends in a cohort of people admitted to a regional head injury unit with all severities of injury in the calendar year 1981.

METHODS

A computerised database with details of 1919 admissions was compared with deaths registered by the NHS Central Register, Scotland for the years 1981 to mid-2002. Death certificate information for matches was analysed.

RESULTS

The 1919 admissions referred to 1871 individuals, comprising 93 severe, 205 moderate, and 1573 minor injuries according to Glasgow coma scale criteria. There were 57 deaths (42 severe head injuries, eight moderate, seven minor) during the initial admission, and 340 (six severe, 33 moderate, 301 minor) in the subsequent years. Substance abuse, principally alcohol, was a factor in 37 deaths, suicide accounted for 20, and accidents for 25. The great majority of these latter deaths were in people under the age of 70 years.

CONCLUSION

Premature deaths after predominantly minor head injury are commonly alcohol related or the result of suicide or accidents.

Modeling the minimally conscious state: measurements of brain function and therapeutic possibilities

The minimally conscious state (MCS) defines a functional level of recovery following severe brain injuries. Patients in MCS demonstrate unequivocal evidence of response to their environment yet fail to recover the ability to communicate. Drawing on recent functional brain-imaging studies, pathological data, and neurophysiological investigations, models of brain function in MCS are proposed. MCS models are compared and contrasted with models of the vegetative state (VS), a condition characterized by wakeful appearance and unconsciousness. VS reflects a total loss of cognitive function and failure to recover basic aspects of the normal physiologic brain state associated with wakefulness. MCS may represent a recovery of the minimal dynamic architecture required to organize behavioral sets and respond to sensory stimuli. Several pathophysiological mechanisms that might limit further recovery in MCS patients are considered. Implications for future research directions and possible therapeutic strategies are reviewed.

Axonal damage: a key predictor of outcome in human CNS diseases

Axonal damage has recently been recognized to be a key predictor of outcome in a number of diverse human CNS diseases, including head and spinal cord trauma, metabolic encephalopathies, multiple sclerosis and other white-matter diseases (acute haemorrhagic leucoencephalitis, leucodystrophies and central pontine myelinolysis), infections [malaria, acquired immunodeficiency syndrome (AIDS) and infection with human lymphotropic virus type 1 (HTLV-I) causing HTLV-I-associated myelopathy (HAM)/tropical spastic paraparesis (TSP)] and subcortical ischaemic damage. The evidence for axonal damage and, where available, its correlation with neurological outcome in each of these conditions is reviewed. We consider the possible pathogenetic mechanisms involved and how increasing understanding of these may lead to more effective therapeutic or preventive interventions.

Neuropathological investigation of cerebral white matter lesions caused by closed head injury

In order to ascertain whether there is widespread axonal disruption of cerebral white matter in the so-called 'diffuse axonal injury' (DAI), a type of closed head injury, proposed by Adams et al. the author investigated his own cases clinicopathologically. Twenty-six male autopsied cases of head injury, aged between 19 and 84, 15 of which had sustained road traffic accidents, were examined; the others were due to falling from heights and so on. The study group all belonged to non-missile head injuries and included 12 cases of diffuse brain injury, as well as 14 cases of focal brain injury, according to the classification of Gennarelli et al. The survival time ranged from 2 h to 21 years. Formalin-fixed brains were cut coronally so as to make paraffin-embedded hemispheric sections. Then these sections were stained conventionally (HE, Bodian, Kluver-Barrera and Holzer) and immunohistochemically (GFAP) to assess axonal decrease, myelin pallor and gliosis by the use of light microscopy. In the 13 chronic cases that died more than 1 month after the accidents, the intensities of gliosis, myelin pallor and axonal decrease tended to correlate with each other. In the 13 acute cases who died less than 1 month after their accident, the degree of axonal decrease in white matter seemed to correlate with the severity of myelin pallor. Regardless of types of trauma, however, axonal retraction balls, the so-called hallmark of DAI, were found only with myelin pallor suggesting the presence of brain swelling after the injury. Therefore these findings indicate that it may be difficult to accept the notion of DAI, that is, the presence of axonal retraction balls without brain swelling. In addition, diffuse vascular injury (2 cases) as well as rarefaction of subcortical white matter (6 cases) were presented and their pathogenesis individually discussed based on a literature review.