Traumatic brain injury and forensic neuropsychology

Relationship between post-traumatic amnesia and white matter integrity in traumatic brain injury using tract-based spatial statistics

This study used tract-based spatial statistics to examine the relationship between post-traumatic amnesia (PTA) and white matter integrity in patients with a traumatic brain injury (TBI). Forty-seven patients with TBI in the chronic stage and 47 age- and sex-matched normal control subjects were recruited to the study. Correlation coefficients were calculated to observe the relationships among the PTA duration, white matter fractional anisotropy (FA) values, and mini-mental state examination (MMSE) results in the patient group. Both before and after Benjamini–Hochberg (BH) corrections, FA values of 46 of the 48 regions of interests of the patient group were lower than those of the control group. The FA values of column and body of fornix, left crus of fornix, left uncinate fasciculus, right hippocampus part of cingulum, left medial lemniscus, right superior cerebellar peduncle, left superior cerebellar peduncle, and left posterior thalamic radiation (after BH correction: the uncinate fasciculus and right hippocampus part of cingulum) in the patient group were negatively correlated with PTA duration. PTA duration was related to the injury severity of eight neural structures, each of which is involved in the cognitive functioning of patients with TBI. Therefore, PTA duration can indicate injury severity of the above neural structures in TBI patients.

Physiological underarousal as a mechanism of aggressive behavior in university athletes with a history of concussion

INTRODUCTION

Research has indicated that athletes who engage in high-risk athletic activities, such as football and hockey, have riskier personalities than their low-risk and nonathlete counterparts (Ahmadi et al., 2011, Procedia Soc Behav Sci, 30 and 247-251; Zuckerman, 1983, Biological bases of sensation seeking, impulsivity, and anxiety, Lawrence Erlbaum Assoc Inc.). For instance, increased sensation-seeking and aggression are common in high-risk athletes, rendering these individuals more likely to sustain a subsequent injury, such as concussion. Elevated levels of certain personality traits, including impulsivity and aggression, have also been observed after concussion (Goswami et al., 2016, Brain Struct Funct, 221 and 1911-1925). The purpose of this study therefore was to determine whether aggressive behavior in university athletes may be accounted for, in part, by a history of concussion, rather than exclusively athletic status.

METHODS

Using a quasi-experimental design, 66 university students (n = 18 nonathletes, n = 24 low-risk athletes, n = 24 high-risk athletes) with (n = 27) and without a history of concussion (n = 39) completed the Buss & Perry Aggression Questionnaire (BPAQ; Buss & Perry, , J Pers Soc Psychol, 63 and 452) and provided electrodermal activation (EDA) as an index of physiological arousal.

RESULTS

It was found that decreased physiological arousal among students with a history of concussion was associated with greater endorsement of physical aggression. Moreover, athletic status did not account for this pattern of aggression, as athletes and nonathletes did not differ in terms of self-reported aggressive tendencies.

CONCLUSIONS

Physiological compromise after concussive injury may act as an independent mechanism of aggressive behavior in athletes beyond factors, such as athletic status.

Effort, symptom validity testing, performance validity testing and traumatic brain injury

BACKGROUND

To understand the neurocognitive effects of brain injury, valid neuropsychological test findings are paramount.

REVIEW

This review examines the research on what has been referred to a symptom validity testing (SVT). Above a designated cut-score signifies a 'passing' SVT performance which is likely the best indicator of valid neuropsychological test findings. Likewise, substantially below cut-point performance that nears chance or is at chance signifies invalid test performance. Significantly below chance is the sine qua non neuropsychological indicator for malingering. However, the interpretative problems with SVT performance below the cut-point yet far above chance are substantial, as pointed out in this review. This intermediate, border-zone performance on SVT measures is where substantial interpretative challenges exist. Case studies are used to highlight the many areas where additional research is needed. Historical perspectives are reviewed along with the neurobiology of effort. Reasons why performance validity testing (PVT) may be better than the SVT term are reviewed.

CONCLUSIONS

Advances in neuroimaging techniques may be key in better understanding the meaning of border zone SVT failure. The review demonstrates the problems with rigidity in interpretation with established cut-scores. A better understanding of how certain types of neurological, neuropsychiatric and/or even test conditions may affect SVT performance is needed.

Neuroimaging biomarkers in mild traumatic brain injury (mTBI)

Reviewed herein are contemporary neuroimaging methods that detect abnormalities associated with mild traumatic brain injury (mTBI). Despite advances in demonstrating underlying neuropathology in a subset of individuals who sustain mTBI, considerable disagreement persists in neuropsychology about mTBI outcome and metrics for evaluation. This review outlines a thesis for the select use of sensitive neuroimaging methods as potential biomarkers of brain injury recognizing that the majority of individuals who sustain an mTBI recover without neuroimaging signs or neuropsychological sequelae detected with methods currently applied. Magnetic resonance imaging (MRI) provides several measures that could serve as mTBI biomarkers including the detection of hemosiderin and white matter abnormalities, assessment of white matter integrity derived from diffusion tensor imaging (DTI), and quantitative measures that directly assess neuroanatomy. Improved prediction of neuropsychological outcomes in mTBI may be achieved with the use of targeted neuroimaging markers.

Evaluating the cognitive consequences of mild traumatic brain injury and concussion by using electrophysiology

OBJECT

Mild traumatic brain injury (MTBI), often referred to as concussion when it occurs in sports, produces persistent cognitive problems in at least 15% of patients. Unfortunately, conventional neuropsychological tests usually yield results within normal limits in this population. The main objective of this event-related potential (ERP) study was to understand brain functioning during the performance of a working memory (WM) task in patients who have sustained an MTBI, mostly due to motor vehicle accident or sports concussion. This study also aimed for a better understanding of the association between brain functioning as measured with ERP, behavioral performance on the WM task, postconcussion symptoms, type of injury (that is, sports concussion vs other types), and time since the injury.

METHODS

Forty-four patients with MTBI (7.6 ± 8.4 months postinjury) were tested on a visual WM task with simultaneous recording of ERP, and were compared with 40 control volunteers who were their equivalent for age and sex. Amplitude and latency of frontal (N200 and N350) and parietal (P200 and P300) ERP waves were measured and were compared between groups. Correlation analyses were also performed between ERP characteristics, clinical variables, and behavioral performance.

RESULTS

A significant group difference was found for behavioral performance on the WM task, in which the MTBI group had a lower percentage of correct answers than the control group (p < 0.05). The patients with MTBI also had smaller amplitudes of both frontal N350 and parietal P300 ERP components when compared with control volunteers (p < 0.05). No changes were found for latency of ERP components. Smaller ERP amplitudes were associated with slower reaction times and worse accuracy on the WM task among patients with MTBI (p < 0.05). Types of injury (that is, sports concussion vs other mechanisms) were not associated with different ERP characteristics.

CONCLUSIONS

Abnormal ERP results are observed in patients after MTBI or sports concussion, even for those in the nonacute stage after their injury. Current standard clinical evaluations most often fail to detect cerebral dysfunction after MTBI, even when patients or athletes report symptoms. Clinicians should be aware that patients with MTBI, including sports concussion, probably have underlying mild but persistent cerebral dysfunctions that require further investigation.

Diffusion tensor imaging findings are not strongly associated with postconcussional disorder 2 months following mild traumatic brain injury

OBJECTIVE

To examine the relation between diffusion tensor imaging (DTI) of the corpus callosum and postconcussion symptom reporting following mild traumatic brain injury (MTBI).

PARTICIPANTS

Sixty patients with MTBI and 34 patients with orthopedic/soft-tissue injuries (Trauma Controls) prospectively enrolled from consecutive admissions to a level 1 trauma center.

PROCEDURE

Diffusion tensor imaging of the corpus callosum was undertaken using a Phillips 3T scanner at 6 to 8 weeks postinjury. Participants also completed a postconcussion symptom checklist. The MTBI group was divided into 2 subgroups based on the International Classification of Diseases, Tenth Revision symptom criteria for postconcussion disorder (PCD): PCD Present (n = 21), PCD Absent (n = 39).

MAIN OUTCOME MEASURES

Measures of fractional anisotropy and mean diffusivity for the genu, body, and splenium of the corpus callosum. Participants also completed the British Columbia Post-Concussion Symptom Inventory.

RESULTS

The MTBI group reported more postconcussion symptoms than the trauma controls. There were no significant differences between MTBI and trauma control groups on all DTI measures. In the MTBI sample, there were no significant differences on all DTI measures between those who did and did not meet the International Classification of Diseases, Tenth Revision research criteria for postconcussion disorder.

CONCLUSIONS

These data do not support an association between white matter integrity in the corpus callosum and self-reported postconcussion syndrome 6 to 8 weeks post-MTBI.

Inter-professional clinical practice guideline for vocational evaluation following traumatic brain injury: a systematic and evidence-based approach

INTRODUCTION

This paper introduces an inter-professional clinical practice guideline for vocational evaluation following traumatic brain injury. This guideline aims to explicate the processes and factors relevant to vocational evaluation to assist evaluators (i.e. health care teams, individuals and employers) in collaboratively determining if clients are able to work and to make recommendations for work entry, re-entry or vocational planning.

METHODS

Methods in the Canadian Medical Association's (CMA) Handbook on Clinical Practice Guideline and the Appraisal of Guidelines for Research and Evaluation (AGREE) instrument were utilized to ensure rigour. Steps in the CMA handbook were followed and included: (1) identifying the guideline's objective and questions; (2) systematic literature review; (3) study selection and quality appraisal; (4) development of clear recommendations by key stakeholders; (5) guideline pilot testing and endorsement.

RESULTS

The resulting guideline includes 17 key recommendations within the seven domains: (1) evaluation purpose and rationale; (2) initial intake process; (3) assessment of the personal domain; (4) assessment of the environment; (5) assessment of occupational/job requirements; (6) analysis and synthesis; (7) evaluation recommendations.

CONCLUSIONS

The guideline may be useful to individually practicing clinicians, health care teams, employers and individuals with TBI. Future research will formally examine the success of the guideline's implementation.

Acute Relationship between Cognitive and Psychological Symptoms of Patients with Mild Traumatic Brain Injury

Objective. The goal of this study was to explore the relationship between acute psychological reactions and cognition as well as postconcussive symptoms in patients with MTBI. Research Methods. Sociodemographic and medical history data were gathered for 59 patients diagnosed with MTBI. Validated and standardized tools were used to assess anxiety, depression, and cognitive function two weeks after trauma. Postconcussive symptoms were assessed with the Rivermead postconcussive questionnaire. Results. Despite the absence of significant neuropsychological deficits, a very high level of anxiety and depression was observed in our cohort. Level of anxiety and depression were positively related to cognitive performances and to postconcussive symptoms. Moreover, patients with preexisting alcohol and psychological problems were more likely to present with acute depression after MTBI. Conclusions. Early psychological rehabilitation should be provided to decrease the intensity and frequency of postconcussive symptoms and diminish the risk of these problems becoming chronic.

Current issues in neurolaw

Traumatic brain injury has received significant attention in recent years. Advances in diagnosis and management have resulted in opportunities to improve patient outcomes; however, controversies in diagnosis and management have resulted in increased interactions between the medical and legal communities. This article highlights some of the areas of controversy in traumatic brain injury litigation with the hope that synchronous resolutions of both legal and medical issues will ultimately benefit patient care. It is imperative that the neuroscience community engage the legal community to facilitate an understanding of the issues and their ramifications. Proactive communication and understanding between medical and legal specialties offer the potential to maximize efficiencies in our health care and legal systems.

Best practice guidelines for forensic neuropsychological examinations of patients with traumatic brain injury

Forensic examiners generally agree that their contributions to the forensic process have to be based on scientific principles, high ethical values, and sound clinical skills and judgment. In part I, the challenges of maintaining high ethical standards as a scientist-practitioner are addressed. In part II, the scientific strengths and weaknesses of our neuropsychological assessments are explored within the context of the 4 articles published in this issue. Specifically, Wood points out that while most traumatic brain injuries (TBIs) compromise the prefrontal cortex (PFC), traditional neuropsychological examinations do not fully capture to what extent PFC damage disrupts cognitive, emotional, and social regulation. New advances in clinical neuroscience are presented to facilitate a more detailed understanding of PFC functioning. Schwarz et al examine how clinical neuropsychology services can adequately handle forensic consultations. Frederick and Bowden, meanwhile, identify the persistent weaknesses of various Symptom Validity Tests in reliably classifying poor effort and malingering. Bailey et al conclude that the findings from sport concussion studies cannot be generalized to clinical populations, who, as a rule, have more premorbid and comorbid vulnerabilities. Finally, part III provides guidelines based on the introductory article by Bigler and Brooks, as well as a synopsis of the main conclusions offered by the contributors in this journal issue. Guidelines for both the diagnosis of mild TBI and the diagnosis of postconcussional disorder are included.