Effects of mild traumatic brain injury cannot be differentiated from substance abuse

Clinical testing of mild traumatic brain injury using computerised eye-tracking tests

Traumatic brain injury (TBI) refers to the alteration of typical brain function that occurs following a blow to the head. Even a mild case of traumatic brain injury (mTBI) can lead to long-term impairment, so accurate and timely detection is vital. Visual symptoms are common following mTBI, so while it may seem to fall outside their typical scope of practice, optometrists are ideally qualified to assess the visual impacts and help with the diagnosis of mTBI. Given that mTBI is challenging to objectively diagnose and has no universally accepted diagnostic criteria, clinicians can lack confidence in diagnosing mTBI, and be hesitant in becoming involved in the management of such patients. The development of easily quantifiable techniques using eye tracking as an objective diagnostic tool provides practitioners with an easier pathway into the field, assigning numerical values to parameters which are difficult to assess using conventional optometric tests. As this evolving technology becomes increasingly integrated into optometric clinical settings, the potential for it to identify deficits accurately and reliably in patients following mTBI, and to monitor both their recovery and the effectiveness of potential treatments will increase. This paper provides an overview of clinical tests, relevant to optometrists, that can uncover oculomotor, attentional, and exteroceptive deficits following a mTBI, so that an optometrist with an interest in eye tracking can play a role in the detection and monitoring of mTBI symptoms.

Heart rate variability following youth concussion: how do autonomic regulation and concussion symptoms differ over time postinjury?

OBJECTIVES

Following youth concussion, objective physiological indicators are needed to corroborate changes in subjective clinical measures. The objectives of the current study were to: (1) explore the effect of concussion on heart rate variability (HRV) across days postinjury in youth athletes aged 13-18 years old, compared with healthy age-matched and sex-matched controls and (2) examine the relationship between postconcussion symptom domains (physical, cognitive, fatigue and emotional) and HRV.

METHODS

Prospective, longitudinal, case-control study (N=44). This study comprised 29 concussed athletes between the ages of 13 and 18 years old (21 females, 8 males) and 15 age-matched and sex-matched controls). All participants completed baseline testing, which included demographic information (age, sex, concussion history), self-reported concussion symptoms (Post-Concussion Symptom Inventory [PCSI]) and a 24-hour heart rate recording via the Polar RS800CX system. The PCSI and HRV were collected weekly while the participant was symptomatic and then 1, 3 and 6 months following symptom resolution. HRV variables included time and frequency domain measures. Data visualisations and mixed effects modelling were used to derive parsimonious models.

RESULTS

HRV increased across days postinjury. Concussion symptom domains (physical, cognitive, fatigue and emotional) all had a significant main effect on HRV; concussed participants who reported more symptoms had higher HRV compared with those who reported fewer symptoms. Visualisations of HRV depict the recovery trajectory as non-linear across time. No significant differences on HRV measures were found between concussed and control participants.

CONCLUSION

These preliminary findings provide the foundation to understand the varied trajectory and relationship between objective physiological measures and subjective symptom reporting.

Understanding the impact of mild traumatic brain injury on veteran service-connected disability: results from Chronic Effects of Neurotrauma Consortium

OBJECTIVES

Disability evaluation is complex. The association between mild traumatic brain injury (mTBI) history and VA service-connected disability (SCD) ratings can have implications for disability processes in the civilian population. We examined the association of VA SCD ratings with lifetime mTBI exposure in three models: any mTBI, total mTBI number, and blast-related mTBI.

METHODS

Participants were 492 Operation Enduring Freedom/Operation Iraqi Freedom/Operation New Dawn veterans from four US VA Medical Centers enrolled in the Chronic Effects of Neurotrauma Consortium study between January 2015 and August 2016. Analyses entailed standard covariate-adjusted linear regression models, accounting for demographic, military, and health-related confounders and covariates.

RESULTS

Unadjusted and adjusted results indicated lifetime mTBI was significantly associated with increased SCD, with the largest effect observed for blast-related mTBI. Every unit increase in mTBI was associated with an increase in 3.6 points of percent SCD. However, hazardous alcohol use was associated with lower SCD.

CONCLUSIONS

mTBI, especially blast related, is associated with higher VA SCD ratings, with each additional mTBI increasing percent SCD. The association of hazardous alcohol use with SCD should be investigated as it may impact veteran health services access and health outcomes. These findings have implications for civilian disability processes.

Alcohol consumption and brain health

Even moderate drinking is linked to pathological changes in the brain

MR Imaging Applications in Mild Traumatic Brain Injury: An Imaging Update

Mild traumatic brain injury (mTBI), also commonly referred to as concussion, affects millions of Americans annually. Although computed tomography is the first-line imaging technique for all traumatic brain injury, it is incapable of providing long-term prognostic information in mTBI. In the past decade, the amount of research related to magnetic resonance (MR) imaging of mTBI has grown exponentially, partly due to development of novel analytical methods, which are applied to a variety of MR techniques. Here, evidence of subtle brain changes in mTBI as revealed by these techniques, which are not demonstrable by conventional imaging, will be reviewed. These changes can be considered in three main categories of brain structure, function, and metabolism. Macrostructural and microstructural changes have been revealed with three-dimensional MR imaging, susceptibility-weighted imaging, diffusion-weighted imaging, and higher order diffusion imaging. Functional abnormalities have been described with both task-mediated and resting-state blood oxygen level-dependent functional MR imaging. Metabolic changes suggesting neuronal injury have been demonstrated with MR spectroscopy. These findings improve understanding of the true impact of mTBI and its pathogenesis. Further investigation may eventually lead to improved diagnosis, prognosis, and management of this common and costly condition. (©) RSNA, 2016.

Whiplash Injury or Concussion? A Possible Biomechanical Explanation for Concussion Symptoms in Some Individuals Following a Rear-End Collision

Study Design Finite element modeling of experimental data. Background The clinical presentations of whiplash injury and concussion have considerable overlap. Both diagnoses are generally based on presenting signs and symptoms, and a history of neck or head trauma. With incomplete knowledge of the trauma, differentiating between whiplash injury and concussion can be clinically challenging. Objectives To estimate the brain strains that develop during rear-end car crashes, evaluate how these strains vary with different head kinematic parameters, and compare these strains to those generated during potentially concussive football helmet impacts. Methods Head kinematic data were analyzed from 2 prior studies, one that focused on head restraint impacts in rear-end crash tests and another that focused on football helmet impacts. These data were used as inputs to a finite element model of the human brain. Brain strains were calculated and compared to different peak kinematic parameters and between the 2 impact conditions. Results Brain strains correlated best with the head's angular velocity change for both impact conditions. The 4 crashes with head angular velocity changes greater than 30 rad/s (greater than 1719°/s) generated the highest brain stains. One crash, in which the head wrapped onto the top of the head restraint, generated brain strains similar to a 9.3-m/s rear football helmet impact, a level previously associated with concussion. Conclusion This work provides new insight into a potential biomechanical link between whiplash injury and concussion, and advances our understanding of how head restraint interaction during a rear-end crash may cause an injury more typically associated with sports-related head impacts. J Orthop Sports Phys Ther 2016;46(10):874-885. doi:10.2519/jospt.2016.7049.

Problem alcohol use in veterans with mild traumatic brain injury: Associations with cognitive performance and psychiatric symptoms

INTRODUCTION

Given that little is known about the associations between alcohol use, cognition, and psychiatric symptoms among veterans with a history of mild traumatic brain injury (mTBI), we aimed to (a) characterize how they differ from veteran controls on a measure of problem drinking; (b) investigate whether problem drinking is associated with demographic or mTBI characteristics; and (c) examine the associations between alcohol use, mTBI history, psychiatric functioning, and cognition.

METHOD

We assessed 59 veterans (n = 32 with mTBI history; n = 27 military controls) for problem alcohol use (Alcohol Use Disorders Identification Test: AUDIT), psychiatric symptoms, and neuropsychological functioning.

RESULTS

Compared to controls, veterans with mTBI history were more likely to score above the AUDIT cutoff score of 8 (p = .016), suggesting a higher rate of problem drinking. Participants with mTBI history also showed elevated psychiatric symptoms (ps < .001) and lower cognitive scores (ps < .05 to < .001). Veterans with higher AUDIT scores were younger (p = .05) and had less education (p < .01) and more psychiatric symptoms (ps < .01), but mTBI characteristics did not differ. After controlling for combat and mTBI history (R(2) = .04, ns) and posttraumatic stress disorder (PTSD) symptoms (ΔR(2) = .08, p = .05), we found that higher AUDIT scores were associated with poorer attention/processing speed, F(9, 37) = 2.55, p = .022; ΔR(2) = .26, p = .03.

CONCLUSIONS

This preliminary study suggested that veterans with mTBI history may be at increased risk for problem drinking. Problem alcohol use was primarily associated with more severe PTSD symptoms and poorer attention/processing speed, though not with combat or mTBI characteristics per se. Importantly, findings emphasize the importance of assessing for and treating problematic alcohol use and comorbid psychiatric symptoms among veterans, including those with a history of neurotrauma.

Prevalence and Predictors of Poor Recovery from Mild Traumatic Brain Injury

Although most patients with mild traumatic brain injury (mTBI) recover within 3 months, a subgroup of patients experience persistent symptoms. Yet, the prevalence and predictors of persistent dysfunction in patients with mTBI remain poorly understood. In a longitudinal study, we evaluated predictors of symptomatic and cognitive dysfunction in adolescents and young adults with mTBI, compared with two control groups-patients with orthopedic injuries and healthy uninjured individuals. Outcomes were assessed at 3 months post-injury. Poor symptomatic outcome was defined as exhibiting a symptom score higher than 90% of the orthopedic control (OC) group, and poor cognitive outcome was defined as exhibiting cognitive performance poorer than 90% of the OC group. At 3 months post-injury, more than half of the patients with mTBI (52%) exhibited persistently elevated symptoms, and more than a third (36.4%) exhibited poor cognitive outcome. The rate of high symptom report in mTBI was markedly greater than that of typically developing (13%) and OC (17%) groups; the proportion of those with poor cognitive performance in the mTBI group exceeded that of typically developing controls (15.8%), but was similar to that of the OC group (34.9%). Older age at injury, female sex, and acute symptom report were predictors of poor symptomatic outcome at 3 months. Socioeconomic status was the only significant predictor of poor cognitive outcome at 3 months.

Errors on the Trail Making Test Are Associated with Right Hemispheric Frontal Lobe Damage in Stroke Patients

Measures of performance on the Trail Making Test (TMT) are among the most popular neuropsychological assessment techniques. Completion time on TMT-A is considered to provide a measure of processing speed, whereas completion time on TMT-B is considered to constitute a behavioral measure of the ability to shift between cognitive sets (cognitive flexibility), commonly attributed to the frontal lobes. However, empirical evidence linking performance on the TMT-B to localized frontal lesions is mostly lacking. Here, we examined the association of frontal lesions following stroke with TMT-B performance measures (i.e., completion time and completion accuracy measures) using voxel-based lesion-behavior mapping, with a focus on right hemispheric frontal lobe lesions. Our results suggest that the number of errors, but not completion time on the TMT-B, is associated with right hemispheric frontal lesions. This finding contradicts common clinical practice—the use of completion time on the TMT-B to measure cognitive flexibility, and it underscores the need for additional research on the association between cognitive flexibility and the frontal lobes. Further work in a larger sample, including left frontal lobe damage and with more power to detect effects of right posterior brain injury, is necessary to determine whether our observation is specific for right frontal lesions.

Specificity of verbal learning impairment and recovery in a marijuana-dependent male: the effects of sustained marijuana abstinence

INTRODUCTION

We present the case of a young adult in treatment for marijuana dependence, with recurrent depression and a history of possible traumatic brain injury, complaining of concentration, memory, and initiation problems.

METHODS

The patient was assessed longitudinally during treatment with a brief neuropsychological battery, as well as measures of marijuana use and mood.

RESULTS

Testing at treatment baseline revealed performance that was generally in the high average range or higher on measures of reaction time and attention, with a selective impairment in verbal learning (borderline to extremely low range). Following 8 weeks of abstinence from marijuana, his verbal learning recovered to expected levels (high average range), with signs of improved learning strategy, efficiency, rate, and capacity. However, his reaction time and attention showed minimal evidence of change.

CONCLUSIONS

This finding is consistent with the literature that demonstrates that marijuana-associated neurocognitive impairments may be most pronounced in the domain of verbal learning and may remit with abstinence. The clinical implications of these case findings and recommendations for neuropsychological assessment of marijuana abusers are discussed.

An update on substance use and treatment following traumatic brain injury

Traumatic brain injury (TBI) is a leading cause of mortality and morbidity among young adults. Substance abusers constitute a disproportionate percentage of these patients. A history of substance abuse predicts increased disability, poorer prognosis, and delayed recovery. While consensus in the literature indicates that substance-abuse rates decline following injury, conflicting literature shows a significant history of brain injury in addicts. We reviewed the literature on substance abuse after TBI to explore the state of knowledge on TBI as a risk factor for substance abuse. While recent reviews regarding substance abuse in TBI patients concur that substance-abuse rates decline even after mild TBI, an emerging literature suggests mild TBI may cause subtle impairments in cognitive, executive, and decision-making functions that are often poorly recognized in early diagnosis and treatment. When combined with difficulties in psychosocial adjustment and coping skills, these impairments may increase the risk for chronic substance abuse in a subset of TBI patients. Preliminary results from veterans indicate these patterns hold in a combat-related post-traumatic stress disorder population with TBI. This increasingly prevalent combination presents a specific challenge in rehabilitation. While this comorbidity presents a challenge for the successful treatment and rehabilitation of both disorders, there is sparse evidence to recommend any specific treatment strategy for these individuals. Mild TBI and substance abuse are bidirectionally related both for risks and treatment. Further understanding the neuropsychiatric pathology and different effects of different types of injuries will likely improve the implementation of effective treatments for each of these two conditions.

Comparability of Neuropsychological Test Profiles in Patients with Chronic Substance Abuse and Mild Traumatic Brain Injury

The purpose of this study was to compare 104 patients with acute uncomplicated mild traumatic brain injury (MTBI) to a sample of 104 patients from an inpatient substance abuse program to determine whether these patients could be differentiated by their pattern of relative cognitive strengths and weaknesses. Patients were matched on age, education, and gender. Eight cognitive measures were used that included tests of attention, memory, and processing speed. There were no statistically significant differences between the two groups on any of the cognitive measures. Using a two-step cluster analysis procedure (i.e., hierarchical and k-means analyses), seven common profiles were identified. There was no significant difference in the proportions of patients from the MTBI or substance abuse group in each of the seven profiles. These results show that patients with uncomplicated MTBIs could not be reliably differentiated from patients with substance abuse problems on these cognitive measures. This is of particular concern for clinicians evaluating the neuropsychological effects of MTBI in individuals with a comorbid history of substance abuse.

"Cognitive Impairment Associated with Toxigenic Fungal Exposure": A Critique and Critical Analysis

Recently Gordon et al. (2004) reported the results of a study relating exposure to toxigenic fungi to cognitive impairment. A number of methodological problems limit the utility of this study, including the authors' not examining a number of potential confounding variables, use of a mild traumatic brain injury group as a comparison, and problematic statistical analyses increasing the Type 1 error rate. Based on these limitations, the authors' conclusion that mold-exposed people have more cognitive and physical symptoms than normal controls is questionable at best. This critique describes some of the problems with the methodology employed and the related difficulty in drawing conclusions from their work.