Imaging modalities in mild traumatic brain injury and sports concussion

Proton magnetic resonance spectroscopy changes in the brainstem in patients after mild traumatic brain injury with loss of consciousness

INTRODUCTION

Loss of consciousness (LOC) is used as a diagnostic feature of mild traumatic brain injury (MTBI). However, only 10% of concussions result in LOC. There are only a limited number of in-vivo studies dealing with unconsciousness and structural and functional integrity of the brainstem in patients with MTBI. The aim of our pilot study was to assess the sensitivity of proton magnetic resonance spectroscopy (¹H-MRS) to detect metabolic changes in the brainstem in patients after MTBI with unconscioussness.

METHODS

Twenty-four patients (12 with LOC, and 12 without LOC) within 3 days of MTBI and 19 healthy controls were examined. All subjects underwent single-voxel ¹H-MRS examination of the upper brainstem. Spectra were evaluated using LCModel software. Ratios of total N-acetylaspartate (tNAA), total choline-containing compounds (tCho) and glutamate plus glutamine (Glx) to total creatine (tCre) were used for calculations.

RESULTS

We found a significant decrease in tNAA/tCre and tCho/tCre ratios in the patient group with LOC when compared with the control group of healthy volunteers (P=0.002 and P=0.041, respectively), and a significant decrease in the tNAA/tCre ratio in the LOC group when compared with patients without LOC (P=0.04). Other metabolite ratios in the brainstem did not show any significant group differences.

CONCLUSION

Our findings indicate that decrease of tNAA/tCre ratio in the upper brainstem using single-voxel ¹H-MRS may provide a potential biomarker for MTBI associated with LOC.

Predictors of Concussion Outcomes in Individuals With ADHD

OBJECTIVES

To describe and delineate the epidemiological profile of concussion injuries in individuals with attention-deficit/hyperactivity disorder (ADHD) by identifying characteristics associated with poorer outcomes.

SETTING

One hundred forty-four multidisciplinary concussion-specialized clinics across Canada.

PARTICIPANTS

Two hundred twenty-two individuals with a diagnosis of ADHD aged 7 to 53 years who sustained a concussion within the last year.

DESIGN

Multicenter cohort study.

MAIN MEASURES

Candidate predictor variables (ie, age, sex, concussion history, loss of consciousness, and internalized and learning disorder comorbidities) were collected through oral interviews. Concussion outcomes (ie, symptom severity and total number of symptoms experienced) were assessed with the Sport Concussion Assessment Tool.

RESULTS

Older age, female sex, and the presence of an internalized disorder predicted poorer concussion outcomes in individuals with ADHD. Males with ADHD reported significantly worse concussion outcomes with increasing age, while outcomes remained fairly stable across age in females.

CONCLUSION

The current findings represent a promising step toward the optimization of concussion management in individuals with ADHD. With a more thorough understanding of the demographic and comorbidity variables, clinical care decisions and intervention strategies can be developed to help individuals with ADHD who might be at a higher risk of poorer outcomes following a concussion.

Deficits in saccades and smooth-pursuit eye movements in adults with traumatic brain injury: a systematic review and meta-analysis

PURPOSE

To conduct a review of literature and quantify the effect that traumatic brain injury (TBI) has on oculomotor functions (OM).

METHODS

A systematic review and meta-analysis was conducted from papers that objectively measured saccades and smooth-pursuit eye movements in mild and severe TBI.

RESULTS

The overall impact of TBI on OM functions was moderate and significant with an effect size of 0.42 from 181 OM case-control comparisons. The heterogeneity, determined using the random effect model, was found to be significant (Q (180) = 367, p < 0.0001, I² = 51) owing to the variety of OM functions (reflexive saccades, antisaccades, memory-guided saccades, self-paced saccades and pursuits) measured and varying post-injury periods.The overall effect on OM functions were similar in mild and severe TBI despite differences in combined effect size of various OM functions. OM functions involving complex cognitive skills such as antisaccades (in mild and severe TBI) and memory-guided saccades (in mild TBI) were the most adversely affected, suggesting that OM deficits may be associated with cognitive deficits in TBI.

CONCLUSION

TBI often results in long-standing OM deficits. Experimental measures of OM assessment reflect neural integrity and may provide a sensitive and objective biomarker to detect OM deficits following TBI.

Moving concussion care to the next level: The emergence and role of concussion clinics in the UK

Concussion is a worldwide issue in sports medicine at present, and in recent years has evolved into a major consideration for sports in the United Kingdom (UK). Governing bodies, sports clinicians, and indeed athletes themselves are dealing with the implications that this injury brings. In parallel with this, innovative means of managing this condition are emerging. The creation of specialized concussion clinics (which mirror those present in the United States and Canada) is one means of enhancing concussion care in the UK. In this chapter, the emergence of concussion clinics in the UK will be discussed. The specific roles of the multidisciplinary teams working in these clinics will be outlined (including the disciplines of sports medicine, radiology, neurology, physiotherapy, and psychology/psychiatry), and the approaches used in the management of concussion in this setting will be explored. Future recommendations for the growth and development of clinic-based concussion care in the UK will also be discussed.

Traumatic brain injury, diabetic neuropathy and altered-psychiatric health: The fateful triangle

Traumatic brain injury is a detrimental medical condition particularly when accompanied by diabetes. There are several comorbidities going along with diabetes including, but not limited to, kidney failure, obesity, coronary artery disease, peripheral vascular disease, hypertension, stroke, neuropathies and amputations. Unlike diabetes type 1, diabetes type 2 is more common in adults who simultaneously suffer from other comorbid conditions making them susceptible to repetitive fall incidents and sustaining head trauma. The resulting brain insult exacerbates current psychiatric disorders such as depression and anxiety, which, in turn, increases the risk of sustaining further brain traumas. The relationship between diabetes, traumatic brain injury and psychiatric health constitutes a triad forming a non-reversible vicious cycle. At the proteomic and psychiatric levels, cellular, molecular and behavioral alterations have been reported with the induction of non-traumatic brain injury in diabetic models such as stroke. However, research into traumatic brain injury has not been systematically investigated. Thus, in cases of diabetic neuropathy complicated with traumatic brain injury, utilizing fine structural and analytical techniques allows the identification of key biological markers that can then be used as innovative diagnostics as well as novel therapeutic targets in an attempt to treat diabetes and its sequelae especially those arising from repetitive mild brain trauma.

Advanced neuroimaging in the clinic: critical appraisal of the evidence base

The shortage of high-quality systematic reviews in the field of radiology limits evidence-based integration of imaging methods into clinical practice and may perpetuate misconceptions regarding the efficacy and appropriateness of imaging techniques for specific applications. Diffusion tensor imaging for patients with mild traumatic brain injury (DTI-mTBI) and dynamic susceptibility contrast MRI for patients with glioma (DSC-glioma) are applications of quantitative neuroimaging, which similarly detect manifestations of disease where conventional neuroimaging techniques cannot. We performed a critical appraisal of reviews, based on the current evidence-based medicine methodology, addressing the ability of DTI-mTBI and DSC-glioma to (a) detect brain abnormalities and/or (b) predict clinical outcomes. 23 reviews of DTI-mTBI and 26 reviews of DSC-glioma met criteria for inclusion. All reviews addressed detection of brain abnormalities, whereas 12 DTI-mTBI reviews and 22 DSC-glioma reviews addressed prediction of a clinical outcome. All reviews were assessed using a critical appraisal worksheet consisting of 19 yes/no questions. Reviews were graded according to the total number of positive responses and the 2011 Oxford Centre for evidence-based medicine levels of evidence criteria. Reviews addressing DTI-mTBI detection had moderate quality, while those addressing DSC-glioma were of low quality. Reviews addressing prediction of outcomes for both applications were of low quality. Five DTI-mTBI reviews, but only one review of DSC-glioma met criteria for classification as a meta-analysis/systematic/quantitative review.

Post-concussion syndrome (PCS) in a youth population: defining the diagnostic value and cost-utility of brain imaging

PURPOSE

Approximately 90% of concussions are transient, with symptoms resolving within 10-14 days. However, a minority of patients remain symptomatic several months post-injury, a condition known as post-concussion syndrome (PCS). The treatment of these patients can be challenging. The goal of our study was to assess the utility and cost-effectiveness of neurologic imaging two or more weeks post-injury in a cohort of youth with PCS.

METHODS

We conducted a retrospective study of 52 pediatric patients with persistent post-concussion symptoms after 3 months. We collected demographics and neuroimaging results obtained greater than 2 weeks post-concussion. Neuroimaging ordered in the first 2 weeks post-concussion was excluded, except to determine the rate of re-imaging. Descriptive statistics and corresponding cost data were collected.

RESULTS

Of 52 patients with PCS, 23/52 (44%) had neuroimaging at least 2 weeks after the initial injury, for a total of 32 diagnostic studies. In summary, 1/19 MRIs (5.3%), 1/8 CTs (13%), and 0/5 x-rays (0%) yielded significant positive findings, none of which altered clinical management. Chronic phase neuroimaging estimated costs from these 52 pediatric patients totaled $129,025. We estimate the cost to identify a single positive finding was $21,000 for head CT and $104,500 for brain MRI.

CONCLUSIONS

In this cohort of pediatric PCS patients, brain imaging in the chronic phase (defined as more than 2 weeks after concussion) was pursued in almost half the study sample, had low diagnostic yield, and had poor cost-effectiveness. Based on these results, outpatient management of pediatric patients with long-term post-concussive symptoms should rarely include repeat neuroimaging beyond the acute phase.

Repetitive concussions in adolescent athletes - translating clinical and experimental research into perspectives on rehabilitation strategies

Sports-related concussions are particularly common during adolescence, a time when even mild brain injuries may disrupt ongoing brain maturation and result in long-term complications. A recent focus on the consequences of repetitive concussions among professional athletes has prompted the development of several new experimental models in rodents, as well as the revision of guidelines for best management of sports concussions. Here, we consider the utility of rodent models to understand the functional consequences and pathobiology of concussions in the developing brain, identifying the unique behavioral and pathological signatures of concussive brain injuries. The impact of repetitive concussions on behavioral consequences and injury progression is also addressed. In particular, we focus on the epidemiological, clinical, and experimental evidence underlying current recommendations for physical and cognitive rest after concussion, and highlight key areas in which further research is needed. Lastly, we consider how best to promote recovery after injury, recognizing that optimally timed, activity-based rehabilitative strategies may hold promise for the adolescent athlete who has sustained single or repetitive concussions. The purpose of this review is to inform the clinical research community as it strives to develop and optimize evidence-based guidelines for the concussed adolescent, in terms of both acute and long-term management.

Multimodal imaging of mild traumatic brain injury and persistent postconcussion syndrome

BACKGROUND

Persistent postconcussion syndrome (PCS) occurs in around 5-10% of individuals after mild traumatic brain injury (mTBI), but research into the underlying biology of these ongoing symptoms is limited and inconsistent. One reason for this could be the heterogeneity inherent to mTBI, with individualized injury mechanisms and psychological factors. A multimodal imaging study may be able to characterize the injury better.

AIM

To look at the relationship between functional (fMRI), structural (diffusion tensor imaging), and metabolic (magnetic resonance spectroscopy) data in the same participants in the long term (>1 year) after injury. It was hypothesized that only those mTBI participants with persistent PCS would show functional changes, and that these changes would be related to reduced structural integrity and altered metabolite concentrations.

METHODS

Functional changes associated with persistent PCS after mTBI (>1 year postinjury) were investigated in participants with and without PCS (both n = 8) and non-head injured participants (n = 9) during performance of working memory and attention/processing speed tasks. Correlation analyses were performed to look at the relationship between the functional data and structural and metabolic alterations in the same participants.

RESULTS

There were no behavioral differences between the groups, but participants with greater PCS symptoms exhibited greater activation in attention-related areas (anterior cingulate), along with reduced activation in temporal, default mode network, and working memory areas (left prefrontal) as cognitive load was increased from the easiest to the most difficult task. Functional changes in these areas correlated with reduced structural integrity in corpus callosum and anterior white matter, and reduced creatine concentration in right dorsolateral prefrontal cortex.

CONCLUSION

These data suggest that the top-down attentional regulation and deactivation of task-irrelevant areas may be compensating for the reduction in working memory capacity and variation in white matter transmission caused by the structural and metabolic changes after injury. This may in turn be contributing to secondary PCS symptoms such as fatigue and headache. Further research is required using multimodal data to investigate the mechanisms of injury after mTBI, but also to aid individualized diagnosis and prognosis.

Counseling athletes on the risk of chronic traumatic encephalopathy

Context:

Chronic traumatic encephalopathy (CTE) is a rare progressive neurologic disorder that can manifest as a combination of cognitive, mood and behavioral, and neurologic symptoms. Despite clinically apparent symptoms, there is no imaging or other diagnostic test that can confirm diagnosis in living subjects. Diagnosis can only be confirmed postmortem by specific histopathologic features within the brain tissue identified on autopsy. CTE represents a unique tauopathy that is distinct from other neurodegenerative diseases.

Evidence Acquisition:

PubMed was searched from 1990 to 2013 for sport concussion and chronic traumatic encephalopathy. Articles were also identified from bibliographies of recent reviews and consensus statements.

Study Design:

Clinical review.

Level of Evidence:

Level 5.

Results:

Although CTE is postulated to occur as a result of repetitive mild traumatic brain injury, the specific etiology and risk factors have not yet been elucidated, and postmortem diagnosis makes causality difficult to determine.

Conclusion:

When counseling athletes and families about the potential association of recurrent concussions and the development of CTE, discussion of proper management of concussion is cornerstone. Unfortunately, to date, there is no equipment that can prevent concussions; however, rule changes and legislation may decrease the risk. It is imperative that return to play is medically supervised by a provider trained in the management of concussion and begins only once symptoms have resolved. In addition, athletes with permanent symptoms should be retired from contact sport.

National Athletic Trainers' Association position statement: management of sport concussion

OBJECTIVE

To provide athletic trainers, physicians, and other health care professionals with best-practice guidelines for the management of sport-related concussions.

BACKGROUND

An estimated 3.8 million concussions occur each year in the United States as a result of sport and physical activity. Athletic trainers are commonly the first medical providers available onsite to identify and evaluate these injuries.

RECOMMENDATIONS

The recommendations for concussion management provided here are based on the most current research and divided into sections on education and prevention, documentation and legal aspects, evaluation and return to play, and other considerations.

Contemporary imaging of mild TBI: the journey toward diffusion tensor imaging to assess neuronal damage

OBJECTIVES

To follow the progression of neuroimaging as a means of non-invasive evaluation of mild traumatic brain injury (mTBI) in order to provide recommendations based on reproducible, defined imaging findings.

METHODS

A comprehensive literature review and analysis of contemporary published articles was performed to study the progression of neuroimaging findings as a non-invasive 'biomarker' for mTBI.

RESULTS

Multiple imaging modalities exist to support the evaluation of patients with mTBI, including ultrasound (US), computed tomography (CT), single photon emission computed tomography (SPECT), positron emission tomography (PET), and magnetic resonance imaging (MRI). These techniques continue to evolve with the development of fractional anisotropy (FA), fiber tractography (FT), and diffusion tensor imaging (DTI).

DISCUSSION

Modern imaging techniques, when applied in the appropriate clinical setting, may serve as a valuable tool for diagnosis and management of patients with mTBI. An understanding of modern neuroanatomical imaging will enhance our ability to analyse injury and recognize the manifestations of mTBI.

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.

The influence of pain on cerebral functioning after mild traumatic brain injury

More than 75% of patients with mild traumatic brain injury (MTBI) report chronic pain whose potential detrimental effects on cognitive recovery need to be identified. The objective of this study was to investigate the relationship between pain, performance on a working memory task, gray matter density, and mid-dorsolateral prefrontal cortex (mid-DLPFC) activation in subjects with a MTBI. For comparison purposes, we performed identical correlation analyses with a group of subjects without MTBI who sustained sports injuries. Twenty-four subjects who experienced a MTBI in the past 12 months, 16 control subjects, and 29 subjects with sport injuries were included. One hour prior to entering the magnetic resonance scanner, the subjects were asked to fill out the pain Visual Analogue Scale. Subsequently, a high-resolution T1-weighted image was acquired followed by a functional magnetic resonance imaging session using the visual externally ordered working memory task. Results showed that MTBI subjects reporting severe pain in the hour preceding the testing had reduced mid-DLPFC activation during the working memory task and poorer performance on the task. Subjects with sport injuries and severe levels of pain showed the reverse pattern: pain was associated with higher activation in the mid-DLPFC and did not correlate with performance. Gray matter density measures were independent of pain level. This study showed that behavioral performance and cerebral functioning are affected by pain after a MTBI. Moreover, this study suggests that pain, cognition, and cerebral functioning interactions could not easily be generalized from one clinical population to another.

Microenvironment changes in mild traumatic brain injury

Traumatic brain injury (TBI) is a major public-health problem for which mild TBI (MTBI) makes up majority of the cases. MTBI is a poorly-understood health problem and can persist for years manifesting into neurological and non-neurological problems that can affect functional outcome. Presently, diagnosis of MTBI is based on symptoms reporting with poor understanding of ongoing pathophysiology, hence precluding prognosis and intervention. Other than rehabilitation, there is still no pharmacological treatment for the treatment of secondary injury and prevention of the development of cognitive and behavioural problems. The lack of external injuries and absence of detectable brain abnormalities lend support to MTBI developing at the cellular and biochemical level. However, the paucity of suitable and validated non-invasive methods for accurate diagnosis of MTBI poses as a substantial challenge. Hence, it is crucial that a clinically useful evaluation and management procedure be instituted for MTBI that encompasses both molecular pathophysiology and functional outcome. The acute microenvironment changes post-MTBI presents an attractive target for modulation of MTBI symptoms and the development of cognitive changes later in life.