Prediction of functional outcomes after traumatic brain injury: a comparison of 2 measures of duration of unconsciousness

Task-based EEG and fMRI paradigms in a multimodal clinical diagnostic framework for disorders of consciousness

Disorders of consciousness (DoC) are generally diagnosed by clinical assessment, which is a predominantly motor-driven process and accounts for up to 40 % of non-communication being misdiagnosed as unresponsive wakefulness syndrome (UWS) (previously known as prolonged/persistent vegetative state). Given the consequences of misdiagnosis, a more reliable and objective multimodal protocol to diagnosing DoC is needed, but has not been produced due to concerns regarding their interpretation and reliability. Of the techniques commonly used to detect consciousness in DoC, task-based paradigms (active paradigms) produce the most unequivocal result when findings are positive. It is well-established that command following (CF) reliably reflects preserved consciousness. Task-based electroencephalography (EEG) and functional magnetic resonance imaging (fMRI) can detect motor-independent CF and reveal preserved covert consciousness in up to 14 % of UWS patients. Accordingly, to improve the diagnostic accuracy of DoC, we propose a practical multimodal clinical decision framework centered on task-based EEG and fMRI, and complemented by measures like transcranial magnetic stimulation (TMS-EEG).

Long-Term Outcomes of Pediatric Traumatic Brain Injury Following Inpatient Rehabilitation

OBJECTIVE

Assess residual disability in youth with traumatic brain injury (TBI) treated in a pediatric inpatient rehabilitation unit and examine associations of disability with inpatient status and measures of concurrent functioning.

SETTING

Large, urban, quaternary care children's hospital in the Midwestern United States.

PARTICIPANTS

Forty-five youth aged 6 to 18 years treated in an inpatient rehabilitation unit for mild-complicated to severe TBI at a minimum of 12 months postdischarge (mean = 3.5 years).

DESIGN

Retrospective chart review of clinical data collected from standard clinical care at admission and discharge combined with follow-up data examining current functioning at the time of study enrollment.

MAIN OUTCOME MEASURES

Glasgow Outcome Scale-Extended, Pediatric Revision (GOS-E Peds), Neurology Quality of Life Measurement System Short Form (NeuroQOL) Social Interaction with Peers and Cognitive Short Forms, Patient Reported Outcomes Measurement Information System (PROMIS) Global Health Scale, Strengths and Difficulties Questionnaire, and the Behavior Rating Inventory of Executive Function, 2nd Edition (BRIEF-2).

RESULTS

Based on parent report at follow-up, 62% of the children had residual TBI-related disabilities on the GOS-E Peds, while 38% reported "good recovery." Children with residual disability also reported more long-term problems in overall health, social relationships, emotional regulation, behaviors, and executive functioning than those with no residual disability. Measures of functional independence and cognitive recovery at discharge were associated with these impairments.

CONCLUSIONS

More than half of the children with TBI in this study had residual disability more than 1 year after inpatient rehabilitation. Findings highlight the associations between measures of functional independence and cognitive recovery during inpatient rehabilitation with later outcomes and underscore the need for continued services to support the needs of children with TBI following their inpatient rehabilitation stay.

The Predictive Value of the Verbal Glasgow Coma Scale in Traumatic Brain Injury: A Systematic Review

BACKGROUND

Traumatic brain injury (TBI) is a major global health concern, imposing significant burdens on individuals and healthcare systems. The Glasgow Coma Scale (GCS), a widely utilized instrument for evaluating neurological status, includes 3 variables: motor, verbal, and eye opening. The GCS plays a crucial role in TBI severity stratification. While extensive research has explored the predictive capabilities of the overall GCS score and its motor component, the Verbal Glasgow Coma Scale (V-GCS) has garnered less attention.

OBJECTIVE

To examine the predictive accuracy of the V-GCS in assessing outcomes in patients with TBI, with a particular focus on functional outcome and mortality. In addition, we intend to compare its predictive performance with other components of the GCS.

METHODS

A systematic review, based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, was conducted utilizing the PubMed, Scopus, and Web of Science databases. Inclusion criteria encompassed 10 clinical studies involving patients with TBI, wherein the level of consciousness was assessed using the verbal GCS score. Predominant statistical measures employed were odds ratios (ORs) and area under the curve (AUC).

RESULTS

Recorded findings consistently underscore that lower V-GCS scores are associated with adverse functional outcomes and mortality in patients with TBI. Despite the predictive accuracy of the V-GCS, the Motor Glasgow Coma Scale (M-GCS) emerges as a superior predictor.

CONCLUSION

In the context of TBI outcome prediction, the V-GCS demonstrates its efficacy as a prognostic tool. However, the M-GCS exhibits superior performance compared with the V-GCS. These insights underscore the multifaceted nature of TBI assessment and emphasize the necessity of considering distinct components of the Glasgow Coma Scale for comprehensive evaluation. Further research is warranted to refine and improve the application of these predictive measures in clinical practice.

Detecting signatures of consciousness in acute brain injury after stimulation with apomorphine and methylphenidate: protocol for a placebo-controlled, randomized, cross-over study

Introduction

Acute brain injury can lead to states of decreased consciousness, that is, disorder of consciousness (DoC). Detecting signs of consciousness early is vital for DoC management in the intensive care unit (ICU), neurorehabilitation and long-term prognosis. Our primary objective is to investigate the potential of pharmacological stimulant therapies in eliciting signs of consciousness among unresponsive or low-responsive acute DoC patients.

Methods

In a placebo-controlled, randomised, cross-over setting, we evaluate the effect of methylphenidate and apomorphine in 50 DoC patients with acute traumatic or non-traumatic brain injury admitted to the ICU. Patients are examined before and after administration of the trial drugs using (1) neurobehavioural scales to determine the clinical level of consciousness, (2) automated pupillometry to record pupillary responses as a signature for awareness and (3) near-infrared spectroscopy combined with electroencephalography to record neurovascular coupling as a measure for cortical activity. Primary outcomes include pupillary dilations and increase in cortical activity during passive and active paradigms.

Ethics

The study has been approved by the ethics committee (Journal-nr: H-21022096) and follows the principles of the Declaration of Helsinki. It is deemed to pose minimal risks and to hold a significant potential to improve treatment options for DoC patients. If the stimulants are shown to enhance cortical modulation of pupillary function and neurovascular coupling, this would warrant a large multicentre trial to evaluate their clinical impact.

Dissemination

Results will be available on EudraCT, clinicaltrialsregister.eu and published in an international peer-reviewed journal.

Trial registration number

EudraCT Number: 2021-001453-31.

Predicting Functional Dependency in Patients with Disorders of Consciousness: A TBI-Model Systems and TRACK-TBI Study

OBJECTIVE

It is not currently possible to predict long-term functional dependency in patients with disorders of consciousness (DoC) after traumatic brain injury (TBI). Our objective was to fit and externally validate a prediction model for 1-year dependency in patients with DoC ≥ 2 weeks after TBI.

METHODS

We included adults with TBI enrolled in TBI Model Systems (TBI-MS) or Transforming Research and Clinical Knowledge in TBI (TRACK-TBI) studies who were not following commands at rehabilitation admission or 2 weeks post-injury, respectively. We fit a logistic regression model in TBI-MS and validated it in TRACK-TBI. The primary outcome was death or dependency at 1 year post-injury, defined using the Disability Rating Scale.

RESULTS

In the TBI-MS Discovery Sample, 1,960 participants (mean age 40 [18] years, 76% male, 68% white) met inclusion criteria, and 406 (27%) were dependent 1 year post-injury. In a TBI-MS held out cohort, the dependency prediction model's area under the receiver operating characteristic curve was 0.79 (95% CI 0.74-0.85), positive predictive value was 53% and negative predictive value was 86%. In the TRACK-TBI external validation (n = 124, age 40 [16] years, 77% male, 81% white), the area under the receiver operating characteristic curve was 0.66 (0.53, 0.79), equivalent to the standard IMPACTcore + CT score (p = 0.8).

INTERPRETATION

We developed a 1-year dependency prediction model using the largest existing cohort of patients with DoC after TBI. The sensitivity and negative predictive values were greater than specificity and positive predictive values. Accuracy was diminished in an external sample, but equivalent to the IMPACT model. Further research is needed to improve dependency prediction in patients with DoC after TBI. ANN NEUROL 2023;94:1008-1023.

Early Measures of TBI Severity Poorly Predict Later Individual Impairment in a Rat Fluid Percussion Model

BACKGROUND

Multiple measures of injury severity are suggested as common data elements in preclinical traumatic brain injury (TBI) research. The robustness of these measures in characterizing injury severity is unclear. In particular, it is not known how reliably they predict individual outcomes after experimental TBI.

METHODS

We assessed several commonly used measures of initial injury severity for their ability to predict chronic cognitive outcomes in a rat lateral fluid percussion (LFPI) model of TBI. At the time of injury, we assessed reflex righting time, neurologic severity scores, and 24 h weight loss. Sixty days after LFPI, we evaluated working memory using a spontaneous alternation T-maze task.

RESULTS

We found that righting time and weight loss had no correlation to chronic T-maze performance, while neurologic severity score correlated weakly.

DISCUSSION

Taken together, our results indicate that commonly used early measures of injury severity do not robustly predict longer-term outcomes. This finding parallels the uncertainty in predicting individual outcomes in TBI clinical populations.

Crash Risk Following Return to Driving After Moderate-to-Severe TBI: A TBI Model Systems Study

OBJECTIVE

To examine motor vehicle crash frequency and risk factors following moderate-to-severe traumatic brain injury (TBI).

SETTING

Eight TBI Model Systems sites. Participants: Adults ( N = 438) with TBI who required inpatient acute rehabilitation.

DESIGN

Cross-sectional, observational design.

MAIN MEASURES

Driving survey completed at phone follow-up 1 to 30 years after injury.

RESULTS

TBI participants reported 1.5 to 2.5 times the frequency of crashes noted in the general population depending on the time frame queried, even when accounting for unreported crashes. Most reported having no crashes; for those who experienced a crash, half of them reported a single incident. Based on logistic regression, age at survey, years since injury, and perception of driving skills were significantly associated with crashes.

CONCLUSION

Compared with national statistics, crash risk is higher following TBI based on self-report. Older age and less time since resuming driving were associated with lower crash risk. When driving was resumed was not associated with crash risk. These results do not justify restricting people from driving after TBI, given that the most who resumed driving did not report experiencing any crashes. However, there is a need to identify and address factors that increase crash risk after TBI.

Predicting Functional Dependency in Patients with Disorders of Consciousness: A TBI-Model Systems and TRACK-TBI Study

Importance

There are currently no models that predict long-term functional dependency in patients with disorders of consciousness (DoC) after traumatic brain injury (TBI).

Objective

Fit, test, and externally validate a prediction model for 1-year dependency in patients with DoC 2 or more weeks after TBI.

Design

Secondary analysis of patients enrolled in TBI Model Systems (TBI-MS, 1988-2020, Discovery Sample) or Transforming Research and Clinical Knowledge in TBI (TRACK-TBI, 2013-2018, Validation Sample) and followed 1-year post-injury.

Setting

Multi-center study at USA rehabilitation hospitals (TBI-MS) and acute care hospitals (TRACK-TBI).

Participants

Adults with TBI who were not following commands at rehabilitation admission (TBI-MS; days post-injury vary) or 2-weeks post-injury (TRACK-TBI).

Exposures

In the TBI-MS database (model fitting and testing), we screened demographic, radiological, clinical variables, and Disability Rating Scale (DRS) item scores for association with the primary outcome.

Main Outcome

The primary outcome was death or complete functional dependency at 1-year post-injury, defined using a DRS-based binary measure (DRS Depend ), indicating need for assistance with all activities and concomitant cognitive impairment.

Results

In the TBI-MS Discovery Sample, 1,960 subjects (mean age 40 [18] years, 76% male, 68% white) met inclusion criteria and 406 (27%) were dependent at 1-year post-injury. A dependency prediction model had an area under the receiver operating characteristic curve (AUROC) of 0.79 [0.74, 0.85], positive predictive value of 53%, and negative predictive value of 86% for dependency in a held-out TBI-MS Testing cohort. Within the TRACK-TBI external validation sample (N=124, age 40 [16], 77% male, 81% white), a model modified to remove variables not collected in TRACK-TBI, had an AUROC of 0.66 [0.53, 0.79], equivalent to the gold-standard IMPACT core+CT score (0.68; 95% AUROC difference CI: -0.2 to 0.2, p=0.8).

Conclusions and Relevance

We used the largest existing cohort of patients with DoC after TBI to develop, test and externally validate a prediction model of 1-year dependency. The model’s sensitivity and negative predictive value were greater than specificity and positive predictive value. Accuracy was diminished in an external sample, but equivalent to the best-available models. Further research is needed to improve dependency prediction in patients with DoC after TBI.

Research Letter: Impact of Obstructive Sleep Apnea Disease Duration on Neuropsychological Functioning After Traumatic Brain Injury: A Veterans Affairs TBI Model Systems Study

OBJECTIVE

To examine the relationship between obstructive sleep apnea (OSA) disease duration and cognitive functioning in those with a history of traumatic brain injury (TBI). We hypothesized that longer OSA duration would predict poorer cognitive performance.

SETTING

Inpatient brain injury units at a Veterans Affairs (VA) Polytrauma Rehabilitation Center.

PARTICIPANTS

Participants in the VA TBI Model Systems multicenter longitudinal study who enrolled in a modular substudy (April 15, 2018, to January 15, 2021) examining cognition following TBI. All participants had received inpatient rehabilitation for TBI and reported a diagnosis of OSA ( n = 89, mean age = 40.8 years, 97% male, 81% White). Reported duration of OSA ranged from 2 to 7 years (mean = 4.2; SD = 3.9).

DESIGN

Retrospective analysis of prospective cohort, cross-sectional.

MAIN MEASURES

Brief Test of Adult Cognition by Telephone (BTACT).

RESULTS

Controlling for age, education, and time to follow commands, OSA disease duration was negatively associated with delayed verbal memory ( R2Δ = 0.053, F(1,84) = 5.479, P = .022). Performance in other cognitive domains was not significantly associated with OSA disease duration.

CONCLUSION

This study provides preliminary evidence that longer duration of OSA (ie, time since diagnosis) has a negative impact on verbal memory in those with a history of hospitalized TBI. This finding extends the literature (which focused on the general population) on the cognitive impact of OSA and is consistent with hypothesized mechanisms such as hippocampal damage and secondary impact of fatigue. Findings suggest that early OSA identification and treatment may be prudent for persons with TBI.

Time to Follow Commands in Severe Traumatic Brain Injury Survivors With Favorable Recovery at 2 Years

BACKGROUND

The recovery of severe traumatic brain injury (TBI) survivors with long-term favorable outlook is understudied. Time to follow commands varies widely in this patient population but has important clinical implications.

OBJECTIVE

To (1) evaluate time to follow commands in severe patients with TBI with favorable outcomes, (2) characterize their trajectory of recovery, and (3) identify predictors associated with delayed cognitive improvement.

METHODS

Participants were recruited prospectively at a Level I trauma center through the Brain Trauma Research Center from 2003 to 2018. Inclusion criteria were age 16 to 80 years, Glasgow Coma Scale score ≤8 and motor score <6, and Glasgow Outcome Scale-Extended measure ≥4 at 2 years postinjury.

RESULTS

In 580 patients, there were 229 (39.5%) deaths and 140 (24.1%) patients had favorable outcomes at 2 years. The mean age was 33.7 ± 14.5 years, median Glasgow Coma Scale was 7 (IQR 6-7), and median Injury Severity Score was 30 (IQR 26-38). The mean time to follow commands was 12.7 ± 11.8 days. On multivariable linear regression, the presence of diffuse axonal injury (B = 9.2 days [4.8, 13.7], P < .0001) or intraventricular hemorrhage (B = 6.4 days [0.5, 12.3], P < .035) was associated with longer time before following commands and patients who developed nosocomial infections (B = 6.5 days [1.6-11.4], P < .01).

CONCLUSION

In severe TBI survivors with favorable outcomes, time to follow commands varied widely. Most patients began to follow commands within 2 weeks. Evidence of diffuse axonal injury, intraventricular hemorrhage, and infections can delay cognitive improvement in the acute period. Patients make considerable recovery up to 2 years after their injury.

Thalamo-Prefrontal Connectivity Correlates With Early Command-Following After Severe Traumatic Brain Injury

Recovery of consciousness after traumatic brain injury (TBI) is heterogeneous and difficult to predict. Structures such as the thalamus and prefrontal cortex are thought to be important in facilitating consciousness. We sought to investigate whether the integrity of thalamo-prefrontal circuits, assessed via diffusion tensor imaging (DTI), was associated with the return of goal-directed behavior after severe TBI. We classified a cohort of severe TBI patients (N = 25, 20 males) into Early and Late/Never outcome groups based on their ability to follow commands within 30 days post-injury. We assessed connectivity between whole thalamus, and mediodorsal thalamus (MD), to prefrontal cortex (PFC) subregions including dorsolateral PFC (dlPFC), medial PFC (mPFC), anterior cingulate (ACC), and orbitofrontal (OFC) cortices. We found that the integrity of thalamic projections to PFC subregions (L OFC, L and R ACC, and R mPFC) was significantly associated with Early command-following. This association persisted when the analysis was restricted to prefrontal-mediodorsal (MD) thalamus connectivity. In contrast, dlPFC connectivity to thalamus was not significantly associated with command-following. Using the integrity of thalamo-prefrontal connections, we created a linear regression model that demonstrated 72% accuracy in predicting command-following after a leave-one-out analysis. Together, these data support a role for thalamo-prefrontal connectivity in the return of goal-directed behavior following TBI.

Improving Diagnosis and Prognosis in Acute Severe Brain Injury: A Multimodal Imaging Protocol

Multi-modal neuroimaging techniques have the potential to dramatically improve the diagnosis of the level consciousness and prognostication of neurological outcome for patients with severe brain injury in the intensive care unit (ICU). This protocol describes a study that will utilize functional Magnetic Resonance Imaging (fMRI), electroencephalography (EEG), and functional Near Infrared Spectroscopy (fNIRS) to measure and map the brain activity of acute critically ill patients. Our goal is to investigate whether these modalities can provide objective and quantifiable indicators of good neurological outcome and reliably detect conscious awareness. To this end, we will conduct a prospective longitudinal cohort study to validate the prognostic and diagnostic utility of neuroimaging techniques in the ICU. We will recruit 350 individuals from two ICUs over the course of 7 years. Participants will undergo fMRI, EEG, and fNIRS testing several times over the first 10 days of care to assess for residual cognitive function and evidence of covert awareness. Patients who regain behavioral awareness will be asked to complete web-based neurocognitive tests for 1 year, as well as return for follow up neuroimaging to determine which acute imaging features are most predictive of cognitive and functional recovery. Ultimately, multi-modal neuroimaging techniques may improve the clinical assessments of patients' level of consciousness, aid in the prediction of outcome, and facilitate efforts to find interventional methods that improve recovery and quality of life.

Reemergence of the language network during recovery from severe traumatic brain injury: A pilot functional MRI study

PRIMARY OBJECTIVE

We hypothesized that, in patients with acute severe traumatic brain injury (TBI) who recover basic language function, speech-evoked blood-oxygen-level-dependent (BOLD) functional MRI (fMRI) responses within the canonical language network increase over the first 6 months post-injury.

RESEARCH DESIGN

We conducted a prospective, longitudinal fMRI pilot study of adults with acute severe TBI admitted to the intensive care unit. We also enrolled age- and sex-matched healthy subjects.

METHODS AND PROCEDURES

We evaluated BOLD signal in bilateral superior temporal gyrus (STG) and inferior frontal gyrus (IFG) regions of interest acutely and approximately 6 months post-injury. Given evidence that regions outside the canonical language network contribute to language processing, we also performed exploratory whole-brain analyses.

MAIN OUTCOMES AND RESULTS

Of the 16 patients enrolled, eight returned for follow-up fMRI, all of whom recovered basic language function. We observed speech-evoked longitudinal BOLD increases in the left STG, but not in the right STG, right IFG, or left IFG. Whole-brain analysis revealed increases in the right supramarginal and middle temporal gyri but no differences between patients and healthy subjects (n = 16).

CONCLUSION

This pilot study suggests that, in patients with severe TBI who recover llanguage function, speech-evoked responses in bihemispheric language-processing cortex reemerge by 6 months post-injury.

Driving patterns, confidence, and perception of abilities following moderate to severe traumatic brain injury: a TBI model system study

OBJECTIVE

Describe driving patterns following moderate-to-severe traumatic brain injury (TBI). Participants: Adults (N = 438) with TBI that required inpatient acute rehabilitation who had resumed driving.

DESIGN

Cross-sectional, observational design.

SETTING

Eight TBI Model System sites.

MAIN MEASURES

A driving survey was completed at phone follow-up.

RESULTS

Most respondents reported driving daily, although 41% reported driving less than before their injury. Driving patterns were primarily associated with employment, family income, sex, residence, and time since injury, but not injury severity. Confidence in driving was high for most participants and was associated with a perception that the TBI had not diminished driving ability. Lower confidence and perceived loss of ability were associated with altered driving patterns.

CONCLUSION

Most people with moderate-to-severe TBI resume driving but perhaps not at pre-injury or normal levels compared to healthy drivers. Some driving situations are restricted. The relationship between low confidence/perceived loss of ability and driving patterns/restrictions suggests people with TBI are exhibiting some degree of caution consistent with those perceptions. Careful assessment of driving skills and monitoring during early stages of RTD is warranted, particularly for younger, male, and/or single drivers who express higher levels of confidence.

Return to Driving After Moderate-to-Severe Traumatic Brain Injury: A Traumatic Brain Injury Model System Study

OBJECTIVE

Describe who is able to return to driving (RTD) after moderate-to-severe traumatic brain injury (TBI), when this occurs, who maintains that activity, and the association with outcome.

DESIGN

Cross-sectional descriptive study.

SETTING

Eight follow-up sites of the TBI Model Systems (TBIMS) program.

PARTICIPANTS

618 participants enrolled in the TBIMS and 88 caregivers (N=706).

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

A survey was completed from 1-30 years postinjury focusing on RTD. Descriptors included demographic information, injury severity, and current employment status. Outcome was assessed at the time of the interview, including depression, quality of life, functional status, and community participation.

RESULTS

Of 706 respondents, 78% (N = 552) RTD, but 14% (N = 77) of these did not maintain that activity. Of those who RTD, 43% (N = 192) did so within 6 months of the injury and 92% did so within 24 months postinjury. The percentage of people driving after TBI did not differ significantly based on age at time of injury or follow-up. There were significant differences between drivers and nondrivers with respect to severity of injury, seizures, race, education, employment, rural vs urban setting, marital status, and family income. We performed a multivariate logistic regression to examine the association between driving status and demographic variables, adjusting for other variables in the model. The strongest associations were with current employment, family income, race, seizures, and severity of injury. Driving was associated with greater community participation, better functional outcomes, fewer symptoms of depression, and greater life satisfaction.

CONCLUSIONS

Over a span of 30 years, three-quarters of people experiencing moderate-to-severe TBI return to driving a personal vehicle, although not everyone maintains this activity. Employment, race, family income, and seizures are strongly associated with RTD.

Assessment of Covert Consciousness in the Intensive Care Unit: Clinical and Ethical Considerations

OBJECTIVE

To propose a practical ethical framework for how task-based functional magnetic resonance imaging (fMRI) and electroencephalography (EEG) may be used in the intensive care unit (ICU) to identify covert consciousness in patients with acute severe traumatic brain injury (TBI).

METHODS

We present 2 clinical scenarios in which investigational task-based fMRI and EEG were performed in critically ill patients with acute severe TBI who appeared unconscious on the bedside behavioral assessment. From these cases, we consider the clinical and ethical challenges that emerge and suggest how to reconcile them. We also provide recommendations regarding communication with families about ICU patients with covert consciousness.

RESULTS

Covert consciousness was detected acutely in a patient who died in the ICU due to withdrawal of life-sustaining therapy, whereas covert consciousness was not detected in a patient who subsequently recovered consciousness, communication, and functional independence. These cases raise ethical challenges about how assessment of covert consciousness in the ICU might inform treatment decisions, prognostication, and perceptions about the benefits and burdens of ongoing care.

CONCLUSIONS

Given that covert consciousness can be detected acutely in the ICU, we recommend that clinicians reconsider evaluative norms for ICU patients. As our clinical appreciation of covert consciousness evolves and its ethical import unfolds, we urge prognostic humility and transparency when clinicians communicate with families in the ICU about goals of care.

Stimulant Therapy in Acute Traumatic Brain Injury: Prescribing Patterns and Adverse Event Rates at 2 Level 1 Trauma Centers

BACKGROUND/OBJECTIVE

Pharmacological stimulant therapies are routinely administered to promote recovery in patients with subacute and chronic disorders of consciousness (DoC). However, utilization rates and adverse drug event (ADE) rates of stimulant therapies in patients with acute DoC are unknown. We aimed to determine the frequency of stimulant use and associated ADEs in intensive care unit (ICU) patients with acute DoC caused by traumatic brain injury (TBI).

METHODS

We retrospectively identified patients with TBI admitted to the ICU at 2 level 1 trauma centers between 2015 and 2018. Patients were included if they were stimulant naive at baseline and received amantadine, methylphenidate, or modafinil during ICU admission. Stimulant dose reduction or discontinuation during ICU admission was considered a surrogate marker of an ADE. Targeted chart review was performed to identify reasons for dose reduction or discontinuation.

RESULTS

Forty-eight of 608 patients with TBI received pharmacological stimulant therapy (7.9%) during the study period. Most patients were diagnosed with severe TBI at presentation (60.4%), although stimulants were also administered to patients with moderate (14.6%) and mild (25.0%) TBI. The median time of stimulant initiation was 11 days post-injury (range: 2-28 days). Median Glasgow Coma Scale score at the time of stimulant initiation was 9 (range: 4-15). Amantadine was the most commonly prescribed stimulant (85.4%) followed by modafinil (14.6%). Seven (14.6%) patients required stimulant dose reduction or discontinuation during ICU admission. The most common ADE resulting in therapy modification was delirium/agitation (n = 2), followed by insomnia (n = 1), anxiety (n = 1), and rash (n = 1); the reason for therapy modification was undocumented in 2 patients.

CONCLUSIONS

Pharmacological stimulant therapy is infrequently prescribed but well tolerated in ICU patients with acute TBI at level 1 trauma centers. These retrospective observations provide the basis for prospective studies to evaluate the safety, optimal dose range, and efficacy of stimulant therapies in this population.

BCI Performance and Brain Metabolism Profile in Severely Brain-Injured Patients Without Response to Command at Bedside

Detection and interpretation of signs of “covert command following” in patients with disorders of consciousness (DOC) remains a challenge for clinicians. In this study, we used a tactile P3-based BCI in 12 patients without behavioral command following, attempting to establish “covert command following.” These results were then confronted to cerebral metabolism preservation as measured with glucose PET (FDG-PET). One patient showed “covert command following” (i.e., above-threshold BCI performance) during the active tactile paradigm. This patient also showed a higher cerebral glucose metabolism within the language network (presumably required for command following) when compared with the other patients without “covert command-following” but having a cerebral glucose metabolism indicative of minimally conscious state. Our results suggest that the P3-based BCI might probe “covert command following” in patients without behavioral response to command and therefore could be a valuable addition in the clinical assessment of patients with DOC.

Early detection of consciousness in patients with acute severe traumatic brain injury

See Schiff (doi:10.1093/awx209) for a scientific commentary on this article. Patients with acute severe traumatic brain injury may recover consciousness before self-expression. Without behavioural evidence of consciousness at the bedside, clinicians may render an inaccurate prognosis, increasing the likelihood of withholding life-sustaining therapies or denying rehabilitative services. Task-based functional magnetic resonance imaging and electroencephalography techniques have revealed covert consciousness in the chronic setting, but these techniques have not been tested in the intensive care unit. We prospectively enrolled 16 patients admitted to the intensive care unit for acute severe traumatic brain injury to test two hypotheses: (i) in patients who lack behavioural evidence of language expression and comprehension, functional magnetic resonance imaging and electroencephalography detect command-following during a motor imagery task (i.e. cognitive motor dissociation) and association cortex responses during language and music stimuli (i.e. higher-order cortex motor dissociation); and (ii) early responses to these paradigms are associated with better 6-month outcomes on the Glasgow Outcome Scale-Extended. Patients underwent functional magnetic resonance imaging on post-injury Day 9.2 ± 5.0 and electroencephalography on Day 9.8 ± 4.6. At the time of imaging, behavioural evaluation with the Coma Recovery Scale-Revised indicated coma (n = 2), vegetative state (n = 3), minimally conscious state without language (n = 3), minimally conscious state with language (n = 4) or post-traumatic confusional state (n = 4). Cognitive motor dissociation was identified in four patients, including three whose behavioural diagnosis suggested a vegetative state. Higher-order cortex motor dissociation was identified in two additional patients. Complete absence of responses to language, music and motor imagery was only observed in coma patients. In patients with behavioural evidence of language function, responses to language and music were more frequently observed than responses to motor imagery (62.5-80% versus 33.3-42.9%). Similarly, in 16 matched healthy subjects, responses to language and music were more frequently observed than responses to motor imagery (87.5-100% versus 68.8-75.0%). Except for one patient who died in the intensive care unit, all patients with cognitive motor dissociation and higher-order cortex motor dissociation recovered beyond a confusional state by 6 months. However, 6-month outcomes were not associated with early functional magnetic resonance imaging and electroencephalography responses for the entire cohort. These observations suggest that functional magnetic resonance imaging and electroencephalography can detect command-following and higher-order cortical function in patients with acute severe traumatic brain injury. Early detection of covert consciousness and cortical responses in the intensive care unit could alter time-sensitive decisions about withholding life-sustaining therapies.

Effects of concussion on the blood-brain barrier in humans and rodents

Traumatic brain injury and the long-term consequences of repeated concussions constitute mounting concerns in the United States, with 5.3 million individuals living with a traumatic brain injury-related disability. Attempts to understand mechanisms and possible therapeutic approaches to alleviate the consequences of repeat mild concussions or traumatic brain injury on cerebral vasculature depend on several aspects of the trauma, including: (1) the physical characteristics of trauma or insult that result in damage; (2) the time “window” after trauma in which neuropathological features develop; (3) methods to detect possible breakdown of the blood–brain barrier; and (4) understanding different consequences of a single concussion as compared with multiple concussions. We review the literature to summarize the current understanding of blood–brain barrier and endothelial cell changes post-neurotrauma in concussions and mild traumatic brain injury. Attention is focused on concussion and traumatic brain injury in humans, with a goal of pointing out the gaps in our knowledge and how studies of rodent model systems of concussion may help in filling these gaps. Specifically, we focus on disruptions that concussion causes to the blood–brain barrier and its multifaceted consequences. Importantly, the magnitude of post-concussion blood–brain barrier dysfunction may influence the time course and extent of neuronal recovery; hence, we include in this review comparisons of more severe traumatic brain injury to concussion where appropriate. Finally, we address the important, and still unresolved, issue of how best to detect possible breakdown in the blood–brain barrier following neurotrauma by exploring intravascular tracer injection in animal models to examine leakage into the brain parenchyma.

Development and application of cognitive-pragmatic language ability assessment protocol for traumatic brain injury

The study aim was to introduce a newly-developed multifaceted cognitive-pragmatic language assessment protocol. This study was also designed to assess the reliability and validity of the assessment protocol in the discrimination between mild traumatic brain injury (mTBI) and normal control. Individuals in this study were 25 to 64 years old. Ten mTBIs and twenty-two control group were recruited for the preliminary study. Their mean ages were 45.20 and 41.23, respectively. For the main study, we recruited 39 mTBIs and 100 healthy individuals whose mean ages were 44.67 and 40.84, respectively. The newly-developed protocol was completed through a systematic review based on an item analysis. We administered the CAPTBI based on nine domains, 22 subcategories, and 57 items. All nine domains of the CAPTBI were found to be significant variables by which mTBI individuals can be distinguished from normal individuals (p < .001). We also presented the cut-off points by education level to maximize the validity of differentiating the two groups. This study is the first attempt to evaluate mTBI by means of the cognitive-linguistic protocol with multiple domains. The CAPTBI is an appropriate tool for differentiating the cognitive-pragmatic language abilities between mTBI and control group.

Time to follow commands remains the most useful injury severity variable for predicting WeeFIM® scores 1 year after paediatric TBI

OBJECTIVE

To investigate the relationship between injury severity variables, particularly time to follow commands (TFC) and long-term functional outcomes in paediatric traumatic brain injury (TBI).

METHODS AND PROCEDURE

Participants included 40 children with moderate-to-severe TBI discharged from inpatient rehabilitation. Measures of severity were initial Glasgow Coma Scale score, TFC, duration of Post Traumatic Amnesia (PTA) and total duration of impaired consciousness (TFC + PTA). Functional outcome was measured by age-corrected Functional Independence Measure for Children (WeeFIM®) scores at 1-year after discharge.

RESULTS

Correlations indicated that injury severity variables (TFC, PTA and TFC + PTA) were all associated with functional outcome. Regression analyses revealed that TFC and TFC + PTA similarly accounted for 49% or 47% of the variance, respectively, in total WeeFIM® score. Thirty-seven of 40 children had good outcome; of the three children with TFC >26 days, two had poor outcome.

CONCLUSION

PTA and TFC + PTA do not provide a benefit over TFC alone for prediction of long-term outcome and TFC is identified earlier in the recovery course. TFC remains an important predictor of functional outcome 1-year after discharge from inpatient rehabilitation after paediatric TBI.

Medical comorbidities in disorders of consciousness patients and their association with functional outcomes

OBJECTIVE

To identify, for patients in states of seriously impaired consciousness, comorbid conditions present during inpatient rehabilitation and their association with function at 1 year.

DESIGN

Abstracted data from a prospective cross-sectional observational study with data collection occurring January 1996 through December 2007.

SETTING

Four inpatient rehabilitation facilities in metropolitan areas.

PARTICIPANTS

The study sample of 68 participants is abstracted from a database of 157 patients remaining in states of seriously impaired consciousness for at least 28 days.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURE

One-year cognitive, motor, and total FIM score.

RESULTS

The most common medical complications during inpatient rehabilitation for the study sample are active seizures (46%), spasticity (57%), urinary tract infections (47%), and hydrocephalus with and without shunt (38%). Presence of ≥3 medical complications during inpatient rehabilitation, controlling for injury severity, is significantly (P<.05) associated with poorer total FIM and FIM motor scores 1 year after injury. The presence of hydrocephalus with and without shunt (r=-.20, -.21, -.18; P ≤.15), active seizures (r=-.31, -.22, -.42), spasticity (r=-.38, -.28, -.40), and urinary tract infections (r=-.25, -.24, -.26) were significantly (P<.10) associated with total FIM, FIM cognitive, and FIM motor scores, respectively.

CONCLUSIONS

Reported findings indicate that persons in states of seriously impaired consciousness with higher numbers of medical complications during inpatient rehabilitation are more likely to have lower functional levels 1-year postinjury. The findings indicate that persons with ≥3 medical complications during inpatient rehabilitation are at a higher risk for poorer functional outcomes at 1 year. It is, therefore, prudent to evaluate these patients for indications of these complications during inpatient rehabilitation.

Major and minor depression after traumatic brain injury

OBJECTIVE

To examine minor as well as major depression at 1 year posttraumatic brain injury (TBI), with particular attention to the contribution of depression severity to levels of societal participation.

DESIGN

Observational prospective study with a 2-wave longitudinal component.

SETTING

Inpatient rehabilitation centers, with 1-year follow up conducted primarily by telephone.

PARTICIPANTS

Persons with TBI (N=1570) enrolled in the TBI Model System database and followed up at 1-year postinjury.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

FIM, Patient Health Questionnaire-9, Participation Assessment with Recombined Tools-Objective, Glasgow Outcome Scale-Extended, and the Satisfaction With Life Scale.

RESULTS

Twenty-two percent of the sample reported minor depression, and 26% reported major depression at 1-year post-TBI. Both levels of depression were associated with sex (women), age (younger), preinjury mental health treatment and substance abuse, and cause of injury (intentional). There was a monotonic dose-response relationship between severity of depression and all 1-year outcomes studied, including level of cognitive and physical disability, global outcome, and satisfaction with life. With other predictors controlled, depression severity remained significantly associated with the level of societal participation at 1-year post-TBI.

CONCLUSIONS

Minor depression may be as common as major depression after TBI and should be taken seriously for its association to negative outcomes related to participation and quality of life. Findings suggest that, as in other populations, minor and major depression are not separate entities, but exist on a continuum. Further research should determine whether people with TBI traverse between the 2 diagnoses as in other patient groups.

Working memory performance following paediatric traumatic brain injury

PRIMARY OBJECTIVE

The present study investigated working memory ability in children who sustained moderate-to-severe traumatic brain injuries in relation to pre-injury, injury-related and developmental factors. It was hypothesized that there would be a correlation between performance- and rater-based working memory measures; factors predictive of working memory impairment would include earlier age at injury, more severe injury, longer time since injury and poorer overall cognitive functioning; and working memory performance would be significantly impaired when compared to normative populations.

METHODS AND PROCEDURES

Working memory was assessed in 62 children using a traditional performance measure (digit span backward) and parent report (Behaviour Rating Inventory of Executive Function (BRIEF)).

MAIN OUTCOMES AND RESULTS

Contrary to prediction, there was no statistical association between performance- and rater-based measures of working memory. Regression analyses revealed injury severity, time-since-injury, overall cognitive ability and attention span were predictive of working memory performance. As a group, working memory was impaired relative to normative samples on both measures.

CONCLUSIONS

Performance- and rater-based working memory measures, while not significantly correlated, are both sensitive to acquired cognitive dysfunction following paediatric traumatic brain injury. Demographic and clinical factors may be used to predict cognitive outcomes, educate caregivers and design clinical interventions.

The Mayo Classification System for Traumatic Brain Injury Severity

PURPOSE

To develop a single TBI severity classification system based on commonly used TBI severity measures and indicators that (1) maximally uses available positive evidence to classify TBI severity in three categories: (a) Moderate-Severe (Definite) TBI, (b) Mild (Probable) TBI, (c) Symptomatic (Possible) TBI; (2) reflects current clinical knowledge and relevance; and (3) classifies a larger number of cases than single indicator systems with reasonable accuracy.

MAIN FINDINGS

The study sample of a defined population consisted of 1501 unique Olmsted County residents with at least one confirmed TBI event from 1985 to 1999. Within the sample, 1678 TBI events were confirmed. Single measures of TBI severity were not available in a large percentage of these events, i.e., Glasgow Coma Scale (GCS) was absent in 1242 (74.0%); loss of consciousness, absent in 178 (70.2%), posttraumatic amnesia (PTA), absent in 974 (58.1%), head CT, not done in 827 (49.3%). The Mayo Classification System for TBI Severity was developed to classify cases based on available indicators that included death due to TBI, trauma-related neuroimaging abnormalities, GCS, PTA, loss of consciousness and specified post-concussive symptoms. Using the Mayo system, all cases were classified. For the Moderate-Severe (Definite) TBI classification, estimated sensitivity was 89% and estimated specificity was 98%.

CONCLUSIONS

By maximally using relevant available positive evidence, the Mayo system classifies a larger number of cases than single indicator systems with reasonable accuracy. This system may be of use in retrospective research and for determination of TBI severity for planning postacute clinical care.

The vegetative state: a report of two cases with a long-term follow-up

OBJECTIVES

To demonstrate that patients with Prolonged Vegetative State (PVS) can show signs of improvements and important changes and, consequently, to strengthen the necessity to evaluate them with long-term serial follow-ups.

SETTING

Rehabilitation of patients with severe traumatic brain injury (TBI).

PARTICIPANTS

Two people with severe TBI discharged after a long period of inpatient rehabilitation in a condition of PVS.

RESULTS

After 5 years some important changes happened and the initial prognosis was proved to be wrong.

CONCLUSION

Sometimes patients declared to be in PVS have the possibility to recover, especially when initial clinical conditions are particularly severe and do not allow the emergence of the state of consciousness. It is important to conduct regular follow-ups to better evaluate changes and, if it is necessary, to re-adjust the rehabilitation accordingly.

Early Impaired Self-awareness, Depression, and Subjective Well-being Following Traumatic Brain Injury

OBJECTIVE

To examine the incidence and intercorrelation of early impaired self-awareness (ISA) and depression after traumatic brain injury (TBI), as well as their contributions to prediction of patients' subjective well-being at discharge from inpatient rehabilitation.

DESIGN

Inception cohort.

SETTING

Inpatient rehabilitation.

PATIENTS

Subjects were 96 patients with TBI seen for inpatient rehabilitation at the Methodist Rehabilitation Center. All subjects had emerged from posttraumatic amnesia prior to assessment for this study.

INTERVENTION

None.

MAIN OUTCOME MEASURE

Subjective well-being as measured by the Satisfaction With Life Scale taken at discharge from inpatient rehabilitation.

RESULTS

Multivariable linear regression analysis revealed that ISA and functional status (Disability Rating Scale total score) at rehabilitation admission made independent contributions to prediction of subjective well-being. Bivariable correlational analyses demonstrated that frequency of depressive symptoms was inversely correlated with Satisfaction With Life Scale scores. Impaired self-awareness and depression were not correlated in this sample.

CONCLUSIONS

Results support the idea that ISA is an important factor in determining subjective well-being in patients with TBI at acute rehabilitation discharge. Early interventions to decrease ISA may improve patients' functional status at rehabilitation discharge.

The vegetative and minimally conscious states: current knowledge and remaining questions

In the last 2 decades, the minimally conscious state has been distinguished conceptually from the vegetative state and operational criteria for these diagnoses have been published. Standardized and individualized assessment tools have been developed to assist with the diagnosis of severe disorders of consciousness and the measurement of clinical improvement. The natural course of recovery and the importance of key prognostic predictors have been elucidated. Important advances have also been made in defining the similarities and differences in the pathophysiology of these two states, and functional imaging modalities have begun to explicate the neural substrate underlying the behavioral features of these disorders. Research on the efficacy of treatments for severe disorders of consciousness lags behind, due to the practical and ethical difficulties in executing large rigorously controlled clinical trials. The past and future scientific developments in this area provide an important background for continuing discussions of the ethical controversies surrounding end-of-life decision making and resource allocation.

Update of neuropathology and neurological recovery after traumatic brain injury

This review focuses on the potential for traumatic brain injury to evoke both focal and diffuse changes within the brain parenchyma, while considering the cellular constituents involved and the subcellular perturbations that contribute to their dysfunction. New insight is provided on the pathobiology of traumatically induced cell body injury and diffuse axonal damage. The consequences of axonal damage in terms of subsequent deafferentation and any potential retrograde cell death and atrophy are addressed. The regional and global metabolic sequelae are also considered. This detailed presentation of the neuropathological consequences of traumatic brain injury is used to set the stage for better appreciating the neurological recovery occurring after traumatic injury. Although the pathological and clinical effects of focal and diffuse damage are usually intermingled, the different clinical manifestations of recovery patterns associated with focal versus diffuse injuries are presented. The recognizable patterns of recovery, involving unconsciousness, posttraumatic confusion/amnesia, and postconfusional restoration, that typically occur across the full spectrum of diffuse injury are described, recognizing that the patient's long-term recovery may involve more idiosyncratic combinations of dysfunction. The review highlights the relationship of focal lesions to localizing syndromes that may be embedded in the evolving natural history of diffuse pathology. It is noted that injuries with primarily focal pathology do not necessarily follow a comparable pattern of recovery with distinct phases. Potential linkages of these recovery patterns to the known neuropathological sequelae of injury and various reparative mechanisms are considered and it is proposed that potential biological markers and newer imaging technologies will better define these linkages.

Measuring High-Level Mobility After Traumatic Brain Injury

High-level mobility is important for participation in many pre-accident activities after traumatic brain injury (TBI). This review examined which measures are used to quantify physical status and mobility after TBI to determine their appropriateness for measuring high-level mobility. Electronic databases, hand searching of several TBI journals, and citation tracking from retrieved articles were used to identify all TBI outcome studies from 1990 through to May 2004. Preliminary screening identified articles that either reported on physical outcome or mobility after TBI or utilized measurement tools with a physical component. Studies were selected for detailed analysis if they reported on mobility or physical outcomes after TBI. The search identified 175 studies that met the inclusion criteria for further analysis. The FIM instrument is the most frequently used outcome measure, highlighting a trend toward using inpatient measures to evaluate long-term outcomes. Only one study used a measurement tool that incorporated a mobility item beyond independent walking and stairs. High-level mobility is seldom measured using standardized outcome measures after TBI, despite independent mobility being one of the major goals of rehabilitation. A high-level mobility scale is needed to address the ceiling effect of outcome scales currently used in TBI rehabilitation and to extend mobility to age-appropriate levels for return to leisure and sporting activities.

Comparison of behavioral deficits and acute neuronal degeneration in rat lateral fluid percussion and weight-drop brain injury models

The behavioral and histological effects of the lateral fluid percussion (LFP) brain injury model were compared with the weight drop impact-acceleration model with 10 min of secondary hypoxia (WDIA + H). LFP injury resulted in significant motor deficits on the beam walk and inclined plane, and memory deficits on the radial arm maze and Morris water maze. Motor deficits following LFP remained throughout 6 weeks of behavioral testing. WDIA + H injury produced significant motor deficits on the beam walk and inclined plane immediately following injury, but these effects were transient and recovered by 14 days post-injury. In contrast to the LFP injury, the WDIA + H injured animals showed no memory deficits on the radial arm maze and Morris water maze. In order to determine if the differences in behavioral outcome between models were due to differences in injury mechanism or injury severity, 10 LFP-injured animals were matched with 10 WDIA-injured animals based on injury severity (i.e., time to regain righting reflex after brain injury). The LFP-matched injury group showed greater impairment than the WDIA + H matched injury group on the radial arm maze and Morris water maze. Histological examination of LFP-injured brains with Fluoro-Jade staining 24 h, 48 h, and 7 days post-injury revealed degenerating neurons in the cortex, thalamus, hippocampus, caudate-putamen, brainstem, and cerebellum, with degenerating fibers tracts in the corpus callosum and other major tracts throughout the brain. Fluoro-Jade staining following WDIA+H injury revealed damage to fibers in the optic tract, lateral olfactory tract, corpus callosum, anterior commissure, caudate-putamen, brain stem, and cerebellum. While both models produce reliable and characteristic behavioral and neuronal pathologies, their differences are important to consider when choosing a brain injury model.