Traumatic brain injury: progress and challenges in prevention, clinical care, and research

Traumatic brain injury (TBI) has the highest incidence of all common neurological disorders, and poses a substantial public health burden. TBI is increasingly documented not only as an acute condition but also as a chronic disease with long-term consequences, including an increased risk of late-onset neurodegeneration. The first Lancet Neurology Commission on TBI, published in 2017, called for a concerted effort to tackle the global health problem posed by TBI. Since then, funding agencies have supported research both in high-income countries (HICs) and in low-income and middle-income countries (LMICs). In November 2020, the World Health Assembly, the decision-making body of WHO, passed resolution WHA73.10 for global actions on epilepsy and other neurological disorders, and WHO launched the Decade for Action on Road Safety plan in 2021. New knowledge has been generated by large observational studies, including those conducted under the umbrella of the International Traumatic Brain Injury Research (InTBIR) initiative, established as a collaboration of funding agencies in 2011. InTBIR has also provided a huge stimulus to collaborative research in TBI and has facilitated participation of global partners. The return on investment has been high, but many needs of patients with TBI remain unaddressed. This update to the 2017 Commission presents advances and discusses persisting and new challenges in prevention, clinical care, and research.

In LMICs, the occurrence of TBI is driven by road traffic incidents, often involving vulnerable road users such as motorcyclists and pedestrians. In HICs, most TBI is caused by falls, particularly in older people (aged ≥65 years), who often have comorbidities. Risk factors such as frailty and alcohol misuse provide opportunities for targeted prevention actions. Little evidence exists to inform treatment of older patients, who have been commonly excluded from past clinical trials—consequently, appropriate evidence is urgently required. Although increasing age is associated with worse outcomes from TBI, age should not dictate limitations in therapy. However, patients injured by low-energy falls (who are mostly older people) are about 50% less likely to receive critical care or emergency interventions, compared with those injured by high-energy mechanisms, such as road traffic incidents.

Mild TBI, defined as a Glasgow Coma sum score of 13–15, comprises most of the TBI cases (over 90%) presenting to hospital. Around 50% of adult patients with mild TBI presenting to hospital do not recover to pre-TBI levels of health by 6 months after their injury. Fewer than 10% of patients discharged after presenting to an emergency department for TBI in Europe currently receive follow-up. Structured follow-up after mild TBI should be considered good practice, and urgent research is needed to identify which patients with mild TBI are at risk for incomplete recovery.

The selection of patients for CT is an important triage decision in mild TBI since it allows early identification of lesions that can trigger hospital admission or life-saving surgery. Current decision making for deciding on CT is inefficient, with 90–95% of scanned patients showing no intracranial injury but being subjected to radiation risks. InTBIR studies have shown that measurement of blood-based biomarkers adds value to previously proposed clinical decision rules, holding the potential to improve efficiency while reducing radiation exposure. Increased concentrations of biomarkers in the blood of patients with a normal presentation CT scan suggest structural brain damage, which is seen on MR scanning in up to 30% of patients with mild TBI. Advanced MRI, including diffusion tensor imaging and volumetric analyses, can identify additional injuries not detectable by visual inspection of standard clinical MR images. Thus, the absence of CT abnormalities does not exclude structural damage—an observation relevant to litigation procedures, to management of mild TBI, and when CT scans are insufficient to explain the severity of the clinical condition.

Although blood-based protein biomarkers have been shown to have important roles in the evaluation of TBI, most available assays are for research use only. To date, there is only one vendor of such assays with regulatory clearance in Europe and the USA with an indication to rule out the need for CT imaging for patients with suspected TBI. Regulatory clearance is provided for a combination of biomarkers, although evidence is accumulating that a single biomarker can perform as well as a combination. Additional biomarkers and more clinical-use platforms are on the horizon, but cross-platform harmonisation of results is needed. Health-care efficiency would benefit from diversity in providers.

In the intensive care setting, automated analysis of blood pressure and intracranial pressure with calculation of derived parameters can help individualise management of TBI. Interest in the identification of subgroups of patients who might benefit more from some specific therapeutic approaches than others represents a welcome shift towards precision medicine. Comparative-effectiveness research to identify best practice has delivered on expectations for providing evidence in support of best practices, both in adult and paediatric patients with TBI.

Progress has also been made in improving outcome assessment after TBI. Key instruments have been translated into up to 20 languages and linguistically validated, and are now internationally available for clinical and research use. TBI affects multiple domains of functioning, and outcomes are affected by personal characteristics and life-course events, consistent with a multifactorial bio-psycho-socio-ecological model of TBI, as presented in the US National Academies of Sciences, Engineering, and Medicine (NASEM) 2022 report. Multidimensional assessment is desirable and might be best based on measurement of global functional impairment. More work is required to develop and implement recommendations for multidimensional assessment. Prediction of outcome is relevant to patients and their families, and can facilitate the benchmarking of quality of care. InTBIR studies have identified new building blocks (eg, blood biomarkers and quantitative CT analysis) to refine existing prognostic models. Further improvement in prognostication could come from MRI, genetics, and the integration of dynamic changes in patient status after presentation.

Neurotrauma researchers traditionally seek translation of their research findings through publications, clinical guidelines, and industry collaborations. However, to effectively impact clinical care and outcome, interactions are also needed with research funders, regulators, and policy makers, and partnership with patient organisations. Such interactions are increasingly taking place, with exemplars including interactions with the All Party Parliamentary Group on Acquired Brain Injury in the UK, the production of the NASEM report in the USA, and interactions with the US Food and Drug Administration. More interactions should be encouraged, and future discussions with regulators should include debates around consent from patients with acute mental incapacity and data sharing. Data sharing is strongly advocated by funding agencies. From January 2023, the US National Institutes of Health will require upload of research data into public repositories, but the EU requires data controllers to safeguard data security and privacy regulation. The tension between open data-sharing and adherence to privacy regulation could be resolved by cross-dataset analyses on federated platforms, with the data remaining at their original safe location. Tools already exist for conventional statistical analyses on federated platforms, however federated machine learning requires further development. Support for further development of federated platforms, and neuroinformatics more generally, should be a priority.

This update to the 2017 Commission presents new insights and challenges across a range of topics around TBI: epidemiology and prevention (section 1 ); system of care (section 2 ); clinical management (section 3 ); characterisation of TBI (section 4 ); outcome assessment (section 5 ); prognosis (Section 6 ); and new directions for acquiring and implementing evidence (section 7 ). Table 1 summarises key messages from this Commission and proposes recommendations for the way forward to advance research and clinical management of TBI.

The continuum of spreading depolarizations in acute cortical lesion development: Examining Leão's legacy

A modern understanding of how cerebral cortical lesions develop after acute brain injury is based on Aristides Leão's historic discoveries of spreading depression and asphyxial/anoxic depolarization. Treated as separate entities for decades, we now appreciate that these events define a continuum of spreading mass depolarizations, a concept that is central to understanding their pathologic effects. Within minutes of acute severe ischemia, the onset of persistent depolarization triggers the breakdown of ion homeostasis and development of cytotoxic edema. These persistent changes are diagnosed as diffusion restriction in magnetic resonance imaging and define the ischemic core. In delayed lesion growth, transient spreading depolarizations arise spontaneously in the ischemic penumbra and induce further persistent depolarization and excitotoxic damage, progressively expanding the ischemic core. The causal role of these waves in lesion development has been proven by real-time monitoring of electrophysiology, blood flow, and cytotoxic edema. The spreading depolarization continuum further applies to other models of acute cortical lesions, suggesting that it is a universal principle of cortical lesion development. These pathophysiologic concepts establish a working hypothesis for translation to human disease, where complex patterns of depolarizations are observed in acute brain injury and appear to mediate and signal ongoing secondary damage.

Recovery After Mild Traumatic Brain Injury in Patients Presenting to US Level I Trauma Centers: A Transforming Research and Clinical Knowledge in Traumatic Brain Injury (TRACK-TBI) Study

Importance

Most traumatic brain injuries (TBIs) are classified as mild (mTBI) based on admission Glasgow Coma Scale (GCS) scores of 13 to 15. The prevalence of persistent functional limitations for these patients is unclear.

Objectives

To characterize the natural history of recovery of daily function following mTBI vs peripheral orthopedic traumatic injury in the first 12 months postinjury using data from the Transforming Research and Clinical Knowledge in Traumatic Brain Injury (TRACK-TBI) study, and, using clinical computed tomographic (CT) scans, examine whether the presence (CT+) or absence (CT-) of acute intracranial findings in the mTBI group was associated with outcomes.

Design, Setting, and Participants

TRACK-TBI, a cohort study of patients with mTBI presenting to US level I trauma centers, enrolled patients from February 26, 2014, to August 8, 2018, and followed up for 12 months. A total of 1453 patients at 11 level I trauma center emergency departments or inpatient units met inclusion criteria (ie, mTBI [n = 1154] or peripheral orthopedic traumatic injury [n = 299]) and were enrolled within 24 hours of injury; mTBI participants had admission GCS scores of 13 to 15 and clinical head CT scans. Patients with peripheral orthopedic trauma injury served as the control (OTC) group.

Exposures

Participants with mTBI or OTC.

Main Outcomes and Measures

The Glasgow Outcome Scale Extended (GOSE) scale score, reflecting injury-related functional limitations across broad life domains at 2 weeks and 3, 6, and 12 months postinjury was the primary outcome. The possible score range of the GOSE score is 1 (dead) to 8 (upper good recovery), with a score less than 8 indicating some degree of functional impairment.

Results

Of the 1453 participants, 953 (65.6%) were men; mean (SD) age was 40.9 (17.1) years in the mTBI group and 40.9 (15.4) years in the OTC group. Most participants (mTBI, 87%; OTC, 93%) reported functional limitations (GOSE <8) at 2 weeks postinjury. At 12 months, the percentage of mTBI participants reporting functional limitations was 53% (95% CI, 49%-56%) vs 38% (95% CI, 30%-45%) for OTCs. A higher percentage of CT+ patients reported impairment (61%) compared with the mTBI CT- group (49%; relative risk [RR], 1.24; 95% CI, 1.08-1.43) and a higher percentage in the mTBI CT-group compared with the OTC group (RR, 1.28; 95% CI, 1.02-1.60).

Conclusions and Relevance

Most patients with mTBI presenting to US level I trauma centers report persistent, injury-related life difficulties at 1 year postinjury, suggesting the need for more systematic follow-up of patients with mTBI to provide treatments and reduce the risk of chronic problems after mTBI.

Recording, analysis, and interpretation of spreading depolarizations in neurointensive care: Review and recommendations of the COSBID research group

Spreading depolarizations (SD) are waves of abrupt, near-complete breakdown of neuronal transmembrane ion gradients, are the largest possible pathophysiologic disruption of viable cerebral gray matter, and are a crucial mechanism of lesion development. Spreading depolarizations are increasingly recorded during multimodal neuromonitoring in neurocritical care as a causal biomarker providing a diagnostic summary measure of metabolic failure and excitotoxic injury. Focal ischemia causes spreading depolarization within minutes. Further spreading depolarizations arise for hours to days due to energy supply-demand mismatch in viable tissue. Spreading depolarizations exacerbate neuronal injury through prolonged ionic breakdown and spreading depolarization-related hypoperfusion (spreading ischemia). Local duration of the depolarization indicates local tissue energy status and risk of injury. Regional electrocorticographic monitoring affords even remote detection of injury because spreading depolarizations propagate widely from ischemic or metabolically stressed zones; characteristic patterns, including temporal clusters of spreading depolarizations and persistent depression of spontaneous cortical activity, can be recognized and quantified. Here, we describe the experimental basis for interpreting these patterns and illustrate their translation to human disease. We further provide consensus recommendations for electrocorticographic methods to record, classify, and score spreading depolarizations and associated spreading depressions. These methods offer distinct advantages over other neuromonitoring modalities and allow for future refinement through less invasive and more automated approaches.

Risk of Posttraumatic Stress Disorder and Major Depression in Civilian Patients After Mild Traumatic Brain Injury: A TRACK-TBI Study

IMPORTANCE

Traumatic brain injury (TBI) has been associated with adverse mental health outcomes, such as posttraumatic stress disorder (PTSD) and major depressive disorder (MDD), but little is known about factors that modify risk for these psychiatric sequelae, particularly in the civilian sector.

OBJECTIVE

To ascertain prevalence of and risk factors for PTSD and MDD among patients evaluated in the emergency department for mild TBI (mTBI).

DESIGN, SETTING, AND PARTICIPANTS

Prospective longitudinal cohort study (February 2014 to May 2018). Posttraumatic stress disorder and MDD symptoms were assessed using the PTSD Checklist for DSM-5 and the Patient Health Questionnaire-9 Item. Risk factors evaluated included preinjury and injury characteristics. Propensity score weights-adjusted multivariable logistic regression models were performed to assess associations with PTSD and MDD. A total of 1155 patients with mTBI (Glasgow Coma Scale score, 13-15) and 230 patients with nonhead orthopedic trauma injuries 17 years and older seen in 11 US hospitals with level 1 trauma centers were included in this study.

MAIN OUTCOMES AND MEASURES

Probable PTSD (PTSD Checklist for DSM-5 score, ≥33) and MDD (Patient Health Questionnaire-9 Item score, ≥15) at 3, 6, and 12 months postinjury.

RESULTS

Participants were 1155 patients (752 men [65.1%]; mean [SD] age, 40.5 [17.2] years) with mTBI and 230 patients (155 men [67.4%]; mean [SD] age, 40.4 [15.6] years) with nonhead orthopedic trauma injuries. Weights-adjusted prevalence of PTSD and/or MDD in the mTBI vs orthopedic trauma comparison groups at 3 months was 20.0% (SE, 1.4%) vs 8.7% (SE, 2.2%) (P < .001) and at 6 months was 21.2% (SE, 1.5%) vs 12.1% (SE, 3.2%) (P = .03). Risk factors for probable PTSD at 6 months after mTBI included less education (adjusted odds ratio, 0.89; 95% CI, 0.82-0.97 per year), being black (adjusted odds ratio, 5.11; 95% CI, 2.89-9.05), self-reported psychiatric history (adjusted odds ratio, 3.57; 95% CI, 2.09-6.09), and injury resulting from assault or other violence (adjusted odds ratio, 3.43; 95% CI, 1.56-7.54). Risk factors for probable MDD after mTBI were similar with the exception that cause of injury was not associated with increased risk.

CONCLUSIONS AND RELEVANCE

After mTBI, some individuals, on the basis of education, race/ethnicity, history of mental health problems, and cause of injury were at substantially increased risk of PTSD and/or MDD. These findings should influence recognition of at-risk individuals and inform efforts at surveillance, follow-up, and intervention.

Intravenous ketamine for the treatment of refractory status epilepticus: a retrospective multicenter study

PURPOSE

To examine patterns of use, efficacy, and safety of intravenous ketamine for the treatment of refractory status epilepticus (RSE).

METHODS

Multicenter retrospective review of medical records and electroencephalography (EEG) reports in 10 academic medical centers in North America and Europe, including 58 subjects, representing 60 episodes of RSE that were identified between 1999 and 2012. Seven episodes occurred after anoxic brain injury.

KEY FINDINGS

Permanent control of RSE was achieved in 57% (34 of 60) of episodes. Ketamine was felt to have contributed to permanent control ("possible" or "likely" responses) in 32% (19 of 60) including seven (12%) in which ketamine was the last drug added (likely responses). Four of the seven likely responses, but none of the 12 possible ones, occurred in patients with postanoxic brain injury. No likely responses were observed when infusion rates were lower than 0.9 mg/kg/h, when ketamine was introduced at least 8 days after SE onset, or after failure of seven or more drugs. Ketamine was discontinued due to possible adverse events in five patients. Complications were mostly attributed to concurrent drugs, especially other anesthetics. Mortality rate was 43% (26 of 60), but was lower when SE was controlled within 24 h of ketamine initiation (16% vs. 56%, p = 0.0047).

SIGNIFICANCE

Ketamine appears to be a relatively effective and safe drug for the treatment of RSE. This retrospective series provides preliminary data on effective dose and appropriate time of intervention to aid in the design of a prospective trial to further define the role of ketamine in the treatment of RSE.

Functional Outcomes Over the First Year After Moderate to Severe Traumatic Brain Injury in the Prospective, Longitudinal TRACK-TBI Study

Importance

Moderate to severe traumatic brain injury (msTBI) is a major cause of death and disability in the US and worldwide. Few studies have enabled prospective, longitudinal outcome data collection from the acute to chronic phases of recovery after msTBI.

Objective

To prospectively assess outcomes in major areas of life function at 2 weeks and 3, 6, and 12 months after msTBI.

Design, Setting, and Participants

This cohort study, as part of the Transforming Research and Clinical Knowledge in TBI (TRACK-TBI) study, was conducted at 18 level 1 trauma centers in the US from February 2014 to August 2018 and prospectively assessed longitudinal outcomes, with follow-up to 12 months postinjury. Participants were patients with msTBI (Glasgow Coma Scale scores 3-12) extracted from a larger group of patients with mild, moderate, or severe TBI who were enrolled in TRACK-TBI. Data analysis took place from October 2019 to April 2021.

Exposures

Moderate or severe TBI.

Main Outcomes and Measures

The Glasgow Outcome Scale-Extended (GOSE) and Disability Rating Scale (DRS) were used to assess global functional status 2 weeks and 3, 6, and 12 months postinjury. Scores on the GOSE were dichotomized to determine favorable (scores 4-8) vs unfavorable (scores 1-3) outcomes. Neurocognitive testing and patient reported outcomes at 12 months postinjury were analyzed.

Results

A total of 484 eligible patients were included from the 2679 individuals in the TRACK-TBI study. Participants with severe TBI (n = 362; 283 men [78.2%]; median [interquartile range] age, 35.5 [25-53] years) and moderate TBI (n = 122; 98 men [80.3%]; median [interquartile range] age, 38 [25-53] years) were comparable on demographic and premorbid variables. At 2 weeks postinjury, 36 of 290 participants with severe TBI (12.4%) and 38 of 93 participants with moderate TBI (41%) had favorable outcomes (GOSE scores 4-8); 301 of 322 in the severe TBI group (93.5%) and 81 of 103 in the moderate TBI group (78.6%) had moderate disability or worse on the DRS (total score ≥4). By 12 months postinjury, 142 of 271 with severe TBI (52.4%) and 54 of 72 with moderate TBI (75%) achieved favorable outcomes. Nearly 1 in 5 participants with severe TBI (52 of 270 [19.3%]) and 1 in 3 with moderate TBI (23 of 71 [32%]) reported no disability (DRS score 0) at 12 months. Among participants in a vegetative state at 2 weeks, 62 of 79 (78%) regained consciousness and 14 of 56 with available data (25%) regained orientation by 12 months.

Conclusions and Relevance

In this study, patients with msTBI frequently demonstrated major functional gains, including recovery of independence, between 2 weeks and 12 months postinjury. Severe impairment in the short term did not portend poor outcomes in a substantial minority of patients with msTBI. When discussing prognosis during the first 2 weeks after injury, clinicians should be particularly cautious about making early, definitive prognostic statements suggesting poor outcomes and withdrawal of life-sustaining treatment in patients with msTBI.

Generalized periodic discharges in the critically ill: a case-control study of 200 patients

OBJECTIVE

Generalized periodic discharges are increasingly recognized on continuous EEG monitoring, but their relationship to seizures and prognosis remains unclear.

METHODS

All adults with generalized periodic discharges from 1996 to 2006 were matched 1:1 to controls by age, etiology, and level of consciousness. Overall, 200 patients with generalized periodic discharges were matched to 200 controls.

RESULTS

Mean age was 66 years (range 18-96); 56% were comatose. Presenting illnesses included acute brain injury (44%), acute systemic illness (38%), cardiac arrest (15%), and epilepsy (3%). A total of 46% of patients with generalized periodic discharges had a seizure during their hospital stay (almost half were focal), vs 34% of controls (p = 0.014). Convulsive seizures were seen in a third of both groups. A total of 27% of patients with generalized periodic discharges had nonconvulsive seizures, vs 8% of controls (p < 0.001); 22% of patients with generalized periodic discharges had nonconvulsive status epilepticus, vs 7% of controls (p < 0.001). In both groups, approximately half died or were in a vegetative state, one-third had severe disability, and one-fifth had moderate to no disability. Excluding cardiac arrest patients, generalized periodic discharges were associated with increased mortality on univariate analysis (36.8% vs 26.9%; p = 0.049). Multivariate predictors of worse outcome were cardiac arrest, coma, nonconvulsive status epilepticus, and sepsis, but not generalized periodic discharges.

CONCLUSION

Generalized periodic discharges were strongly associated with nonconvulsive seizures and nonconvulsive status epilepticus. While nonconvulsive status epilepticus was independently associated with worse outcome, generalized periodic discharges were not after matching for age, etiology, and level of consciousness.

Terminal spreading depolarization and electrical silence in death of human cerebral cortex

OBJECTIVE

Restoring the circulation is the primary goal in emergency treatment of cerebral ischemia. However, better understanding of how the brain responds to energy depletion could help predict the time available for resuscitation until irreversible damage and advance development of interventions that prolong this span. Experimentally, injury to central neurons begins only with anoxic depolarization. This potentially reversible, spreading wave typically starts 2 to 5 minutes after the onset of severe ischemia, marking the onset of a toxic intraneuronal change that eventually results in irreversible injury.

METHODS

To investigate this in the human brain, we performed recordings with either subdural electrode strips (n = 4) or intraparenchymal electrode arrays (n = 5) in patients with devastating brain injury that resulted in activation of a Do Not Resuscitate-Comfort Care order followed by terminal extubation.

RESULTS

Withdrawal of life-sustaining therapies produced a decline in brain tissue partial pressure of oxygen (p_ti O₂ ) and circulatory arrest. Silencing of spontaneous electrical activity developed simultaneously across regional electrode arrays in 8 patients. This silencing, termed "nonspreading depression," developed during the steep falling phase of p_ti O₂ (intraparenchymal sensor, n = 6) at 11 (interquartile range [IQR] = 7-14) mmHg. Terminal spreading depolarizations started to propagate between electrodes 3.9 (IQR = 2.6-6.3) minutes after onset of the final drop in perfusion and 13 to 266 seconds after nonspreading depression. In 1 patient, terminal spreading depolarization induced the initial electrocerebral silence in a spreading depression pattern; circulatory arrest developed thereafter.

INTERPRETATION

These results provide fundamental insight into the neurobiology of dying and have important implications for survivable cerebral ischemic insults. Ann Neurol 2018;83:295-310.

Diagnosing Level of Consciousness: The Limits of the Glasgow Coma Scale Total Score

In nearly all clinical and research contexts, the initial severity of a traumatic brain injury (TBI) is measured using the Glasgow Coma Scale (GCS) total score. However, the GCS total score may not accurately reflect level of consciousness, a critical indicator of injury severity. We investigated the relationship between GCS total scores and level of consciousness in a consecutive sample of 2,455 adult subjects assessed with the GCS 69,487 times as part of the multi-center Transforming Research and Clinical Knowledge in TBI (TRACK-TBI) study. We assigned each GCS subscale score combination a level of consciousness rating based upon published criteria for the following disorders of consciousness (DoC) diagnoses: coma, vegetative state/unresponsive wakefulness syndrome, minimally conscious state, and post-traumatic confusional state, and present our findings using summary statistics and four illustrative cases. Participants had the following characteristics: mean (standard deviation) age 41.9 (17.6) years, 69% male, initial GCS 3-8=13%; 9-12=5%; 13-15=82%. All GCS total scores between 4-14 were associated with more than one DoC diagnosis; the greatest variability was observed for scores of 7-11. Furthermore, a wide range of total scores were associated with identical DoC diagnoses. Importantly, a diagnosis of coma was only possible with GCS total scores of 3-6. The GCS total score does not accurately reflect level of consciousness based on published DoC diagnostic criteria. To improve the classification of patients with TBI and to inform the design of future clinical trials, clinicians and investigators should consider individual subscale behaviors and more comprehensive assessments when evaluating TBI severity.

The Curing Coma Campaign: Framing Initial Scientific Challenges-Proceedings of the First Curing Coma Campaign Scientific Advisory Council Meeting

Coma and disordered consciousness are common manifestations of acute neurological conditions and are among the most pervasive and challenging aspects of treatment in neurocritical care. Gaps exist in patient assessment, outcome prognostication, and treatment directed specifically at improving consciousness and cognitive recovery. In 2019, the Neurocritical Care Society (NCS) launched the Curing Coma Campaign in order to address the "grand challenge" of improving the management of patients with coma and decreased consciousness. One of the first steps was to bring together a Scientific Advisory Council including coma scientists, neurointensivists, neurorehabilitationists, and implementation experts in order to address the current scientific landscape and begin to develop a framework on how to move forward. This manuscript describes the proceedings of the first Curing Coma Campaign Scientific Advisory Council meeting which occurred in conjunction with the NCS Annual Meeting in October 2019 in Vancouver. Specifically, three major pillars were identified which should be considered: endotyping of coma and disorders of consciousness, biomarkers, and proof-of-concept clinical trials. Each is summarized with regard to current approach, benefits to the patient, family, and clinicians, and next steps. Integration of these three pillars will be essential to the success of the Curing Coma Campaign as will expanding the "curing coma community" to ensure broad participation of clinicians, scientists, and patient advocates with the goal of identifying and implementing treatments to fundamentally improve the outcome of patients.

Prognostic Value of Spreading Depolarizations in Patients With Severe Traumatic Brain Injury

Importance

Advances in treatment of traumatic brain injury are hindered by the inability to monitor pathological mechanisms in individual patients for targeted neuroprotective treatment. Spreading depolarizations, a mechanism of lesion development in animal models, are a novel candidate for clinical monitoring in patients with brain trauma who need surgery.

Objective

To test the null hypothesis that spreading depolarizations are not associated with worse neurologic outcomes.

Design, Setting, and Participants

This prospective, observational, multicenter cohort study was conducted from February 2009 to August 2013 in 5 level 1 trauma centers. Consecutive patients who required neurological surgery for treatment of acute brain trauma and for whom research consent could be obtained were enrolled; participants were excluded because of technical problems in data quality, patient withdrawal, or loss to follow-up. Primary statistical analysis took place from April to December 2018. Evaluators of outcome assessments were blinded to other measures.

Interventions

A 6-contact electrode strip was placed on the brain surface during surgery for continuous electrocorticography during intensive care.

Main Outcomes and Measures

Electrocorticography was scored for depolarizations, following international consensus procedures. Six-month outcomes were assessed by the Glasgow Outcome Scale-Extended score.

Results

A total of 157 patients were initially enrolled; 19 were subsequently excluded. The 138 remaining patients (104 men [75%]; median [interquartile range] age, 45 [29-64] years) underwent a median (interquartile range) of 75.5 (42.2-117.1) hours of electrocorticography. A total of 2837 spreading depolarizations occurred in 83 of 138 patients (60.1% incidence) who, compared with patients who did not have spreading depolarizations, had lower prehospital systolic blood pressure levels (mean [SD], 133 [31] mm Hg vs 146 [33] mm Hg; P = .03), more traumatic subarachnoid hemorrhage (depolarization incidences of 17 of 37 [46%], 18 of 32 [56%], 22 of 33 [67%], and 23 of 30 patients [77%] for Morris-Marshall Grades 0, 1, 2, and 3/4, respectively; P = .047), and worse radiographic pathology (in 38 of 73 patients [52%] and 42 of 60 patients [70%] for Rotterdam Scores 2-4 vs 5-6, respectively; P = .04). Of patients with depolarizations, 32 of 83 (39%) had only sporadic events that induced cortical spreading depression of spontaneous electrical activity, whereas 51 of 83 patients (61%) exhibited temporal clusters of depolarizations (≥3 in a 2-hour span). Nearly half of those with clusters (23 of 51 [45%]) also had depolarizations in an electrically silent area of the cortex (isoelectric spreading depolarization). Patients with clusters did not improve in motor neurologic examinations from presurgery to postelectrocorticography, while other patients did improve. In multivariate ordinal regression adjusting for baseline prognostic variables, the occurrence of depolarization clusters had an odds ratio of 2.29 (95% CI, 1.13-4.65; P = .02) for worse outcomes.

Conclusions and Relevance

In this cohort study of patients with acute brain trauma, spreading depolarizations were predominant but heterogeneous and independently associated with poor neurologic recovery. Monitoring the occurrence of spreading depolarizations may identify patients most likely to benefit from targeted management strategies.

High-dose midazolam infusion for refractory status epilepticus

OBJECTIVE

This study compares 2 treatment protocols allowing low vs high continuous IV midazolam (cIV-MDZ) doses.

METHODS

We compared adults with refractory status epilepticus treated with a protocol allowing for high-dose cIV-MDZ (n = 100; 2002-2011) with those treated with the previous lower-dose cIV-MDZ (n = 29; 1996-2000). We collected data on baseline characteristics, cIV-MDZ doses, seizure control, hospital course, and outcome.

RESULTS

Median maximum cIV-MDZ dose was 0.4 mg/kg/h (interquartile range [IQR] 0.2, 1.0) for the high-dose group and 0.2 mg/kg/h (IQR 0.1, 0.3) for the low-dose group (p < 0.001) with similar duration of infusion. Median time from status epilepticus onset to cIV-MDZ start was 1 day (IQR 1, 3) for the high-dose group and 2 days (IQR 1, 5) for the low-dose group (p = 0.016). "Withdrawal seizures" (occurring within 48 hours of discontinuation of cIV-MDZ) were less frequent in the high-dose group (15% vs 64%, odds ratio 0.10, 95% confidence interval 0.03-0.27). "Ultimate cIV-MDZ failure" (patients requiring change to a different cIV antiepileptic medication) and hospital complications were not different between groups. Hypotension was more frequent with higher cIV-MDZ doses but was not associated with worse outcome. Discharge mortality was lower in the high-dose group (40% vs 62%, odds ratio 0.34, 95% confidence interval 0.13-0.92 in multivariate analysis).

CONCLUSIONS

High-dose cIV-MDZ treatment of refractory status epilepticus can be performed safely, is associated with a lower seizure rate after cIV-MDZ discontinuation, and may be associated with lower mortality than traditional lower-dose protocols.

CLASSIFICATION OF EVIDENCE

This study provides Class III evidence that midazolam at higher infusion rates is associated with a reduction in seizure recurrence within 48 hours after discontinuation and may be associated with lower mortality.

Is pentobarbital safe and efficacious in the treatment of super-refractory status epilepticus: a cohort study

Introduction

Seizures refractory to third-line therapy are also labeled super-refractory status epilepticus (SRSE). These seizures are extremely difficult to control and associated with poor outcome. We aimed to characterize efficacy and side-effects of continuous infusions of pentobarbital (cIV-PTB) treating SRSE.

Methods

We retrospectively reviewed continuous electroencephalography (cEEG) reports for all adults with RSE treated with cIV-PTB between May 1997 and April 2010 at our institution. Patients with post-anoxic SE and those receiving cIV-PTB for reasons other than RSE were excluded. We collected baseline information, cEEG findings, side-effects and functional outcome at discharge and one year.

Results

Thirty one SRSE patients treated with cIV-PTB for RSE were identified. Mean age was 48 years old (interquartile range (IQR) 28,63), 26% (N = 8) had a history of epilepsy. Median SE duration was 6.5 days (IQR 4,11) and the mean duration of cIV-PTB was 6 days (IQR 3,14). 74% (N = 23) presented with convulsive SE. Underlying etiology was acute symptomatic seizures in 52% (N = 16; 12/16 with encephalitis), remote 30% (N = 10), and unknown 16% (N = 5). cIV-PTB controlled seizures in 90% (N = 28) of patients but seizures recurred in 48% (N = 15) while weaning cIV-PTB, despite the fact that suppression-burst was attained in 90% (N = 28) of patients and persisted >72 hours in 56% (N = 17). Weaning was successful after adding phenobarbital in 80% (12/15 of the patients with withdrawal seizures). Complications during or after cIV-PTB included pneumonia (32%, N = 10), hypotension requiring pressors (29%, N = 9), urinary tract infection (13%, N = 4), and one patient each with propylene glycol toxicity and cardiac arrest. One-third (35%, N = 11) had no identified new complication after starting cIV-PTB. At one year after discharge, 74% (N = 23) were dead or in a state of unresponsive wakefulness, 16% (N = 5) severely disabled, and 10% (N = 3) had no or minimal disability. Death or unresponsive wakefulness was associated with catastrophic etiology (p = 0.03), but none of the other collected variables.

Conclusions

cIV-PTB effectively aborts SRSE and complications are infrequent; outcome in this highly refractory cohort of patients with devastating underlying etiologies remains poor. Phenobarbital may be particularly helpful when weaning cIV-PTB.

Pathological Computed Tomography Features Associated With Adverse Outcomes After Mild Traumatic Brain Injury: A TRACK-TBI Study With External Validation in CENTER-TBI

Question

Are different patterns of intracranial injury on head computed tomography associated with prognosis after mild traumatic brain injury (mTBI)?

Findings

In this cohort study, subarachnoid hemorrhage, subdural hematoma, and contusion often co-occurred and were associated with both incomplete recovery and more severe impairment out to 12 months after injury, while intraventricular and/or petechial hemorrhage co-occurred and were associated with more severe impairment up to 12 months after injury; epidural hematoma was associated with incomplete recovery at some points but not with more severe impairment. Some intracranial hemorrhage patterns were more strongly associated with outcomes than previously validated demographic and clinical variables.

Meaning

In this study, different pathological features on head computed tomography carried different implications for mild traumatic brain injury prognosis to 1 year.

Importance

A head computed tomography (CT) with positive results for acute intracranial hemorrhage is the gold-standard diagnostic biomarker for acute traumatic brain injury (TBI). In moderate to severe TBI (Glasgow Coma Scale [GCS] scores 3-12), some CT features have been shown to be associated with outcomes. In mild TBI (mTBI; GCS scores 13-15), distribution and co-occurrence of pathological CT features and their prognostic importance are not well understood.

Objective

To identify pathological CT features associated with adverse outcomes after mTBI.

Design, Setting, and Participants

The longitudinal, observational Transforming Research and Clinical Knowledge in Traumatic Brain Injury (TRACK-TBI) study enrolled patients with TBI, including those 17 years and older with GCS scores of 13 to 15 who presented to emergency departments at 18 US level 1 trauma centers between February 26, 2014, and August 8, 2018, and underwent head CT imaging within 24 hours of TBI. Evaluations of CT imaging used TBI Common Data Elements. Glasgow Outcome Scale–Extended (GOSE) scores were assessed at 2 weeks and 3, 6, and 12 months postinjury. External validation of results was performed via the Collaborative European NeuroTrauma Effectiveness Research in Traumatic Brain Injury (CENTER-TBI) study. Data analyses were completed from February 2020 to February 2021.

Exposures

Acute nonpenetrating head trauma.

Main Outcomes and Measures

Frequency, co-occurrence, and clustering of CT features; incomplete recovery (GOSE scores <8 vs 8); and an unfavorable outcome (GOSE scores <5 vs ≥5) at 2 weeks and 3, 6, and 12 months.

Results

In 1935 patients with mTBI (mean [SD] age, 41.5 [17.6] years; 1286 men [66.5%]) in the TRACK-TBI cohort and 2594 patients with mTBI (mean [SD] age, 51.8 [20.3] years; 1658 men [63.9%]) in an external validation cohort, hierarchical cluster analysis identified 3 major clusters of CT features: contusion, subarachnoid hemorrhage, and/or subdural hematoma; intraventricular and/or petechial hemorrhage; and epidural hematoma. Contusion, subarachnoid hemorrhage, and/or subdural hematoma features were associated with incomplete recovery (odds ratios [ORs] for GOSE scores <8 at 1 year: TRACK-TBI, 1.80 [95% CI, 1.39-2.33]; CENTER-TBI, 2.73 [95% CI, 2.18-3.41]) and greater degrees of unfavorable outcomes (ORs for GOSE scores <5 at 1 year: TRACK-TBI, 3.23 [95% CI, 1.59-6.58]; CENTER-TBI, 1.68 [95% CI, 1.13-2.49]) out to 12 months after injury, but epidural hematoma was not. Intraventricular and/or petechial hemorrhage was associated with greater degrees of unfavorable outcomes up to 12 months after injury (eg, OR for GOSE scores <5 at 1 year in TRACK-TBI: 3.47 [95% CI, 1.66-7.26]). Some CT features were more strongly associated with outcomes than previously validated variables (eg, ORs for GOSE scores <5 at 1 year in TRACK-TBI: neuropsychiatric history, 1.43 [95% CI .98-2.10] vs contusion, subarachnoid hemorrhage, and/or subdural hematoma, 3.23 [95% CI 1.59-6.58]). Findings were externally validated in 2594 patients with mTBI enrolled in the CENTER-TBI study.

Conclusions and Relevance

In this study, pathological CT features carried different prognostic implications after mTBI to 1 year postinjury. Some patterns of injury were associated with worse outcomes than others. These results support that patients with mTBI and these CT features need TBI-specific education and systematic follow-up.

Antibody response of mice to lactate dehydrogenase-elevating virus during infection and immunization with inactivated virus

BALB/c and Swiss mice were infected with lactate dehydrogenase-elevating virus (LDV) or immunized with glutaraldehyde-inactivated or ether-extracted virus and their plasma was monitored for anti-LDV IgG and IgM levels by ELISA and indirect fluorescent antibody staining, for neutralizing antibodies, for sensitized antibody-virus complexes, for immune complexes, and for total plasma IgG and IgM. In infected mice, anti-LDV IgM was transiently formed during the first 2 weeks post infection (p.i.) but only at a low level. Anti-LDV IgG was produced in a biphasic manner with an initial peak at about 10 days p.i. and a secondary rise reaching a maximum level 30-80 days p.i. which was retained throughout the persistent phase of infection. The concomitant appearance of comparable levels of low molecular weight immune complexes suggests that most anti-LDV IgG was complexed with LDV proteins. Also, as early as 10 days p.i., infectious antibody-LDV complexes developed, which were neutralizable by rabbit anti-mouse IgG, whereas antibodies that neutralize the infectivity of exogenously added LDV appeared only 1-2 months p.i. Throughout infection, most of the anti-LDV IgG was directed to VP-3, the envelope glycoprotein of LDV, which was found to exist in at least 10 distinct forms ranging in molecular weight from 24 to 42 kDa. Anti-LDV IgG levels as high as those observed in infected mice developed in mice immunized with inactivated LDV. Antibodies to glutaraldehyde-inactivated LDV were also mainly directed to VP-3, but exhibited no neutralizing activity. The polyclonal B cell activation associated with a persistent LDV infection and the formation of immune complexes were not observed in mice immunized with inactivated virus.

Direct current electrocorticography for clinical neuromonitoring of spreading depolarizations

Spreading depolarizations cause cortical electrical potential changes over a wide spectral range that includes slow potentials approaching the direct current (or 0 Hz) level. The negative direct current shift (<0.05 Hz) is an important identifier of cortical depolarization and its duration is a measure of potential tissue injury associated with longer lasting depolarizations. To determine the feasibility of monitoring the full signal bandwidth of spreading depolarizations in patients, we performed subdural electrocorticography using platinum electrode strips and direct current-coupled amplifiers in 27 patients with acute brain injury at two neurosurgical centers. While large baseline direct current offsets developed, loss of data due to amplifier saturation was minimal and rates of baseline drift throughout recordings were generally low. Transient negative direct current shifts of spreading depolarizations were easily recognized and in 306/551 (56%) cases had stereotyped, measurable characteristics. Following a standardized training session, novice scorers achieved a high degree of accuracy and interobserver reliability in identifying depolarizations, suggesting that direct current-coupled recordings can facilitate bedside diagnosis for future trials or clinical decision-making. We conclude that intracranial monitoring of slow potentials can be achieved with platinum electrodes and that unfiltered, direct current-coupled recordings are advantageous for identifying and assessing the impact of spreading depolarizations.

Electroencephalogram in the intensive care unit: a focused look at acute brain injury

Over the past decades, electroencephalography (EEG) has become a widely applied and highly sophisticated brain monitoring tool in a variety of intensive care unit (ICU) settings. The most common indication for EEG monitoring currently is the management of refractory status epilepticus. In addition, a number of studies have associated frequent seizures, including nonconvulsive status epilepticus (NCSE), with worsening secondary brain injury and with worse outcomes. With the widespread utilization of EEG (spot and continuous EEG), rhythmic and periodic patterns that do not fulfill strict seizure criteria have been identified, epidemiologically quantified, and linked to pathophysiological events across a wide spectrum of critical and acute illnesses, including acute brain injury. Increasingly, EEG is not just qualitatively described, but also quantitatively analyzed together with other modalities to generate innovative measurements with possible clinical relevance. In this review, we discuss the current knowledge and emerging applications of EEG in the ICU, including seizure detection, ischemia monitoring, detection of cortical spreading depolarizations, assessment of consciousness and prognostication. We also review some technical aspects and challenges of using EEG in the ICU including the logistics of setting up ICU EEG monitoring in resource-limited settings.

Which Spreading Depolarizations Are Deleterious To Brain Tissue?

Spreading depolarizations (SDs) are profound disruptions of cellular homeostasis that slowly propagate through gray matter and present an extraordinary metabolic challenge to brain tissue. Recent work has shown that SDs occur commonly in human patients in the neurointensive care setting and have established a compelling case for their importance in the pathophysiology of acute brain injury. The International Conference on Spreading Depolarizations (iCSD) held in Boca Raton, Florida, in September of 2018 included a discussion session focused on the question of "Which SDs are deleterious to brain tissue?" iCSD is attended by investigators studying various animal species including invertebrates, in vivo and in vitro preparations, diseases of acute brain injury and migraine, computational modeling, and clinical brain injury, among other topics. The discussion included general agreement on many key issues, but also revealed divergent views on some topics that are relevant to the design of clinical interventions targeting SDs. A draft summary of viewpoints offered was then written by a multidisciplinary writing group of iCSD members, based on a transcript of the session. Feedback of all discussants was then formally collated, reviewed and incorporated into the final document. It is hoped that this report will stimulate collection of data that are needed to develop a more nuanced understanding of SD in different pathophysiological states, as the field continues to move toward effective clinical interventions.

Proceedings of the First Curing Coma Campaign NIH Symposium: Challenging the Future of Research for Coma and Disorders of Consciousness

Coma and disorders of consciousness (DoC) are highly prevalent and constitute a burden for patients, families, and society worldwide. As part of the Curing Coma Campaign, the Neurocritical Care Society partnered with the National Institutes of Health to organize a symposium bringing together experts from all over the world to develop research targets for DoC. The conference was structured along six domains: (1) defining endotype/phenotypes, (2) biomarkers, (3) proof-of-concept clinical trials, (4) neuroprognostication, (5) long-term recovery, and (6) large datasets. This proceedings paper presents actionable research targets based on the presentations and discussions that occurred at the conference. We summarize the background, main research gaps, overall goals, the panel discussion of the approach, limitations and challenges, and deliverables that were identified.

Impact of prolonged periodic epileptiform discharges on coma prognosis

BACKGROUND

Periodic epileptiform discharges (PEDs) are a frequent finding in comatose patients undergoing continuous EEG (cEEG) monitoring, but their clinical significance is unclear. PET and SPECT studies indicate that PEDs can be associated with focal hypermetabolism and hyperemia, suggesting that in some cases this pattern may be ictal and potentially harmful. We hypothesized that frequent PED activity in comatose patients is associated with reduced likelihood of recovery of consciousness.

METHODS

We identified all comatose patients treated in the Columbia neuro-ICU between June 2008 and August 2009 who underwent ten or more consecutive days of video cEEG monitoring (N = 67), and classified them into three groups: those with (1) prolonged PEDs (five or more consecutive days), (2) intermittent PEDs (at least one but fewer than five consecutive days), and (3) no PEDs. Outcome at discharge was assessed by the Glasgow Outcome Scale and classified as dead (GOS 1), vegetative (GOS 2), and command-following (GOS 3-5).

RESULTS

Mean age was 56 years, mean admission Glasgow Coma Scale score was seven, and the median duration of cEEG monitoring was 18 (range 10-111) days. The most common diagnoses were hypoxic-ischemic encephalopathy (18%), subarachnoid hemorrhage (16%), epilepsy (15%), encephalitis (15%), metabolic encephalopathy (13%), and intracerebral hemorrhage (12%). 37% of patients (N = 25) had prolonged PEDs, 31% (N = 21) had intermittent PEDs, and 31% (N = 21) had no PEDs. Prolonged PEDs were associated with the presence of SIRPIDS (P = 0.009), electrographic seizures (P = 0.019), and number of AEDs administered (P < 0.0001). However, the presence of intermittent or prolonged PED activity had no impact on mortality (31% overall) or recovery of consciousness (command-following) at the time of discharge (36% overall).

CONCLUSION

Persistent spontaneous PED activity in comatose patients is associated with SIRPIDs and electrographic seizures, but has no impact on the likelihood of survival or recovery of consciousness.

What Should a Clinician Do When Spreading Depolarizations are Observed in a Patient?

The International Conference on Spreading Depolarizations (iCSD) held in Boca Raton, Florida, in the September of 2018 devoted a section to address the question, "What should a clinician do when spreading depolarizations are observed in a patient?" Discussants represented a wide range of expertise, including neurologists, neurointensivists, neuroradiologists, neurosurgeons, and pre-clinical neuroscientists, to provide both clinical and basic pathophysiology perspectives. A draft summary of viewpoints offered was then written by a multidisciplinary writing group of iCSD members, based on a transcript of the session. Feedback of all discussants was formally collated, reviewed, and incorporated into the final document which was subsequently approved by all authors.

Response Rates to Anticonvulsant Trials in Patients with Triphasic-Wave EEG Patterns of Uncertain Significance

BACKGROUND

Generalized triphasic waves (TPWs) occur in both metabolic encephalopathies and non-convulsive status epilepticus (NCSE). Empiric trials of benzodiazepines (BZDs) or non-sedating AED (NSAEDs) are commonly used to differentiate the two, but the utility of such trials is debated. The goal of this study was to assess response rates of such trials and investigate whether metabolic profile differences affect the likelihood of a response.

METHODS

Three institutions within the Critical Care EEG Monitoring Research Consortium retrospectively identified patients with unexplained encephalopathy and TPWs who had undergone a trial of BZD and/or NSAEDs to differentiate between ictal and non-ictal patterns. We assessed responder rates and compared metabolic profiles of responders and non-responders. Response was defined as resolution of the EEG pattern and either unequivocal improvement in encephalopathy or appearance of previously absent normal EEG patterns, and further categorized as immediate (within <2 h of trial initiation) or delayed (>2 h from trial initiation).

RESULTS

We identified 64 patients with TPWs who had an empiric trial of BZD and/or NSAED. Most patients (71.9%) were admitted with metabolic derangements and/or infection. Positive clinical responses occurred in 10/53 (18.9%) treated with BZDs. Responses to NSAEDs occurred in 19/45 (42.2%), being immediate in 6.7%, delayed but definite in 20.0%, and delayed but equivocal in 15.6%. Overall, 22/64 (34.4%) showed a definite response to either BZDs or NSAEDs, and 7/64 (10.9%) showed a possible response. Metabolic differences of responders versus non-responders were statistically insignificant, except that the 48-h low value of albumin in the BZD responder group was lower than in the non-responder group.

CONCLUSIONS

Similar metabolic profiles in patients with encephalopathy and TPWs between responders and non-responders to anticonvulsants suggest that predicting responders a priori is difficult. The high responder rate suggests that empiric trials of anticonvulsants indeed provide useful clinical information. The more than twofold higher response rate to NSAEDs suggests that this strategy may be preferable to BZDs. Further prospective investigation is warranted.

The Effect of Antidepressants on Depression After Traumatic Brain Injury: A Meta-analysis

OBJECTIVE

Following traumatic brain injury (TBI), depressive symptoms are common and may influence recovery. We performed a meta-analysis to estimate the benefit of antidepressants following TBI and compare the estimated effects between antidepressants and placebo.

PARTICIPANTS

Multiple databases were searched to find prospective pharmacological treatment studies of major depressive disorder (MDD) in adults following TBI.

MAIN MEASURES

Effect sizes for antidepressant medications in patients with TBI were calculated for within-subjects designs that examined change from baseline after receiving medical treatment and treatment/placebo designs that examined the differences between the antidepressants and placebo groups.

DESIGN

A random-effects model was used for both analyses.

RESULTS

Of 1028 titles screened, 11 were included. Pooled estimates showed nonsignificant difference in reduction of depression scores between medications and placebo (standardized mean difference of 5 trials = -0.3; 95% CI, -0.6 to 0.0; I = 17%), and a significant reduction in depression scores for individuals after pharmacotherapy (mean change = -11.2; 95% CI, -14.7 to -7.6 on the Hamilton Depression Scale; I = 87%).

CONCLUSIONS

This meta-analysis found no significant benefit of antidepressant over placebo in the treatment of MDD following TBI. Pooled estimates showed a high degree of bias and heterogeneity. Prospective studies on the impact of antidepressants in well-defined cohorts of TBI patients are warranted.