Quantitative pupillometry as a biomarker for prediction of return to play in mild traumatic brain injury: a Military Traumatic Brain Injury Initiative study.

OBJECTIVE: This study aimed to determine the validity of quantitative pupillometry to predict the length of time for return to full activity/duty after a mild traumatic brain injury (mTBI) in a cohort of injured cadets at West Point. METHODS: Each subject received baseline (T0) quantitative pupillometry, in addition to evaluation with the Balance Error Scoring System (BESS), Standardized Assessment of Concussion (SAC), and Sport Concussion Assessment Tool 5th Edition Symptom Survey (SCAT5). Repeat assessments using the same parameters were conducted within 48 hours of injury (T1), at the beginning of progressive return to activity (T2), and at the completion of progressive return to activity protocols (T3). Pupillary metrics were compared on the basis of length of time to return to full play/duty and the clinical scores. RESULTS: The authors' statistical analyses found correlations between pupillometry measures at T1, including end-initial diameter and maximum constriction velocity, with larger change and faster constriction predicting earlier return to play. There was also an association with maximum constriction velocity at baseline (T0), predicting faster return to play. CONCLUSIONS: The authors conclude that that pupillometry may be a valuable tool for assessing time to return to duty from mTBI by providing a measure of baseline resiliency to mTBI and/or autonomic dysfunction in the acute phase after mTBI.

Bilateral amygdala stimulation reduces avoidance behavior in a predator scent posttraumatic stress disorder model.

OBJECTIVE The predator scent model of posttraumatic stress disorder (PTSD) produces prolonged abnormal anxiety and avoidance-like behaviors. Increased basolateral amygdala activity has been shown to correlate with severity of PTSD symptoms in human studies. Modulation of this increased amygdala activity by deep brain stimulation led to improved symptoms in prior studies that used a foot shock model of inducing PTSD. The predator scent model is a different technique that induces long-lasting avoidance behavioral responses by exposing the animal to an inescapable scent of one of its predators. The authors hypothesize that high-frequency stimulation of the bilateral basolateral amygdala will decrease avoidance and anxiety-like behaviors in a predator scent rodent model of PTSD. METHODS Rodents underwent cat urine exposure in a place preference protocol. Avoidance in the place preference paradigm and anxiety-like behavior in the elevated plus maze were measured before and after high-frequency stimulation. RESULTS Predator scent exposure resulted in long-term significant avoidance behavior in rodents. Bilateral stimulation significantly decreased avoidance behavior in rodents compared to no stimulation following predator scent exposure. There were no significant differences in anxiety behaviors on the elevated plus maze between stimulated and unstimulated cohorts. CONCLUSIONS Bilateral stimulation of the basolateral amygdala leads to decreased avoidance behavior compared to controls in a predator scent model of PTSD.

Safety of Chemical DVT Prophylaxis in Severe Traumatic Brain Injury with Invasive Monitoring Devices.

BACKGROUND: Patients with traumatic brain injuries (TBIs) have an increased risk of developing a deep vein thrombosis (DVT), but the risk of hemorrhage expansion with intracranial monitoring devices remains unknown. We sought to determine the safety of chemical DVT prophylaxis in severe TBI patients with invasive intracranial pressure monitors. METHODS: We retrospectively reviewed all patients with severe TBI admitted to the neurosurgical intensive care unit of a large tertiary care center over a three-year period. RESULTS: 155 patients were included with an incidence of DVT of 12 %. The median length of time to a stable head CT was 2 days, and the median time to initiation of chemical DVT prophylaxis was 3.6 days. The odds of DVT increased with intraparenchymal hemorrhage [OR 7.21, 95 % CI (1.43-36.47), p = 0.0169], non-White ethnicity [OR 7.86, 95 % CI (1.23-50.35), p = 0.0295], female gender [OR 13.93, 95 % CI (2.47-78.73), p = 0.0029], smoking [OR 4.32, 95 % CI (1.07-17.51), p = 0.0405], no anticoagulation [OR 25.39, 95 % CI (4.26-151.48), p < 0.001], and an IVC filter [OR 15.82, 95 % CI (3.14-79.76), p < 0.001]. Twenty-eight (18 %) of these subjects experienced in-hospital mortality. The risk of in-hospital death was significantly increased among those who did not receive anticoagulation. This study found no association between DVT formation, hemorrhage expansion, or increased risk from invasive monitoring devices between various doses of unfractionated heparin (UH) and low-molecular-weight heparin (LMWH). CONCLUSION: We conclude that DVT prophylaxis with either LMWH or UH is safe with intracranial pressure monitors in place.

Bilateral abducens nerve palsy following ligamentous C1-C2 distraction.

PURPOSE: Posttraumatic abducens nerve palsy is well documented following head injury, but only few case reports exist on sixth nerve palsy after cervical spine trauma. Bilateral abducens palsy following vertical C1-C2 ligamentous distraction has not been described yet. METHODS: We report two patients who sustained motor vehicle accident-related C1-C2 distraction injury and were diagnosed with posttraumatic bilateral abducens nerve palsy. RESULTS: Patients underwent surgical stabilization of the upper cervical spine and demonstrated a remarkable recovery of the sixth nerve deficit up to 1 year after injury. CONCLUSION: We hypothesize that ligamentous C1-C2 distraction leads to caudal displacement of the brainstem in relation to the cranial base causing traction injury to the abducens nerve at its entry into Dorello's canal in the cavernous sinus.

A Review of Electrolyte, Mineral, and Vitamin Changes After Traumatic Brain Injury.

INTRODUCTION: Despite the prevalence of traumatic brain injury (TBI) in both civilian and military populations, the management guidelines developed by the Joint Trauma System involve minimal recommendations for electrolyte physiology optimization during the acute phase of TBI recovery. This narrative review aims to assess the current state of the science for electrolyte and mineral derangements found after TBI. MATERIALS AND METHODS: We used Google Scholar and PubMed to identify literature on electrolyte derangements caused by TBI and supplements that may mitigate secondary injuries after TBI between 1991 and 2022. RESULTS: We screened 94 sources, of which 26 met all inclusion criteria. Most were retrospective studies (n = 9), followed by clinical trials (n = 7), observational studies (n = 7), and case reports (n = 2). Of those, 29% covered the use of some type of supplement to support recovery after TBI, 28% covered electrolyte or mineral derangements after TBI, 16% covered the mechanisms of secondary injury after TBI and how they are related to mineral and electrolyte derangements, 14% covered current management of TBI, and 13% covered the potential toxic effects of the supplements during TBI recovery. CONCLUSIONS: Knowledge of mechanisms and subsequent derangements of electrolyte, mineral, and vitamin physiology after TBI remains incomplete. Sodium and potassium tended to be the most well-studied derangements after TBI. Overall, data involving human subjects were limited and mostly involved observational studies. The data on vitamin and mineral effects were limited, and targeted research is needed before further recommendations can be made. Data on electrolyte derangements were stronger, but interventional studies are needed to assess causation.

Incidence of Traumatic Brain Injuries within the Prehospital Trauma Registry System.

BACKGROUND: Traumatic brain injury (TBI) is often underreported or undetected in prehospital civilian and military settings. This study evaluated the incidence of TBI within the Prehospital Trauma Registry (PHTR) system. METHODS: We reviewed PHTR and the linked Department of Defense Trauma Registry (DoDTR) records of casualties from January 2003 through May 2019 for diagnostic data and surgical reports. RESULTS: A total of 709 casualties met inclusion criteria. The most common mechanism was blast, including 328 (51%) in the non-TBI and 45 (63%) in the TBI cohorts. The median injury severity scores in the non-TBI and TBI cohorts were 5 and 14, respectively. The survival scores in the non-TBI and TBI cohorts were 98% and 92%, respectively. Subdural hematomas, followed by subarachnoid hemorrhages were the most common classifiable brain injuries. Other nonspecific TBIs occurred in 85% of the TBI cohort casualties. Seventy-two cases (10%) were documented by the Role 1 clinician. Based on coding or operative data, 15 of the 72 (21%) were identified as TBIs. Of the 637 cases, which could not be decided based on coding or operative data, TBI was suspected in 42 (7%) cases based on Role 1 records. CONCLUSIONS: Over 1 in 10 casualties presenting to a Role 1 facility had a TBI requiring transfer to a higher level of care. Our findings suggest the need for improved diagnostic technologies and documentation systems at Role 1 facilities for accurate TBI diagnosis and reporting.

Quantitative Pupillometry Predicts Return to Play and Tracks the Clinical Evolution of Mild Traumatic Brain Injury in US Military Academy Cadets: A Military Traumatic Brain Injury Initiative Study.

BACKGROUND AND OBJECTIVES: The objective of this study was to determine the utility of the pupillary light reflex use as a biomarker of mild traumatic brain injury (mTBI). METHODS: This prospective cohort study was conducted at The US Military Academy at West Point. Cadets underwent a standard battery of tests including Balance Error Scoring System, Sports Concussion Assessment Tool Fifth Edition Symptom Survey, Standard Assessment of Concussion, and measure of pupillary responses. Cadets who sustained an mTBI during training events or sports were evaluated with the same battery of tests and pupillometry within 48 hours of the injury (T1), at the initiation of a graded return to activity protocol (T2), and at unrestricted return to activity (T3). RESULTS: Pupillary light reflex metrics were obtained in 1300 cadets at baseline. During the study period, 68 cadets sustained mTBIs. At T1 (<48 hours), cadets manifested significant postconcussion symptoms (Sports Concussion Assessment Tool Fifth Edition P < .001), and they had decreased cognitive performance (Standardized Assessment of Concussion P < .001) and higher balance error scores (Balance Error Scoring System P < .001) in comparison with their baseline assessment (T0). The clinical parameters showed normalization at time points T2 and T3. The pupillary responses demonstrated a pattern of significant change that returned to normal for several measures, including the difference between the constricted and initial pupillary diameter (T1 P < .001, T2 P < .05), dilation velocity (T1 P < .01, T2 P < .001), and percent of pupillary constriction (T1 P < .05). In addition, a combination of dilation velocity and maximum constriction velocity demonstrates moderate prediction ability regarding who can return to duty before or after 21 days (area under the curve = 0.71, 95% CI [0.56-0.86]). CONCLUSION: This study's findings indicate that quantitative pupillometry has the potential to assist with injury identification and prediction of symptom severity and duration.

Feasibility and acceptability for LION, a fully remote, randomized clinical trial within the VA for light therapy to improve sleep in Veterans with and without TBI: An MTBI2 sponsored protocol: LION: A remote RCT protocol within VA.

Sleep-wake disturbances frequently present in Veterans with mild traumatic brain injury (mTBI). These TBI-related sleep impairments confer significant burden and commonly exacerbate other functional impairments. Therapies to improve sleep following mTBI are limited and studies in Veterans are even more scarce. In our previous pilot work, morning bright light therapy (MBLT) was found to be a feasible behavioral sleep intervention in Veterans with a history of mTBI; however, this was single-arm, open-label, and non-randomized, and therefore was not intended to establish efficacy. The present study, LION (light vs ion therapy) extends this preliminary work as a fully powered, sham-controlled, participant-masked randomized controlled trial (NCT03968874), implemented as fully remote within the VA (target n=120 complete). Randomization at 2:1 allocation ratio to: 1) active: MBLT (n=80), and 2) sham: deactivated negative ion generator (n=40); each with identical engagement parameters (60-min duration; within 2-hrs of waking; daily over 28-day duration). Participant masking via deception balanced expectancy assumptions across arms. Outcome measures were assessed following a 14-day baseline (pre-intervention), following 28-days of device engagement (post-intervention), and 28-days after the post-intervention assessment (follow-up). Primary outcomes were sleep measures, including continuous wrist-based actigraphy, self-report, and daily sleep dairy entries. Secondary/exploratory outcomes included cognition, mood, quality of life, circadian rhythm via dim light melatonin onset, and biofluid-based biomarkers. Participant drop out occurred in <10% of those enrolled, incomplete/missing data was present in <15% of key outcome variables, and overall fidelity adherence to the intervention was >85%, collectively establishing feasibility and acceptability for MBLT in Veterans with mTBI.

Normative Values for Pupillary Light Reflex Metrics Among Healthy Service Academy Cadets.

INTRODUCTION: Assessments of the pupil's response to light have long been an integral part of neurologic examinations. More recently, the pupillary light reflex (PLR) has shown promise as a potential biomarker for the diagnosis of mild traumatic brain injury. However, to date, few large-scale normative data are available for comparison and reference, particularly, in military service members. The purpose of this study was to report normative values for eight PLR measurements among healthy service academy cadets based on sex, age, sleep, race, ethnicity, anisocoria, and concussion history. METHODS: Freshmen entering a U.S. Service Academy completed a quantitative pupillometric assessment in conjunction with baseline concussion testing. PLR measurements were conducted using a Neuroptics PLR-3000 with a 121 µW light stimulus. The device measured maximum and minimum pupil diameter (mm), latency (time to maximum pupil constriction post-light stimulus [s]), peak and average constriction velocity (mm/s), average dilation velocity (mm/s), percentage pupil constriction, and T75 (time for pupil re-dilation from minimum pupil diameter to 75% maximum diameter [s]). During baseline testing, cadets also reported concussion history (yes and no) and hours slept the night before (<5.5 and ≥5.5). Normative values for each PLR measurement were calculated as mean ± SD, percentiles, and interquartile range. Mann-Whitney U tests were used to assess differences based on sex, concussion history, ethnicity, and hours slept for each PLR measurement. Kruskall-Wallis testing was used to assess differences based on age, race, and anisocoria. Alpha was set at .05 and nonparametric effect sizes (r) were calculated for statistically significant results. Effect sizes were interpreted as no effect (r < .1), small (r ≥.1-<.3), medium (r ≥.3-<.5), or large (r ≥ .5). All procedures were reviewed and approved by the local institutional review board and the U.S. Army Human Research Protection Office before the study was conducted. Each subject provided informed consent to participate in the study before data collection. RESULTS: Of the 1,197 participants baselined, 514 cadets (131 female; 18.91 ± 0.96 years) consented and completed a valid baseline pupillometric assessment. Eighty participants reported at least one previous concussion and participants reported an average of 5.88 ± 1.63 h slept the previous night. Mann-Whitney U results suggest females had larger initial (z = -3.240; P = .001; r = .10) and end pupil diameter (z = -3.080; P = .002; r = .10), slower average dilation velocity (z = 3.254; P = .001; r = .11) and faster T75 values (z = -3.342; P = .001; r = .11). Age, sleep, and race stratified by sex, also displayed a significant impact on specific PLR metrics with effect sizes ranging from small to medium, while ethnicity, anisocoria, and concussion history did not display an impact on PLR metrics. CONCLUSION: This study provides the largest population-specific normative values for eight PLR measurements. Initial and end pupil diameter, dilation velocity, and the T75 metrics differed by sex; however, these differences may not be clinically significant as small effect size was detected for all metrics. Sex, age, sleep, and race may impact specific PLR metrics and are worth consideration when performing PLR assessments for mild traumatic brain injury management.

Tranexamic Acid Improves Survival in the Setting of Severe Head Injury in Combat Casualties.

INTRODUCTION: Approximately 1.7 million people sustain traumatic brain injuries (TBI) annually in the US. To reduce morbidity and mortality, management strategies aim to control progressive intracranial bleeding. This study analyzes the association between Tranexamic Acid (TXA) administration and mortality among casualties within the Department of Defense Trauma Registry, specifically focusing on subsets of patients with varying degree of head injury severities. METHODS: Besides descriptive statistics, we used inverse probability weighted (for age, military service category, mechanism of injury, total units of blood units administered), and injury severity (ISS) and Abbreviated Injury Scale (AIS) head score adjusted generalized linear models to analyze the association between TXA and mortality. Specific subgroups of interest were increasing severities of head injury and further stratifying these by Glasgow Coma Score of 3-8 and severe overall bodily injuries (ISS>=15). RESULTS: 25,866 patients were included in the analysis. 2,352 (9.1%) received TXA and 23,514 (90.9%) did not receive TXA. Among those with ISS>=15 (n=6,420), 21.2% received TXA. Among those with any head injury (AIS head injury severity score>=1; n=9,153), 7.2% received TXA. The median ISS scores were greater in the TXA versus no-TXA group (17 versus 6). Weighted and adjusted models showed overall, there was 25% lower mortality risk between those who received TXA at any point and those who did not (OR:0.75, 95% CI: 0.59, 0.95). Further, as the AIS severity score increased from >=1 (1.08; 0.80, 1.47) to >=5 (0.56; 0.33, 0.97), the odds of mortality decreased. CONCLUSIONS: TXA may potentially be beneficial in patients with severe head injuries, especially those with severe overall injury profiles. There is a need of definitive studies to confirm this association.

A Narrative Review of Existing and Developing Biomarkers in Acute Traumatic Brain Injury for Potential Military Deployed Use.

INTRODUCTION: Traumatic brain injury (TBI) is a leading cause of morbidity and mortality in both adult civilian and military populations. Currently, diagnostic and prognostic methods are limited to imaging and clinical findings. Biomarker measurements offer a potential method to assess head injuries and help predict outcomes, which has a potential benefit to the military, particularly in the deployed setting where imaging modalities are limited. We determine how biomarkers such as ubiquitin C-terminal hydrolase-L1 (UCH-L1), glial fibrillary acidic protein (GFAP), S100B, neurofilament light chain (NFL), and tau proteins can offer important information to guide the diagnosis, acute management, and prognosis of TBI, specifically in military personnel. MATERIALS AND METHODS: We performed a narrative review of peer-reviewed literature using online databases of Google Scholar and PubMed. We included articles published between 1988 and 2022. RESULTS: We screened a total of 73 sources finding a total of 39 original research studies that met inclusion for this review. We found five studies that focused on GFAP, four studies that focused on UCH-L1, eight studies that focused on tau proteins, six studies that focused on NFL, and eight studies that focused on S100B. The remainder of the studies included more than one of the biomarkers of interest. CONCLUSIONS: TBI occurs frequently in the military and civilian settings with limited methods to diagnose and prognosticate outcomes. We highlighted several promising biomarkers for these purposes including S100B, UCH-L1, NFL, GFAP, and tau proteins. S100B and UCH-L1 appear to have the strongest data to date, but further research is necessary. The robust data that explain the optimal timing and, more importantly, trending of these biomarker measurements are necessary before widespread application.

Epidemiology of cranial infections in battlefield-related penetrating and open cranial injuries.

BACKGROUND: Penetrating brain injuries are a potentially lethal injury associated with substantial morbidity and mortality. We examined characteristics and outcomes among military personnel who sustained battlefield-related open and penetrating cranial injuries during military conflicts in Iraq and Afghanistan. METHODS: Military personnel wounded during deployment (2009-2014) were included if they sustained an open or penetrating cranial injury and were admitted to participating hospitals in the United States. Injury characteristics, treatment course, neurosurgical interventions, antibiotic use, and infection profiles were examined. RESULTS: The study population included 106 wounded personnel, of whom 12 (11.3%) had an intracranial infection. Posttrauma prophylactic antibiotics were prescribed in more than 98% of patients. Patients who developed central nervous system (CNS) infections were more likely to have undergone a ventriculostomy ( p = 0.003), had a ventriculostomy in place for a longer period (17 vs. 11 days; p = 0.007), had more neurosurgical procedures ( p < 0.001), and have lower presenting Glasgow Coma Scale ( p = 0.01) and higher Sequential Organ Failure Assessment scores ( p = 0.018). Time to diagnosis of CNS infection was a median of 12 days postinjury (interquartile range, 7-22 days) with differences in timing by injury severity (critical head injury had median of 6 days, while maximal [currently untreatable] head injury had a median of 13.5 days), presence of other injury profiles in addition to head/face/neck (median, 22 days), and the presence of other infections in addition to CNS infections (median, 13.5 days). The overall length of hospitalization was a median of 50 days, and two patients died. CONCLUSION: Approximately 11% of wounded military personnel with open and penetrating cranial injuries developed CNS infections. These patients were more critically injured (e.g., lower Glasgow Coma Scale and higher Sequential Organ Failure Assessment scores) and required more invasive neurosurgical procedures. LEVEL OF EVIDENCE: Prognostic and Epidemiological; Level IV.

Committee on Surgical Combat Casualty Care position statement: Neurosurgical capability for the optimal management of traumatic brain injury during deployed operations.

BACKGROUND: Experiences over the last three decades of war have demonstrated a high incidence of traumatic brain injury (TBI) resulting in a persistent need for a neurosurgical capability within the deployed theater of operations. Despite this, no doctrinal requirement for a deployed neurosurgical capability exists. Through an iterative process, the Joint Trauma System Committee on Surgical Combat Casualty Care (CoSCCC) developed a position statement to inform medical and nonmedical military leaders about the risks of the lack of a specialized neurosurgical capability. METHODS: The need for deployed neurosurgical capability position statement was identified during the spring 2021 CoSCCC meeting. A triservice working group of experienced forward-deployed caregivers developed a preliminary statement. An extensive iterative review process was then conducted to ensure that the intended messaging was clear to senior medical leaders and operational commanders. To provide additional context and a civilian perspective, statement commentaries were solicited from civilian clinical experts including a recently retired military trauma surgeon boarded in neurocritical care, a trauma surgeon instrumental in developing the Brain Injury Guidelines, a practicing neurosurgeon with world-renowned expertise in TBI, and the chair of the Committee on Trauma. RESULTS: After multiple revisions, the position statement was finalized, and approved by the CoSCCC membership in February 2023. Challenges identified include (1) military neurosurgeon attrition, (2) the lack of a doctrinal neurosurgical capabilities requirement during deployed combat operations, and (3) the need for neurosurgical telemedicine capability and in-theater computed tomography scans to triage TBI casualties requiring neurosurgical care. CONCLUSION: Challenges identified regarding neurosurgical capabilities within the deployed trauma system include military neurosurgeon attrition and the lack of a doctrinal requirement for neurosurgical capability during deployed combat operations. To mitigate risk to the force in a future peer-peer conflict, several evidence-based recommendations are made. The solicited civilian commentaries strengthen these recommendations by putting them into the context of civilian TBI management. This neurosurgical capabilities position statement is intended to be a forcing function and a communication tool to inform operational commanders and military medical leaders on the use of these teams on current and future battlefields. LEVEL OF EVIDENCE: Prognostic and Epidemiological; Level V.

Incidence of post-traumatic seizures in children during combat operations in Afghanistan and Iraq.

OBJECTIVES: Children represent a significant portion of the patient population treated at combat support hospitals. There is significant data regarding post injury seizures in adults but with children it is lacking. We seek to describe the incidence of post-traumatic seizures within this population. METHODS: This is a secondary analysis of previously described data from the Department of Defense Trauma Registry (DODTR). Within our dataset, we searched for documentation of seizures after admission. RESULTS: Of the 3439 encounters in our dataset, we identified 37 casualties that had a documented seizure after admission. Most were in the 1-4 year age group (37.8%), male (59.4%), injured by explosive (40.5%), with serious injuries to the head/neck (75.6%). The median ISS was higher in the seizure group (22 versus 10, p<0.001). Most survived to hospital discharge with no statistically significant increased mortality noted in the seizure group (seizure 90.2% versus 91.8%, p = 1.000). In the prehospital setting, the seizure group was more frequently intubated (16.2% versus 6.0%, p = 0.023), received ketamine (20.0% versus 3.2%, p<0.001), and administered an anti-seizure medication (5.4% versus 0.1%, p = 0.001). In the hospital setting, the seizure group was more frequently intubated (56.7% versus 17.7%, p<0.001), had intracranial pressure monitoring (24.3% versus 2.6%, p<0.001), craniectomy (10.8% versus 2.5%, p = 0.014), and craniotomy (21.6% versus 4.7%, p<0.001). CONCLUSIONS: Within our dataset, we found an incidence of 1% of pediatric casualties experiencing a post-traumatic seizure. While this number appears infrequent, there is likely significant under detection of subclinical seizures.

Ketamine Boluses Are Associated with a Reduction in Intracranial Pressure and an Increase in Cerebral Perfusion Pressure: A Retrospective Observational Study of Patients with Severe Traumatic Brain Injury.

Background: Increased intracranial pressure (ICP) and hypotension have long been shown to lead to worse outcomes in the severe traumatic brain injury (TBI) population. Adequate sedation is a fundamental principle in TBI care, and ketamine is an attractive option for sedation since it does not commonly cause systemic hypotension, whereas most other sedative medications do. We evaluated the effects of ketamine boluses on both ICP and cerebral perfusion pressure (CPP) in patients with severe TBI and refractory ICP. Methods: We conducted a retrospective review of all patients admitted to the neurointensive care unit at a single tertiary referral center who had a severe traumatic brain injury with indwelling intracranial pressure monitors. We identified those patients with refractory intracranial pressure who received boluses of ketamine. We defined refractory as any sustained ICP greater than 20 mmHg after the patient was adequately sedated, serum Na was at goal, and CO2 was maintained between 35 and 40 mmHg. The primary outcome was a reduction in ICP with a subsequent increase in CPP. Results: The patient cohort consisted of 44 patients with a median age of 30 years and a median presenting Glasgow Coma Scale (GCS) of 5. The median reduction in ICP after administration of a ketamine bolus was -3.5 mmHg (IQR -9 to +1), and the postketamine ICP was significantly different from baseline (p < 0.001). Ketamine boluses led to an increase in CPP by 2 mmHg (IQR -5 to +12), which was also significantly different from baseline (p < 0.001). Conclusion: In this single-institution study of patients with severe traumatic brain injury, ketamine boluses were associated with a reduction in ICP and an increase in CPP. This was a retrospective review of 43 patients and is therefore limited in nature, but further randomized controlled trials should be performed to confirm the findings.

Factors Affecting Outcomes in Geriatric Traumatic Subdural Hematoma in a Neurosurgical Intensive Care Unit.

BACKGROUND AND OBJECTIVE: Geriatric patients (age ≥65 years) who sustain a traumatic brain injury have an increased risk of poor outcomes and higher mortality compared with younger cohorts. We aimed to evaluate the risk factors for discharge outcomes in a geriatric traumatic subdural hematoma population, stratified by age and pretraumatic medical comorbidities. This was a single-center retrospective cohort study of geriatric patients (N = 207). METHODS: Patient charts were evaluated for factors including patient characteristics, comorbidities, injury-related and seizure-related factors, neurosurgical intervention, and patient disposition on discharge. RESULTS: Bivariate and multivariate analyses showed that age was nonpredictive of patient outcomes. Underlying vasculopathic comorbidities were the primary determinant of posttraumatic seizure, surgical, and discharge outcomes. Multifactor analysis showed that patients who went on to develop status epilepticus (n = 11) had a higher frequency of vasculopathic comorbidities with strong predictive power in poor patient outcomes. CONCLUSIONS: Our findings suggest a need to establish unique prognostic risk factors based on patient outcomes that guide medical and surgical treatment in geriatric patients.

Epidemiology, patterns of care and outcomes of traumatic brain injury in deployed military settings: Implications for future military operations.

BACKGROUND: Traumatic brain injury (TBI) is prevalent and highly morbid among Service Members. A better understanding of TBI epidemiology, outcomes, and care patterns in deployed settings could inform potential approaches to improve TBI diagnosis and management. METHODS: A retrospective cohort analysis of Service Members who sustained a TBI in deployed settings between 2001 and 2018 was conducted. Among individuals hospitalized with TBI, we compared the demographic characteristics, mechanism of injury, injury type, and severity between combat and noncombat injuries. We compared diagnostic tests and procedures, evacuation patterns, return to duty rates and days in care between individuals with concussion and those with severe TBI. RESULTS: There were 46,309 service members with TBI and 9,412 who were hospitalized; of those hospitalized, 55% (4,343) had isolated concussion and 9% (796) had severe TBI, of whom 17% (132/796) had multiple injuries. Overall mortality was 2% and ranged from 0.1% for isolated concussion to 18% for severe TBI. The vast majority of TBI were evacuated by rotary wing to role 3 or higher, including those with isolated concussion. As compared with severe TBI, individuals with isolated concussion had fewer diagnostic or surgical procedures performed. Only 6% of service members with severe TBI were able to return to duty as compared with 54% of those with isolated concussion. Traumatic brain injury resulted in 123,677 lost duty days; individuals with isolated concussion spent a median of 2 days in care and those with severe TBI spent a median of 17 days in care and a median of 6 days in the intensive care unit. CONCLUSION: While most TBI in the deployed setting are mild, TBI is frequently associated with hospitalization and multiple injuries. Overtriage of mild TBI is common. Improved TBI capabilities applicable to forward settings will be critical to the success of future multidomain operations with limitations in air superiority. LEVEL OF EVIDENCE: Prognostic and Epidemiologic; Level III.

Attitudes Toward Neurosurgery Education for the Nonneurosurgeon: A Survey Study and Critical Analysis of U.S. Military Training Techniques and Future Prospects.

BACKGROUND: The U.S. military requires medical readiness to support forward-deployed combat operations. Because time and distance to neurosurgical capabilities vary within the deployed trauma system, nonneurosurgeons are required to perform emergent cranial procedures in select cases. It is unclear whether these surgeons have sufficient training in these procedures. METHODS: This quality-improvement study involved a voluntary, anonymized specialty-specific survey of active-duty surgeons about their experience and attitudes toward U.S. military emergency neurosurgical training. RESULTS: Survey responses were received from 104 general surgeons and 26 neurosurgeons. Among general surgeons, 81% have deployed and 53% received training in emergency neurosurgical procedures before deployment. Only 16% of general surgeons reported participating in craniotomy/craniectomy procedures in the last year. Nine general surgeons reported performing an emergency neurosurgical procedure while on deployment/humanitarian mission, and 87% of respondents expressed interest in further predeployment emergency neurosurgery training. Among neurosurgeons, 81% had participated in training nonneurosurgeons and 73% believe that more comprehensive training for nonneurosurgeons before deployment is needed. General surgeons proposed lower procedure minimums for competency for external ventricular drain placement and craniotomy/craniectomy than did neurosurgeons. Only 37% of general surgeons had used mixed/augmented reality in any capacity previously; for combat procedures, most (90%) would prefer using synchronous supervision via high-fidelity video teleconferencing over mixed reality. CONCLUSIONS: These survey results show a gap in readiness for neurosurgical procedures for forward-deployed general surgeons. Capitalizing on capabilities such as mixed/augmented reality would be a force multiplier and a potential means of improving neurosurgical capabilities in the forward-deployed environments.

An Analysis of Intracranial Hemorrhage in Wartime Pediatric Casualties.

BACKGROUND: Children make up a significant cohort of patients treated at combat support hospitals. Where traumatic head injury, including intracranial hemorrhage (ICH), is well studied in military adults, such research is lacking regarding pediatric patients. We seek to describe the incidence and outcomes of ICH within this population. METHODS: This is a secondary analysis of a previously published dataset from the Department of Defense Trauma Registry for all pediatric casualties in Iraq and Afghanistan from January 2007 to January 2016. Within our dataset, we searched for casualties with an ICH. RESULTS: Of the 3439 pediatric encounters in our dataset, we identified 495 (14%) casualties that had at least 1 type of ICH. Most were between 5 and 12 years of age, male (74%), and injured by an explosive (42%). Of the casualties with ICHs, 82 had epidural (16.6%), 237 had subdural (47.9%), 153 had subarachnoid (30.9%), 157 had parenchymal bleeds (31.7%), and 239 had ICHs not otherwise specified (48.3%). In the hospital setting, the epidural group was more frequently treated with skull decompression (41%) and craniotomy with skull elevation (28%). The subdural group was more frequently treated with a craniectomy (17%) and the parenchymal group had more frequent intracranial pressure monitoring (18%). In our dataset, 22 received ketamine prehospital (4.4%) and most were discharged alive from the hospital (79%). CONCLUSIONS: Within our dataset, we identified 495 cases of ICH in pediatric patients. Most survived to hospital discharge despite less than half undergoing a decompression procedure.

The Expanding Role of Quantitative Pupillometry in the Evaluation and Management of Traumatic Brain Injury.

Traumatic brain injury is a rapidly increasing source of morbidity and mortality across the world. As such, the evaluation and management of traumatic brain injuries ranging from mild to severe are under active investigation. Over the last two decades, quantitative pupillometry has been increasingly found to be useful in both the immediate evaluation and ongoing management of traumatic brain injured patients. Given these findings and the portability and ease of use of modern pupillometers, further adoption and deployment of quantitative pupillometers into the preclinical and hospital settings of both resource rich and medically austere environments.