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.

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.

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.

Committee on Surgical Combat Casualty Care Position Statement: Neurosurgical Capability for the Optimal Management of Traumatic Brain injury During Deployed Operations. Including Invited Commentaries

BACKGROUND

Experiences over the last 3 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 theatre 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 non-medical 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 tri-service 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 (BIG), a practicing neurosurgeon with world-renowned expertise in TBI, and the Chair of the Committee on Trauma (COT).

RESULTS

After multiple revisions, Position Statement was finalized it was 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; 3) the need for neurosurgical telemedicine capability and in-theatre CT 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. These 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

Brief Report, 3.

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.

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.

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.

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.

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.

Prehospital Detection of Life-Threatening Intracranial Pathology: An Unmet Need for Severe TBI in Austere, Rural, and Remote Areas

Severe traumatic brain injury (TBI) is a leading cause of death and disability worldwide, especially in low- and middle-income countries, and in austere, rural, and remote settings. The purpose of this Perspective is to challenge the notion that accurate and actionable diagnosis of the most severe brain injuries should be limited to physicians and other highly-trained specialists located at hospitals. Further, we aim to demonstrate that the great opportunity to improve severe TBI care is in the prehospital setting. Here, we discuss potential applications of prehospital diagnostics, including ultrasound and near-infrared spectroscopy (NIRS) for detection of life-threatening subdural and epidural hemorrhage, as well as monitoring of cerebral hemodynamics following severe TBI. Ultrasound-based methods for assessment of cerebrovascular hemodynamics, vasospasm, and intracranial pressure have substantial promise, but have been mainly used in hospital settings; substantial development will be required for prehospital optimization. Compared to ultrasound, NIRS is better suited to assess certain aspects of intracranial pathology and has a smaller form factor. Thus, NIRS is potentially closer to becoming a reliable method for non-invasive intracranial assessment and cerebral monitoring in the prehospital setting. While one current continuous wave NIRS-based device has been FDA-approved for detection of subdural and epidural hemorrhage, NIRS methods using frequency domain technology have greater potential to improve diagnosis and monitoring in the prehospital setting. In addition to better technology, advances in large animal models, provider training, and implementation science represent opportunities to accelerate progress in prehospital care for severe TBI in austere, rural, and remote areas.

Secondary Overtriage in Patients with Complicated Mild Traumatic Brain Injury: An Observational Study and Socioeconomic Analysis of 1447 Hospitalizations

BACKGROUND

Secondary overtriage is a problematic phenomenon because it creates unnecessary expense and potentially results in the mismanagement of healthcare resources. The rates of secondary overtriage among patients with complicated mild traumatic brain injury (cmTBI) are unknown.

OBJECTIVE

To determine the rate of secondary overtriage among patients with cmTBI using the institutional trauma registry.

METHODS

An observational study using retrospective analysis of 1447 hospitalizations including all consecutive patients with cmTBI between 2004 and 2013. Data on age, sex, race/ethnicity, insurance status, GCS, Injury Severity Score (ISS), Trauma Injury Severity Score, transfer mode, overall length of stay (LOS), LOS within intensive care unit, and total charges were collected and analyzed.

RESULTS

Overall, the rate of secondary overtriage among patients with cmTBI was 17.2%. These patients tended to be younger (median: 41 vs 60.5 yr; P < .001), have a lower ISS (9 vs 16; P < .001), and were more likely to be discharged home or leave against medical advice.

CONCLUSION

Our findings provide evidence to the growing body of literature suggesting that not all patients with cmTBI need to be transferred to a tertiary care center. In our study, these transfers ultimately incurred a total cost of $13 294 ($1337 transfer cost) per patient.

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.

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.