Walter Carr

Introduction: Mortars enhance the lethality of Warfighters and protect them during combat. Accurate use of weapon systems is critical for mission success and to minimize health hazards, such as blast overpressure exposure. Although safety guidance exists and helps prevent accidents and injuries, military training is dynamic, and human factors such as fatigue and elevated core body temperature can increase the risk of error. In collaboration across the Defense Center for Public Health–Aberdeen and Walter Reed Army Institutes of Research, and MITRE, the team developed and evaluated the Augmented Reality Guidance System (ARGS) to support Department of War (DoW) decision making, serve as a force multiplier to enhance training, and support public health (e.g., monitor blast exposures). Materials and Methods: ARGS leverages emerging concepts in machine learning computer vision technology. It provides augmented reality, real-time, and after-action feedback to guide the actions of service members to mitigate unnecessary risks and support training and military operational medicine. ARGS uses the ZED stereo-camera, which is relatively low cost, waterproof, and intended for indoor and outdoor use, along with custom machine learning models for the DoW training use case. Through these models, ARGS evaluates the use of protective equipment by service members, the locations of individuals relative to weapon systems, and the use of the weapon systems. The team conducted 3 data collections at DoW mortar training events at 2 sites. The team implemented real-time facial blurring to preserve privacy and obtained feedback from instructors and unit leaders. Results: The ARGS models successfully identified helmet use, individual’s heads above the level of the mortar muzzle (which increases blast overpressure exposure), and individuals located downrange. The first real-world data collection enhanced the existing computer vision models (80:20 train-test split), and the updated models resulted in perfect detection of 134 mortar rounds fired during that session. At the second data collection, the updated ARGS computer vision models were evaluated in real time. Across all 3 training events the models accurately identified 99% of 539 rounds fired from the 60 mm, 81 mm, and 120 mm mortars. In the first training event, there were 13 false positives (e.g., because of false detection during mortar tube cleaning). After assessment the team developed a model to detect mortar cleaning and was able to detect all 32 cleaning evolutions recorded at the sites with one false positive. Across the training events, ARGS identified an average of 5.88 individuals around the weapon systems and a high instance of personnel within 20 ft of the weapon system with their head above the level of the mortar muzzle (>90% of rounds fired), which could be an opportunity for changes to training to reduce exposure. In addition to safety metrics, ARGS output includes rate of fire data, which is a common performance measure. Conclusion: ARGS shows promise for real-time support of range safety and after action review to enhance training effectiveness. ARGS identified and communicated safety information and deviations during training. This capability can help monitor and mitigate blast overpressure exposure and improve training to reduce injuries.

Introduction: Military service members training with heavy weapons systems are exposed to low-level blast (LLB) overpressure, sometimes resulting in acute symptoms similar to mild traumatic brain injury (mTBI). There is a need for a quick and effective screening tool to identify early deficits and changes associated with blast exposure and minimizing potential ensuing effects. Recently, researchers developed the modified Vestibular/Ocular Motor Screening (mVOMS), designed to assess signs and symptoms of mTBI. modified Vestibular/Ocular Motor Screening consists of four physical movement conditions: smooth pursuits, horizontal saccades, horizontal vestibular-ocular reflex, and visual motion sensitivity to capture the provocation of the vestibular system (headache, dizziness, nausea, fogginess). After completing each activity, service members were asked whether the symptoms were present or absent. Modified Vestibular/Ocular Motor Screening offers a practical solution as it can be administered in approximately 2 minutes and is 85% accurate in identifying mTBI. Similarly, military settings, where time is often constrained in addressing potential mTBI can benefit from the efficiency and reliability of mVOMS, making it well-suited for training settings; however, the use of mVOMS to detect acute blast exposure effects in service members has not been explored, which was the primary purpose of this study. A secondary purpose was to explore the relationship between mVOMS and self-reported mTBI symptoms without provocation by physical motion, as well as eye-tracking. Materials and Methods: This was a prospective cohort study design involving 42 male military personnel training with mortar systems and 15 male, healthy, unexposed controls. Participants reported demographics and over three separate visits, a self-reported symptoms questionnaire, mVOMS, and smooth pursuit eye tracking assessment. Independent samples t-tests and chi-square analyses, along with Pearson’s and rank-biserial correlations, compared demographic and outcome variables between exposed and control groups from the three visits, including individual measures of blast exposure magnitude. A series of receiver operating characteristic (ROC) curves with area under the curve (AUC) were used to evaluate the accuracy of mVOMS, mTBI symptoms, and eye tracking to identify exposed from control groups. This study has been approved by the Walter Reed Army Institute of Research Institutional Review Board. Results: Participants’ mean age was 25 ± 3.42 years with mean duration of service 4 ± 2.43 years. Service members exposed to blast reported more symptoms after performing the mVOMS physical movement challenges. The discriminatory power of the change from pre-exposure in mVOMS (AUC = 0.72) was comparable with the change in self-reported symptoms. In contrast to the change from pre-exposure, post-exposure single timepoint evaluation revealed mVOMS is superior (AUC = 0.70) compared to self-reported symptoms (AUC = 0.51). Modified Vestibular/Ocular Motor Screening was also positively correlated with blast exposure measures suggesting that increasing blast exposure levels are associated with increasing mVOMS scores. Conclusions: These results demonstrate that mVOMS in individuals exposed to LLB elicits a response that may be more sensitive than self-report alone. Our data suggests that mVOMS may be useful to screen for mTBI symptomology in service members following blast exposure when administered as a single timepoint test, as it is quick, simple to interpret, and requires minimal training to administer.

Liquid biopsies are revolutionizing the fields of prenatal non-invasive testing and cancer diagnosis by leveraging the genetic differences between mother and fetus, and, host and cancer. In the absence of genetic variance, epigenetics has been used to decipher the cell-of-origin of cell-free DNA (cfDNA). Liquid biopsies are minimally invasive and thus represent an attractive option for hard to biopsy tissues such as the brain. Here we report the first evidence of neuron derived cfDNA and cerebellum cfDNA within acute neurotrauma and chronic neurodegeneration, establishing the first class of peripheral biomarkers with specificity for the cell-type and brain-region undergoing potential injury and/or neurodegeneration.

Repeated exposure to low-level blast is a characteristic of a few select occupations and there is concern that such occupational exposures present risk for traumatic brain injury. These occupations include specialized military and law enforcement units that employ controlled detonation of explosive charges for the purpose of tactical entry into secured structures. The concern for negative effects from blast exposure is based on rates of operator self-reported headache, sleep disturbance, working memory impairment, and other concussion-like symptoms. A challenge in research on this topic has been the need for improved assessment tools to empirically evaluate the risk associated with repeated exposure to blast overpressure levels commonly considered to be too low in magnitude to cause acute injury. Evaluation of serum-based neurotrauma biomarkers provides an objective measure that is logistically feasible for use in field training environments. Among candidate biomarkers, ubiquitin carboxy-terminal hydrolase L1 (UCH-L1) has some empirical support and was evaluated in this study. We used daily blood draws to examine acute change in UCH-L1 among 108 healthy military personnel who were exposed to repeated low-level blast across a 2-week period. These research volunteers also wore pressure sensors to record blast exposures, wrist actigraphs to monitor sleep patterns, and completed daily behavioral assessments of symptomology, postural stability, and neurocognitive function. UCH-L1 levels were elevated as a function of participating in the 2-week training with explosives, but the correlation of UCH-L1 elevation and blast magnitude was weak and inconsistent. Also, UCH-L1 elevations did not correlate with deficits in behavioral measures. These results provide some support for including UCH-L1 as a measure of central nervous system effects from exposure to low-level blast. However, the weak relation observed suggests that additional indicators of blast effect are needed.

Objective: To investigate anecdotal reports suggesting that repeated exposure to low-level explosive blast has myriad health impacts, including an array of neurological effects. Participants: A total of 184 anonymous survey respondents from military and nonmilitary law enforcement populations (135 exposed to occupational blast and 49 controls). Design: Survey of self-reported history of occupational exposure to repeated low-level blast (breaching blast) and symptomology similar to concussion. Results: Findings suggest that number and severity of symptoms increase with history of chronic blast exposure (F = 18.26, P < .001) and that symptoms can interfere with daily activity (t = 2.60, P = .010). Conclusion: Given the prevalence of repeated exposure to blast among some military and civilian law enforcement occupations, the results of this survey study support a role for blast surveillance programs as well as continued research on health impacts of low-level repeated blast exposure.

The U.S. military has developed prophylactic interventions to mitigate effects from stress. The project reported is a first of its kind descriptive assessment of the delivery of resilience training...