Longitudinal Investigation of Neurotrauma Serum Biomarkers, Behavioral Characterization, and Brain Imaging in Soldiers Following Repeated Low-Level Blast Exposure (New Zealand Breacher Study)

Kamimori, Gary H.; LaValle, Christina R.; Eonta, Stephanie E.; Carr, Walter; Tate, Charmaine; Wang, Kevin

doi:10.1093/milmed/usx186

Cited by 38 publications

(18 citation statements)

References 12 publications

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“…Anecdotally, adherence to personnel protective equipment (PPE) usage may not be consistent across units and personnel, and is a point of further investigation. This data is at odds with previous findings from a breacher population, however, the total number of exposures (2–4 maximum) are far fewer in the breacher setting on a given day (16). Without the information about the exposure conditions, such as OP or acoustic pressure and stand-offs distances, it is hard to make meaningful comparisons.…”

Section: Conclusion/summarycontrasting

confidence: 95%

“…Personnel Assessment Pre and post personnel assessments were conducted over a single day of data collection (prior to blast/training, end of day/training) using previously established symptom metrics (3, 9, 10, 16) that employed a five-point likert-type scale ranging from 0- did not experience the symptom at all, to 4- a severe problem—constantly present, feels like it could affect individual's performance. Subjects were all male and averaged 30.34 + 4.93 years old (min 24, max 36) and 11.5 + 4.92 years of service (min 6, max 15.5).…”

Section: Methodsmentioning

confidence: 99%

“…Without the information about the exposure conditions, such as OP or acoustic pressure and stand-offs distances, it is hard to make meaningful comparisons. In addition, the breacher population tends to stand 2–3 times the mean safe distance in the Quantico breaching school to mitigate the effects from breaching exposures (16).…”

Section: Conclusion/summarymentioning

confidence: 99%

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The Role of Very Low Level Blast Overpressure in Symptomatology

et al. 2019

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Blast overpressure exposure has been linked to transient, but measurably deteriorated performance and symptomatologies in law enforcement and military personnel. Overlapping sub-concussive symptomatology associated with the very low level blast overpressures (vLLB) but high sound pressure (<3 psi) associated with these exposures has largely been ignored. Notably, the current vLLB or acoustic literature has focused exclusively on auditory defects, and has not addressed the broader concerns of Soldier health and readiness. This work was prompted by reports of symptomatology such as headache, nausea, slowed reaction time, and balance/hearing complications among personnel undergoing frequent exposures to low overpressure accompanied by high acoustic pressures. To more fully address the consequences associated with low overpressure exposures (<3 psi), a pilot proof-of-concept study was implemented, and data was acquired at two sites on the Fort Benning grenade course range. Findings indicated overpressures ranged from 0.14 to 0.42 psi (0.97–2.89 kPa) at range 1 and 0.22–0.30 psi (1.52–2.07 kPa) on range 2 of the grenade course. Corresponding sound-meter data varied from 153.72 to 163.22 dBP. Headache and long think were the most frequently reported symptoms (3/6 instructors), with lightheadedness, ringing of the ears, restlessness, frustration, and irritability also increasing in 2/6 of the instructors post exposure. Long think (prolonged thinking), ringing of the ears, restlessness, and irritability were the most severe symptoms, with the highest reported post exposure value rating a 3 on the 0–4-point scale. We demonstrate that low-level repeated overpressure exposure can result in transient symptomatology that overlaps with sub-concussive like effects.

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Section: Conclusion/summarycontrasting

confidence: 95%

Section: Methodsmentioning

confidence: 99%

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The Role of Very Low Level Blast Overpressure in Symptomatology

et al. 2019

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“…Military personnel are often exposed to blast overpressure during training with explosives as well as heavy (e.g., mortars, rockets & machine guns) and light (rifles & pistols) weapons and during combat [1,2]. Recent research has demonstrated that exposure to blast overpressure can result in deficits in neurocognitive performance [3,4] and changes in blood biomarkers [5][6][7][8][9] in the absence of a medically diagnosable injury such as concussion. At present any acute or subacute reported symptoms short of a medically diagnosed injury are not entered into an individual's medical record or other service records.…”

Section: Introductionmentioning

confidence: 99%

Sensor orientation and other factors which increase the blast overpressure reporting errors

et al. 2020

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This study compared the response of the wearable sensors tested against the industry-standard pressure transducers at blast overpressure (BOP) levels typically experienced in training. We systematically evaluated the effects of the sensor orientation with respect to the direction of the incident shock wave and demonstrated how the averaging methods affect the reported pressure values. The evaluated methods included averaging peak overpressure and impulse of all four sensors mounted on a helmet, taking the average of the three sensors, or isolating the incident pressure equivalent using two sensors. The experimental procedures were conducted in controlled laboratory conditions using the shock tube, and some of the findings were verified in field conditions with live fire charges during explosive breaching training. We used four different orientations (0˚, 90˚, 180˚, and 270˚) of the headform retrofitted with commonly fielded helmets (ACH, ECH, Ops-Core) with four B3 Blast Gauge sensors. We determined that averaging the peak overpressure values overestimates the actual dosage experienced by operators, which is caused by the reflected pressure contribution. This conclusion is valid despite the identified limitation of the B3 gauges that consistently underreport the peak reflected overpressure, compared to the industry-standard sensors. We also noted consistent overestimation of the impulse. These findings demonstrate that extreme caution should be exercised when interpreting occupational blast exposure results without knowing the orientation of the sensors. Pure numerical values without the geometrical, training-regime specific information such as the position of the sensors, the distance and orientation of the trainee to the source of the blast wave, and weapon system used will inevitably lead to erroneous estimation of the individual and cumulative blast overpressure (BOP) dosages. Considering that the 4 psi (~28 kPa) incident BOP is currently accepted as the threshold exposure safety value, a misinterpretation of exposure level may lead to an inaccurate estimation of BOP at the minimum standoff distance (MSD), or exclusion criteria.

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“…The early confirmation connecting the LLB with neurological abnormalities are the studies on breachers, which were reported more than a decade ago by operating independently military medical providers from multiple countries (2). The cluster of subjective symptoms described as “breacher's brain” including a headache, fatigue, a slowed thought process and an increase in memory deficits bear a striking resemblance to symptoms of concussion (2, 8–10). These reports led to several blast exposure studies which focused on outcome measures (e.g., biomarkers, neuroimaging, cognitive performance, and symptom reporting).…”

Section: Introductionmentioning

confidence: 99%

Occupational Blast Wave Exposure During Multiday 0.50 Caliber Rifle Course

et al. 2019

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Research on blast overpressure (BOP) experienced by military personnel in operations like breaching, identifies transient, measurable effects on operator readiness. Specifically, blast seems to be associated with suppressed response speed and cognitive function. This work evaluates 50 caliber weapon systems to ascertain BOP effects from the weapon usage. Marksmen were a collection of professionals who use 0.50 caliber weapon systems as part of their daily activities, and the environment measured was during a training course. The 20 human subjects were equipped with B3 blast gauges and occupational BOP exposure monitored over the course of 3 day training period with measurements taken from 500+ shots. We noted a considerable variation in total cumulative peak pressure (50-350 psi) and impulse (25-180 psi•ms) values. The frequency analysis (number of shots fired by the trainee) revealed that the number of exposures per day varied between 4 and 27 per day (peak at 7: 14.3% of the data), and 2 to 17 per hour (peak at 8: 18% of the data). The cumulative number of exposures was 24-50 per trainee. The neurocognitive performance was evaluated using Defense Automated Neurobehavioral Assessment (DANA) Rapid: Simple Reaction Time (SRT), Procedural Reaction Time (PRT) and Go/No-Go (GNG). The results recorded before the training were a baseline for each training day and compared with the results recorded after and at the end of the day. Only PRT and GNG tests revealed a cumulative increase in proportion of subjects with slowed reaction times over the progression of course with concomitant dispersion increase at the end of the day. Noticeably, on average 2/3rd of the trainees performed faster, while 1/3rd of trainees performed these tasks slower, but there was no correlation with the cumulative pressure dosage. The fatigue appears as an aggravating factor affecting the neurocognitive performance, and a more sophisticated evaluation regimen is necessary to discern potential neurological effects. Additional investigation is needed to understand the increasing dispersion of results between subjects and future works should be mindful of such continued trends. Future work should seek to determine the recovery period and longitudinal effects of heavy usage of these weapon systems.

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Longitudinal Investigation of Neurotrauma Serum Biomarkers, Behavioral Characterization, and Brain Imaging in Soldiers Following Repeated Low-Level Blast Exposure (New Zealand Breacher Study)

Cited by 38 publications

References 12 publications

The Role of Very Low Level Blast Overpressure in Symptomatology

The Role of Very Low Level Blast Overpressure in Symptomatology

Sensor orientation and other factors which increase the blast overpressure reporting errors

Occupational Blast Wave Exposure During Multiday 0.50 Caliber Rifle Course

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