Head Acceleration Research Articles

Vergence increases the amplitude of lateral ocular vestibular evoked myogenic potentials.

The angular and linear vestibulo-ocular reflex responses are greater when viewing near targets to compensate for the relatively larger translation of the eyes with respect to the target. Our aim was to measure vestibular evoked myogenic potentials using a lateral ocular electrode montage (oVEMP) with a laterally applied stimulus using a mini-shaker during both far- and near-viewing (vergence) distances to determine whether vergence affects the oVEMP response as it does the semicircular canal vestibulo-ocular reflex response. Our results show that during vergence, the p1 and n1-p1 amplitude of the lateral oVEMP response increases significantly, whereas the latencies do not change significantly. We suggest that the physiological basis for this vergence-mediated amplitude increase in potentials may be the same as those already documented using transient linear head accelerations. Our data also suggest that irregular vestibular afferents are likely mediating the vergence-mediated gain increase during linear head accelerations because only irregular afferents are stimulated during short, transient 500Hz stimuli.

Brain Perfusion Bridges Virtual-Reality Spatial Behavior to TPH2 Genotype for Head Acceleration Events.

Neuroimaging demonstrates that athletes of collision sports can suffer significant changes to their brain in the absence of concussion, attributable to head acceleration event (HAE) exposure. In a sample of 24 male Division I collegiate football players, we examine the relationships between tryptophan hydroxylase 2 (TPH2), a gene involved in neurovascular function, regional cerebral blood flow (rCBF) measured by arterial spin labeling, and virtual reality (VR) motor performance, both pre-season and across a single football season. For the pre-season, TPH2 T-carriers showed lower rCBF in two left hemisphere foci (fusiform gyrus/thalamus/hippocampus and cerebellum) in association with higher (better performance) VR Reaction Time, a dynamic measure of sensory-motor reactivity and efficiency of visual-spatial processing. For TPH2 CC homozygotes, higher pre-season rCBF in these foci was associated with better performance on VR Reaction Time. A similar relationship was observed across the season, where TPH2 T-carriers showed improved VR Reaction Time associated with decreases in rCBF in the right hippocampus/amygdala, left middle temporal lobe, and left insula/putamen/pallidum. In contrast, TPH2 CC homozygotes showed improved VR Reaction Time associated with increases in rCBF in the same three clusters. These findings show that TPH2 T-carriers have an abnormal relationship between rCBF and the efficiency of visual-spatial processing that is exacerbated after a season of high-impact sports in the absence of diagnosable concussion. Such gene-environment interactions associated with behavioral changes after exposure to repetitive HAEs have been unrecognized with current clinical analytical tools and warrant further investigation. Our results demonstrate the importance of considering neurovascular factors along with traumatic axonal injury to study long-term effects of repetitive HAEs.

An evaluation of occupant dynamics during moderate-to-high speed side impacts.

The present study examined trends in occupant dynamics during side impact testing in vehicle models over the past decade. "Moderate-to-high" speed side impacts (delta-V ≥15 km/h) were analyzed. The Insurance Institute for Highway Safety (IIHS) side impact crash data was examined (N = 126). The test procedure involved a moving deformable barrier (MDB) impacting the sides of stationary vehicles at 50.0 km/h. Instrumented 5th-percentile female SID IIs dummies were positioned in the driver and left rear passenger seats. Occupant head, neck, shoulder, torso, spine, and pelvis/femur responses (times histories, peaks, and time-to-peak values) were evaluated and compared to injury assessment reference values (IARVs). The effects of delta-V, vehicle model year, vehicle body type, and occupant seating position on dynamic responses were examined. The vehicle lateral delta-Vs ranged from 15.9 to 34.5 km/h. The MY2018-2020 demonstrated lower peak dynamics than MY2010-2013, for the driver head acceleration (53.7 ± 11.3g vs 46.4 ± 11.6g), shoulder lateral forces (1.7 ± 0.7 kN vs 1.5 ± 0.2 kN), average rib deflection (29.8 ± 8.3 mm vs 28.4 ± 6.2 mm), spine accelerations at T4 (51.4 ± 23.4g vs 39.6 ± 5.9g) and T12 (56.3 ± 18.5g vs 45.2 ± 9.6g), iliac forces (1.9 ± 1.0 kN vs 1.2 ± 0.9 kN), and acetabular forces (1.9 ± 0.8 kN vs 1.3 ± 0.5 kN). The driver indicated statistically higher dynamic responses than the left rear passenger. Higher wheelbase vehicles generally showed lower occupant loading than the smaller vehicles. In conclusion, a reduction in occupant loading and risks for injury was observed in vehicle models over the past decade. This provides further insight into injury mechanisms, occupant dynamics simulations, and seat/restraint design.

A comparison of different models of passive seat suspensions

Long duration exposure to vehicle induced vibration causes various ailments to humans. Amongst the various components of the human-vehicle system, the seat suspension plays a major role in determining the level of vibration transferred to humans. However, optimising the suspension for maximising human comfort leads to poor vehicle handling characteristics. Thus, predicting human comfort through various seat suspension models is a widely researched topic. However, the appropriate seat suspension model to be used has not been identified so far. Neither has any prior work reported integrating models of all the components necessary for this analysis, namely human body, cushion, seat suspension and vehicle chassis, each with the appropriate level of complexity. This work uses a two-dimensional 12 DoF seated human body model with inclined backrest support, a nonlinear cushion model, a seat suspension model and a full vehicle model. Two kinds of road profiles – one with random roughness and one with a bump – have been used. It then compares the performance of five different seat suspension models based on a number of human comfort related parameters (seat to head transmissibility, suspension travel, seat acceleration, cushion contact force and head acceleration in both vertical and fore-aft directions) and vehicle handling parameters (vertical, rolling and pitching acceleration of chassis). The results clearly show the superiority of the configuration which involves a spring parallel to an inclined multi-stage damper. A separate analysis was also done to judge whether the integration of the vehicle model (with its associated complication) was necessary for this analysis. A comparison of the human body’s internal forces, moments, acceleration, and absorbed power with and without the vehicle model clearly indicates the need of using the former.

Natural oscillatory modes of 3D deformation of the human brain in vivo

Natural modes and frequencies of three-dimensional (3D) deformation of the human brain were identified from in vivo tagged magnetic resonance images (MRI) acquired dynamically during transient mild acceleration of the head. Twenty 3D strain fields, estimated from tagged MRI image volumes in 19 adult subjects, were analyzed using dynamic mode decomposition (DMD). These strain fields represented dynamic, 3D brain deformations during constrained head accelerations, either involving rotation about the vertical axis of the neck or neck extension. DMD results reveal fundamental oscillatory modes of deformation at damped frequencies near 7 Hz (in neck rotation) and 11 Hz (in neck extension). Modes at these frequencies were found consistently among all subjects. These characteristic features of 3D human brain deformation are important for understanding the response of the brain in head impacts and provide valuable quantitative criteria for the evaluation and use of computer models of brain mechanics.

Impact Performance Comparison of Advanced Snow Sport Helmets with Dedicated Rotation-Damping Systems

Rotational acceleration of the head is a principal cause of concussion and traumatic brain injury. Several rotation-damping systems for helmets have been introduced to better protect the brain from rotational forces. But these systems have not been evaluated in snow sport helmets. This study investigated two snow sport helmets with different rotation-damping systems, termed MIPS and WaveCel, in comparison to a standard snow sport helmet without a rotation-damping system. Impact performance was evaluated by vertical drops of a helmeted Hybrid III head and neck onto an oblique anvil. Six impact conditions were tested, comprising two impact speeds of 4.8 and 6.2 m/s, and three impact locations. Helmet performance was quantified in terms of the linear and rotational kinematics, and the predicted probability of concussion. Both rotation-damping systems significantly reduced rotational acceleration under all six impact conditions compared to the standard helmet, but their effect on linear acceleration was less consistent. The highest probability of concussion for the standard helmet was 89%, while helmets with MIPS and WaveCel systems exhibited a maximal probability of concussion of 67 and 7%, respectively. In conclusion, rotation-damping systems of advanced snow sport helmets can significantly reduce rotational head acceleration and the associated concussion risk.

Development of a wearable device for the early diagnosis of neurodegenerative diseases

The progressive evolution of information and sensing technologies is giving pulse to the development of wearable mobile devices in search of life quality improvement. A relevant field of application is healthcare, with the development of wireless unobtrusive wearable solutions for the continuous remote health monitoring of patients. These wearable devices are particularly important for neurodegenerative diseases due to the possibility of early stage diagnoses through continuous monitoring to collect earlier significant data. Discovering specific symptoms and early defining medical treatments can delay, if not stop, the pathology progress whereas, once major symptoms like restricted or impaired mobility has appeared, the patients already underwent relevant and irreversible brain damage. The aim of this work is to show the development of the Neuroglass, a wearable smart glasses device for early stage diagnosis and monitoring of Parkinsonian-type neurodegenerative diseases. The designed frame is compliant to the standards and in order to embed the sensors to collect data from head and eyes movements since one of the early symptoms of Parkinson’s disease has proven to be eye tremors. Preliminary laboratory tests, e.g. head accelerations measurements for different body movements, were carried out in order to choose properly the characteristics and positioning of the sensors; afterwards the device’s frame was designed by means of a 3D parametric CAD and built by additive manufacturing. The design was validated by first experimental test on monitoring eye movements and blinks.

Heading in Soccer: Does Kinematics of the Head-Neck-Torso Alignment Influence Head Acceleration?

There is little scientific evidence regarding the cumulative effect of purposeful heading. The head-neck-torso alignment is considered to be of great importance when it comes to minimizing potential risks when heading. Therefore, this study determined the relationship between head-neck-torso alignment (cervical spine, head, thoracic spine) and the acceleration of the head, the relationship between head acceleration and maximum ball speed after head impact and differences between head accelerations throughout different heading approaches (standing, jumping, running). A total of 60 male soccer players (18.9 ± 4.0 years, 177.6 ± 14.9 cm, 73.1 ± 8.6 kg) participated in the study. Head accelerations were measured by a telemetric Noraxon DTS 3D Sensor, whereas angles for the head-neck-torso alignment and ball speed were analyzed with a Qualisys Track Manager program. No relationship at all was found for the standing, jumping and running approaches. Concerning the relationship between head acceleration and maximum ball speed after head impact only for the standing header a significant result was calculated (p = 0.024, R2 = .085). A significant difference in head acceleration (p < .001) was identified between standing, jumping and running headers. To sum up, the relationship between head acceleration and head-neck-torso alignment is more complex than initially assumed and could not be proven in this study. Furthermore first data were generated to check whether the acceleration of the head is a predictor for the resulting maximum ball speed after head impact, but further investigations have to follow. Lastly, we confirmed the results that the head acceleration differs with the approach.

Quantifying a Learning Curve for Video Head Impulse Test: Pitfalls and Pearls.

Objective: The video head impulse test (vHIT) is nowadays a fast and objective method to measure vestibular function. However, its usability is controversial and often considered as a test performed by experts only. We sought to study the learning curve of novices and to document all possible mistakes and pitfalls in the process of learning.Methods: In a prospective cohort observational study, we included 10 novices. We tested their ability to perform correctly horizontal head impulses recorded with vHIT. We assessed vHITs in 10 sessions with 20 impulses per session giving a video instruction after the first session (S1) and individual feedback from an expert for session 2 (S2) up to session 10 (S10). We compared VOR gain, the HIT acceptance rate by the device algorithm, mean head velocity, acceleration, excursion, and overshoot between sessions.Results: A satisfying number of accepted HITs (80%) was reached after an experience of 160 vHITs. Mean head velocity between sessions was always in accepted limits. Head acceleration was too low at the beginning (S1) but improved significantly after the video instruction (p = 0.001). Mean head excursion and overshoot showed a significant improvement after 200 head impulses (p < 0.001 each).Conclusions: We showed that novices can learn to perform head impulses invHIT very fast provided that they receive instructions and feedback from an experienced examiner. Video instructions alone were not sufficient. The most common pitfall was a low head acceleration.

The Effect of Player Contact Characteristics on Head Impact Exposure in Youth Football Games

To reduce head impact exposure (HIE) in youth football, further understanding of the context in which head impacts occur and the associated biomechanics is needed. The objective of this study was to evaluate the effect of contact characteristics on HIE during player versus player contact scenarios in youth football. Head impact data and time-synchronized video were collected from 4 youth football games over 2 seasons in which opposing teams were instrumented with the Head Impact Telemetry (HIT) System. Coded contact characteristics included the player's role in the contact, player speed and body position, contact height, type, and direction, and head contact surface. Head accelerations were compared among the contact characteristics using mixed-effects models. Among 72 instrumented athletes, 446 contact scenarios (n = 557 impacts) with visible opposing instrumented players were identified. When at least one player had a recorded impact, players who were struck tended to have higher rotational acceleration than players in striking positions. When both players had a recorded impact, lighter players and taller players experienced higher mean head accelerations compared with heavier players and shorter players. Understanding the factors influencing HIE during contact events in football may help inform methods to reduce head injury risk.

Effect of Coach Feedback and Awareness of Head Impact Exposure on Practice Structure in Youth Football.

With the concern of concussion risk and repetitive head impacts in youth football, organizations have adopted rules that limit contact during practice. However, rule changes are not ubiquitous among organizations and are challenging to monitor and enforce. Ultimately, football practice activities are determined by coaches, but it is unknown whether providing objective data to coaches relating activities to their athletes' head impact exposure (HIE) would alter practice structure or help reduce HIE. This study evaluated the effect of coach awareness of HIE on practice structure over time. Head impact data from three intervention (56 players) and three control (38 players) teams were collected over two youth football seasons. Athletes were instrumented with the Head Impact Telemetry (HIT) System and time-synchronized video was recorded for practices and games. Impact frequencies and head accelerations were compiled into weekly HIE practice and game reports and shared with the head coach of each intervention team. Time per drill, impact rate, and impact magnitude were compared across three time frames (pre-season, mid-season, and late-season) using generalized linear models. Control teams had higher impact rates than intervention teams in all drills across time frames. Among all teams, 95th percentile linear and rotational accelerations were highest during mid-season. Among intervention teams, more time was spent on scrimmage and skill development from pre-season to late-season, with less time spent on tackling. This study suggests that receiving objective data informing HIE in practice may contribute to changes in practice structure and help inform intervention efforts to improve head impact safety in football.

Investigation into the work related hazard from impact force on helmeted motor cyclist in Nigeria

Risk exposure of motorcyclist could be overwhelming when riding especially without protective wears on. Helmet which serves as protection to the most delicate part of the rider comes with different designs and quality in the study area, This study considered two common types of helmet used by the study population with the aim of assessing impact force on the cyclist as well as characterize the same. The investigation show that JC Yoli has performance metrics of percent risk, severity index and head acceleration (<1, 73, 245) which guarantee safety of the user. The percent risk, severity of accident and head acceleration significantly influence the impact force which can result head injury, spinal cord injury and death of rider involve in an accident. This research also suggests the use of helmet that has protective face mask that could prevent the spread of COVID 19 amongst the riders of business motorcyclist.

Directed Differentiation of Human Pluripotent Stem Cells into Inner Ear Organoids.

The sensory epithelia of the inner ear contain mechanosensitive hair cells that detect sound and head acceleration. This protocol details a 3D differentiation method to generate inner ear organoids containing sensory epithelia with hair cells. Human pluripotent stem cells are aggregated in low-binding 96-well plates and treated in chemically defined media with extracellular matrix to promote epithelialization. Small molecules and recombinant proteins are applied in a stepwise manner to recapitulate the morphogenic cues (BMP, TGF-β, FGF, and WNT) present during inner ear development in vivo. These treatments induce the sequential formation of nonneural ectoderm, otic-epibranchial progenitor domain, and otic placodes. The derived otic placodes then undergo self-guided morphogenesis to form otic vesicles, which eventually give rise to sensory epithelia containing hair cells and supporting cells, as well as neurons with synaptic formations to hair cells. This human stem cell-derived inner ear organoid system provides an ideal platform to study human inner ear development and disease in vitro.

Kinematic analysis of hammer head acceleration motion during the turn phase in hammer throwers with different record levels

Kinematic analysis of hammer head acceleration motion during the turn phase in hammer throwers with different record levels

Accidental Injuries Caused by Automotive Frontal Collision

ABSTRACT This study aimed to use a simulated vehicle to asses quantitatively the head and neck injuries of the occupants, in a frontal car crash, when the driver has only one hand on the steering wheel, such as while using a cell phone when driving. First, we conducted a survey of NHTSA reports on real laboratory tests of frontal collisions involving sedans. The effects of these collisions on the neck of a Hybrid III 50th percentile male crash test dummy were measured in terms of average head acceleration and force along the X, Z, and Y-axes. These acceleration, force and torque values obtained from the NHTSA database were used to validate the simulated model. The results obtained were compared with case E, the standard dummy position used in frontal collision tests. The results obtained in the simulation of the four cases of driving with only one hand demonstrate a probability of more than 67% that the driver will sustain AIS+2 injuries during a frontal crash. In all the cases, the skull fracture percentage was the most representative, occurring between 89 and 94% of cases where the driver had only one hand on the steering wheel.

The Influence of Occupant Grip on Ceiling Handrail and Injury Assessment in Collision

With the rapid increase in the number of cars, to bring a variety of convenience to mankind, at the same time, a number of traffic safety problems also followed, which causing serious injuries and property losses, bring more pain and regret to the people. Therefore, to accurately assess the damage of the personnel in the collision safety accident is very useful to improve the safety performance and functionality of the vehicle. so, the crash dummy plays an important role in the research of crash safety. At present, in the study of human body injury in the collision with dummy, the influence of roof handrails grasping state was not considered. Therefore, the software of LS-PREPOST and Oasys PRIM-ER are used to build model of automobile cockpit and dummy with hand grip ability, the acceleration environment of frontal crash was simulated by adding B-pillar acceleration curve from real vehicle crash test. Comparing injuries of dummies in free sitting posture and holding the roof armrest in collision. he simulation results show that when the dummy was grasping the roof armrest, the peak value of head acceleration and HIC values were 6.1% and 30.2% lower than the dummy was sitting freely, the maximum value of shear force, tensile force and bending moment of the neck were reduced by 87.4%, 76.9% and 42.9% respectively, and the maximum value of chest compression was reduced by 16.9%. The results provide a reference for the research of passive safety in collision.

Changes in White Matter of the Cervical Spinal Cord after a Single Season of Collegiate Football.

The involvement of the central nervous system (CNS), specifically the white matter tracts in the cervical spinal cord, was examined with diffusion tensor imaging (DTI) following exposure to repetitive head acceleration events (HAEs) after a single season of collegiate football. Fifteen National Collegiate Athletic Association (NCAA) Division 1 football players underwent DTI of the cervical spinal cord (vertebral level C1–4) at pre-season (before any contact practices began) and post-season (within 1 week of the last regular season game) intervals. Helmet accelerometer data were also collected in parallel throughout the season. From pre-season to post-season, a significant decrease (p < 0.05) of axial diffusivity was seen within the right spino-olivary tract. In addition, a significant decrease (p < 0.05) in global white matter fractional anisotropy (FA) along with increases (p < 0.05) in global white matter mean diffusivity (MD) and radial diffusivity (RD) were found. These changes in FA from pre-season to post-season were significantly moderated by previous concussion history (p < 0.05) and number of HAEs over 80 g (p < 0.05). Despite the absence of sports-related concussion (SRC), we present measurable changes in the white matter integrity of the cervical spinal cord suggesting injury from repetitive HAEs, or SRC, may include the entirety of the CNS, not just the brain.

Active Head Auto-Rotations in Patients With Benign Paroxysmal Positional Vertigo.

BackgroundUtricular degeneration is the source of traveling otoconia inside the semicircular canals in patients with benign paroxysmal positional vertigo (BPPV). The underlying pathology is not clear. The aim of this study was to analyze vestibulo-ocular reflex (VOR) during sudden head accelerations in those patients since clinical reports designating an association of BPPV with inner ear problems are increasing.MethodsVOR reaction to impulsive head rotations were tested in 34 patients with BPPV (13 lateral, 21 posterior canal BPPV) and 15 healthy subjects in a prospective controlled study. Main outcome measure was the gain (the ratio of head and eye velocity) of vertical and horizontal head auto-rotations to the pathologic and normal sides.ResultsAll patients with BPPV and control subjects had normal gain (≥ 0.9) at 1 and 2 Hz but the gain decreased at higher frequencies. No statistically significant difference was found when comparing the gain between the horizontal head rotations toward the pathologic and those toward the normal side (P = 0.89, P = 0.90, P = 0.78, P = 0.20 and P = 0.16, at 1, 2, 3, 4 and 5 Hz, respectively) and between upward and downward vertical head rotations (P = 0.28, P = 0.53 and P = 0.15, at 1, 2 and 3 Hz, respectively) in patients with lateral and posterior canal BPPV.ConclusionVOR gain was reduced in some patients. However, head auto-rotation test (HART) does not show any functional abnormality of VOR during head rotations toward the pathologic side. HART is not suitable as a screening test for BPPV.

Analysis of protective effects on different restraint systems of the six-year-old child occupants

In order to simulate the injury of rear children occupants in the frontal impact, a previously validated six-year-old child Finite Element (FE) model was used to load ECE R44 testing conditions. Through the resultant head acceleration, pressure, brain tissue Von Mises stress, brain tissue shear stress, shear force and axial force of neck, compression of chest and abdomen to compare the protective effects of the six-year-old rear seat occupant on forward-facing child seat restraint system and booster in different collision speeds. The results indicate that: when the collision speed is low, there is little difference of the child FE model's injury criteria in the two restraint systems, while the protective effect of child seat restraint system to the children is better than booster with the increase of the collision speed.

Analysis of protective effects on different restraint systems of the six-year-old child occupants

In order to simulate the injury of rear children occupants in the frontal impact, a previously validated six-year-old child Finite Element (FE) model was used to load ECE R44 testing conditions. Through the resultant head acceleration, pressure, brain tissue Von Mises stress, brain tissue shear stress, shear force and axial force of neck, compression of chest and abdomen to compare the protective effects of the six-year-old rear seat occupant on forward-facing child seat restraint system and booster in different collision speeds. The results indicate that: when the collision speed is low, there is little difference of the child FE model's injury criteria in the two restraint systems, while the protective effect of child seat restraint system to the children is better than booster with the increase of the collision speed.