Validating a Device for Whiplash Motion Simulation in a Porcine Model

Whiplash injury is a common outcome following minor automobile collisions. One theorizedmechanism for whiplash injury is that the rapid head and neck motions induced by a collision caninjure nerve cells in the dorsal root ganglia through pressure gradients developed in the spinalcanal and surrounding tissues. This injury mechanism has previously been studied in humancadaver and porcine models. However, the whiplash motion simulation methods in the latterstudies lacked the control necessary to explore the independent effects of head rotation andretraction on the measured spinal pressures. This project aimed to address the limitations ofprevious porcine whiplash studies by developing and validating a new whiplash motion simulationdevice to enable further study of this injury mechanism. The new proposed device consists of twoservomotors which can be programmed to precisely actuate a headplate through mechanicallinkages. For the current study, an inert surrogate model was used for preliminary testing of thedevice using a whiplash motion profile from previous porcine studies. The time scale of the motionprofile was adjusted to incrementally increase severity. The positional accuracy and repeatabilityof the device was assessed through marker tracking of the headplate and logging of the motorencoder positions. Angular rates and linear accelerations of the plate were also measured. Testingdemonstrated the strengths of the proposed device in accurately and repeatably replicatingprogrammed motion profiles. Some design modifications can potentially enable simulatingwhiplash motion severities commensurate with previous porcine whiplash studies. With futuretesting using this device, our understanding of the pressure-induced whiplash injury mechanismcan be improved, which can inform effective treatments and preventative measures for whiplashinjury

HEAD IMPACTS DURING SPARRING: DIFFERENCES AND SIMILARITIES BETWEEN MOUTHGUARD, SKIN, AND HEADGEAR SENSORS

The timely identification of concussions is essential to ensuring athlete safety. In contact sports, many devices are available to measure head impacts, but concerns remain regarding their ability to accurately estimate the number and magnitude of those impacts. This study measured head impacts during boxing sparring simultaneously with three sensors – a mouthguard, a skin patch and a headgear patch – and video analysis. The objective was to assess and compare the number, quality, and magnitude of impact events across sensor types. All sensors had issues related to decoupling from the skull, although the mouthguard appeared to generate better estimates than the patches of the number of impacts and impact-induced head kinematics

Electrical Vestibular Stimuli Evoke Robust Muscle Activity in Deep and Superficial Neck Muscles in Humans

Neck muscle activity evoked by vestibular stimuli is a clinical measure for evaluating the function of the vestibular apparatus. Cervical vestibular-evoked myogenic potentials (cVEMP) are most commonly measured in the sternocleidomastoid muscle (and more recently the splenius capitis muscle) in response to air-conducted sound, bone-conducted vibration or electrical vestibular stimuli. It is currently unknown, however, whether and how other neck muscles respond to vestibular stimuli. Here we measured activity bilaterally in the sternocleidomastoid, splenius capitis, sternohyoid, semispinalis capitis, multifidus, rectus capitis posterior, and obliquus capitis inferior using indwelling electrodes in two subjects exposed to binaural bipolar electrical vestibular stimuli. All recorded neck muscles responded to the electrical vestibular stimuli (0–100 Hz) provided they were active. Furthermore, the evoked responses were inverted on either side of the neck, consistent with a coordinated contribution of all left-right muscle pairs acting as antagonists in response to the electrically-evoked vestibular error of head motion. Overall, our results suggest that, as previously observed in cat neck muscles, broad connections exist between the human vestibular system and neck motoneurons and highlight the need for future investigations to establish their neural connections

Head Impact Magnitude in American High School Football

OBJECTIVES: To describe determinants of head impact magnitudes between various play aspects in high school football. METHODS: Thirty-two high school American football players wore Head Impact Telemetry System instrumented helmets to capture head impact magnitude (linear acceleration, rotational acceleration, and Head Impact Technology severity profile [HITsp]). We captured and analyzed video from 13 games (n = 3888 viewable head impacts) to determine the following play aspects: quarter, impact cause, play type, closing distance, double head impact, player's stance, player's action, direction of gaze, athletic readiness, level of anticipation, player stationary, ball possession, receiving ball, and snapping ball. We conducted random intercepts general linear mixed models to assess the differences in head impact magnitude between play aspects (α = 0.05). RESULTS: The following aspects resulted in greater head impact magnitude: impacts during the second quarter (HITsp: P = .03); contact with another player (linear, rotational, HITsp: P < .001); initial head impact when the head is struck twice (linear, rotational, HITsp: P < .001); longer closing distances, especially when combined with a 3-point stance or when being struck in the head (linear: P = .03); the 2-point stance (linear, rotational, HITsp: P < .001); and offensive linemen not snapping the ball compared with those snapping the ball (rotational: P = .02, HITsp: P = .02). CONCLUSIONS: Preventing head impacts caused by contact with another player may reduce head impact magnitude in high school football. Rule or coaching changes that reduce collisions after long closing distances, especially when combined with the 3-point stance or when a player is being struck in the head, should be considered

Electrical vestibular stimuli evoke robust muscle activity in deep and superficial neck muscles in humans

Neck muscle activity evoked by vestibular stimuli is a clinical measure for evaluating the function of the vestibular apparatus. Cervical vestibular-evoked myogenic potentials (cVEMP) are most commonly measured in the sternocleidomastoid muscle (and more recently the splenius capitis muscle) in response to air-conducted sound, bone-conducted vibration or electrical vestibular stimuli. It is currently unknown, however, whether and how other neck muscles respond to vestibular stimuli. Here we measured activity bilaterally in the sternocleidomastoid, splenius capitis, sternohyoid, semispinalis capitis, multifidus, rectus capitis posterior, and obliquus capitis inferior using indwelling electrodes in two subjects exposed to binaural bipolar electrical vestibular stimuli. All recorded neck muscles responded to the electrical vestibular stimuli (0-100 Hz) provided they were active. Furthermore, the evoked responses were inverted on either side of the neck, consistent with a coordinated contribution of all left-right muscle pairs acting as antagonists in response to the electrically-evoked vestibular error of head motion. Overall, our results suggest that, as previously observed in cat neck muscles, broad connections exist between the human vestibular system and neck motoneurons and highlight the need for future investigations to establish their neural connections

Trunk muscle recruitment patterns in simulated precrash events

Objectives: To quantify trunk muscle activation levels during whole body accelerations that simulate precrash events in multiple directions and to identify recruitment patterns for the development of active human body models. Methods: Four subjects (1 female, 3 males) were accelerated at 0.55\ua0g (net Δv = 4.0\ua0m/s) in 8 directions while seated on a sled-mounted car seat to simulate a precrash pulse. Electromyographic (EMG) activity in 4 trunk muscles was measured using wire electrodes inserted into the left rectus abdominis, internal oblique, iliocostalis, and multifidus muscles at the L2–L3 level. Muscle activity evoked by the perturbations was normalized by each muscle\u27s isometric maximum voluntary contraction (MVC) activity. Spatial tuning curves were plotted at 150, 300, and 600\ua0ms after acceleration onset. Results: EMG activity remained below 40% MVC for the three time points for most directions. At the 150- and 300\ua0 ms time points, the highest EMG amplitudes were observed during perturbations to the left (–90\ub0) and left rearward (–135\ub0). EMG activity diminished by 600\ua0ms for the anterior muscles, but not for the posterior muscles. Conclusions: These preliminary results suggest that trunk muscle activity may be directionally tuned at the acceleration level tested here. Although data from more subjects are needed, these preliminary data support the development of modeled trunk muscle recruitment strategies in active human body models that predict occupant responses in precrash scenarios

Research priorities in the field of posttraumatic pain and disability: Results of a transdisciplinary consensus-generating workshop

© Copyright 2016 David M.Walton et al. Background. Chronic or persistent pain and disability following noncatastrophic \u27musculoskeletal\u27 (MSK) trauma is a pervasive public health problem. Recent intervention trials have provided little evidence of benefit from several specific treatments for preventing chronic problems. Such findings may appear to argue against formal targeted intervention for MSK traumas. However, these negative findings may reflect a lack of understanding of the causal mechanisms underlying the transition from acute to chronic pain, rendering informed and objective treatment decisions difficult. The Canadian Institutes of Health Research (CIHR) Institute ofMusculoskeletalHealth and Arthritis (IMHA) has recently identified better understanding of causalmechanisms as one of three priority foci of their most recent strategic plan. Objectives. A 2-day invitation-only active participation workshop was held inMarch 2015 that included 30 academics, clinicians, and consumers with the purpose of identifying consensus research priorities in the field of trauma-relatedMSK pain and disability, prediction, and prevention. Methods. Conversations were recorded, explored thematically, and member-checked for accuracy. Results. From the discussions, 13 themes were generated that ranged from a focus on identifying causal mechanisms and models to challenges with funding and patient engagement. Discussion. Novel priorities included the inclusion of consumer groups in research from the early conceptualization and design stages and interdisciplinary longitudinal studies that include evaluation of integrated phenotypes and mechanisms

The influence of perturbation amplitude awareness on the reflex neck muscle response of seated subjects

The muscle and kinematic responses of subjects exposed to postural perturbations have been shown to vary with platform acceleration when this acceleration was covaried with platform velocity or displacement. The purpose of the current study was to isolate platform acceleration and examine its effect on the neck muscle response and head kinematics of seated subjects exposed to anterior perturbations. Thirty-six subjects (20 females, 16 males) underwent two blocks of 36 perturbations. Three different perturbations with peak accelerations of 7.7, 14.7, and 21.7 m/s2 up to a common velocity of 0.5 m/s were used. In one block, subjects received an audible warning corresponding to the platform acceleration magnitude, and in the other block, no advance warning was given. Onset and amplitude of the sternocleidomastoid and cervical paraspinal muscle responses were measured using surface electromyography. Kinematic measures included linear and angular accelerations and displacements of the head. The results showed no differences in either the preperturbation posture or the muscle or kinematic responses between the warned and unwarned trials. Significant differences were observed in the onset and amplitude of the muscle and kinematic variables with perturbation acceleration, although these response differences were not linearly graded with perturbation acceleration. Gradation of muscle activation times has not been previously observed in postural perturbation studies, and their gradation with platform acceleration in the current study suggested that platform acceleration was a strong regulator of the reflex muscle response in postural perturbations

Motion of the Head and Neck of Female and Male Volunteers in Rear Impact Car-to-Car Tests at 4 and 8 km/h

ABSTRACT In this study indications of differences in motion pattern of females and males have been found. The objective was to quantify dynamic motion responses of female and male volunteers in rear impact tests. Such data can be used as an input in the development process of improved occupant models such as computational models and crash test dummies. High-speed video data from rear impact tests at 4 km/h and 8 km/h with 12 female and 11 male volunteers was analysed. The females in this study had smaller rearward horizontal and angular motions of the head and T1 compared to the males. Furthermore, the females had more pronounced rebound motion