Head-neck Segment Research Articles

Latex vascular injection as method for enhanced neurosurgical training and skills.

Tridimensional medical knowledge of human anatomy is a key step in the undergraduate and postgraduate medical education, especially in surgical fields. Training simulation before real surgical procedures is necessary to develop clinical competences and to minimize surgical complications. Latex injection of vascular system in brain and in head-neck segment is made after washing out of the vascular system and fixation of the specimen before and after latex injection. Using this latex injection technique, the vascular system of 90% of brains and 80% of head-neck segments are well-perfused. Latex-injected vessels maintain real appearance compared to silicone, and more flexible vessels compared to resins. Besides, latex makes possible a better perfusion of small vessels. Latex vascular injection technique of the brain and head-neck segment is a simulation model for neurosurgical training based on real experiencing to improve surgical skills and surgical results.

Age-Related Change of Head Control in Response to Postural Perturbations

<h3>Research Objectives</h3> To explore if older adults, particularly those over 75 years, have more zero-crossings to restore head stabilization than young adults after postural perturbations. <h3>Design</h3> Cross-sectional study. <h3>Setting</h3> Laboratory setting. <h3>Participants</h3> A convenient sample of 57 healthy participants without a current or past history of neck-related dysfunction, trauma, deformities, and uncontrolled balance issues were recruited. They were grouped by age: Young (18-30 yrs, age: 22.3±3.8), Young-Old (60-74 yrs, age: 67.2±3.8), and Old-Old (>75+ yrs, age: 81.1±5.3). <h3>Interventions</h3> Not applicable. <h3>Main Outcome Measures</h3> Accelerometers (Delsys) were attached on the forehead and C7 of participants as they experienced the unexpected platform translations (Neurocom). A total of six trials were performed in random order including three anterior and posterior perturbations. The linear head acceleration in the vertical, anteroposterior, and mediolateral axis were extracted. A custom Matlab code computed the resultant head acceleration, detected the head re-stabilization time of each trail, and determined the number of zero-crossings during the head re-stabilization of three axes. <h3>Results</h3> Significant less zero-crossings in the Young group were noted in the vertical (p = 0.011, η2 = 0.07) and AP (p = 0.030, η2 = 0.05) axes of posterior platform translation. Despite no statistical differences found in other conditions, a trend of increased zero-crossing with aging was suggested. The Old-Old group consistently showed the greatest number of zero-crossings across all the conditions. <h3>Conclusions</h3> Older adults appear to recruit a different head stabilization strategy in response to postural perturbations. The oldest age group (over 75 years) seems to show more vigorous neuromuscular control to restore the postural stabilization in the head-neck segment after the perturbation than the younger counterparts. <h3>Author(s) Disclosures</h3> Authors declared that none of us had relevant or material financial interests that relate to the research described in this research project.

Sex Differences in Neck Strength Force and Activation Patterns in Collegiate Contact Sport.

The purpose of this study was to assess changes in cervical musculature throughout contact-heavy collegiate ice hockey practices during a regular season of NCAA Division III ice hockey teams. In this cross-sectional study, 36 (male n = 13; female n = 23) ice hockey players participated. Data were collected over 3 testing sessions (baseline; pre-practice; post-practice). Neck circumference, neck length, head-neck segment length, isometric strength and electromyography (EMG) activity for flexion and extension were assessed. Assessments were completed approximately 1h before a contact-heavy practice and 15 min after practice. For sternocleidomastoid (SCM) muscles, males had significantly greater peak force and greater time to peak force versus females. For both left and right SCMs, both sexes had significantly greater peak EMG activity pre-practice versus baseline, and right (dominant side) SCM time to peak EMG activity was decreased post-practice compared to pre-practice. There were no significant differences for EMG activity of the upper trapezius musculature, over time or between sexes. Sex differences observed in SCM force and activation patterns of the dominant side SCM may contribute to head stabilization during head impacts. Our study is the first investigation to report changes in cervical muscle strength in men's and women's ice hockey players in the practical setting.

Mapping of Vertical Femoral Neck Fractures in Young Patients Using Advanced 2 and 3-Dimensional Computed Tomography.

To better describe the pathoanatomy of young patients' femoral neck fractures with the goal of improving surgeons' decisions for treatment including reduction and fixation. This is a retrospective study of patient records, plain radiographs, and the modern computed tomography scans to study the pathoanatomy of Pauwels II and III femoral neck fractures (coronal angle >30 degrees) in young adults. One American College of Surgeons Level 1 trauma center. All patients 18-49 years of age with a surgically repaired Pauwels' II and III (>30 degrees) femoral neck fracture between 2013 and 2017. Fifty-six adult patients younger than 50 years were identified with a femoral neck fracture in the study period, of whom 30 met study criteria. We evaluated plain radiography and computed tomography data including fracture orientation, characteristics of fracture morphology including size, shape, and dimensions, comminution, displacement, and deformity. Fracture morphology typically included a wide-based caudal head-neck segment (80%) that ends at a variable location along the medial calcar, sometimes as caudal as the lesser trochanter. Comminution was present in 90% of cases mostly located in the inferior quadrant, but anterior or posterior to the void left by the head-neck's caudal segment. The fractures orientations and deformities were reported by means and ranges. We investigated and reported on the pathoanatomy of high-energy femoral neck fractures in young adults with the goal of increasing understanding of the injury and improving surgeons' ability to provide for improved treatment decisions and quality fracture repair. Diagnostic Level IV. See Instructions for Authors for a complete description of levels of evidence.

COMPARISON OF NECK MUSCLE ELECTROMYOGRAPHY ACTIVITY IN RESPONSE TO EXTERNAL FORCE BETWEEN STATIC AND DYNAMIC LOADING

Understanding the behavior of neck muscles is essential to accurately simulate the human head-neck segment movement especially for low-speed motor vehicle crash situation. Some head-neck mathematical models were designed using neck muscle activation behavior in isometric contraction (static loading) as the properties of neck muscle activation. However, neck muscle activation pattern and strength capability may vary between static and dynamic loading. This study aimed to determine the differences between neck muscle activation level under static and dynamic loading. A neck strength test involving 22 human volunteers was conducted with two different tasks in extension and flexion direction with three different loads. The neck muscle activation level is determined through measuring the electromyography (EMG) responses of selected flexor and extensor muscles using surface bilateral electrode and recorded. The findings showed that neck muscle activation level was significantly greater in dynamic loading than static loading ([Formula: see text]). These implied that more efforts from neck muscles were required to resist against dynamic loading than static loading. Nonetheless, the differences in EMG activities between these two loading conditions progressively decreased when more loads were applied. This study has established an empirical model to describe the relationship between neck muscle activation level and force output for both loading condition in flexion and extension.

Sex Differences in the Clinical Incidence of Concussions, Missed School Days, and Time Loss in High School Student-Athletes: Part 1

Background: Sports-related concussion (SRC) injury rates are well established in collegiate athletics through epidemiological studies using the National Collegiate Athletic Association Injury Surveillance System. However, few studies have examined sex differences, time loss, and missed school days in high school athletes, especially at the state level. Purpose: To identify sex differences in the clinical incidence of SRCs, missed school days, and time loss in high school student-athletes. Study Design: Descriptive epidemiological study. Methods: A total of 193,757 (116,434 male and 77,323 female) student-athletes (10th grade ± 1.1) participating in Michigan High School Athletic Association (MHSAA)–sponsored athletic activities were recorded in the Head Injury Reporting System. Certified athletic trainers, school athletic administrators, and coaches from MHSAA high schools reported SRC data and overall participation for the 2015-2016 academic year. Total concussive injuries, as well as missed school days and time loss for each concussive injury, were reported. The clinical incidence was calculated by dividing the number of SRCs in a particular category by the number of participants in that category and presented with 95% CIs. Relative risk ratios (RRs) were determined for sex-comparable sports. Results: The overall clinical incidence for all sports was 1.7 per 100 player-seasons (95% CI, 1.6-1.8) and 1.9 (95% CI, 1.8-2.0) for male sports and 1.5 (95% CI, 1.4-1.6) for female sports. Female athletes were at a 1.9 (95% CI, 1.8-2.2) times greater risk for enduring SRCs than male athletes in sex-comparable sports, with a greater risk in baseball/softball (RR, 2.7 [95% CI, 1.9-3.8]), basketball (RR, 2.5 [95% CI, 2.1-2.9]), and soccer (RR, 1.6 [95% CI, 1.4-1.9]). Female student-athletes had significantly longer time loss than male student-athletes (P < .001). The mean number of missed school days did not differ between sexes (P = .70). Conclusion: High school female student-athletes have a higher risk for an SRC in all sex-comparable sports except lacrosse. This may be because of biomechanical differences of the head-neck segment, hormonal differences, and the fact that female athletes are more likely to report symptoms after a suspected SRC. Clinical Relevance: Despite sex differences in the clinical incidence of SRCs and time loss from participation in high school sports, the numbers of missed school days are relatively similar between sexes.

Sex and age differences in head acceleration during purposeful soccer heading

ABSTRACTDifferences in head–neck segment mass, purposeful heading technique, and cervical strength and stiffness may contribute to differences in head accelerations across sex and age. The purpose of this study was to compare head acceleration across sex and age (youth [12–14 years old], high school and collegiate) during purposeful soccer heading. One-hundred soccer players (42 male, 58 female, 17.1 ± 3.5 years, 168.5 ± 20.3 cm, 61.5 ± 13.7 kg) completed 12 controlled soccer headers at an initial ball velocity of 11.2 m/s. Linear and rotational accelerations were measured using a triaxial accelerometer and gyroscope and were transformed to the head centre-of-mass. A MANOVA revealed a significant multivariate main effect for sex (Pillai’s Trace = .165, F(2,91) = 11.868, p < .001), but not for age (Pillai’s Trace = .033, F(4,182) = 0.646, p = .630). Peak linear and rotational accelerations were higher in females (40.9 ± 13.3 g; 3279 ± 1065 rad/s2) than males (27.6 ± 8.5 g, 2219 ± 823 rad/s2). These data suggest that under controlled soccer heading conditions, females may be exposed to higher head accelerations than males.

Biomechanics of head-neck segment during breakfall motion of various judo-throw techniques

Biomechanics of head-neck segment during breakfall motion of various judo-throw techniques

Sex Differences in Anthropometrics and Heading Kinematics Among Division I Soccer Athletes.

Background:Soccer players head the ball repetitively throughout their careers; this is also a potential mechanism for a concussion. Although not all soccer headers result in a concussion, these subconcussive impacts may impart acceleration, deceleration, and rotational forces on the brain, leaving structural and functional deficits. Stronger neck musculature may reduce head-neck segment kinematics.Hypothesis:The relationship between anthropometrics and soccer heading kinematics will not differ between sexes. The relationship between anthropometrics and soccer heading kinematics will not differ between ball speeds.Study Design:Pilot, cross-sectional design.Level of Evidence:Level 3.Methods:Division I soccer athletes (5 male, 8 female) were assessed for head-neck anthropometric and neck strength measurements in 6 directions (ie, flexion, extension, right and left lateral flexions and rotations). Participants headed the ball 10 times (25 or 40 mph) while wearing an accelerometer secured to their head. Kinematic measurements (ie, linear acceleration and rotational velocity) were recorded at 2 ball speeds.Results:Sex differences were observed in neck girth (t = 5.09, P < 0.001), flexor and left lateral flexor strength (t = 3.006, P = 0.012 and t = 4.182, P = 0.002, respectively), and rotational velocity at both speeds (t = −2.628, P = 0.024 and t = −2.227, P = 0.048). Neck girth had negative correlations with both linear acceleration (r = −0.599, P = 0.031) and rotational velocity at both speeds (r = −0.551, P = 0.012 and r = −0.652, P = 0.016). Also, stronger muscle groups had lower linear accelerations at both speeds (P < 0.05).Conclusion:There was a significant relationship between anthropometrics and soccer heading kinematics for sex and ball speeds.Clinical Relevance:Neck girth and neck strength are factors that may limit head impact kinematics.

Minimizing Head Acceleration in Soccer: A Review of the Literature.

Physicians and healthcare professionals are often asked for recommendations on how to keep athletes safe during contact sports such as soccer. With an increase in concussion awareness and concern about repetitive subconcussion, many parents and athletes are interested in mitigating head acceleration in soccer, so we conducted a literature review on factors that affect head acceleration in soccer. We searched electronic databases and reference lists to find studies using the keywords 'soccer' OR 'football' AND 'head acceleration'. Because of a lack of current research in soccer heading biomechanics, this review was limited to 18 original research studies. Low head-neck segment mass predisposes athletes to high head acceleration, but head-neck-torso alignment during heading and follow-through after contact can be used to decrease head acceleration. Additionally, improvements in symmetric neck flexor and extensor strength and neuromuscular neck stiffness can decrease head acceleration. Head-to-head impacts and unanticipated ball contacts result in the highest head acceleration. Ball contacts at high velocity may also be dangerous. The risk of concussive impacts may be lessened through the use of headgear, but headgear may also cause athletes to play more recklessly because they feel a sense of increased security. Young, but physically capable, athletes should be taught proper heading technique in a controlled setting, using a carefully planned progression of the skill.

Influence of Cervical Muscle Fatigue on Musculo-Tendinous Stiffness of the Head-Neck Segment during Cervical Flexion.

AimThe aim of this study is to determine if the fatigue of cervical muscles has a significant influence on the head-neck segment musculo-tendinous stiffness.MethodsTen men (aged 21.2 ± 1.9 years) performed four quick-release trials of flexion at 30 and 50% MVC before and after the induction of muscular fatigue on cervical flexors. Electromyographic activity was recorded on the sternocleidomastoids (SCM) and spinal erectors (SE), bilaterally. Musculo-tendinous stiffness was calculated through the quick-release method adapted to the head-neck segment.ResultsWe noticed a significant linear increase of the head-neck segment musculo-tendinous stiffness with the increase of exertion level both before (P < 0.0001) and after the fatigue procedure (P < 0.0001). However, this linear relationship was not different before and after the fatigue procedure. EMG analysis revealed a significant increase of the root mean square for the right SCM (P = 0.0002), the left SCM (P < 0.0001), the right SE (P < 0.0001), and the left SE (P < 0.0001) and a significant decrease of the median power frequency only for the right (P = 0.0006) and the left (P = 0.0003) SCM with muscular fatigue.DiscussionWe did not find significant changes in the head-neck segment musculo-tendinous stiffness with fatigue of cervical muscles. We found a significant increase in EMG activity in the SCM and the SE after the induction of fatigue of the SCM. Our findings suggest that with fatigue of cervical flexors, neck muscle activity is modulated in order to maintain the musculo-tendinous stiffness at a steady state.

Musculo-tendinous stiffness of head–neck segment in the sagittal plane: An optimization approach for modeling the cervical spine as a single-joint system

Despite the multi-linked architecture of the cervical spine, all previous studies that have made estimations of mechanical properties of the neck have considered the head–neck segment as a rigid link, with a fixed center of rotation at C7. The aim of this study was to consider the head–neck segment as a changeable geometry system for locating the resultant center of rotation and for calculating the musculo-tendinous stiffness by the quick-release method. Head kinematics during quick-releases was analyzed by recording the trajectory of surface markers. With an optimization procedure, the position of the resultant center of rotation of the head–neck segment was estimated. Thereafter, the angular displacement and acceleration of the head, together with the isometric torque developed by the cervical muscles were used to calculate the segment's stiffness. The results showed a consistent center of rotation and a significant increase of the musculo-tendinous stiffness with increasing torque.

Relationship Between Cervical Spine Injury and Helmet Use in Motorcycle Road Crashes

Motorcycle helmets have been proven to prevent head injury and reduce fatality in road crashes. However, certain studies indicate that the helmet increases the mass to the head, and thus the potential of neck injury due to the flexion/extension of the head-neck segment in a road crash may increase. This study was conducted to evaluate the effects of motorcycle helmets and the ways in which the accidents that occurred affected the incidence of cervical spine injury. Nevertheless, it is not intended to and does not discredit the fact that helmet use prevents many motorcyclists from sustaining serious and fatal head injuries. A total of 76 cases were collected and analyzed based on the data collected from real-world crashes. The Abbreviated Injury Scale (AIS) was used to assess the severity of injury, whereas the statistical Pearson χ(2) correlation method was used for analysis. The results showed that motorcycle helmets did not affect the severity of cervical spine injury. However, when the samples were further subcategorized into different crash modes, it was found that helmets affect the incidence of a severe cervical spine injury. In frontal collisions, the use of helmets significantly reduces the severity of cervical spine injury, whereas in rear-end, side impact, and skidded accidents, the use of helmets increases the probability of a severe cervical spine injury. However, in the latter crash modes, a motorcyclist without a helmet will have to trade-off with head injury. A logistic regression model has been developed with respective crash modes and the probabilities of risk in having severe cervical spine injury have been calculated. Future designs in motorcycle helmets should therefore consider the significance of nonfrontal accidents and the interaction of helmet with other parts of the body by possibly considering the weight of the helmet.

Musculo-tendinous stiffness of the in vivo head-neck segment in response to quick-releases: A reproducibility study

This study was designed to assess the reproducibility of head-neck musculo-tendinous stiffness (HMS) findings of the head-neck segment in response to quick-release in flexion and extension. The HMS was expressed as the slope of the isometric torque-angular displacement curve of the head-neck segment derived from the first 15 ms from the peak acceleration following release at different exertion levels (10% to 80% MVC). A test—retest methodology (7 days interval) was performed to assess the measurement reproducibility. The results showed a linear relationship between the flexion and extension torque and angular displacement (0.94 < R 2 < 0.99). Moreover, HMS findings evidenced good to excellent reproducibility using relative (ICC) as well as absolute (SEM) parameters. It was concluded that that simple kinematic assessment was appropriate for investigating HMS. Nevertheless, multiple-segmentation of the head-neck segment could lead, according to exertion level, to geometrical changes after the release.

Spine virtual traumas under multiple impact situations

The cervical spine segment is a very complex and mobile structure of the human body. Once trauma situation occurs, the head-neck segment is highly loaded leading to severe trauma with a lethal or permanent incapacity risk. Cervical spine was largely studied from its mechanical properties to frontal impact to investigate whiplash mechanisms. For pedestrian, cyclist and motorcyclist accidents, the head-neck segment is loaded under various impact directions. Also, how these impact directions can have an incidence on the injury mechanisms, potential injury and their severity? To answer this question, the finite element simulation using existing dedicated models could be a valuable tool. By simulating frontal, lateral, rear and oblique dynamic loadings on the HUMOS head-neck segment, a first numerical study showed weakness area on the spinal segment whatever the impact condition.

Gender Differences in Head???Neck Segment Dynamic Stabilization during Head Acceleration

Recent epidemiological research has revealed that gender differences exist in concussion incidence but no study has investigated why females may be at greater risk of concussion. Our purpose was to determine whether gender differences existed in head-neck segment kinematic and neuromuscular control variables responses to an external force application with and without neck muscle preactivation. Forty (20 females and 20 males) physically active volunteers participated in the study. The independent variables were gender, force application (known vs unknown), and force direction (forced flexion vs forced extension). The dependent variables were kinematic and EMG variables, head-neck segment stiffness, and head-neck segment flexor and extensor isometric strength. Statistical analyses consisted of multiple multivariate and univariate analyses of variance, follow-up univariate analyses of variance, and t-tests (P < or = 0.05). Gender differences existed in head-neck segment dynamic stabilization during head angular acceleration. Females exhibited significantly greater head-neck segment peak angular acceleration (50%) and displacement (39%) than males despite initiating muscle activity significantly earlier (SCM only) and using a greater percentage of their maximum head-neck segment muscle activity (79% peak activity and 117% muscle activity area). The head-neck segment angular acceleration differences may be because females exhibited significantly less isometric strength (49%), neck girth (30%), and head mass (43%), resulting in lower levels of head-neck segment stiffness (29%). For our subject demographic, the results revealed gender differences in head-neck segment dynamic stabilization during head acceleration in response to an external force application. Females exhibited significantly greater head-neck segment peak angular acceleration and displacement than males despite initiating muscle activity earlier (SCM only) and using a greater percentage of their maximum head-neck segment muscle activity.

A Simplified Model for Head-Neck Segment Fast Movements in the Frontal Plane

The objective of the current work is to develop a simplified model representing the physiological systems acting during fast head movements in frontal plane. All the contributions mechanically concurring to the head movement have been considered: voluntary force generation, viscosity, stiffness, physiological limit to movement range, gravitational field contribution and gamma reflex, depending on spindle activity. Model parameters have been partly derived form literature, when possible, whereas undetermined blocks parameters have been determined by optimising model output correspondence to real data acquired by ELITETM system in specific designed experimental set-ups. The optimisation have been performed by genetic algorithms. Results show that the model studied is very well representing fast head movements in the whole range of inclination in the frontal plane. Such model is, thus, proposed as a tool for transforming kinematics data on head movements in "neural equivalent data", especially for the assessing head control deasease and planning properly the rehabilitation process.

Proximal Femoral Osteotomy

A trigonometric analysis of the effect of a proximal femoral osteotomy, either dome or cuneiform, on leg length was done to aid the preoperative planning for this surgery. Change in leg length may be determined for a dome osteotomy by multiplying the length of the head-neck segment by the difference between the cosines of the preoperative and postoperative neck-shaft angles as measured from the vertical. A series of determinations are tabulated for a variety of head-neck lengths and angulation changes. When a cuneiform osteotomy is being done, the effect of the wedge can be determined and should be considered. Also to be considered are a tendency for spontaneous correction and growth stimulation from the osteotomy.

Immunohistochemical Localization of Antigens in Human Spermatozoa

A high sensitivity indirect immunohistochemical technique was employ ed to study the development and localization of antigenic sites in human sperm during transport through the male genital tract. The technique involved horseradish peroxidase as label and rabbit antibodies against a human testicular protein preparation and against washed testicular and seminal sperm seminal plasma and serum protein fractions. Through complement fixation antibodies crossreacted with the highest titer occurring with antiseminal plasma and the lowest with antitesticular protein fraction. Antiseminal plasma reacted with the acrosome posterior head cap neck and the intermediate segment of seminal sperm. Only acrosome and on occasion the neck of testicular or epididymal sperm showed reactivity. Sperm antiwashed with saline or water reacted only with the acrosome and the neck of seminal sperm though there was slight staining of the acrosome of testicular and epididymal cells. Antitesticular protein fraction reacted with the acrossome and neck of testicular and epididymal sperm though the reaction was less evident with seminal sperm cells. Antiserum proteins especially albumin and gamma globulin selectively stained the acrosome of seminal sperm though testicular and epididymal sperm cells did not show as definite a reaction. The results tend to support the existence of progressive layers of antigenic proteins covering the head neck and intermediate segment of sperm though the presence of intrinsic antigens cannot be discounted until more sophisticated experimental techniques are available.