Head Retraction Research Articles

Unsupervised machine learning for clustering forward head posture, protraction and retraction movement patterns based on craniocervical angle data in individuals with nonspecific neck pain

ObjectivesThe traditional understanding of craniocervical alignment emphasizes specific anatomical landmarks. However, recent research has challenged the reliance on forward head posture as the primary diagnostic criterion for neck pain. An advanced relationship exists between neck pain and craniocervical alignment, which requires a deeper exploration of diverse postures and movement patterns using advanced techniques, such as clustering analysis. We aimed to explore the complex relationship between craniocervical alignment, and neck pain and to categorize alignment patterns in individuals with nonspecific neck pain using the K-means algorithm.MethodsThis study included 229 office workers with nonspecific neck pain who applied unsupervised machine learning techniques. The craniocervical angles (CCA) during rest, protraction, and retraction were measured using two-dimensional video analysis, and neck pain severity was assessed using the Northwick Park Neck Pain Questionnaire (NPQ). CCA during sitting upright in a comfortable position was assessed to evaluate the resting CCA. The average of midpoints between repeated protraction and retraction measures was considered as the midpoint CCA. The K-means algorithm helped categorize participants into alignment clusters based on age, sex and CCA data.ResultsWe found no significant correlation between NPQ scores and CCA data, challenging the traditional understanding of neck pain and alignment. We observed a significant difference in age (F = 140.14, p < 0.001), NPQ total score (F = 115.83, p < 0.001), resting CCA (F = 79.22, p < 0.001), CCA during protraction (F = 33.98, p < 0.001), CCA during retraction (F = 40.40, p < 0.001), and midpoint CCA (F = 66.92, p < 0.001) among the three clusters and healthy controls. Cluster 1 was characterized by the lowest resting and midpoint CCA, and CCA during pro- and -retraction, indicating a significant forward head posture and a pattern of retraction restriction. Cluster 2, the oldest group, showed CCA measurements similar to healthy controls, yet reported the highest NPQ scores. Cluster 3 exhibited the highest CCA during protraction and retraction, suggesting a limitation in protraction movement.DiscussionAnalyzing 229 office workers, three distinct alignment patterns were identified, each with unique postural characteristics; therefore, treatments addressing posture should be individualized and not generalized across the population.

Measurement proprieties of the CROM instrument for assessing head posture, neck retraction and protraction

BackgroundThe CROM instrument is widely used clinically and in research to measure neck range of motion. However, its measurement proprieties during the assessment of protraction and retraction movements were not examined so far. ObjectiveTo analyse the intra- and inter-rater reliability, the concurrent validity of the CROM for measuring head posture, retraction and protraction in healthy subjects. MethodsThirty-three asymptomatic subjects were recruited and assigned in a random order to one of two raters. After a 10-min break, they were examined by a second rater (Assessment 1). After a 30-min break, both raters repeated the examination (Assessment 2). The examination consisted of measuring the head posture, maximum head protraction and maximum retraction. Each movement was repeated 3 times and measured simultaneously with the CROM and with a 3D capture system laboratory. ResultsThe intra-rater reliability of the CROM was excellent for both raters for head posture and all head movements (ICC>0.9, 95% CI: 0.82–0.99, p < 0.01). The inter-rater reliability was excellent for head posture (ICC>0.95, 95% CI: 0.92–0.98, p < 0.01) and good-to-excellent for all movements at both time-points (ICC = 0.73–0.98, 95%CI: 0.45–0.99, p < 0.01). The validity analysis showed moderate-to-strong correlation between instruments for the head posture and head movements [(r) = -0.47 to −0.78), 95% CI: 0.99 to −0.24, p < 0.01]. ConclusionThe CROM instrument has good-to-excellent reliability and adequate validity for measuring cervical position and displacement in the sagittal plane.

Flexed elbow, abducted shoulder, forearm supinated (FABS) reconstruction from three-dimensional elbow MRI: diagnostic performance assessment in biceps head anatomy and pathology

To determine inter-reader analysis and diagnostic performance on digitally reconstructed virtual flexed, abducted, supinated (FABS) imaging from three-dimensional (3D) isotropic elbow magnetic resonance imaging (MRI). Six musculoskeletal radiologists independently evaluated elbow MRI images with virtual FABS reconstructions, blinded to clinical findings and final diagnoses. Each radiologist recorded a binary result as to whether the tendon was intact and if both heads were visible, along with a categorical value to the type of tear and extent of retraction in centimetres where applicable. Kappa and interclass correlation (ICC) were reported with 95% confidence intervals. Areas under the receiver operating curve (AUC) were reported. FABS reconstructions were obtained successfully in all 48 cases. With respect to tendon intactness, visibility of both heads, and type of tear, the Kappa values were 0.66 (0.53-0.78), 0.24 (0.12-0.37), and 0.55 (0.43-0.66), respectively. For the extent of retraction, the ICC was 0.85 (0.79-0.91) when including the tendons with and without retraction and 0.78 (0.61-0.91) when only including tendons with retraction. For tear versus no tear, AUC values were 0.82 (0.74-0.89) to 0.96 (0.91-1.01). Digital reconstruction of FABS positioning is feasible and allows good assessment of individual tendon head tears and retraction with high diagnostic performance.

General Anesthesia in Red-footed Tortoise (Chelonoides carbonaria) for Gastric Foreign Body Removal

Background: The anatomical, physiological, and pharmacological characteristics of reptiles make anesthesia in chelonians particularly challenging. Specific literature regarding safe anesthetic protocols that provide immobilization, antinociception, amnesia, and unconsciousness are scarce. Thus, this paper aims to report the case of a red-footed tortoise submitted to long-duration general anesthesia to celiotomy for foreign body removal. Case: An adult red-footed tortoise (Chelonoides carbonaria), 5.9 kg, was admitted due to hyporexia after ingesting a metallic fishhook. Serial radiographs confirmed the diagnosis and location of the foreign body in the stomach. The animal was premedicated with 0.03 mg/kg dexmedetomidine, 6 mg/kg ketamine, and 0.4 mg/kg butorphanol intramuscularly. After 90 min we inserted a 22G jugular catheter and proceeded to anesthesia induction with 5 mg/kg propofol. We intubated the animal with a 2.5 mm uncuffed endotracheal and started fluid therapy at a rate of 5 mL/kg/h. Surgical anesthesia was maintained with isoflurane in 0.21 oxygen, in a non-rebreathing circuit (baraka), under spontaneous breathing. Expired isoflurane was maintained between 3 and 4.5%. Due to reduced respiratory rate and hypercapnia, we opted for implementing manually-assisted positive pressure ventilation. Morphine (0.5 mg/kg) was administered at 10 and 87 min after the beginning of the surgery for further analgesia when the isoflurane requirement increased significantly. We did not detect any alterations in heart and body temperature. Surgical anesthesia lasted 6 h. During anesthesia recovery, voluntary head retraction and coordinated movement of the limbs occurred at 240 and 540 min after the extubation, respectively. In 2 days, the patient returned to voluntary feeding, being very active and responsive to stimulus. The post-surgical hematologic evaluation was unremarkable. Discussion: Pre-anesthetic medication aimed to promote sedation and preemptive analgesia. Due to its minimal cardiorespiratory depression, we chose the combination of ketamine, dexmedetomidine, and butorphanol. Dexmedetomidine reduced the ketamine dose and caused sufficient muscle relaxation and immobilization to perform the jugular catheter placement. Butorphanol is an agonist-antagonist opioid; that is why we decided to add it to the protocol for antinociception. However, due to signs of nociceptive response (increased isoflurane requirements and heart rate), and considering the evidence of a predominance of μ receptors in reptiles, we administered low-dose morphine twice during the procedure. Propofol was chosen as an induction agent at a dose sufficient to allow endotracheal intubation. Since reptilians often show apnea in the presence of 100% oxygen, we used a 0.21 oxygen fraction. Despite this, the patient showed respiratory depression. Due to right to left cardiac shunt, sudden changes in the direction of the blood can lead to very rapid changes in the serum concentrations of isoflurane, which leads to frequent oscillations in the anesthetic depth and consequently the need for vaporizer adjustments, which may justify the high expired isoflurane fraction during the procedure. Despite that, physiological parameters were maintained within normal ranges for the species, with slight variations during the surgical procedure. We conclude that the proposed anesthetic protocol is safe for long-duration anesthesia in chelonians, ensuring cardiovascular and respiratory stability. Thus, this report may help veterinarians to perform safe anesthesia in tortoises submitted to invasive surgical procedures. Keywords: testudines, dexmedetomidine, ketamine, butorphanol. Descritores: testudines, dexmedetomidina, cetamina, butorfanol.

Behavioural and physiological responses to simulated predator-induced stress in the eastern box turtle, Terrapene carolina carolina

Abstract In spite of the fully-hinged shell being the defining characteristic of box turtles, few studies have quantified the behavioural use of the shell in response to predator encounters. While it is often assumed that box turtles simply withdraw into their shell in response to threats, we expected variability among individuals in shell usage and in the degree of head and limb retraction because withdrawal is likely to be costly. We tested the behavioural and physiological responses of free-ranging eastern box turtles to stimuli of varying intensity: observation only, a visual stimulus, a poke on the leg, or a pinch on the leg before being flipped. The more intense the simulated predatory stimulus, the more likely turtles were to fully close their shell. However, stimulus intensity did not affect plasma corticosterone or lactate levels. This may be due to too brief or weak of a stimulus, increased parasympathetic activity, or seasonal effects. Upon capture and during handling, almost all turtles withdrew into their shells and closed their anterior plastron, although fewer closed their posterior plastron, and a few engaged in other behaviours such as biting and urinating. Older, larger turtles were able to close their shells with greater strength than younger and smaller turtles. Our results indicate that in spite of their fully closable shell, box turtles exhibit a graded response to perceived threats. This suggests that full closure of the shell is likely to be costly and occurs only in response to the most intense stimuli.

A comparison of anti-whiplash seats during low/moderate speed rear-end collisions

Objectives: The Insurance Institute for Highway Safety (IIHS) rates automotive seats as good, acceptable, marginal, and poor on their abilities to prevent whiplash injuries during rear-end collisions. The goal of this study was to compare the performance of some good- and poor-rated seats at speed changes below 16 km/h where some whiplash injuries occur.Methods: A BioRID II anthropometric test device (ATD) underwent rear-end collisions from 2 to 14 km/h while seated on one of two Volvo Whiplash Prevention seats (WHIPS), a Saab Active Head Restraint seat (SAHR), or a General Motors High Retention seat (GMHR). The WHIPS and SAHR seats were rated good whereas the GMHR seat was rated poor by the IIHS. The ATD’s kinematics, kinetics and three neck injury criteria were evaluated across the range of collision severities.Results: Most of the head and torso kinematics, kinetics and injury criteria exhibited graded responses with increasing collision severities. Only head extension angle remained relatively similar across all speed changes. Differences between the good- and poor-rated seats were most apparent in the upper neck loads and moments, and head retraction for speed changes greater than 6 km/h.Conclusions: The relatively similar occupant responses across all seats could explain the marginal reductions in whiplash injury risk between good- and poor-rated seats in field studies. Further research into the design of anti-whiplash devices is required to better understand the link between occupant response and injury, and to better mitigate the risk of whiplash injuries during rear-end collisions.

Face-making: task-specific facial tensions and grimacing in musicians

> I have been told that my facial expressions while playing are quite pronounced, and numerous audience members have asked me what in the world I am saying to myself...

Classical conditioning in earthworms employing an odorous conditioned stimulus

The study of associative learning in invertebrates has become an essential tool for exploring their cognitive abilities and for studying the biological bases of learning and memory. In this experiment with earthworms, we paired a rose odour conditioned stimulus (CS) with a bright light unconditioned stimulus (US). After these pairings, the head retraction response — which is initially elicited by the bright light — is eventually evoked by the rose odour. This is the first demonstration of classical conditioning of an odour in earthworms (vibrations are usually employed as CSs), using a procedure that enables us to rule out an explanation in terms of pseudoconditioning.

A Neonate with Exaggerated Startle and Tonic Spasms

AbstractHyperekplexia is a rare, potentially treatable inherited disorder of glycinergic neurotransmission, which is characterized by neonatal onset exaggerated startle response to somatosensory, auditory stimuli, and episodic tonic spasm. Prolonged tonic spasms can be life-threatening and associated with apnea and bradycardia. Awareness about this condition avoids misdiagnosis such as tonic seizures and epilepsy. We describe a term newborn with episodic tonic stiffness mistaken for seizures. Classical exaggerated startle reaction, positive head retraction response to glabellar tap, and characteristic video electroencephalogram confirmed the diagnosis.

Glia Modulate a Neuronal Circuit for Locomotion Suppression during Sleep in C. elegans

SUMMARYGlia have been suggested to regulate sleep-like states in vertebrates and invertebrates alike. In the nematode Caenorhabditis elegans, sleep is associated with molting between larval stages. To understand if glia modulate neural circuits driving sleep in C. elegans larvae, we ablated the astrocyte-like CEPsh glia. We found that glia-ablated animals exhibit episodes of immobility preceding sleep, prolonged sleep, molting-independent short-duration locomotory pausing, and delayed development. CEPsh glia ensheath synapses between the sleep-associated ALA neuron and its postsynaptic partner AVE, a major locomotion interneuron. While AVE calcium transients normally correlate with head retraction, glia ablation results in prolonged calcium transients that are uncoupled from movement. Strikingly, all these glia ablation defects are suppressed by the ablation of ALA. Our results suggest that glia attenuate sleep-promoting inhibitory connections between ALA and AVE, uncovering specific roles for glia in sleep behavior. We propose that similar mechanisms may underlie glial roles in sleep in other animals.

What are the anatomical predictive factors of degenerative superior labrum anterior to posterior lesion in rotator cuff tear?

The purpose of this study was to evaluate the influence of anatomical factors degenerative superior labrum anterior to posterior lesion in rotator cuff tear. The study included 421 middle-aged patients treated using arthroscopic surgery for rotator cuff tears. Patients were divided into two groups based on the superior labrum anterior-to-posterior (SLAP). Glenoid inclination, glenoid length, humeral head diameter, acromio-humeral distance (AHD) head-glenoid difference (HGD), head glenoid angle (HGA), size and retraction of rotator cuff tears were evaluated in both groups. In conclusion, a HGD exceeding 10mm could be anatomically predictive of degenerative SLAP.Level of evidence: Case series, Level IV.

Side-necked Versus Hidden-necked: A Comparison of Shell Morphology Between Pleurodiran and Cryptodiran Turtles

Abstract: This study explores the potential morphological differences between pleurodiran and cryptodiran turtle shells. Pleurodires (Suborder Pleurodira), as suggested by their name, retract their heads into the shell by bending the neck to the side; this is different from cryptodires (Suborder Cryptodira), which withdraw their necks along a sagittal plane. Pleurodires also have evolved a unique pelvic morphology typified by two columnar pelvic elements sutured to both the carapace and plastron; in contrast, the pelvic girdle in cryptodires is loosely connected to the shell. These differences might put very different selective pressures on shell shape in these animals: The different head retraction strategies in the two groups could lead pleurodires to evolve wider and flatter anterior apertures while the differences in pelvic structure might permit the evolution of flatter carapaces (particularly in the posterior carapace) and narrower bridges as compared to cryptodires. We used 3D landmark data to char...

Inverse Relationship between Biting and Head Retraction in an Ontogenetic Series of Sonoran Mud Turtles (Kinosternon sonoriense)

Abstract The propensity for defensive biting in turtles should vary ontogenetically. In species with plastral kinesis, the effectiveness of retraction into the shell as a defensive mechanism increases with body size. Therefore, adults should be less likely to bite and more likely to retract than are juveniles. We tested this hypothesis by measuring biting propensity and retraction propensity from an ontogenetic series of Kinosternon sonoriense (Sonora Mud Turtle), a species with plastral kinesis. As predicted, biting in K. sonoriense was restricted to younger, smaller turtles, whereas capacity for retraction was restricted to older, larger turtles.

Modular organization of the head retraction responses elicited by electrical painful stimulation of the facial skin in humans

ObjectiveTo explore whether the trigeminocervical reflexes (TCRs) show a reflex receptive field organization in the brainstem. MethodsThe facial skin of 16 healthy subjects was electrically stimulated at nine sites reflecting the distribution of the three branches of the trigeminal nerve. The reflex-evoked EMG responses were measured bilaterally from the neck muscles and the head and neck kinematic reactions were detected. ResultsTCRs are site dependent. There was a vertical gradient in the magnitude of the reflex responses. EMG and kinematic reflexes were larger when evoked from ophthalmic and maxillary sites than from mandibular ones. The reflex responses exhibited a crossed right–left behavior. Stimulation of the lateral sites evoked larger reflex responses in the contralateral trapezium muscle as well as head rotation and neck bending away from the stimulated side. ConclusionThis modular arrangement of the TCRs seems to be related to withdrawal strategies aimed at protecting the face from injuries, in accordance with the functional role that each group of muscles plays in head and neck motion. SignificanceIt is likely that the CNS may exploit the neck muscle synergies revealed by the painful stimulation of the skin face in order to control the head and neck movements.

A primitive heron (Aves: Ardeidae) from the Miocene of Central Asia

A robust quadrate from the Middle Miocene of Mongolia represents a new genus of Ardeidae that combines the similarities to Nycticorax and Tigrisoma, both of which have been recovered in basal positions in recent phylogenies of the Ardeidae, and to cf. Pikaihao from the Middle Miocene of Africa. The confluence of mandibular facets on the medial condyle and pterygoid condyle in the new genus, Nycticorax, and cf. Pikaihao is likely to be symplesiomorphic, as it is shared with nearly all other waterbirds (except for the Ciconiidae), including the immediate outgroup (Threskiornithidae). However, the medial supraorbital crest is a likely synapomorphy of the new genus and cf. Pikaihao. The similarities to Trigrisoma support its basal position, as recovered from molecular sequences and proposed by a pre-cladistic morphological analysis. Since both the night herons and Tigrisoma have heads that are proportionally much larger than those of the large day herons, it appears that the Ardeidae started their evolution with relatively heavy heads, which may have contributed to the origins of the family-specific head retraction in flight.

Cloacal swab sampling is a reliable and harmless source of DNA for population and forensic genetics in tortoises

Testudo graeca, Testudo hermanni and Testudo marginata are endangered species listed in the IUCN Red List and Appendix II of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES). Correct identification of species and distinct population units can support sound conservation projects and forensic applications. However, the collection of biological samples is not always easy or harmless. Blood sampling is usually invasive and risky. Salivary swab sampling is commonly used in other reptiles but can be unsafe for tortoises by the reason of their head retraction escape response. Cloacal swab sampling should be easier and less risky. In this study, we genotyped 37 tortoises at eight microsatellite loci and compared the reliability of individual genotypes obtained from blood, cloacal and buccal swabs. Results showed that performances of cloacal samples are comparable with those of buccal and blood samples, and proved that cloacal sampling is an alternative and reliable source of DNA for tortoise genotyping.

Modeling length-tension properties of RCPm muscles during voluntary retraction of the head

Head retraction exercises are one of several commonly used clinical tools that are used to assess and treat patients with head and neck pain and to aid in restoration of a normal neutral head posture. Retraction of the head results in flexion of the occipitoatlantal (OA) joint and stretching of rectus capitis posterior minor (RCPm) muscles. The role that retraction of the head might have in treating head and neck pain patients is currently unknown.RCPm muscles arise from the posterior tubercle of the posterior arch of C1 and insert into the occipital bone inferior to the inferior nuchal line and lateral to the midline. RCPm muscles are the only muscles that attach to the posterior arch of C1. The functional role of RCPm muscles has not been clearly defined.The goal of this project was to develop a three-dimensional, computer-based biomechanical model of the posterior aspect of the OA joint. This model should help clarify why voluntary head retraction exercises seem to contribute to the resolution of head and neck pain and restoration of a normal head posture in some patients.The model documents that length-tension properties of RCPm muscles are significantly affected by variations in the physical properties of the musculotendonous unit. The model suggests that variations in the cross sectional area of RCPm muscles due to pathologies that weaken the muscle, such as muscle atrophy, may reduce the ability of these muscles to generate levels of force that are necessary for the performance of normal, daily activities. The model suggests that the main benefit of the initial phase of head retraction exercises may be to strengthen RCPm muscles through eccentric contractions, and that the main benefit of the final phase of retraction may be to stretch the muscles as the final position is held.

Muscle Pathologies After Cervical Spine Distortion-Like Exposure—A Porcine Model

Objective: Histological evaluation of porcine posterior cervical muscles after a forceful translational and extensional head retraction simulating high-speed rear end impact. Methods: Four anesthetized pigs were exposed to a cervical spine distortion (CSD)-like motion in a lying position. After 2 different survival times of 4 and 6 h (posttrauma), the pigs were euthanized and tissue sampling of posterior cervical muscles was performed. A standard histological staining method involving paraffin-embedded sections was used to analyze the muscles, focusing on injury signs like hemorrhage and inflammatory cell reaction. A pig that was not subjected to impact was used as a control pig and was subjected to the same procedure to exclude any potential artifacts from the autopsy. Results: The differentiation of 8 different posterior neck muscles in the dissection process was successful in more than 50 percent for each muscle of interest. Staining and valid analysis was possible from all extracted samples. Muscle injuries to the deepest posterior neck muscles could be found, especially in the musculus obliquus samples, which showed laminar bleedings in 4 out of 4 samples. In addition, in 4 out of 4 samples we were able to see increased cellular reactions. The splenius muscle also showed bleeding in all 4 samples. All animals showed muscle injury signs in more than three quarters of analyzed neck muscles. Differences between survival times of 4 and 6 h in terms of muscular injury were not of primary interest and could not be found. Conclusions: By simulating a CSD-like motion we were able to confirm injuries in the posterior cervical muscles under severe loading conditions. Further studies need to be conducted to determine whether these muscle injuries also occur under lower exposure forces. Supplemental materials are available for this article. Go to the publisher's online edition of Traffic Injury Prevention to view the supplemental file.

The startle response during whiplash: a protective or harmful response?

Whiplash injuries are common following rear-end collisions. During such collisions, initially relaxed occupants exhibit brisk, stereotypical muscle responses consisting of postural and startle responses that may contribute to the injury. Using prestimulus inhibition, we sought to determine if the startle response elicited during a rear-end collision contributes to head stabilization or represents a potentially harmful overreaction of the body. Three experiments were performed. In the first two experiments, two groups of 14 subjects were exposed to loud tones (124 dB) preceded by prestimulus tones at either four interstimulus intervals (100-1,000 ms) or five prestimulus intensities (80-124 dB). On the basis of the results of the first two experiments, 20 subjects were exposed to a simulated rear-end collision (peak sled acceleration = 2 g; speed change = 0.75 m/s) preceded by one of the following: no prestimulus tone, a weak tone (85 dB), or a loud tone (105 dB). The prestimulus tones were presented 250 ms before sled acceleration onset. The loud prestimulus tone decreased the amplitude of the sternocleidomastoid (16%) and cervical paraspinal (29%) muscles, and key peak kinematics: head retraction (17%), horizontal head acceleration (23%), and head angular acceleration in extension (23%). No changes in muscle amplitude or kinematics occurred for the weak prestimulus. The reduced muscle and kinematic responses observed with loud tones suggest that the startle response represents an overreaction that increases the kinematics in a way that potentially increases the forces and strains in the neck tissues. We propose that minimizing this overreaction during a car collision may decrease the risk of whiplash injuries.

Reliability of Measuring the Cervical Sagittal Translation Mobility with a Simple Method in a Clinical Setting

Introduction. The cervical sagittal translation mobility is related to neck pain. A practical method for measuring the specific cervical mobility is needed. The aim was to describe a simple method for measuring the cervical sagittal translation mobility and to evaluate its reliability in a clinical setting. Method. The head protraction and retraction ranges of thirty healthy seated subjects were measured from a dorsal reference plane by two physiotherapists utilizing a tape measure. A standard inclinometer/goniometer was used to minimize angular movements of the head during the translational movements. The measurements were made twice for each subject with a two-hours interval between each measurement. The inter-rater and intra-rater agreements were evaluated with intraclass correlation coefficients (ICCs) and with the distribution of the difference of the measurements. The systematic differences were analysed with the Wilcoxon signed rank test. Results. The intra-rater agreement was good. The inter-rater agreement was moderate in the first measurement and good in the second. A systematic difference was noted between raters in the first measurement but not in the second, possibly indicating a learning effect. Discussion. The method used in the study is simple and reliable and can be recommended for clinical use.