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Background: Laryngoscopy is a diagnostic procedure utilized in critical care to examine and visualize the larynx through the diversion of upper airway structures. Its primary functions are airway management and tracheal intubation. The objective of this study was to detect the predictors of laryngeal exposure during microlaryngeal surgery (MLS). Methods: An analytical cross-sectional study was conducted on a consecutive sample of 100 patients presenting laryngeal lesions that were trans-orally microsurgeries to treat various glottic diseases (biopsies revealed 68% benign lesions such as vocal fold polyps, cysts, and nodules, and 32% glottic masses) and prepared for MLS. Results: This study included 100 patients presenting laryngeal lesions from both sexes with the age of 47.0 ± 14.7 years, in multivariate logistic regression analysis, all these parameters were significant predictors for Cormack–Lehane and Italian Grading (P < 0.05). Body mass index (BMI) (OR = 3.449, 95% CI = 2.463–8.187), mandibular protrusion test (OR = 2.981, 95% CI = 1.922–4.044), mento-sternal length (OR = 3.722, 95% CI = 1.980–7.794), and atlanto-occipital joint (AOJ) extension (OR = 1.572, 95% CI = 1.865–4.263). Cormack–Lehane and Italian Grading was significantly associated with BMI, mandibular protrusion test, Mallampati Index, mento-thyroid, mento-sternal length, and AOJ extension, it increased with BMI of > 35, with more protruded mandible (class C), higher Mallampati Index (class III) and shorter mento-sternal distance (≤ 12.5 cm). Conclusions: During microlaryngeal surgery, BMI, mandibular protrusion test, Mallampati Index, mento sternal and AOJ extension were significant predictors of Cormack–Lehane and Italian Grading which makes it easier for laryngeal exposure. [ABSTRACT FROM AUTHOR]

Objective: Recent studies indicate that 3 morphological types of atlanto-occipital joint (AOJ) exist in the craniovertebral junction and are associated with type II basilar invagination (BI) and atlanto-occipital instability. However, the actual biomechanical effects remain unclear. This study aims to investigate biomechanical differences among AOJ types I, II, and III, and provide further evidence of atlanto-occipital instability in type II BI. Methods: Models of bilateral AOJ containing various AOJ types were created, including I-I, I-II, II-II, II-III, and III-III models, with increasing AOJ dysplasia across models. Then, 1.5 Nm torque simulated cervical motions. The range of motion (ROM), ligament and joint stress, and basion-dental interval (BDI) were analyzed. Results: The C0–1 ROM and accompanying rotational ROM increased progressively from model I-I to model III-III, with the ROM of model III-III showing increases between 27.3% and 123.8% indicating ultra-mobility and instability. In contrast, the C1–2 ROM changes were minimal. Meanwhile, the stress distribution pattern was disrupted; in particular, the C1 superior facet stress was concentrated centrally and decreased substantially across the models. The stress on the C0–1 capsule ligament decreased during cervical flexion and increased during bending and rotating loading. In addition, BDI gradually decreased across the models. Further analysis revealed that the dens showed an increase of 110.1% superiorly and 11.4% posteriorly, indicating an increased risk of spinal cord impingement. Conclusion: Progressive AOJ incongruity critically disrupts supportive tissue loading, enabling incremental atlanto-occipital instability. AOJ dysplasia plays a key biomechanical role in the pathogenesis of type II BI. [ABSTRACT FROM AUTHOR]

To evaluate the feasibility of a novel method for occipitocervical fixation (OCF) through the endonasal corridor. Thin-cut computed tomography scans were obtained for 5 cadaveric specimens. Image segmentation was used to reconstruct 3D models of each O-C1 joint complex. Using computer-aided design software, plates were custom-designed to span each O-C1 joint, sit flush onto the bony surface, and accommodate screws. The final models were 3D-printed in titanium. For implantation, specimens were held in pin-fixation and registered to neuronavigation. A rigid 0º endoscope was used for endonasal visualization. An inverted U-shaped nasopharyngeal flap was raised to expose the occipital condyles and C1. The plates were introduced and fixed with bone screws. Computed tomography scans were obtained to assess screw accuracy and proximity to critical neurovascular structures. Screw entry points and trajectories were recorded. Endonasal OCF was performed on 5 cadaveric specimens. The mean starting point for occipital condyle screws was 6.17 mm lateral and 5.38 mm rostral to the medial O-C1 joint. Mean axial and sagittal trajectories were 7.98° and 6.71°, respectively. The mean starting point for C1 screws was 16.11 mm lateral to the C1 anterior tubercle and 6.39 mm caudal to the medial O-C1 joint. Mean axial and sagittal trajectories were 10.97° and −9.91°, respectively. Endonasal OCF is technically and anatomically feasible. The application of this technique may allow for same-stage endonasal decompression and fixation, offering a minimally invasive alternative to current methods of fixation and advancing surgeons' ability to treat pathology of the craniovertebral junction. Next steps will focus on biomechanical testing. [ABSTRACT FROM AUTHOR]

Objective While the transcondylar approach is technically challenging, it provides generous ventral and caudal exposure to the craniovertebral junction. This approach requires navigation around multiple eloquent neurovascular structures including the lower cranial nerves, vertebral artery and its branches, and the brainstem. Superficial exposure, including incision location and muscle dissection, can dramatically affect the surgical angle and maneuverability at depth. Methods We demonstrate the transcondylar approach in a step-by-step fashion in a formalin-embalmed, latex-injected cadaver head. Dissection within each layer of the suboccipital muscles was performed. A small cohort with an illustrative case is also included herein. Results The sternocleidomastoid (SCM) muscle was retracted anteriorly; the splenium capitis, semispinalis capitis, and longissimus capitis muscles were disconnected from the superior nuchal line and reflected inferomedially. The suboccipital muscle group was fully exposed. The superior and inferior oblique muscles were disconnected from the transverse process of C1. The superior oblique and the rectus capitis posterior major muscles were then dissected off the inferior nuchal line, and the suboccipital muscle group was retracted inferomedially en bloc. The greater auricular nerve was retracted laterally with the SCM, and the greater occipital nerve was retracted inferomedially with the suboccipital muscle group. Conclusion This technique avoids the obstructive muscle bulk that results from a myocutaneous approach while maximizing deep exposure. Understanding the detailed muscular anatomical relationship with the insertion location and suboccipital nerves is key to complete and safe extracranial dissection. Diligent dissection helps minimize postoperative pain and muscle spasm while optimizing the closure technique. [ABSTRACT FROM AUTHOR]

Individuals with psychotic disorders often lead sedentary lives, heightening the risk of developing forward head posture. Forward head posture affects upper cervical vertebrae, raising the likelihood of daily discomforts like skeletal misalignment, neck pain, and reduced cardiorespiratory fitness. Improving cardiorespiratory fitness in psychotic disorders is relevant, given its proven benefits in enhancing physical and mental health. This study investigates forward head posture by measuring craniovertebral angles in psychotic disorders and the relationship with reduced cardiorespiratory fitness. To determine whether forward head posture is specific to psychotic disorders, we also included individuals with autism spectrum disorder and healthy controls. Among 85 participants (32 psychotic disorders, 26 autism spectrum disorder, 27 healthy controls), photogrammetric quantification revealed a significantly lower mean craniocervical angle in psychotic disorders compared to autism spectrum disorder (p = < 0.02) and the healthy control group (p = < 0.01). Reduced craniovertebral angle is related to diminished cardiorespiratory fitness in psychosis (R2 = 0.45, p = < 0.01) but not in other control groups. This study found reduced craniovertebral angles, indicating forward head posture in psychotic disorders. Moreover, this relates to diminished cardiorespiratory fitness. Further research is needed to examine the underlying causes and to investigate whether this can be reversed through physical therapy. [ABSTRACT FROM AUTHOR]

Introduction: The atlas vertebra is an atypical cervical vertebra thereby having certain important features to accommodate the widest diameter of spinal cord. Its position is vital as it is closely related to medulla oblongata containing respiratory, cardiac and vascular centers. These centers can get compromised by varying degree of traumatic conditions involving atlanto-axial complex or atlantooccipital joint pathologies. Therefore, maintaining the stability of this complex is pivotal. Among the various surgical procedures posterior fixation is often adopted to maintain the stability of atlanto occipital joint. The Aim of present study was to perform the morphometrical analysis in dry adult atlas vertebra. Material and methods: This cross-sectional study was conducted on 43 dry, undamaged human Atlas vertebra (C1) of unknown sex, age and race obtained from the bone bank of department of Anatomy, Government medical college Srinagar. Results: The transverse and the anteroposterior diameter of atlas in millimeters (mm) were 79.83 ± 6.59 and 45.52 ± 4.23 respectively, the anteroposterior and the transverse diameter of vertebral canal in millimeters were 3 2 . 6 3 ± 3.07 and 30.21 ± 2.89 respectively. The Length of right and the left vertebral artery groove in millimeters were 15.31 ± 3.81 and 15.91 ± 2.63 respectively. Length and width of right superior articular facet was 21.3 ± 2.46 and 14.73 ± 1.83 respectively and the length and width of right inferior articular facet was 17.14 ± 2.03 and 11.84 ± 2.13 respectively. Length and width of left superior articular facet was 21.03 ± 2.36 and 14.43 ± 2.03 respectively and the length and width of left inferior articular facet was 16.83 ± 2.36 and 10.05 ± 2.31 respectively. Conclusion: The precise knowledge of various morphometric parameters of atlas and their comparison with the studies conducted by other researcher's will be very benevolent in the manufacturing of instruments related to atlas vertebrae. The current study will contribute to a better knowledge of diverse bone dimensions, which may aid with preoperative planning and diagnostics when operating near vital structures like the vertebral artery and nerve roots. [ABSTRACT FROM AUTHOR]

Atlanto-occipital assimilation is a congenital craniovertebral junction malformation where the partial or complete fusion of the atlas and occiput occurs. Atlanto-occipital assimilation can be associated with numerous complications, including basilar invagination, atlantoaxial subluxation, Chiari malformation, congenital vertebral bodies fusion, and cord compression. As a result, vigilant identification and accurate reporting of atlanto-occipital assimilation are essential. The purpose of this review article is to discuss the numerous complications and associations of atlanto-occipital assimilation, such that an accurate diagnosis could be made for this commonly missed pathology. [ABSTRACT FROM AUTHOR]

The vertebral column, a defining trait of all vertebrates, is organized as a concatenated chain of vertebrae, and therefore its support to the body depends on individual vertebral morphology. Consequently, studying the morphology of the vertebral centrum is of anatomical and clinical importance. Grass carp (GC) is a member of the infraclass Teleostei (teleost fish), which accounts for the majority of all vertebrate species; thus, its vertebral anatomical structure can help us understand vertebrate development and vertebral morphology. In this study, we have investigated the morphology and symmetry of the grass carp vertebral centrum using high‐resolution micro‐CT scans. To this end, three abdominal vertebrae (V9, V10, & V11) from eight grass carp were micro‐CT scanned and then segmented using Dragonfly (ORS Inc.). Grass carp vertebral centrum conformed to the basic teleost pattern and demonstrated an amphicoelous shape (biconcave hourglass). The centrum's cranial endplate was smaller, less circular, and shallower compared to the caudal endplate. While the vertebral centrum demonstrated bilateral symmetry along the sagittal plane (left/right), the centrum focus was shifted dorsally and cranially, breaking dorsoventral and craniocaudal symmetry. The sum of these findings implies that the caudal aspect of grass carp vertebral centrum is bigger and more robust. Currently, we have no information whether this is due to nature, for example, differences in gene expression, or nurture, for example, environmental effect. As the vertebral parapophyses and spinous processes are slanted caudally, the direction of muscle action during swimming may create a gradient of stresses from cranial to caudal, resulting in a more robust caudal aspect of the vertebral centrum. Expanding our study to include additional quadrupedal and bipedal (i.e., human) vertebrae, as well as testing if these morphological aspects of the vertebrae are indeed plastic and can be affected by environmental factors (i.e., temperature or other stressors) may help answer this question. [ABSTRACT FROM AUTHOR]

This study documents the prevalence, mean intensity, mean abundance, aggregation, and seasonal variation of Amblyomma dissimile Koch in free-living snakes in the tropical humid climate of the Centro municipality of Tabasco, Mexico. A total of 19 snakes of seven species were captured manually during trail walks by trained personnel and carefully inspected for ticks. A morphological characterization identified the ticks as A. dissimile. Estimates indicated that 52.6% of the snakes had been parasitized by this tick. A total of 213 ticks were collected. The mean abundance was 11.2 (95% CI= 4-36), and the mean intensity was 21.3 (95% CI=8-57.1). Adult ticks were the most abundant, followed by nymphs and larvae. The most common parasitized body area was the first third of the snake's body, followed by the second, third, and finally, the head. Half of the inspected snakes were parasitized, and the ticks were found most frequently in the atlantooccipital joint area at the entrance to the stomach. There were high parasitic indices, abundances, and intensities, and Boa imperator Daudin was the most parasitized snake. More parasitized snakes were observed during the dry season. The study compiles relevant information about the presence of A. dissimile and their host snakes in Tabasco, Mexico. Resumen Este estudio documenta la prevalencia, intensidad media, abundancia media, agregación y variación estacional de Amblyomma dissimile Koch en serpientes de vida libre en el clima tropical húmedo del municipio Centro de Tabasco, México. Un total de 19 serpientes de siete especies fueron capturadas manualmente por personal capacitado durante recorridos en senderos. Cada serpiente fué cuidadosamente inspeccionada en busca de garrapatas. La caracterización morfológica permitió identificar a las garrapatas como A. dissimile. Las estimaciones indicaron que el 52.6% de las serpientes estaban parasitadas por esta garrapata. Se colectaron 213 garrapatas. La abundancia media fue 11.2 (IC 95%= 4-36), y la intensidad media fue 21.3 (IC 95%=8-57.1). Las garrapatas adultas fueron las más abundantes, seguidas de ninfas y larvas. El área corporal parasitada más común fue el primer tercio del cuerpo de la serpiente, seguido del segundo, tercero y finalmente la cabeza. La mitad de las serpientes inspeccionadas estaban parasitadas y las garrapatas se encontraron con mayor frecuencia de la zona de la articulación atlantooccipital a la entrada del estómago. Se detectaron índices altos para la abundancia e intensidad parasitaria, las serpientes de la especie Boa imperator Daudin fue la más parasitada. Se observó mayor cantidad de serpientes parasitadas durante la estación seca. El estudio recopila información relevante sobre la presencia de A. dissimile y sus serpientes hospedadoras en Tabasco, México. [ABSTRACT FROM AUTHOR]

Key Clinical Message: This case report describes successful bystander cardiopulmonary resuscitation after a cardiopulmonary arrest due to a traffic accident, followed by early diagnosis and treatment of a traumatic atlanto‐occipital dislocation, resulting in successful community reintegration. [ABSTRACT FROM AUTHOR]

Systemic sclerosis or scleroderma is an uncommon autoimmune condition with a global incidence of 8 to 56 new cases per million per year, which commences from skin and progresses to affect multiple systems in the body. It is marked by abnormalities in blood vessels, sclerosis of connective tissues and atrophy of skin and internal organs. The systemic sclerosis treatment depends on the disease manifestation and are usually treated with vasodilators (for vasculopathy improvement and prevention of Raynaud's phenomenon), prostacyclin analogues (for the prevention of Raynaud's phenomenon refractory to oral vasodilators), immunosuppressants like methotrexate, cyclophosphamide, mycophenolate mofetil, low dose corticosteroids (for the treatment of skin hardening, interstitial lung disease and inflammatory arthritis) and antifibrotics like endothelin receptor antagonists (for the treatment of pulmonary artery hypertension). Avascular necrosis in systemic sclerosis can arise as a result of the macrovascular and microvascular effects of vasculitis and corticosteroid therapy. The multisystem involvement of systemic sclerosis can impact every aspect of anaesthetic care especially airway management. During perioperative management, numerous systemic manifestations like pulmonary artery hypertension, interstitial lung disease and cardiac arrhythmia should be considered. The regional anaesthesia serves as a safe alternative to general anaesthesia and useful adjunct in the management of postoperative pain, but can be technically challenging. This case report described a 61-year-old female patient who had a history of systemic sclerosis for past 25 years and was scheduled for a total hip replacement due to avascular necrosis and secondary osteoarthritis of the left hip. The patient was having difficult cannulation, interstitial lung disease and anticipated difficult airway because of microstomia, limited mouth opening and limited flexion and extension at atlantooccipital joint. But the patient was successfully managed with combined spinal epidural anaesthesia, which provided effective pain control and minimised the perioperative risk associated with general anaesthesia. [ABSTRACT FROM AUTHOR]

Objective and background: This study focuses on the atlas, a pivotal component of the craniovertebral junction, bridging the cranium and spinal column. Notably, variations in its arches are documented globally, necessitating a thorough assessment and categorization due to their significant implications in clinical, diagnostic, functional, and therapeutic contexts. The primary objective is to ascertain the frequency of these anatomical deviations in the atlas arches among a Colombian cohort using cone-beam computed tomography (CBCT). Methodology: Employing a descriptive, cross-sectional approach, this research scrutinizes the structural intricacies of the atlas arches in CBCT scans. Analytical parameters included sex distribution and the nature of anatomical deviations as per Currarino's classification. Statistical analyses were conducted to identify significant differences, including descriptive statistics and Chi-square tests. A systematic review of the literature was conducted in order to enhance the current Currarino's classification. Results: The study examined 839 CBCT images, with a nearly equal sex distribution (49.7% female, 50.3% male). Anatomical variations were identified in 26 instances (3%), displaying a higher incidence in females (X2 [(1, N = 839) = 4.0933, p = 0.0430]). The most prevalent variation was Type A (2.5%), followed by Type B (0.4%), and Type G (0.2%) without documenting any other variation. The systematic review yielded 7 studies. A novel classification system for these variations is proposed, considering global prevalence data in the cervical region. Conclusion: The study highlights a statistically significant predominance of Type A variations in the female subset. Given the critical nature of the craniovertebral junction and supporting evidence, it recommends an amendment to Currarino's classification to better reflect these clinical observations. A thorough study of anatomical variations of the upper cervical spine is relevant as they can impact important functional aspects such as mobility as well as stability. Considering the intricate anatomy of this area and the pivotal function of the atlas, accurately categorizing the variations of its arches is crucial for clinical practice. This classification aids in diagnosis, surgical planning, preventing iatrogenic incidents, and designing rehabilitation strategies. [ABSTRACT FROM AUTHOR]

Key Clinical Message This case report describes successful bystander cardiopulmonary resuscitation after a cardiopulmonary arrest due to a traffic accident, followed by early diagnosis and treatment of a traumatic atlanto‐occipital dislocation, resulting in successful community reintegration.

Purpose: The treatment of unstable atlas fractures remains a controversial topic. The study aims at assessing the prognosis and efficacy of osteosynthesis for unstable atlas fractures through a review of the current literature and additionally aims to compare outcomes between the transoral and posterior approaches. Methods: A systematic review of databases including PubMed, EMBASE, Cochrane, Web of Science, CNKI, and Wanfang was conducted. Titles and abstracts were screened by two reviewers to identify studies meeting pre-defined inclusion criteria for comprehensive analysis. Results: The systematic review included 28 articles, 19 employing the posterior approach and 9 utilizing the transoral approach. It covered osteosynthesis in 297 patients with unstable atlas fractures, comprising 169 treated via the posterior approach and 128 via the transoral approach. Analysis revealed high healing rates and clinical improvement in both approaches, evidenced by improvements in the visual analog scale, range of motion, atlantodens interval, and lateral displacement distance post-surgery. Conclusion: Osteosynthesis offers effective treatment for unstable atlas fractures. Both transoral and posterior approaches can achieve good clinical outcomes for fracture, and biomechanical studies have confirmed that osteosynthesis can maintain the stability of the occipitocervical region, preserve the motor function of the atlantoaxial and occipito-atlantoaxial joints, and greatly improve the quality of life of patients. However, variations exist in the indications and surgical risks associated with each method, necessitating their selection based on a thorough clinical evaluation of the patient's condition. [ABSTRACT FROM AUTHOR]

There are many morphometric studies on Chiari malformation type I (CMI) patients, most of which focus on the posterior cranial fossa (PCF). Less attention has been paid to the atlanto-occipital joint. In this study, we aim to evaluate the morphological characteristics of the atlanto-occipital joint in CMI patients. The cervical CT imaging data of adult patients diagnosed with CMI but without any bony malformation in craniovertebral junction (CVJ) who were treated by the authors between January 2014 and December 2019 were retrospectively analyzed. The equal number of sex and age-matched healthy individuals were included as the control group. The morphometric analysis was performed by measuring the length and depth of the atlanto-occipital joint, and the depth/length ratio was calculated to evaluate the curvature of the joint. A total of 47 patients (15 males and 32 females) were included. The mean age of patients was 47.49 ± 9.01 years (range 19–62 years). The mean depth/length ratio of the atlanto-occipital joint in CMI patients was 0.141 ± 0.065 (range 0.027 − 0.274), which was smaller than that of control individuals (0.228 ± 0.057, range 0.069 − 0.379). And the difference was statistically significant (p <.01). The atlanto-occipital joints in CMI patients are significantly flatter compared with those in healthy controls. This morphological variation could lead to differences of the atlanto-occipital stability between CMI patients and normal population, which may be related to the pathogenesis of CMI. [ABSTRACT FROM AUTHOR]

Background and Aim: Intubation with Macintosh requires flexing the lower cervical spine and extending the atlanto-occipital joint to create a "line of sight." Primary aim of study was to compare the extent of cervical spine movement during laryngoscopy using conventional Macintosh laryngoscope and Airtraq. Material and Methods: A total of 25 patients of either sex between the age group of 18 and 60 years, having American Society of Anesthesiologists (ASA) physical status of Grade-I and Grade-II, scheduled for elective surgery under image control requiring general anesthesia and intubation were enrolled. A baseline image of the lateral cervical spine including the first four cervical vertebrae was taken by an image intensifier. After administration of general anesthesia, laryngoscopy was first performed using a Macintosh laryngoscope and a second X-ray image of the lateral cervical spine was taken. The second laryngoscopy using a Airtraq laryngoscope was done and the third image of the lateral cervical spine was taken. Angles between occiput and C1; C1 and C2; C2 and C3; C3 and C4; and occiput and C4 were calculated. Atlanto-occipital distance (AOD) was calculated as the distance between occiput and C1. Results: Macintosh showed greater cervical movement as compared with Airtraq but a significant difference in the movement was observed at C2-C3 and C0-C4. Baseline mean AOD was 2.21 ± 1.25 mm, after Macintosh and Airtraq laryngoscopy was found to be 1.13 ± 0.60 and 1.6 ± 0.78 mm, respectively, and was found to be significant (P < 0.05). Conclusion: We conclude that Airtraq allows intubation with less movement of the upper cervical spine makes Airtraq preferred equipment for intubation in patients with a potential cervical spine injury. [ABSTRACT FROM AUTHOR]

The purpose of this study was to examine the effects of standing versus sitting body position on the craniovertebral angle (CVA) in young adults without pathology; and to investigate whether mean differences between positional CVA measures in subjects with severe forward head posture (FHP) are distinct from age-matched controls with normal head posture. Ninety-eight young adults (68 women, 30 men) without pathology (OVERALL; n = 98) volunteered for the study; those with CVA > 53° were also included in a normal posture group (NORM; n = 14); those with CVA < 45° were also included in a severe FHP group (SEV; n = 15). CVA assessments were conducted in standing and sitting. Mean difference comparison of change in mean CVA between conditions revealed significantly (p < 0.05) higher CVA values in standing condition (OVERALL: 50.0 ± 5.2°; NORM: 56.6 ± 2.7°; SEV: 41.2 ± 3.2°) compared to sitting condition (OVERALL: 47.8 ± 5.7°; NORM: 55.9 ± 2.8°; SEV: 39.0 ± 4.0°). Mean difference comparison of between-group change in mean CVA between conditions revealed greater CVA change (p < 0.05) in the SEV group (2.2 ± 2.1°) versus the NORM group (0.8 ± 1.2°). Sitting CVA values may be lower (indicating greater FHP) than standing CVA values in young adults. Differences between standing and sitting CVA measures may be greater in young adults with severe FHP compared to peers with normal head posture. Study findings support standing as a standardized body position for CVA assessment in young adults without pathology. [ABSTRACT FROM AUTHOR]

Objective This study aimed to establish a novel grading system, based on the craniovertebral junction compression severity index (CVJCSI) for multidirectional quantification at the foramen magnum plane for Chiari malformation type I (CMI). Methods The CVJCSI grading system was established to stratify patients based on the ventral (modified clivoaxial angle < 138°), dorsal (tonsil herniation), and central (brainstem herniation) CVJ (craniovertebral junction) compression, the CVJCSI grading system was established to stratify patients. The optimal surgical method for each grade was recommended by intragroup comparisons regarding the efficacy of the three operations. Finally, according to the CVJCSI grading system, a prospective validation trial was performed and surgically treated for internal validation. Results Based on the retrospective study (n = 310), the CVJCSI included six grades: I: syrinx alone without compression; II: dorsal compression; III: dorsal and central compression; IV: ventral compression; V: dorsal and ventral compression; and VI: ventral, dorsal, and central compression. Among all available variables, only the CVJCSI and surgical methods significantly affected the CCOS. The CCOS scores, overall and for each CVJCSI grade, increased in the prospective cohort (n = 42) compared with that in the retrospective analysis. Conclusions The CVJCSI can be used to stratify CMI patients. The higher the CVJCSI grade, the more severe the CVJ compression and the worse posterior fossa deformity. Meanwhile, the CVJCSI was negatively correlated with the CCOS. The lower the CVJCSI grade, the better the response to surgery, and the less-invasive surgical procedures were warranted. Finally, the prospective cohort study validated the proposed CVJCSI-based surgical protocols. [ABSTRACT FROM AUTHOR]

This document is a reply to a letter regarding a study on the displacement of the atlantoaxial joint in patients with os odontoideum. The authors respond to the comments made by Fei Ma and co-authors, addressing their concerns about the congenital anomalies in lateral atlantoaxial joints (LAJs) and the correlation between the displacement direction of os odontoideum with atlantoaxial displacement (AAD) and the axial superior facet slope (ASFS). The authors also discuss the potential methods for preventing AAD and preserving atlantoaxial functions in patients without spine syndromes. The document concludes by stating that the study did not receive any funding and the authors have no conflicts of interest. [Extracted from the article]

Porcine models in injury biomechanics research often involve measuring head or brain kinematics. Translation of data from porcine models to other biomechanical models requires geometric and inertial properties of the pig head and brain, and a translationally relevant anatomical coordinate system (ACS). In this study, the head and brain mass, center of mass (CoM), and mass moments of inertia (MoI) were characterized, and an ACS was proposed for the pre-adolescent domestic pig. Density-calibrated computed tomography scans were obtained for the heads of eleven Large White × Landrace pigs (18–48 kg) and were segmented. An ACS with a porcine-equivalent Frankfort plane was defined using externally palpable landmarks (right/left frontal process of the zygomatic bone and zygomatic process of the frontal bone). The head and brain constituted 7.80 ± 0.79% and 0.33 ± 0.08% of the body mass, respectively. The head and brain CoMs were primarily ventral and caudal to the ACS origin, respectively. The mean head and brain principal MoI (in the ACS with origin at respective CoM) ranged from 61.7 to 109.7 kg cm2, and 0.2 to 0.6 kg cm2, respectively. These data may aid the comparison of head and brain kinematics/kinetics data and the translation between porcine and human injury models. [ABSTRACT FROM AUTHOR]

Introduction: Endotracheal intubation is considered the gold standard for airway management and is usually done by direct laryngoscopy, which requires a 35° flexion of the neck and a 15° extension at the atlanto-occipital joint for optimum visualisation of the glottic opening. Immobilisation of the neck to prevent secondary damage to the spinal cord during intubation in patients with cervical spine injuries limits glottic view, thus making laryngoscopy and intubation extremely difficult. Hence, intubating devices that can provide glottic view without neck manipulation are needed in this population. Objectives: This cross-sectional study aimed to compare the laryngeal views and change in hemodynamic parameters during endotracheal intubation using McCoy & McGrath laryngoscopes in cervical spine-immobilised patients. Methods: A total of 62 cervical spine immobilised patients belonging to the age group 18 to 60 years posted for elective surgeries under general anesthesia in Medical College, Thrissur were studied. 31 of them were intubated using a McCoy laryngoscope, while the rest were intubated using a McGrath videolaryngoscope. Manual in-line axial stabilisation of the neck was done by an assistant. We recorded and compared changes in hemodynamic parameters and laryngeal views based on the Cormack-Lehane classification in the first five minutes after intubation between the two groups. Results: The two groups were similar with respect to demographic data and airway examination. A statistically significant improvement in laryngeal view was observed with the McGrath videolaryngoscope compared to the McCoy laryngoscope, with a p value of .002. No significant difference was noted in hemodynamic parameters at all-time points between the two groups. Conclusion: McGrath videolaryngoscope improves the glottic view compared to McCoy laryngoscope in cervical spine immobilised patients, with no significant difference found between the two in hemodynamic response to laryngoscopy and intubation. [ABSTRACT FROM AUTHOR]

Craniovertebral junction (CVJ) is one of the more complex parts of the spinal column. It provides mobility to the cranium and houses the spinal cord. In a healthy subject, the CVJ contributes 25% of the flexion–extension motion and 50% of the axial rotation of the neck. This work reports instrumentation development and results for evaluating implant performance in the stabilized CVJ after surgical procedures. Typically, some bony parts of the vertebrae causing compression to the spinal cord are removed and subsequently stabilized by the instrumenting implant in the CVJ. Pose estimation of the Cadaveric CVJ region is estimated using a monocular vision-based setup. The cervical spine's first three vertebrae surround the CVJ area, where most cervical spine mobility originates. We aim to evaluate the performance of vision-based intervertebral motion estimation of the Cadaver's CVJ in the Indian population, particularly in older people. A series of tests were performed on the Cadaver's CVJ to evaluate the vision system-based motion estimation performance. [ABSTRACT FROM AUTHOR]

Purpose: Management of Anderson and D'Alonzo type II odontoid fractures continues to be controversial despite extensive research and increasing prevalence. To the authors' knowledge, the three odontoid ligaments, the alar ligament, the vertical portion of the cruciate ligament, and the transverse ligament, have not been biomechanically examined in type II odontoid fracture in spite of their potential significance in management. Therefore, this study aims to explore the intersegmental rotations of the craniovertebral junction following Anderson and D'Alonzo type II odontoid fracture and various combinations of ligament ruptures. Methods: A validated C0-C7 cervical spine finite element model was employed to address the research objectives. The model was subjected to flexion-extension, lateral bending, and axial rotation under eight distinct injury conditions apart from the intact state. Prescribed rotations were applied to the top of the cranium while the C7 inferior surface was fixed. Rotation-moment data were retrieved from the model. Results: Type II odontoid fracture caused mixed forms of instability considering flexion-extension. In lateral bending, the fracture alone did not have a significant effect, whereas the disruption of ligaments led to moderate rotation increments. Notably, in axial rotation, the fracture was the most crucial factor for stability. Conclusions: Overall, type II odontoid fracture was found to be the main destabilizing element. Nonetheless, the vertical cruciate and the transverse ligament played a modest role in stabilization. The alar ligament provided minimal or no stability. Furthermore, instances were observed where both the vertical cruciate and the transverse ligament were necessary to prevent more instability. [ABSTRACT FROM AUTHOR]

Objective: In neurosurgery, posterior approaches intended at the craniovertebral junction are frequently used. The most popular procedures for treating upper cervical instability are C1 lateral mass, C2 pedicle, and C1-C2 transarticular screw stabilization. Due to their proximity to neural structures and the presence of the high-riding vertebral artery (VA), these techniques are complicated. The risk of VA damage can be decreased by mobilizing the VA. Using cadaveric specimens in this study was aimed to demonstrate C2 pedicle and C1-C2 transarticular screw placement with VA mobilization and a novel C2 inferior corpus screw placement technique. Methods: In this study, twelve adult cadaveric specimens and two adult dry cadaveric C2 bones were used with the permission and decision of the University Research Ethics Committee. Colored silicone was injected into the arteries and veins of these twelve cadaveric specimens. Then, muscle dissection was performed stepwise, and the C2 vertebrae of the cadavers were revealed with a surgical microscope. Each specimen and entire stages of the dissections were recorded photographically. After cadaver dissections, screw placement was performed with three different techniques. Finally, radiological imaging was done with fluoroscopy. Results: After dissection, the lateral mass of the C2 vertebra was observed, and lateral to it, the transverse process and foramen were detected with the help of a hook. Next, the posterior wall of the VA groove was removed using a 1 mm thin plate Kerrison rongeur until the VA loop could partially be observed the VA. This enables us to find the top of the loop of the VA and mobilize it inferiorly using a dissector. Following this step, the C1-2 transarticular, C2 pedicle, and the novel C2 inferior corpus screw placement can be performed safely by directly visualizing the artery. Conclusions: Due to the nearby neurologic and vascular structures, placing the C2 pedicle and C1-2 transarticular screw is a challenging procedure, especially in high-riding VA cases. However, it is possible to place the C2 pedicle, C1-2 transarticular, and novel C2 inferior corpus screw after the mobilization of the VA. This study aimed to show all of them together on a cadaver for the first time, to understand the anatomy of the C2 vertebra, and to use screw placement techniques to minimize the risk of complications. [ABSTRACT FROM AUTHOR]

Study Design: Retrospective, cross-sectional Objectives: To identify trauma patients with confirmed tears of the transverse atlantal ligament on cervical MRI and measure several parameters of atlanto-axial alignment on cervical CT, including the anterior atlantodens interval, to determine which method is most sensitive in predicting transverse atlantal ligament injury. Methods: Adult trauma patients who suffered a transverse atlantal ligament tear on cervical MRI were identified retrospectively. The cervical CT and MRI exams for these patients were reviewed for the following: anterior and lateral atlantodens interval widening, lateral C1 mass offset, C1–C2 rotatory subluxation, and transverse atlantal ligament injuries on cervical MRI. Results: Twenty-six patients were identified with a tear of the transverse atlantal ligament on cervical MRI. Twelve percent of these patients demonstrated an anterior dens interval measuring greater than 2 mm, 26% of patients demonstrated lateral mass offset of C1 on C2 (average offset of 2.4 mm), 18% of patients demonstrated an asymmetry greater than 1 mm between the left and right lateral atlantodens interval, and one patient demonstrated atlanto-axial rotation measuring greater than 20%. Ten patients had an accompanying C1 burst fracture and eight patients had a C2 fracture. One patient demonstrated widening of the atlanto-occipital joint space greater than 2 mm indicative of craniocervical dissociation injury. Conclusions: An anterior atlantodens interval measuring greater than 2 mm is an unreliable methodology to screen trauma patients for transverse altantal ligament injuries and atlanto-axial instability. Moreover, C1 lateral mass offset, lateral atlantodens asymmetry, and atlanto-axial rotation were all poor predictors of transverse atlantal ligament tears. [ABSTRACT FROM AUTHOR]

Purpose: Sheep are used as a large-animal model for otology research and can be used to study implantable hearing devices. However, a method for temporal bone extraction in sheep, which enables various experiments, has not been described, and literature on middle ear access is limited. We describe a method for temporal bone extraction and an extended facial recess surgical approach to the middle ear in sheep. Methods: Ten temporal bones from five Hampshire sheep head cadavers were extracted using an oscillating saw. After craniotomy and removal of the brain, a coronal cut was made at the posterior aspect of the orbit followed by a midsagittal cut of the occipital bone and disarticulation of the atlanto-occipital joint. Temporal bones were surgically prepared with an extended facial recess approach. Micro-CT scans of each temporal bone were obtained, and anatomic dimensions were measured. Results: Temporal bone extraction was successful in 10/10 temporal bones. Extended facial recess approach exposed the malleus, incus, stapes, and round window while preserving the facial nerve, with the following surgical considerations: minimally pneumatized mastoid; tegmen (superior limit of mastoid cavity) is low-lying and sits below temporal artery; chorda tympani sacrificed to optimize middle ear exposure; incus buttress does not obscure view of middle ear. Distance between the superior aspect of external auditory canal and tegmen was 2.7 (SD 0.9) mm. Conclusion: We identified anatomic landmarks for temporal bone extraction and describe an extended facial recess approach in sheep that exposes the ossicles and round window. This approach is feasible for studying implantable hearing devices. [ABSTRACT FROM AUTHOR]

ABSTRACT Objective: The present study aims to dissect and identify the Barkow ligament (LB) in fetal specimens and describe its anatomical characteristics to contribute to its knowledge in the pediatric population and the clinical and surgical application of conditions associated with the Craniovertebral Junction (CVJ). ). Methods: This work evaluated 19 human fetuses aged 28-38 weeks. Of these, six specimens constituted the final sample and were studied through detailed dissections using coronal sections in an anterior approach up to the region described by the LB. Results: In all specimens, a thin fibrous band was found, horizontal and anterior to the axis tooth, with bilateral fixation on the occipital condyles, corroborating the results found for describing LB in adults. Conclusion: The LB is a congenital ligament that resists the extension of the atlantooccipital joint and may play a role in the stability of the CVJ. Level of Evidence III; Diagnostic Study.

BACKGROUND: The development and evolution of atlas are complex, and there are a few research reports. CT imaging can clearly show the atlas. It is of great clinical significance to clarify the normal development process, anatomical structure, variation and malformation of atlas. OBJECTIVE: To show the normal development and variation of atlas using CT imaging. METHODS: The atlas CT data of patients aged 0-14 years in the picture archiving and communication system of Xiamen Children’s Hospital and Zhongshan Hospital of Xiamen University were collected, and the CT data of 732 patients were finally included. The observation items included: The ossification centers of anterior arch and vertebral arch, the epiphyseal plates of vertebral arch, anterior and posterior median, the tubercle of transverse ligament and the variation and deformity of atlas. RESULTS AND CONCLUSION: (1) Among 732 cases of atlas, CT images exhibited that 679 (92.76%) had normal development, 53 (7.24%) variation or deformity. Among them, there were 27 cases of incomplete bone ring, 23 cases of accessory ossification center and accessory epiphyseal plate, and 3 cases of atlantooccipital joint deformity. (2) There were three ossification centers, including two lateral vertebral arches and one anterior arch. The bilateral ossification centers of two vertebral arches appeared in the fetal period; the anterior arch ossification center of one vertebral arch appeared from 2 days to 2 years after birth, the median age with 6 months and the interquartile-range with 4-11 months. (3) There were four epiphyseal plates, including two vertebral arch epiphyseal plates, one anterior median epiphyseal plate, and one posterior median epiphyseal plate. The two epiphyseal closures of vertebral arch were at the median age of 6.2 years, interquartile-range of 4.5-7.0. The occurrence rate of anterior median epiphyseal plate was 37.43%. That of anterior median was at the median age of 4.8 years, interquartile-range of 2.8-6.0 years and the posterior median at 2.8 years, interquartile-range of 2-3.8 years. (4) The appearance of transverse ligament nodules was at the median age of 9 years, interquartile-range of 5.5-10. (5) These findings have concluded that there is a specific age range between the appearance of ossification center and the closing of epiphyseal plate. The variations or deformities of atlas are mainly the incomplete bone ring, accessory ossification center or epiphyseal line. CT image showing the development or deformity of atlas is clear and accurate, which has many advantages. [ABSTRACT FROM AUTHOR]

Background Surgical treatment of ventral and ventrolateral lesions of the craniocervical junction are among the most challenging neurosurgical pathologies to treat. Three surgical techniques, the far lateral approach (and its variations), the anterolateral approach, and the endoscopic far medial approach can be used to approach and resect lesions in this area. Objective The aim of the study is to examine the surgical anatomy of three skull base approaches to the craniocervical junction and review surgical cases to better understand the indications and possible complications for each of these approaches. Methods Cadaveric dissections with standard microsurgical and endoscopic instruments were performed for each of the three surgical approaches, and key steps and surgically relevant anatomy were documented. Six patients with appropriate pre-, post-, and intraoperative imaging and video documentation are presented and discussed accordingly. Results Based on our institutional experience, all three approaches can be utilized to safely and effectively approach a wide variety of neoplastic and vascular pathology. Unique anatomical characteristics, lesion morphology and size, and tumor biology should all be considered when determining the optimal approach. Conclusion Preoperative assessment of surgical corridors with 3D illustrations helps to define the best surgical corridor. 360 degree knowledge of the anatomy of craniovertebral junction allows safe surgical approach and treatment of ventral and ventrolateral located lesions using one of the three approaches. [ABSTRACT FROM AUTHOR]

Objective: To introduce novel parameters in determining directions of os odontoideum (OO) with atlantoaxial displacement (AAD) and compensations of cervical sagittal alignment after displacement. Methods: Analysis was performed on 96 cases receiving surgeries for upper cervical myelopathy caused by OO with AAD from 2011 to 2021. Twenty-four patients were included in the OO group and divided into the OO-anterior displacement (AD) group and the OO-posterior displacement (PD) group by displacement. Seventy-two patients were included as the control (Ctrl) group and divided into Ctrl-positive (Ctrl-P) group and Ctrl-negative (Ctrl-N) group by axial superior facet slope (ASFS) in a neutral position. ASFS, the sum of C2 slope (C2S) and axial superior facet endplate angle (ASFEA), was measured and calculated by combining cervical supine CT with standing X-ray. Cervical sagittal parameters were measured to analyse the atlantoaxial facet and compensations after AAD. Results: Atlas inferior facet angle (AIFA), ASFS, and ASFEA in Ctrl-P significantly differed from OO-AD.C0-C1, C1-C2, C0-C2, C2-C7, C2-C7 SVA, and C2S in Ctrl-P significant differed from the OO-AD group. C2-C7 SVA and C2S in Ctrl-N significantly were smaller than the OO-PD group. C1-C2 correlated with C0-C1 and C2-C7 negatively in the OO group. Slight kyphosis of C1-C2 in OO-AD was compared with lordosis of C1-C2 in Ctrl-P, inducing increased extension of C0-C1 and C2-C7. Mildly increased lordosis of C1-C2 in OO-PD was compared with C1-C2 in Ctrl-N, triggering augmented flexion of C0-C1 and C2-C7. Conclusion: ASFS was vital in determining directions of OO with AAD and explaining compensations. ASFS and ASFEA could provide pre- and intraoperative guidelines. Key Points: • ASFS may determine the directions and compensatory mechanisms of AAD secondary to OO. • ASFS could be achieved by the sum of ASFEA and C2S. [ABSTRACT FROM AUTHOR]

Objective: Unusual clinical course. Background: High-performance athletes, such as archers, require optimal proprioception and balance. Subclinical or underestimated metabolic and pathomechanic alterations in the suboccipital myofascia could lead to loss of performance in balance and proprioception. Therapeutic optimization of myofascia and its complex structures through noninvasive stimulation by mechanotransductive vibropressure could be a preliminary key factor in high-performance athletes for high-performance sport. Case Reports: This study was conducted with 6 athletes from the Brazilian Olympic archery team to evaluate the impact of the Atlasprofilax intervention on body balance. The results were measured using a standardized medical stabilometric platform, which assessed static balance and proprioception capacity. One athlete underwent the intervention before the entire team was tested for balance and reflexes in their archery performance. The study found that the intervened athlete showed improved balance and reflexes, as indicated by superior scores in the risk of fall assessment and fall index. The results suggest the potential for the Atlasprofilax intervention to improve body balance and proprioception in high-performance athletes. Conclusions: A single intervention using the Atlasprofilax method in 1 of 6 Olympic archers resulted in significant improvement in balance and proprioception when compared with that of the non-intervened athletes. This preliminary evidence suggests that the Atlasprofilax intervention on the suboccipital myofascia may have a positive impact on enhancing balance and performance in elite athletes by improving proprioception. [ABSTRACT FROM AUTHOR]

The craniovertebral junction (CVJ) involves the atlas, axis, and occiput along with the atlanto-occipital and atlantoaxial joints. The anatomy and neural and vascular anatomy of the junction render the CVJ unique. Specialists treating disorders that affect the CVJ must appreciate its intricate anatomy and should be well versed in its biomechanics. This first article in a three-article series provides an overview of the functional anatomy and biomechanics of the CVJ. [ABSTRACT FROM AUTHOR]

To describe and evaluate the steps required to perform a combined endoscopic endonasal/transoral transclival transodontoid approach for anterior decompression of the craniovertebral junction. The endoscopic endonasal transclival transodontoid approach combined with endoscopic transoral decompression was performed on 4 cadaveric specimens. Evaluation of this combined technique; a review of the literature; and the nuances, advantages, and pitfalls are reported. Adequate wide anterior decompression was achieved in all specimens. This combined approach allowed the preservation of the anterior arch of C1 without injuring the eustachian tube anatomy and avoiding internal carotid artery manipulation. Mastery of both techniques allows for a safe and comfortable surgical corridor. The transoral and transnasal approaches should not be considered as either/or techniques, but rather as a complement to each other. However, as with all new or developing techniques, there is a steep learning curve, which requires ample training in the skull base laboratory. [ABSTRACT FROM AUTHOR]

Purpose: The objective was to analyze the role of the thoracolumbar sagittal flexibility on the outcome after posterior spinal fusion of Lenke 1 and 2 adolescent idiopathic scoliosis with last touched vertebra as the lowest instrumented vertebra. Methods: We included 105 thoracic AIS patients who had a posterior spinal fusion with a 2 years minimum follow-up. Thoracolumbar junction flexibility was assessed on dynamic sagittal X-rays and compared to the standing position. Adding-on was defined according to radiographic Wang criteria. The junction was considered flexible if the variability from the static position to flexion and/or extension was greater than 10°. Results: Mean age of the patients was 14 ± 2 years. The preoperative mean Cobb angle was 61 ± 12.7° and 27.5 ± 7.7° after surgery. Mean follow-up was 3.1 years. Twenty-nine patients (28%) developed an adding-on. Thoracolumbar junction range of motion was higher (p = 0.017) with higher flexibility in flexion (p < 0.001) in the no adding-on group. In no adding-on group, 53 patients (70%) had a flexible thoracolumbar junction, and 23 patients (30%) had a stiff thoracolumbar junction in flexion and flexible in extension. In adding-on group, 27 patients (93%) had a stiff thoracolumbar junction, and 2 patients (7%) had a flexible junction in flexion and stiff in extension. Conclusion: The flexibility of the thoracolumbar junction is a determining factor in the surgical outcome after posterior spinal fusion for AIS and should be considered in correlation with the frontal and sagittal alignment of the spine. [ABSTRACT FROM AUTHOR]

Background and purpose: The purpose of this study was to identify and classify the different types of anterior atlanto-occipital membrane complex injuries on MRI and evaluate for the presence, size, and location of a prevertebral effusion on the preceding CT exams. Materials and methods: Patients who suffered an anterior atlanto-occipital membrane complex injury were identified retrospectively utilizing Nuance mPower software. An anatomic-based description of the location of the anterior atlanto-occipital membrane complex injury was recorded along with any additional osteoligamentous trauma of the craniocervical junction. The preceding cervical CT exams for these patients were reviewed for the presence and location of a prevertebral effusion. Results: Fifty patients were identified with an acute, post-traumatic anterior atlanto-occipital membrane complex injury. Three distinct patterns of anterior atlanto-occipital membrane complex injury were observed. Nineteen patients demonstrated increased STIR signal with disruption of the anterior atlanto-occipital membrane, ten patients demonstrated increased STIR signal with disruption of the anterior atlanto-axial membrane, and twenty-one patients demonstrated increased STIR signal with disruption of both the anterior atlanto-occipital membrane and anterior atlanto-axial membrane. An effusion at the C1-C2 level was present in greater than 90% of patients with anterior atlanto-occipital membrane complex injury. Conclusions: The presence of a craniocervical prevertebral effusion on CT in trauma patients may raise suspicion for an injury to the anterior atlanto-occipital membrane complex and potentially trigger additional investigation with cervical MRI. [ABSTRACT FROM AUTHOR]

Key Clinical Message: Craniovertebral junction (CVJ) schwannomas are rare tumors, showing direct involvement of the atlanto‐occipital and atlanto‐axial joints. Microsurgical removal is the standard of care to improve symptoms and local control, but stereotactic radiosurgery (SRS) is an option. Both, surgery, and SRS, may show risks of severe complications. A 41‐year‐old male was referred to our department after incidental finding of a right‐sided C1 tumor. A CT angiogram with 3D reconstructions showed the close relationship between the tumor and the right vertebral artery (VA). A post‐contrast enhancement MRI revealed the presence of an extradural mass, sited at the level of the CVJ, mainly at the level of the right articular mass of C1. After multidisciplinary assessment, involving the gamma‐knife and neurosurgical teams, we performed a microsurgical resection of the tumor. Histology confirmed the diagnosis of schwannoma. At 1 year follow‐up the patient is stable, with no recurrence of the tumor. CVJ schwannoma's current standard of care is surgical resection, but longitudinal studies are required, and should promoted promptly since the recent introduction of the new version of GKSRS that allow the treatment of CVJ's lesions. [ABSTRACT FROM AUTHOR]

Introduction. Due to its complex anatomy and function the craniovertebral junction (CVJ) is prone to several pathological conditions. The unique topography of neuro-vascular and bony structures makes surgical management of this area particularly challenging. Methods. A systematic online literature search was conducted in PubMed, Google Scholar, Scopus, and Web of Science with keywords relating to Chiari malformation, Wallenberg syndrome, Syringomyelia, and atlantoaxial dislocations. Results. This paper presents an up-to-date summary of the pathogenesis and surgical management of Chiari malformation, Wallenberg syndrome, syringomyelia, and atlantoaxial dislocation with particular emphasis on developmental and surgical anatomy. Conclusion. In such complex pathologies of the CVJ, the many factors contributing to the patient's condition and the aspects playing a key role in the treatment process are all difficult to be considered concurrently. A better and universal surgical technique is impossible to be established. [ABSTRACT FROM AUTHOR]

A 15‐year‐old pony was presented for acute neurological signs. Neurological examination suggested a brainstem lesion, blood laboratory tests detected an active inflammatory process, and upper respiratory endoscopy identified a suppurative lesion at the dorsal aspect of the right guttural pouch. Computed tomography was performed and findings were consistent with pituitary abscess, meningitis, and atlanto‐occipital joint septic arthritis. Imaging findings were confirmed based on cerebrospinal and synovial fluid cultures and necropsy. Computed tomography provided important information for identifying the cause of the patient's neurological signs and helped the owner make a final decision for euthanasia. [ABSTRACT FROM AUTHOR]

The craniovertebral junction (CVJ) is a complex transition area between the skull and cervical spine. Pathologies such as chordoma, chondrosarcoma and aneurysmal bone cysts may be encountered in this anatomical area and may predispose individuals to joint instability. An adequate clinical and radiological assessment is mandatory to predict any postoperative instability and the need for fixation. There is no common consensus on the need for, timing and setting of craniovertebral fixation techniques after a craniovertebral oncological surgery. The aim of the present review is to summarize the anatomy, biomechanics and pathology of the craniovertebral junction and to describe the available surgical approaches to and considerations of joint instability after craniovertebral tumor resections. Although a one-size-fits-all approach cannot encompass the extremely challenging pathologies encountered in the CVJ area, including the possible mechanical instability that is a consequence of oncological resections, the optimal surgical strategy (anterior vs posterior vs posterolateral) tailored to the patient's needs can be assessed preoperatively in many instances. Preserving the intrinsic and extrinsic ligaments, principally the transverse ligament, and the bony structures, namely the C1 anterior arch and occipital condyle, ensures spinal stability in most of the cases. Conversely, in situations that require the removal of those structures, or in cases where they are disrupted by the tumor, a thorough clinical and radiological assessment is needed to timely detect any instability and to plan a surgical stabilization procedure. We hope that this review will help shed light on the current evidence and pave the way for future studies on this topic. [ABSTRACT FROM AUTHOR]

The foramen magnum (FM) is the key component of the craniovertebral junction, which connects the brain stem and medulla spinalis and is closely related to vital structures. FM dimensions are of great clinical importance. Considering the similarity in shape between FM and orbita, we thought that there might be a relationship between the lengths (sagittal diameter) and widths (transverse diameter) of these structures. Since it is not possible to reach FM directly, we set up our hypothesis as can we calculate the foramen magnum dimensions from orbital measurements before proceeding to costly tests. We also investigated this harmony in the skulls we used in the study. In the study, 21 dried skull bones from the Turkish population were used. FM and right Orbital length and width measurements were made. Precision digital caliper was used for measurements. Statistical validity and reliability analyzes were performed to prove the agreement between the measurements. We found that the length of the orbit and FM in the sagittal plane is close to each other, with 34.74±2.11 mm and 34.99±3.0 mm, and the width of the orbit in the coronal plane is approximately 1.40 times the width of the FM. We proved that the estimation of FM dimensions based on orbital measurements is also statistically valid and safe. Using orbital measurements, it is possible to estimate FM dimensions which are difficult to reach directly in living humans. [ABSTRACT FROM AUTHOR]

The purpose of this study is to compare axial rotation range of motion for the upper cervical spine during three movements: axial rotation, rotation + flexion + ipsilateral lateral bending and rotation + extension + contralateral lateral bending before and after occiput-atlas (C0–C1) stabilization. Ten cryopreserved C0–C2 specimens (mean age 74 years, range 63–85 years) were manually mobilized in 1. axial rotation, 2. rotation + flexion + ipsilateral lateral bending and 3. rotation + extension + contralateral lateral bending without and with a screw stabilization of C0–C1. Upper cervical range of motion and the force used to generate the motion were measured using an optical motion system and a load cell respectively. The range of motion (ROM) without C0–C1 stabilization was 9.8° ± 3.9° in right rotation + flexion + ipsilateral lateral bending and 15.5° ± 5.9° in left rotation + flexion + ipsilateral lateral bending. With stabilization, the ROM was 6.7° ± 4.3° and 13.6° ± 5.3°, respectively. The ROM without C0–C1 stabilization was 35.1° ± 6.0° in right rotation + extension + contralateral lateral bending and 29.0° ± 6.5° in left rotation + extension + contralateral lateral bending. With stabilization, the ROM was 25.7° ± 6.4° (p = 0.007) and 25.3° ± 7.1°, respectively. Neither rotation + flexion + ipsilateral lateral bending (left or right) or left rotation + extension + contralateral lateral bending reached statistical significance. ROM without C0–C1 stabilization was 33.9° ± 6.7° in right rotation and 28.0° ± 6.9° in left rotation. With stabilization, the ROM was 28.5° ± 7.0° (p = 0.005) and 23.7° ± 8.5° (p = 0.013) respectively. The stabilization of C0–C1 reduced the upper cervical axial rotation in right rotation + extension + contralateral lateral bending and right and left axial rotations; however, this reduction was not present in left rotation + extension + contralateral lateral bending or both combinations of rotation + flexion + ipsilateral lateral bending. [ABSTRACT FROM AUTHOR]

Anatomical knowledge of the occipital condyle (OC) and its relationships to surrounding structures is important for avoiding injury during craniovertebral junction (CVJ) surgeries. This study was conducted to evaluate the morphology and morphometry of OC and its relationship to foramen magnum, jugular foramen (JF), and hypoglossal canal (HC). Morphometric parameters including length, width, height, and distances from the OC to surrounding structures were measured. The oval-like condyle was the most common OC shape, representing for 33.0% of all samples. The mean length, width and height of OC were 21.3±2.4, 10.5±1.4, and 7.4±1.1 mm, respectively. Moreover, OC was classified into three types based on its length. The most common OC length in both sexes was moderate length or type II (62.5%). The mean distance between anterior tips and posterior tips of OC to basion, and opisthion were 11.5±1.4, 39.1±3.3, 25.2±2.2, and 27.4±2.7 mm, respectively. The location of intracranial orifice of HC was commonly found related to middle 1/3 of OC in 45.0%. JF was related to the anterior 2/3 of OC in 81.0%, the anterior 1/3 of OC in 12.5%, and the entire OC length in 6.5%. These morphological analysis and morphometric data should be taken into consideration before performing surgical operation to avoid CVJ instability and neurovascular structure injury [ABSTRACT FROM AUTHOR]

Purpose: To establish reference ranges for four most commonly used diagnostic measures of craniocervical instability (CCI) in three cervical sagittal positions. This necessitated development of a reliable measurement protocol using upright, dynamic MRI (udMRI), to determine differences in the extent of motion between positions, and whether age and sex correlate with these measures. Materials and Methods: Deidentified udMRIs of 50 adults, referred for reasons other than CCI, were captured at three positions (maximal flexion, maximal extension and neutral). Images were analyzed, providing measures of basion-axial interval, basion-axial angle, basion-dens interval (BDI) and the Grabb–Oakes line (GOL) for all three positions (12 measures per participant). All measures were independently recorded by a radiologist and neurosurgeon to determine their reliability. Descriptive statistics, correlations, paired and independent t-tests were used. Mean (± 2 SD) identified the reference range for all four measures at each craniocervical position. Results: The revised measurement protocol produced inter-rater reliability indices of 0.69–0.97 (moderate–excellent). Fifty adults' (50% male; mean age 41.2 years (± 9.7)) reference ranges for all twelve measures were reported. Except for the BDI and GOL when moving between neutral and full flexion, significant extents of movement were identified between the three craniocervical positions for all four measures (p ≤ 0.005). Only a minor effect of age was found. Conclusions: This is the first study to provide a rigorous standardized protocol for four diagnostic measures of CCI. Reference ranges are established at mid and ends of sagittal cervical range corresponding to where exacerbations of signs and symptoms are commonly reported. [ABSTRACT FROM AUTHOR]

Today, a median suboccipital craniotomy with access to the cavity of the fourth ventricle through the foramen of Magendie is widely used to remove neoplasms of the fourth ventricle and brainstem. However, according to modern literature, the median approach to the posterior cranial fossa is associated with a high risk of cerebrospinal fluid (CSF) leakage and pseudomeningocele. We propose a modified unilateral uvulotonsillar approach via a median suboccipital open-door craniotomy, which can potentially reduce the incidence of CSF leakage and preserve the ligamentous apparatus of the craniovertebral junction. Herein, we describe the implementation of this approach on cadaveric material and provide a clinical case. The material used for the study was 3 cadavers and 1 clinical case. Step-by-step dissection imitating the described approach was carried out. During the dissection, surgical landmarks were identified at the macro- and microstages, which should be considered when performing the proposed approach. A detailed description of the technique for performing open-door craniotomy, the features of the incision in the dura mater, unilateral dissection of the uvulotonsillar fissure, and the structures of the cavity of the fourth ventricle that could be visualized through this approach were described. This approach allows preservation of the normal anatomy of the craniovertebral junction and stable fixation of the bone flap. Unilateral dissection of the uvulotonsillar fissure provides adequate visualization of almost all parts of the rhomboid fossa, and the convenience of suturing the minimal arcuate incision in the dura mater potentially reduces the risk of CSF leakage. [ABSTRACT FROM AUTHOR]

Our knowledge about the underlying pathomechanisms of craniocervical junction abnormalities (CCJA) in dogs mostly derives from measurements based on tomographic imaging. These images are static and the positioning of the dogs' head does not reflect the physiological in vivo position of the craniocervical junction (CCJ). Aberrant motion patterns and ranges of motion (ROM) in sound individuals of CCJA predisposed breeds may be a pathogenetic trigger. To further extend our limited knowledge of physiological motion of the CCJ, this prospective, comparative study investigates the in vivo motion patterns and ROM of the CCJ in walk and trot in sound Cavalier King Charles Spaniels and Chihuahuas. The Labrador retriever is used as a reference breed without predisposition for CCJA. This is the first detailed description of CCJ movement of trotting dogs. Biplanar fluoroscopy images, recorded in walking and trotting dogs, were matched to a virtual reconstruction of the skull and cranial cervical spine utilising Scientific Rotoscoping. Kinematic data reveal the same motion patterns among all breeds and gaits with individual temporal and spatial differences in each dog. A stride cycle-dependent lateral rotation of the cranial cervical spine and axial rotation of the atlantoaxial joint in trot in dogs is described for the first time. The ROM of the atlantoaxial and atlantooccipital joints in walk and trot were not statistically significantly greater in the CCJA-predisposed breeds CKCS and Chihuahua. ROM values of all translational and rotational degrees of freedom were larger in walk than trot, although this is only statistically significant for the atlantoaxial joint. Until proven otherwise, a more species-specific than breed-specific general motion pattern of the CCJ in walking and trotting, clinically sound dogs must be assumed. Species-specific anatomic properties of the CCJ seem to supersede breed-specific anatomical differences in clinically sound dogs. [ABSTRACT FROM AUTHOR]

The craniovertebral junction (CVJ) is an anatomically complex region of the axial skeleton that provides protection of the brainstem and the upper cervical spinal cord. Structural malformation of the CVJ gives rise to life-threatening neurological deficits, such as quadriplegia and dyspnea. Unfortunately, genetic studies on human subjects with CVJ malformation are limited and the pathogenesis remains largely elusive. In this study, we recruited 93 individuals with CVJ malformation and performed exome sequencing. Manual interpretation of the data identified three pathogenic variants in genes associated with Mendelian diseases, including CSNK2A1, MSX2, and DDX3X. In addition, the contribution of copy number variations (CNVs) to CVJ malformation was investigated and three pathogenic CNVs were identified in three affected individuals. To further dissect the complex mutational architecture of CVJ malformation, we performed a gene-based rare variant association analysis utilizing 4371 in-house exomes as control. Rare variants in LGI4 (carrier rate = 3.26%, p = 3.3 × 10–5) and BEST1 (carrier rate = 5.43%, p = 5.77 × 10–6) were identified to be associated with CVJ malformation. Furthermore, gene set analyses revealed that extracellular matrix- and RHO GTPase-associated biological pathways were found to be involved in the etiology of CVJ malformation. Overall, we comprehensively dissected the genetic underpinnings of CVJ malformation and identified several novel disease-associated genes and biological pathways. [ABSTRACT FROM AUTHOR]

Introduction: Alar ligament is a paired craniocervical junction ligaments which stabilizes the atlantooccipital and atlantoaxial joints. The main purpose of the study was to compare the normal anatomy of alar ligament on MRI between male and female. The prevalence of alar ligament visualized on MRI and its characteristics were also studied apart from determining the association between the heights of respondents with alar ligament signal intensity and dimensions. Methods: Fifty healthy volunteers were studied using 3.0T MR scanner (Siemens Magnetom Spectra) by 2-mm proton density, T2 and fat-suppression sequences. Alar ligament visualization, dimensions and variability of the ligament courses, shapes and signal intensity characteristics were determined. Results: The orientation of the ligament was laterally ascending in most of the subjects (60%), predominantly oval in shaped (54%) and 67% showed inhomogenous signal. Females are 70% less likely to exhibit alar ligament signal inhomogeneity than males. There were positive correlation between height and the craniocaudal diameter of the alar ligament as well as the anteroposterior diameter, which were statistically significant (r = 0.25, n = 100, p = 0.01 and r = 0.201, n = 100, p = 0.045 respectively). Conclusion: Tremendous variability of alar ligament shows that clinical and multimodality correlation needs to be exercised, especially in evaluating alar ligament MR signal in male. Taller individuals otherwise tend to have longer and thicker ligaments. Future studies with larger samples of alar ligaments including trauma cases are also recommended to supplant a new classification system of alar ligament injury. [ABSTRACT FROM AUTHOR]

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Background: Fixed severe hyperkyphotic deformities spread over more than five vertebral levels represent a therapeutic challenge, especially when the deformity apex is located at the thoraco-lumbar junction, thus requiring a huge amount of correction. The aim of this article is to describe an innovative all-posterior corrective technique based on multilevel non-contiguous thoracic pedicle subtraction ostoeotomy (PSO). Materials and methods: A retrospective review of three patients with fixed severe thoracic hyperkyphosis (a deformity angle of over 70°) with a thoraco-lumbar apex (between T11 and L1) treated by simultaneous two-level thoracic PSO and thoraco-lumbar posterior fusion was performed. Radiographic and clinical records were evaluated pre-operatively, post-operatively and at last follow-up (after a minimum of 2 years). Each variable was presented as mean ± SD (standard deviation). Statistical analyses were performed using paired t-tests (P value < 0.05 was considered significant). Results: The mean local deformity angle decreased by 75% (from 81.3° ± 2.1° to 20.7° ± 1.4°, p < 0.001), the post-operative thoracic kyphosis decreased by 46% (from 61.4° ± 2.4° to 33.2° ± 0.9°, p < 0.001) and the sagittal vertical axis decreased by 73% (from 14.7 cm ± 0.8 cm to 3.9 cm ± 0.3 cm, p < 0.001). No differences were observed in the radiological results between post-operative values and those at the final follow-up. The average Oswestry Disability Index (ODI) score reduced from 65.7 ± 1.8 pre-operatively to 17.3 ± 1.7 at last follow-up (p < 0.001). No neurological, mechanical nor infective complication occurred. Conclusions: The presented technique, although technically demanding, proved to be a safe and effective alternative for the management of fixed severe thoraco-lumbar junction hyperkyphotic deformities. Level of evidence: IV TRIAL REGISTRATION Retrospectively registered [ABSTRACT FROM AUTHOR]