Prophase I is a remarkable stage of meiotic division during which homologous chromosomes pair together and exchange DNA by meiotic recombination. Fluorescence microscopy of meiotic chromosome spreads is a central tool in the study of this process, with chromosome axis proteins being visualized as extended filaments upon which recombination proteins localize in focal patterns.Chromosome pairing and recombination are dynamic processes, and hundreds of recombination foci can be present in some meiotic nuclei. As meiotic nuclei can exhibit significant variations in staining patterns within and between nuclei, particularly in mutants, manual analysis of images presents challenges for consistency, documentation, and reproducibility. Here we share a combination of complementary computational tools that can be used to partially automate the quantitative analysis of meiotic images. (1) The segmentation of axial and focal staining patterns to automatically measure chromosome axis length and count axis-associated (and non-axis associated) recombination foci; (2) Quantification of focus position along chromosome axes to investigate spatial regulation; (3) Simulation of random distributions of foci within the nucleus or along the chromosome axes to statistically investigate observed foci-axis associations and foci-foci associations; (4) Quantification of chromosome axis proximity to investigate relationships with chromosome synapsis/asynapsis; (5) Quantification of and orientation of focus-axis distances. Together, these tools provide a framework to perform routine documentation and analysis of meiotic images, as well as opening up routes to build on this initial output and perform more detailed analyses.

Neck injury fractures are commonly associated with high-impact trauma, such as motor vehicle accidents or falls from heights. However, this case underscores that it is possible to sustain such a fracture even from minor falls. As of now, there are no such reported cases. This case report highlights the importance of a thorough medical history when assessing patients with neck pain following falls. A 59-year-old male experienced a fainting episode after suffering from vomiting and diarrhea, resulting in him hitting his head. The patient attributed his neck pain to a sudden twisting of his neck. The pain originated from the base of his skull, primarily on the left side, extending to the scalp and the left shoulder. After enduring four days of intense pain that limited his ability to rotate his neck and bend to tie his shoes, he sought medical attention and underwent a neck CT scan, which led to the diagnosis of a \"hangman\'s fracture.\" This injury was diagnosed in a clinical setting. Healthcare providers should inquire about the circumstances of the fall, the patient\'s position, associated symptoms, and any relevant pre-existing conditions. This approach ensures an accurate diagnosis and timely treatment. Comprehensive history-taking is essential for identifying high-risk situations and preventing complications that may arise from overlooked minor falls, ultimately enhancing patient safety, especially in cases of neck and spine injuries.

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The craniocervical junction (CCJ) forms the bridge between the skull and the spine, a highly mobile group of joints that allows the mobility of the head in every direction. The CCJ plays a major role in protecting the inferior brainstem (bulb) and spinal cord, therefore also requiring some stability. Children are subjected to multiple constitutive or acquired diseases involving the CCJ: primary bone diseases such as in FGFR-related craniosynostoses or acquired conditions such as congenital torticollis, cervical spine luxation, and neurological disorders. To design efficient treatment plans, it is crucial to understand the relationship between abnormalities of the craniofacial region and abnormalities of the CCJ. This can be approached by the study of control and abnormal growth patterns. Here we report a model of normal skull base growth by compiling a collection of geometric models in control children. Focused analyses highlighted specific developmental patterns for each CCJ bone, emphasizing rapid growth during infancy, followed by varying rates of growth and maturation during childhood and adolescence until reaching stability by 18 years of age. The focus was on the closure patterns of synchondroses and sutures in the occipital bone, revealing distinct closure trajectories for the anterior intra-occipital synchondroses and the occipitomastoid suture. The findings, although based on a limited dataset, showcased specific age-related changes in width and closure percentages, providing valuable insights into growth dynamics within the first 2 years of life. Integration analyses revealed intricate relationships between skull and neck structures, emphasizing coordinated growth at different stages. Specific bone covariation patterns, as found between the first and second cervical vertebrae (C1 and C2), indicated synchronized morphological changes. Our results provide initial data for designing inclusive CCJ geometric models to predict normal and abnormal growth dynamics.

BACKGROUND: Pathological destruction of the axis vertebra leads to a highly unstable condition in an upper cervical spine. As surgical resection and anatomical reconstruction of the second cervical vertebrae represents a life threatening procedure, less radical approaches are preferred and only few cases of C2 prosthesis are described in literature.
METHODS: The focus of this case report is a 21-year-old man with a pathological fracture of C2 managed primarily surgically with the C1-C3 dorsal fusion. Due to the progression of giant cell tumor and destruction of the axis vertebra, C2 prosthesis through anterior approach and dorsal occipito-cervical fusion C0-C4 were performed. Postoperative infection was managed surgically with a 2-staged dorsal debridement, ostheosynthesis material change and autologous bone graft. After a 4 week-intravenous therapy with the ceftriaxone in combination with the amoxicillin/clavulanate, followed by 12 week per oral therapy with amoxicillin/clavulanate in combination with ciprofloxacin, the complete recovery of the infection was achieved. Radiotherapy was initiated 2 months after the last revision surgery and the patient showed a good clinical outcome with stable construct at a 1 year follow-up. A review of literature of all reported C2 prosthesis cases was performed CONCLUSION: C2 prosthesis allows a more radical resection in pathological processes involving the axis vertebra. Combined with the posterior fusion, immediate stability is achieved. Anterior surgical approach is through a highly unsterile oral environment which presents a high-risk of postoperative infection.

OBJECTIVE: Both two-level anterior cervical corpectomy and fusion (t-ACCF) and posterior open-door laminoplasty (ODLP) are effective surgical procedures for the treatment of ossification of the posterior longitudinal ligament (OPLL). Previous studies have identified different effects of different surgical procedures on the upper and subaxial cervical spine (UCS, SCS), however, there are no studies on the effects of t-ACCF and ODLP on the occipito-atlantoaxial complex. Therefore, the purpose of this study is to compare the changes in sagittal parameters and range of motion (ROM) of the occipito-atlantoaxial complex in OPLL patients treated with t-ACCF and ODLP.
METHODS: This was a retrospective study that included 74 patients who underwent t-ACCF or ODLP for the treatment of OPLL from January 2012 to August 2022 at our institution. Preoperative, 3-month, and 1-year postoperative cervical neutral, flexion-extension, and lateral flexion radiographs were taken. Sagittal parameters including Cobb angle of C2-7, C0-2, C0-1, C1-2, C2 slope, and the ROM were measured. The clinical outcome was assessed using the JOA, VAS, and NDI scores preoperatively and at 3 and 12 months postoperatively. Multiple linear regression was employed to identify factors influencing changes in UCS.
RESULTS: In the ODLP group, the SCS (C2-7) Cobb angle was significantly reduced (12.85 ± 10.0 to 7.68 ± 11.27; p < 0.05), and the UCS (C0-2) Cobb angle was significantly compensated for at 1 year postoperatively compared with the t-ACCF group (3.05 ± 4.09 vs 0.79 ± 2.62; p < 0.01). The SCS and lateral flexion ROM of the ODLP group was better maintained than t-ACCF (14.51 ± 6.00 vs 10.72 ± 3.79; 6.87 ± 4.56 vs 3.81 ± 1.67; p < 0.01). The compensatory increase in C0-2, C0-1, and C1-2 ROM was pronounced in both groups, especially in the ODLP group. The results of multiple linear regression showed that only the surgical procedure was a significant factor influencing UCS.
CONCLUSIONS: The loss of the SCS Cobb angle was more pronounced in ODLP relative to t-ACCF, resulting in a significant compensatory increase in UCS and atlantoaxial Cobb angle. The ROM of the UCS, atlantooccipital, and atlantoaxial joints was significantly increased in both groups, this may accelerate degenerative changes in the occipital-atlantoaxial complex, may leading to poorer outcomes in the long-term; of these, ODLP should receive more attention. In contrast, t-ACCF better maintains normal curvature of the SCS and occipito-atlantoaxial complex but loses more ROM.

BACKGROUND: This is a report of a series of 14 patients who presented with a range of \"atypical\" cranial, spinal, and systemic symptoms that started after they suffered a relatively severe injury to the head and/or neck several months or years before surgical treatment. The implications of diagnosing and treating central or axial atlantoaxial dislocation (CAAD) is discussed. Also, the role of dynamic rotatory and lateral head tilt imaging in the diagnosis and treatment is analyzed.
METHODS: Of the 14 patients, 7 were men and 7 were women, with an age range of 21-64 years (average, 42 years). Due to the severity of the presenting neurological and non-neurological symptoms, all the patients had lost their occupation and were heavily dependent on painkillers and/or antidepressant drugs. In addition to other characteristic clinical and radiological evidence, CAAD was diagnosed made based on the facet alignments on lateral profile imaging in the neutral head position. Dynamic head flexion-extension, lateral head tilt, and neck rotation imaging findings confirmed and subclassified CAAD. All 14 patients underwent atlantoaxial fixation surgery.
RESULTS: A personalized self-assessment clinical scoring parameter and the World Health Organization Disability Assessment Schedule 2.0 was used to evaluate the outcome. One patient did not follow-up after surgery. At a minimum follow-up of 6 months after atlantoaxial fixation surgery, the remaining 13 patients experienced relief from all major symptoms.
CONCLUSIONS: Diagnosing and treating CAAD can have major therapeutic implications for patients presenting with progressively worsening disabling clinical symptoms following relatively severe head and/or neck trauma.

The typical mammalian neck consisting of seven cervical vertebrae (C1-C7) was established by the Late Permian in the cynodont forerunners of modern mammals. This structure is precisely adapted to facilitate movements of the head during feeding, locomotion, predator evasion, and social interactions. Eutheria, the clade including crown placentals, has a fossil record extending back more than 125 million years revealing significant morphological diversification in the Mesozoic. Yet very little is known concerning the early evolution of eutherian cervical morphology and its functional adaptations. A specimen of Zalambdalestes lechei from the Late Cretaceous of Mongolia boasts exceptional preservation of an almost complete series of cervical vertebrae (C2-C7) revealing a highly modified axis (C2). The significance of this cervical morphology is explored utilizing an integrated approach combining comparative anatomical examination across mammals, muscle reconstruction, geometric morphometrics and virtual range of motion analysis. We compared the shape of the axis in Zalambdalestes to a dataset of 88 mammalian species (monotremes, marsupials, and placentals) using three-dimensional landmark analysis. The results indicate that the unique axis morphology of Zalambdalestes has no close analog among living mammals. Virtual range of motion analysis of the neck strongly implies Zalambdalestes was capable of exerting very forceful head movements and had a high degree of ventral flexion for an animal its size. These findings reveal unexpected complexity in the early evolution of the eutherian cervical morphology and suggest a feeding behavior similar to insectivores specialized in vermivory and defensive behaviors in Zalambdalestes akin to modern spiniferous mammals.

BACKGROUND: Previous analyses have suggested variations in cervical spine canal morphology according to ethnicity, possibly in part due to variations in the posterior elements. The potential for these variations to affect the placement of instrumentation is uncertain. The aim of this study was to report on the feasibility of C2 lamina screw insertion in a New Zealand cohort including analysis of Māori, the indigenous people of New Zealand.
METHODS: A trauma computed tomography database was accessed to identify suitable images. On axial images, where the isthmus was at its widest, the outer diameter (OD) and inner diameter (ID) of the lamina were measured. Screw length was measured from a proposed entry point to the contralateral junction of the lamina and lateral mass. The spinolaminar angle was measured as the angle subtended by the screw trajectory and midsagittal plane. A 5.5-mm OD was accepted as a threshold for the feasibility of lamina screw placement.
RESULTS: One hundred eighty-seven images were assessed: 115 New Zealand European and 72 Māori. The mean age of the cohort was 41.9 years (SD 19.6), and most patients (64%) were men. For the entire cohort, mean OD was 6.6 and 6.8 mm on the right and left, respectively; the mean inner diameter was 3.5 and 3.8 mm; mean screw length was 31.5 and 31.5 mm; and mean spinolaminar angle was 46.0° and 46.1°. C2 lamina screw placement was feasible in a majority of patients. Considering only Māori patients, placement was feasible in 96% of right and 94% of left laminae in men but 72% of right and 72% of left laminae in women.
CONCLUSIONS: In a majority of patients, C2 lamina screw placement is feasible. However, advanced imaging must be carefully assessed preoperatively because data suggest that Māori women may not necessarily have optimal anatomy.Clinical RelevanceCare needs to be taken when assessing and planning surgery inpatients of different ethnicities because variations may exist in the morphology of the posterior elements of C2, leading to variation in optimal fixation strategy.Level of Evidence3.

This technical report illustrates the technique to perform computed tomography (CT)-guided bone biopsies in the body and dens of the axis (C2 vertebra) through a posterior transpedicular approach with the use of preoperative contrast-enhanced scans to highlight the course of the vertebral artery. The technique is presented through two exemplification cases: a pediatric patient with osteoblastoma and secondary aneurysmal bone cyst and one adult patient with melanoma metastasis. This case highlights the potential of the CT-guided posterolateral/transpedicular approach for performing safe and effective biopsies in the body and dens of C2, even in pediatric patients.