Does ponticulus posticus affect vertebral artery diameter.

PURPOSE: Ponticulus Posticus, atlantooccipital ligament ossification-induced anomaly, surrounds the vertebral artery and the first cervical nerve root. It is believed to wrap around the first cervical nerve root and the vertebral artery, causing compression. We hypothesized that it would also reduce the diameter of the vertebral artery. METHODS: Between January 1, 2022, and December 31, 2022, cervical spine CT scans taken for any reason were retrospectively reviewed. The images of 1365 patients suitable for evaluation were evaluated by two expert radiologists in 3 dimensions. Among patients with PP, those who underwent cervical angiography were identified for vertebral artery diameter measurement. RESULTS: The average age of the 1365 individuals included in the study (732 males, 633 females) was 55.78 (± 18.85) with an age range of 1-96. Among this group, PP was detected in 288 individuals, resulting in a total prevalence of 21.1%. Right and left vertebral artery diameters were significantly lower in patients with complete PP compared to the absent group (p < 0,001, p < 0,001, respectively). Additionally, it was observed that width and height diameters and artery diameters were positively correlated in patients with Complete PP. CONCLUSIONS: Ponticulus posticus can cause vertebrobasilar insufficiency by reducing the diameter of the vertebral artery. Therefore, imaging and detailed evaluation of this region are important in symptomatic patients.

Cervical epidural hematoma masquerading as thrombosis of intracranial flow diverter in situ: A diagnostic and therapeutic conundrum.

Cervical epidural hematoma (EDH) is a rare but very serious cause of acute neurologic compression that needs early diagnosis and rapid intervention. Acute hemiparesis is an infrequent presentation of cervical EDH and often mimics cerebrovascular accident. In this case, we describe the management of a case of cervical EDH presenting as acute hemiparesis in an elderly female patient which mimicked as thrombosis of intracranial flow diverter in situ. The report emphasizes that cervical EDH should be considered as differential diagnosis in patients who present with acute hemiparesis especially, who are on antiplatelets or anticoagulants. Also, in a patient considered high-risk for surgery, conservative management can be considered under close supervision and intensive monitoring, especially, in non-expanding hematoma and non-progressive neurological deterioration.

Intelligent Evaluation Method of Human Cervical Vertebra Rehabilitation Based on Computer Vision.

With the changes in human work and lifestyle, the incidence of cervical spondylosis is increasing substantially, especially for adolescents. Cervical spine exercises are an important means to prevent and rehabilitate cervical spine diseases, but no mature unmanned evaluating and monitoring system for cervical spine rehabilitation training has been proposed. Patients often lack the guidance of a physician and are at risk of injury during the exercise process. In this paper, we first propose a cervical spine exercise assessment method based on a multi-task computer vision algorithm, which can replace physicians to guide patients to perform rehabilitation exercises and evaluations. The model based on the Mediapipe framework is set up to construct a face mesh and extract features to calculate the head pose angles in 3-DOF (three degrees of freedom). Then, the sequential angular velocity in 3-DOF is calculated based on the angle data acquired by the computer vision algorithm mentioned above. After that, the cervical vertebra rehabilitation evaluation system and index parameters are analyzed by data acquisition and experimental analysis of cervical vertebra exercises. A privacy encryption algorithm combining YOLOv5 and mosaic noise mixing with head posture information is proposed to protect the privacy of the patient's face. The results show that our algorithm has good repeatability and can effectively reflect the health status of the patient's cervical spine.

Serum biomarkers associated with radiographic skeletal maturity indicators: A systematic review and meta-analysis.

OBJECTIVE: To evaluate the relevant scientific literature to determine the association between different serum biomarker levels and radiographic skeletal maturity indicators. DATA SEARCH, SCREENING AND ELIGIBILITY: A literature search was carried out on PubMed, Cochrane Library, Google Scholar, Semantic Scholar, Science Direct and Opengrey.eu up to November 2021 and 7466 records were retrieved via the electronic search. Study selection, data extraction and subsequent risk of bias assessment (RoB) was carried out independently by two authors. In case of any discrepancy, a third author was consulted. RESULTS: After the exclusion of duplicates and the application of inclusion exclusion criteria, 19 studies (published in 25 articles) were included in the systematic review out of which 17 had a cross-sectional and two had a cohort study design. For the meta-analysis, based on the homogeneity, five cross-sectional studies measuring serum IGF-1 levels were incorporated. The meta-analysis revealed that the serum IGF-1 levels peak at the CS4 stage (401.77 ng/mL [333.50 - 470.05]) in the pooled group. However, in the subgroup analysis, it was found that the serum IGF-1 levels peak at CS3 in girls (422.82 ng/mL [377.46-468.18]) and CS4 in boys (487.04 ng/mL [391.83-582.25]). CONCLUSION: Among the various biomarkers evaluated, serum IGF-1 was the most associated with different stages of radiographic skeletal maturity indicators with its levels peaking at CS3 in girls and CS4 in boys.

Atlas and Talus.

This article explores the history of the terms atlas and talus and discusses the unexpected implications of their use in human anatomy. Renaissance anatomists decided to call the first cervical vertebra the atlas. But the name atlas was first used by the ancient Romans for the seventh cervical vertebra. The most common explanation why the first cervical vertebra is called atlas is that the vertebra holds up the globe of the cranium the way Atlas holds up the globe of the heavens. However, an important part of the myth of Atlas is that the Titan was being punished. The seventh cervical vertebra was so named due to its suitability for supporting burdens. (Pollux, 1900) Switching the designation atlas from the seventh to the first cervical vertebra in human anatomy implies that the point of man's burden has shifted from his shoulders to his head. What an anatomist is saying by making, or accepting, this change is that man's true burden is not a physical load, but rather, it is his mind. We explore the implications of this switch, and how it is represented in Renaissance anatomy diagrams. Long before the first cervical vertebra was called atlas it was known as the astragalus, the same term used for the talus, or ankle bone. We examine the many different terms that were used for the ankle bone during the Middle Ages and Renaissance, as well as the connection of the term talus with Greek mythology.

A study of ultrasound-guided perineural injection of the caudal cervical spinal nerve roots in equine cadavers.

OBJECTIVES: To develop an ultrasound-guided cervical perineural injection technique for horses and to evaluate and compare the distribution of contrast agent among perineural, intra-articular and periarticular injections. STUDY DESIGN: Prospective, experimental cadaveric study. ANIMALS: A total of 14 equine cadaveric necks. METHODS: Bilateral ultrasound-guided perineural injection technique for the caudal cervical spinal nerve roots (CSNRs 5-7) was developed. Paramagnetic or iodinated contrast was injected and the distribution of contrast was evaluated using magnetic resonance (MR) or computed tomography (CT) imaging, respectively. The presence of contrast in the CSNR region was determined by an observer unaware of the technique used for each injection performed. The ability of the perineural injection technique to distribute contrast agent to the CSNR region was compared with intra-articular and periarticular injection techniques. RESULTS: Perineural injection delivered contrast agent to the CSNR region 100% of the time and was significantly different when compared with intra-articular injection (p = 0.008). There was no difference in ability to deliver contrast agent to the CSNR region between the perineural and periarticular injection techniques or between the intra-articular and periarticular injection techniques. CONCLUSION AND CLINICAL RELEVANCE: The ultrasound-guided perineural injection technique developed in this study accurately delivered contrast agent to the CSNR region in equine cadavers. This technique could potentially be used for the diagnosis and treatment of cervical pain in horses, particularly in cases where intra-articular cervical articular process joint injections have not been beneficial. Further studies are necessary to assess the effectiveness of the ultrasound-guided perineural injection technique in live horses.

[Minimally invasive treatment of cervical1-2 epidural neurilemmoma].

OBJECTIVE: To explore the minimally invasive surgical method for cervical1-2 epidural neurilemmoma. METHODS: The clinical features, imaging characteristics and surgical methods of 63 cases of cervical1-2 epidural neurilemmoma from July 2010 to December 2018 were reviewed and analyzed. Pain and numbness in occipitocervical region were the common clinical symptoms. There were 58 cases with pain, 30 cases with numbness, 3 cases with limb weakness and 2 cases with asymptomatic mass. Magnetic resonance imaging (MRI) showed that the tumors located in the cervical1-2 epidural space with diameter of 1-3 cm. The equal or slightly lower T1 and equal or slightly higher T2 signals were found on MRI. The tumors had obvious enhancement. Individualized laminotomy was performed according to the location and size of the tumors, and axis spinous processes were preserved as far as possible. Resection of tumor was performed strictly within the capsule. RESULTS: Total and subtotal resection of tumor were achieved in 60 and 3 cases respectively, and no vertebral artery injury was found. The operation time ranged from 60 to 180 minutes, with an average of 92.83 minutes. The hospitalization time ranged from 3 to 9 days, with an average of 5.97 days. All tumors were confirmed as neurilemmoma by pathology. There was no postoperative infection or cerebrospinal fluid leakage. There was no new-onset dysfunction except 9 cases of numbness in the nerve innervation area. The period of follow-up ranged from 6 months to 8 years (median: 3 years). All the new-onset dysfunction recovered completely. Pain disappeared in all of the 58 patients with pain. Numbness recovered completely in 27 patients while slight numbness remained in another 3 patients. Three patients with muscle weakness recovered completely. The spinal function of all the patients restored to McCormick grade Ⅰ. No recurrence was found on MRI. No cervical spine instability or deformity was found on X-rays. CONCLUSION: It is feasible to resect cervical1-2 epidural neurilemmoma by full use of the anatomical space between atlas and axis and individual laminotomy. It is helpful to prevent cervical instability or deformity by minimizing the destruction of cervical2 bone and preserving normal muscle attachment to cervical2 spinous process. Strict intracapsular resection can effectively prevent vertebral artery injury.

Suffocation by massive blood aspiration due to intraoral gun-shot injury -the oldest museum specimen in the Institute of Forensic Medicine in Belgrade.

The forensic museum specimen presented in this paper is the oldest specimen in the collection of the Institute of Forensic Medicine in Belgrade. It comprises a jar containing six cervical vertebras connected to a small amount of dry connective tissue. During the autopsy, the cervical part of the spine was completely opened posteriorly: the base of the odontoid process of the axis was crushed, but the transverse and posterior longitudinal ligaments and the spinal cord were intact. Attached to the specimen, there is a partly cored piece of lead which looks like a severely deformed handgun projectile, approximately 12 mm in diameter. The deceased was a 23-year-old man who committed suicide with a gun in a public park. The gun used was most probably a Nagant M1893 revolver, popular in the region until the end of the Second World War. The pathologist, Dr. Eduard Michel, concluded that the immediate cause of death was asphyxiation due to massive blood aspiration caused by an intraoral gunshot wound. Although the revolver model used is a low-velocity firearm, in such cases the shock wave secondary to the impact of the projectile on the second vertebral bone is likely to have been the cause of widespread neuro-axonal damage at the level of the spinal cord, however, Dr. Michel assumed that death was not instantaneous due to massive hemoaspiration. Nevertheless, without examination of all internal organs and the cervical spine, this case could have remained unexplained.

Morphometric Assessment of Third and Fourth Cervical Vertebra Based on Hassel and Farman Method: A Radiographic Study.

AIM: To assess third and fourth cervical vertebra morphologic dimensions as per the cervical vertebral maturation stage proposed by Hassel and Farman from 7 to 18 years. MATERIALS AND METHODS: A cross-sectional radiographic study was conducted on 264 participants within an age-group of 7-18 years who were further categorized into six subgroups having an interval of 1 year and 11 months chronologic age. The maturation stage and morphometric evaluation of the cervical vertebra were assessed for the same patient. The maturation stage was assessed as per the morphologic classification given by Hassel and Farman. The morphometric evaluation was assessed by measuring the anterior (AH3 and AH4), vertebral body (H3 and H4), posterior heights, and anteroposterior width (APW3 and APW4) of third and fourth cervical vertebra in millimeters which was carried out with the help of "IC measure software." One-way analysis of variance (ANOVA), Tukey's multiple comparison, and Spearman's correlation coefficient were utilized to determine the significance and correlation between the vertebral maturation and millimetric measurement between age-groups. The multiple comparison levels were set at 0.05 level of significance. RESULTS: A high significant correlation was observed between PH3 and APW3 (r, 0.737**). Moderate significant correlation was observed with H3 and PH3 (r, 0.605**, 0.640*), and APW3, APW4 (r, 0.534**, 0.614*) in the initiation stage in both the vertebrae; AH3, H3 (r, 0.498**) and H3, APW3 (r, 0.576**) in deceleration stage. A negative moderate significant correlation between AH4, PH4 (r, -0.691**) was observed in the deceleration stage. The transition, maturation, and completion stages did not reveal any significant correlation. CONCLUSION: Significant morphologic difference was observed among all the stages of vertebral maturation. Higher dimensions were observed among males. Anteroposterior width had the highest dimension. Significant morphometric changes were observed in stages of maturation and transition stages. CLINICAL SIGNIFICANCE: The dimensions of anterior, vertebral, and posterior height of the third and fourth cervical vertebra can supplement in identifying the precise morphologic classification whenever there is an overlap in the opinion of staging cervical vertebral maturation based on Hassel and Farman.

Age estimation in Turkish children and young adolescents using fourth cervical vertebra.

This study aimed to test radiographic projections of the posterior and anterior sides of the C4 vertebral body for age estimation in a cross-sectional sample of Turkish children and adolescents from the Baskent University Faculty of Dentistry. A sample of 232 x-rays from individuals aged between 5 and 15 years (101 boys and 131 girls) was analysed to investigate the correlation of age and changes in the projection ratio of the anterior and posterior sides of the body of the fourth cervical vertebra (Vba) in lateral cephalograms. The Normal Bayesian Calibration (NBC) model for age estimation was used to assess the relationship between Vba and age. The intra-observer repeatability and inter-observer agreement were 0.95 and 0.94, respectively. Age distribution gradually increased as Vba increased up to 14 years in both sexes. The difference between chronological and estimated ages did not increase with the increase in age. Calibration distributions of the dataset by the evaluation of Vba suggested mean absolute errors (MAEs) of 0.879 years and 0.906 years (mean interquartile ranges (MIQRs) 1.290 and 1.435 years)) in boys and girls, respectively. The biases of the estimates (ßERR) were 0.013 and 0.027 for boys and girls, respectively. In conclusion, the NBC method on Vba variable appears to be suitable for age estimation in Turkish children and adolescents.

Radiological Findings of the Cervical Spine in Rheumatoid Arthritis: What a Rheumatologist Should Know.

PURPOSE OF REVIEW: Rheumatoid arthritis (RA) is a chronic inflammatory disease affecting mainly the peripheral skeleton in a symmetrical manner rather than the axial skeleton, but when it occurs it can affect the cervical spine (CS). Although CS involvement is a frequent radiographic finding in RA, the clinical features are scarce, but potentially life-threatening with severe neurological deficits or even death due to brain stem compression. The commonest site of inflammation of the CS is the articulation between C1 and C2 vertebrae, the atlanto-axial region. The radiological finding observed in this region is the atlanto-axial subluxation (AAS). For the evaluation of CS in RA the classical diagnostic technique used mostly is conventional radiography (CR). Since CR does not provide good information regarding synovial inflammation, other imaging modalities are used such as magnetic resonance imaging and computed tomography. However, CR is the most valuable tool for screening CS in RA patients. Thus, we reviewed the literature until December 2019 for studies regarding CS radiological manifestations using CR in RA patients. RECENT FINDINGS: We found that the frequency of radiological findings varies substantially, ranging between 0.7-95% in different studies. The commonest radiological feature was the AAS followed by subaxial subluxation. Because CS involvement can often be clinically asymptomatic, its assessment should not be forgotten by physicians and should be assessed using CR which is an easy to perform technique and gives important information as a screening tool.

Comparative effectiveness of PEEK rods versus titanium alloy rods in cervical fusion in a new sheep model.

BACKGROUND: Pedicle screw and rod instrumentation based on titanium can produce satisfying strength and stiffness for spinal fusion. However, excessive stiffness produced by titanium rods may cause stress shielding. Thus, polyetheretherketone (PEEK) rods with a low modulus of elasticity were introduced as substitutes for titanium rods. The purpose of this paper is to compare the effectiveness of PEEK rods versus titanium alloy rods in anterior spinal fusion with a new sheep model. METHODS: Sheep models of anterior-posterior cervical fusion were innovatively adopted in our study. Twenty-four sheep were randomly divided into a control group and a treatment group that received anterior-posterior cervical fixation with titanium rods or PEEK rods, respectively. Then, surgical segments were harvested and assessed by X-ray, micro-CT and histological examination to evaluate the efficiency of bone fusion. RESULTS: No complications related to fixation were found during the research process. The results of the X-ray showed a stronger spinal fusion in the PEEK rod groups than in the titanium rod group at 12 weeks postoperatively, and both groups underwent bone fusion at 24 weeks postoperatively. The results of micro-CT showed that fixation with PEEK rods achieved better bone ingrowth at an early postoperative stage (12 weeks) compared to fixation with titanium rods (bone volume fraction (BVF): 20.26 ± 4.36% vs 14.48 ± 3.49%, p < 0.05). The same trend was detected in the histological analysis, where the mineralized bone fraction in the experiment group (21.01 ± 3.48%) was significantly higher than that in the control group (16.73 ± 2.95%). In addition, better osseointegration was found in the experiment group at the early postoperative stage at 12 weeks (bone apposition (BA): 16.22 ± 3.24% vs 11.67 ± 3.63%, p < 0.05). However, there were no significant differences at 24 weeks postoperatively. CONCLUSION: PEEK rods can be used safely in a sheep model of anterior-posterior cervical fixation. Compared to traditional titanium rods, earlier and more evident bone fusion was found in the PEEK rods group. These slides can be retrieved under Electronic Supplementary Material.

[Forensic value of the odontoid process of the second cervical vertebra as the initial object for DNA identification]. / Sudebno-meditsinskoe znachenie zuba II sheinogo pozvonka kak iskhodnogo ob"ekta dlya identifikatsionnykh DNK-issledovanii.

Aim of this study is to evaluate the suitability of the fragments of the skeleton obtained from the burials from more than 50 years ago for identificational DNA-analysis. Anatomical and structural features of the odontoid process of the second cervical vertebra are presented, as well as the data of histological examination of the odontoid process and the body of the second cervical vertebra. We conclude that odontoid process of the second cervical vertebra have practical significance as starting material for obtaining high-molecular DNA in identification cases of skeletal human remains.

A new variant ligament of the atlantooccipital joint: the lateral oblique atlantooccipital ligament.

PURPOSE: During routine dissection of the anterior craniocervical junction (CCJ), a variant ligament just anterior to the articular capsule of the atlantooccipital joint was observed. To our knowledge, no literature has previously described this ligament. Therefore, the aim of this study was to clarify the anatomy, incidence, and biomechanics of this undescribed structure of the anterior atlantooccipital joint. METHODS: Twenty-six sides from 13 fresh-frozen adult cadavers were used for this study and the morphology of the variant ligament examined. When present, its length, width, thickness, and the angle from the midline of the CCJ were measured. RESULTS: The variant ligament identified, when present, is distinct and located anterior to the atlantooccipital joint capsule traveling between the occipital bone and the transverse process of the atlas. The ligament was found on 12 of 26 sides (46.2%). The mean length of the ligament was 32.0 ± 5.5 mm. The ligament became taut with contralateral lateral flexion and the ipsilateral rotation of the atlantooccipital joint. CONCLUSIONS: We propose that this ligament may be termed the lateral oblique atlantooccipital ligament. To date, this structure has not been described in any textbooks or reports in the extant medical literature. Although its function is not clear, based on its course and connections, it might function as a secondary stabilizer of the atlantooccipital joint. As the stability of the craniocervical junction is of paramount importance, knowledge of normal and variant anatomical structures in this region is important for the surgeon treating patients with pathology of this region. These slides can be retrieved under Electronic Supplementary Material.

Monostotic fibrous dysplasia at C7 treated with vertebroplasty: a case report and review of the literature.

BACKGROUND: Monostotic fibrous dysplasia (MFD) involving the spine is rare, and the treatment options are controversial. Surgery is needed when patients suffer from persistent pain, spinal cord compression/injury, and vertebral collapse/instability. Treatment methods include biopsy/observation, corpectomy with instrumented fusion, posterior fusion, vertebroplasty (VP), curettage and bone graft, and complete removal of the vertebra with a combined anterior and posterior fusion procedure. CASE PRESENTATION: The patient was a 56-year-old woman with a 2-year history of neck pain. No obvious abnormalities were detected on neurological or physical examination, and laboratory findings were all within normal limits. An imaging examination suggested a C7 vertebral bone tumor. The patient refused to continue conservative observation treatment and requested surgery. Open VP of the C7 vertebral body was carried out, and her postoperative neck pain was completely relieved. The postoperative pathological results supported the diagnosis of fibrous dysplasia, and the patient was ultimately diagnosed with MFD. At the 12-month follow-up visit, the patient reported no clinical symptoms, and no signs of tumor recurrence were detected. CONCLUSION: VP can relieve pain while stabilizing the spine. Thus, the surgical treatment of MFD vertebral lesions by VP is a valuable option.

Suboccipital myodural bridges revisited: Application to cervicogenic headaches.

There seems to be no complete demonstration of the suboccipital fascial configuration. In 30 human fetuses near term, we found two types of candidate myodural bridge: (1) a thick connective tissue band running between the rectus capitis posterior major and minor muscles (rectus capitis posterior major [Rma], rectus capitis posterior minori [Rmi]; Type 1 bridge; 27 fetuses); and (2) a thin fascia extending from the upper margin of the Rmi (Type 2 bridge; 20 fetuses). Neither of these bridge candidates contained elastic fibers. The Type 1 bridge originated from: (1) fatty tissue located beneath the semispinalis capitis (four fetuses); (2) a fascia covering the multifidus (nine); (3) a fascia bordering between the Rma and Rmi or lining the Rma (13); (4) a fascia covering the inferior aspect of the Rmi (three); and (5) a common fascia covering the Rma and obliquus capitis inferior muscle (nine). Multiple origins usually coexisted in the 27 fetuses. In the minor Type 2 bridge, composite fibers were aligned in the same direction as striated muscle fibers. Thus, force transmission via the thin fascia seemed to be effective along a straight line. However, in the major Type 1 bridges, striated muscle fibers almost always did not insert into or originate from the covering fascia. Moreover, at and near the dural attachment, most composite fibers of Type 1 bridges were interrupted by subdural veins and dispersed around the veins. In newborns, force transmission via myodural bridges was likely to be limited or ineffective. The postnatal growth might determine a likely connection between the bridge and headache. Clin. Anat. 32:914-928, 2019. © 2019 Wiley Periodicals, Inc.

Morphometry evaluations of cervical osseous endplates based on three dimensional reconstructions.

PURPOSE: Accurate and comprehensive data on cervical endplates is essential for developing and improving cervical devices. However, current literature on vertebral disc geometry is scarce or not suitable. The aim of this study was to obtain quantitative parameters of cervical endplates and provide morphometric references for designing cervical devices. METHODS: In this study, 19 human cervical spine cadaveric specimens were considered. Employing a reverse engineering system, the surface information of each endplate was recorded in digital cloud and then 3D reconstructed. A measurement protocol that included three sagittal and three frontal surface curves was developed. The information of surface curves and endplate concavity were obtained and analyzed. The parametric equations of endplate surfaces were deduced based on coordinates of landmarks, and the reliability was verified. RESULTS: The cervical endplate surface had a trend that to be transversely elongated gradually. The concavity depths of inferior endplates (1.88 to 2.13 mm) were significantly larger than those of superior endplates (0.62 to 0.84 mm). The most-concave points in inferior endplates were concentrated in the central portion, while always located in post-median region in superior endplates. CONCLUSION: These results will give appropriate guidelines to design cervical prostheses without sacrificing valuable bone stock. The parametric equations applied for generating surface profile of cervical endplates may provide great convenience for subsequent studies.

Arcuate foramen: "Anatomical variation shape or adaptation legacy?"

PURPOSE: The groove of the vertebral artery on the posterior arch of the atlas (sulcus arteriae vertebralis) may become a complete or partial osseous foramen: the arcuate foramen. The presence of a complete or partial arcuate foramen is a rare anatomical variant described in a minority of patients and it seems to be associated with vertigo, vertebro-basilar insufficiency, posterior circulation strokes, and musculoskeletal pain. As the number and morphology of cervical vertebrae is highly preserved, we questioned about its significance from an evolutionary point of view. We thus investigated through an extensive literature review if the arcuate foramen is a pure anatomical variation shape or if it might represent an adaptation legacy. METHODS: We observed five atlas of an extinct species, the Late Pleistocene Mammoths (M. primigenius), and we compared them with five atlas of a closely related existent species, the African elephant (L. africana). RESULTS: All the mammoths' atlas had an arcuate foramen through which the vertebral artery passed before turning anteriorly and becoming intradural. This foramen was not present in elephants' atlas, where only a groove was observed, such as in the majority of patients. CONCLUSION: We would like to raise the hypothesis that this peculiar morphology of mammoths' atlas might have contributed, in association with other factors, to their precocious extinction and that the arcuate foramen might represent a disadvantage in the evolutionary process, with a low prevalence in humans being the result of a natural selection.

[Change of esophageal length measured on computed tomography after corrective osteotomy for cervicothoracic kyphosis in patients with ankylosing spondylitis and its clinical significance].

Objective: To investigate the change of esophageal length measured on computed tomography after C(7) pedicle subtraction osteotomy (PSO) for cervicothoracic kyphosis in ankylosing spondylitis (AS) patients and its clinical significance. Methods: Eight male AS patients with cervicothoracic kyphosis, who underwent PSO at C(7) level from December 2014 to November 2018 at Nanjing Drum Tower Hospital, were retrospectively reviewed. The mean age was (35±7) years (range, 26-49 years). The cervicothoracic kyphosis, C(2)-T(1) sagittal vertical axis (SVA) and angle of fusion levels (AFL) were measured on lateral cervical radiographs and chin-brow vertical angle (CBVA) was measured on clinical photographs preoperatively and postoperatively. Anterior height of the osteotomized vertebra (AHOV) and esophageal length from the lower endplate of C(6) to the inferior endplate of the lower instrumented vertebrae were measured on sagittal plane of reconstructed computed tomography preoperatively and postoperatively. Oswestry Disability Index (ODI), Neck Disability Index (NDI) and Numerical Rating Scale (NRS) were collected to evaluate the clinical outcomes. Results: The average follow-up duration was (15±9) months (range, 3-51 months). The average correction of cervicothoracic kyphosis, C(2)-T(1)SVA, AFL and CBVA was 35.9°±7.3°, (44.7±11.6) mm, 32.0°±4.8° and 38.1°±11.5°, respectively. The average reduction of AHOV was (5.6±1.6) mm. ODI was improved from 17±14 preoperatively to 13±10 at the final follow-up. The NDI before operation and at the final follow-up was 18±15 and 10±6, respectively. The preoperative NRS was 4.8±2.4, and it decreased to 1.0±1.2 at the final follow-up. The change of esophageal length showed significant correlation with the improvement of cervicothoracic kyphosis, C(2)-T(1)SVA, AFL and CBVA(r=0.84, 0.83, 0.83, 0.73, all P<0.05). Conclusions: The operation of C(7)PSO increases esophageal length after cervicothoracic kyphosis in AS patients. The esophageal elongation is closely related with changes of parameters measured on radiographs and clinical photographs. Spine surgeons should be aware of the potential risk of esophagus-related complications caused by esophagus lengthening after C(7)PSO.