Post-traumatic Central or Axial atlantoaxial dislocation (CAAD) presenting with 'atypical' symptoms- Analysing the role of dynamic imaging on the basis of experience with 14 patients treated by atlantoaxial fixation surgery

AIM

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 relatively severe injury to the head and/or neck several months or years prior to the surgical treatment. Implications of diagnosing and treating central or axial atlantoaxial instability (CAAD) is discussed. Role of dynamic rotatory and lateral head tilt imaging in the diagnosis and treatment is analysed.

MATERIAL AND METHODS

There were 7 males and 7 females and their ages ranged from 21 to 64 years (average 42 years). Due to the severity of presenting neurological and non-neurological symptoms, all patients lost their occupation and were heavily dependent on painkillers and/or antidepressant drugs. In addition to other tell-tale clinical and radiological evidence, diagnosis of CAAD was made based on facetal alignments on lateral profile imaging in neutral head position. Dynamic head flexion-extension, lateral head tilt and neck rotation imaging confirmed and subclassified CAAD. All patients underwent atlantoaxial fixation surgery.

RESULT

A personalized self-assessment clinical scoring parameter and the WHODAS 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, there was relief from all major symptoms in the rest of 13 patients.

CONCLUSIONS

Diagnosing and treating CAAD can have 'major' therapeutic implications in patients presenting with progressively worsening disabling clinical symptoms following relatively severe head/neck trauma.

Feasibility of C2 Lamina Screw Placement in a New Zealand Cohort: Computed Tomography Analysis According to Ethnicity and Gender

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.

The effect of temporomandibular joint dysfunction on the craniocervical mandibular system: A retrospective study

BACKGROUND

Temporomandibular disorders are the most common condition affecting the orofacial region, resulting in pain and dysfunction.

OBJECTIVE

This study aimed to elucidate the ambiguous association between cervical features and temporomandibular disorders by measuring the rotations between the skull-atlas, atlas-axis and mandible-atlas and examining the relationship between these rotations and temporomandibular disorders.

METHODS

Cone-beam computed tomography (CBCT) images from 176 patients, 97 females and 79 males with an average age of 25.7 years were used in this study. The patients were divided into two groups: those with joint dysfunction (n = 88) and those without (n = 88). The study employed various methods to determine rotations in the skull-atlas, atlas-axis and mandible atlas based on anatomical landmarks and measurements. These methods include the use of specific planes, angles and distances to identify and measure rotation. Data analysis was performed using the TURCOSA statistical software (Turcosa Analytics Ltd Co, Turkey, www.turcosa.com.tr).

RESULTS

The results showed that the degree of rotation between the skull and the atlas was higher in the TMD group than in the control group (p < .001). Similarly, Atlas-axis rotation was significantly higher in the TMD group (p < .001). However, no significant difference was found between mandible atlas rotations in the two groups (p = .546). The study also found a significant difference between the direction of rotation between the atlas and axis and the direction of mandible atlas rotation (p < .001) as well as between skull and atlas rotations and mandible-atlas rotations (p < .001).

CONCLUSION

Overall, the study suggests that there is a relationship between the skeletal structures of the cranio-cervico-mandibular system and TMD. Skull-atlas and atlas-axis rotations may play an important role in the aetiology of TMD in individuals with TMD. Therefore, it is important to evaluate rotations in the skull-atlas-axis region for the treatment of TMD.

Gut microbiota and its metabolic products in acute respiratory distress syndrome

The prevalence rate of acute respiratory distress syndrome (ARDS) is estimated at approximately 10% in critically ill patients worldwide, with the mortality rate ranging from 17% to 39%. Currently, ARDS mortality is usually higher in patients with COVID-19, giving another challenge for ARDS treatment. However, the treatment efficacy for ARDS is far from satisfactory. The relationship between the gut microbiota and ARDS has been substantiated by relevant scientific studies. ARDS not only changes the distribution of gut microbiota, but also influences intestinal mucosal barrier through the alteration of gut microbiota. The modulation of gut microbiota can impact the onset and progression of ARDS by triggering dysfunctions in inflammatory response and immune cells, oxidative stress, cell apoptosis, autophagy, pyroptosis, and ferroptosis mechanisms. Meanwhile, ARDS may also influence the distribution of metabolic products of gut microbiota. In this review, we focus on the impact of ARDS on gut microbiota and how the alteration of gut microbiota further influences the immune function, cellular functions and related signaling pathways during ARDS. The roles of gut microbiota-derived metabolites in the development and occurrence of ARDS are also discussed.

The role of spatial words in the spatialisation of time

Language about time is an integral part of how we spatialise time. Factors like temporal focus can be related to time spatialisation as well. The current study investigates the role of language in how we spatialise time, using a temporal diagram task modified to include the lateral axis. We asked participants to place temporal events provided in non-metaphorical, sagittal metaphorical, and non-sagittal metaphorical scenarios on a temporal diagram. We found that sagittal metaphors elicited sagittal spatialisations of time, whereas the other two types elicited lateral spatialisations. Participants sometimes used the sagittal and lateral axes in combination to spatialise time. Exploratory analyses indicated that individuals' time management habits, temporal distance, and event order in written scenarios were related to time spatialisations. Their temporal focus scores, however, were not. Findings suggest that temporal language plays an important role in how we map space onto time.

Exosome-Mediated Transfer of circ-GLIS3 Enhances Temozolomide Resistance in Glioma Cells Through the miR-548m/MED31 Axis

Background: Temozolomide (TMZ) resistance plays a critical role in the treatment of glioma. This research explored how circRNAs affect the chemosensitivity of glioma cells. Materials and Methods: The authors performed gene sequencing and selected circRNAs specifically expressed in TMZ-R cells and used them as target genes for subsequent studies. By knocking out the target gene, the authors clarify its effect on TMZ-R glioma proliferation, invasion, migration, and cell apoptosis; and through tumor-burdened animals, the authors explore the effect of the target gene in an in vivo environment. Results: The authors revealed that circ-GLIS3 was significantly upregulated in TMZ-R glioma cells. Functionally, knocking down circ-GLIS3 could inhibit proliferation, invasion, and migration abilities of TMZ-R glioma cells. Moreover, downregulation of circ-GLIS3 could induce cell cycle arrest and apoptosis, while miR-548m inhibition and MED31 mRNA could reverse this progress. In vivo silencing of circ-GLIS3 could induce cell apoptosis and suppressed tumor growth. Mechanistically, circ-GLIS3 positively upregulated MED31 expression by sponging miR-548m. Conclusions: All these results demonstrate that circ-GLIS3 accelerates TMZ-R glioma progression through the miR-548m/MED31 axis.

Full-endoscopic uniportal retropharyngeal odontoidectomy: A preliminary case report

Summary of background data

Odontoidectomy aims to decompress the medulla oblongata and is usually performed through the classical transoral approach, which affects oropharynx and accompanied with high rate of complications comprising swallowing and respiratory tract. We have developed a minimal invasive method via a standard cervical anterior approach: full-endoscopic trans-cervical odontoidectomy, which provides an alternative access for the resection of odontoid process and medulla oblongata decompression without traversing potentially contaminated cavities.

Methods

From 2018 to 2020, three patients with either odontoid process lesion or basilar invagination underwent full-endoscopic uniportal trans-cervical odontoidectomy with/without combining the posterior instrumentation. With fluoroscopic guidance, a uniportal endoscope sleeve was placed inside of the odontoid process; then odontoid process was gradually resected from the inside to outside under endoscopic monitoring. Postoperative images and clinical data were collected during post-op follow-up.

Result

Patients were soon extubated after surgery when patients wake up from general anesthesia. There were no severely perioperative complications, especially dysphagia and airway obstruction, and the symptoms and neurological function was improved immediately after surgery. The final pathology of one patient with odontoid osteolytic lesion was confirmed as plasmacytoma. The postoperative CT scans proved that the range of odontoid process resection was consistent with the preoperative expectation.

Conclusion

In summary, our proposed endoscopic trans-cervical odontoidectomy provides a valid choice for non-oral approach, which would reduce postoperative approach related complications and accelerate postoperative recovery.

CT and MRI characterization of presumed persistent ossiculum terminale in dogs

Anecdotally, during the review of CT and MRI studies of canine patients including the cranial cervical spine, authors have identified a small osseous structure between the atlas (C1) and axis (C2) with no relevant clinical signs. This structure appeared comparable to a "persistent ossiculum terminale" in humans. The aim of this retrospective, multi-center, case series study was to describe the CT and MRI features of presumed persistent ossiculum terminale in a group of dogs presented with unrelated medical conditions.  Two databases (the imaging database of the teleradiology service VetCT Specialists and the clinical database of the University of Vienna) were scrutinized by different approaches. Medical records of dogs that underwent imaging investigation (CT and/or MRI) that included the atlanto-axial junction were reviewed. Data collected included signalment, sex, breed, age, presenting symptoms, and final diagnosis. Eighteen dogs met the inclusion criteria. Mean age was 85 months (6-166) and breed variation was present. A total of 20 imaging studies were evaluated: CT was performed in 17 dogs; MRI in three dogs; two dogs had both MRI and CT performed. In all cases the presence of at least one small osseous body on the cranial aspect of the odontoid process compatible with a persistent ossiculum terminale was identified as a possible incidental finding without any overt clinical implications. Findings indicated that a small osseous body on the cranial aspect of the odontoid process (presumed persistent ossiculum terminale) in CT and MRI studies may be present in dogs with no clinical signs of neurologic disease.

A radiographic study of dorsovolar wrist axes and a database of angular measurements on axial computed tomography images

OBJECTIVES

This study aims to identify the most accurate dorsovolar principal axis of the distal radius and carpus identified on axial computed tomography (CT) sections and to establish normative data for angular measurements among these axes.

PATIENTS AND METHODS

Between December 2019 and December 2021, normal axial CT images of wrists of a total of 42 individuals (25 males, 17 females; mean age: 31±8.4 years; range, 18 to 45 years) were retrospectively analyzed. Eight axes were identified on axial CT images: four distal radial axes (the volar cortical, medial cortical, central, and sigmoid notch axes) and four carpal axes (the scapholunate, lunotriquetral, capitohamate, and pisotrapezial axes). Twenty-two angular parameters were measured with reference to four principal axes (the volar cortical, medial cortical, central, and pisotrapezial axes).

RESULTS

The mean sigmoid notch rotation (version) angles relative to the four principal axes were 8±5° (range, -2° to 18°), 6±5° (range, -2° to 13°), 1±5° (range, -8° to 14°), and 4±4° (range, -3° to 15°), respectively. The mean scapholunate rotation angles were -13±5° (range, -27° to -6°), -15±6° (range, -29° to -8°), -21±5° (range, -30° to -11°), and -8±5° (range, -28° to -6°), respectively. Among four principal axes, the volar cortical and medial cortical axes were nearly collinear with both of relatively fixed carpal axes. The four principal axes showed angular differences between 2° and 8° with each other. There was no significant difference between men and women for all measurements.

CONCLUSION

The axial CT sections can be used to describe the various angulations between the normal wrist axes such as the sigmoid notch and scapholunate joint rotation angles. Despite slight differences among the four principal axes, the volar cortical and medial cortical axes are more consistent with the relatively fixed carpal axes.

Classifications of Odontoid Process Fractures: A Systematic Review and Proposal of a New Simplified Classification System Based on Embryology

Odontoid fractures are the most common cervical spine fractures in the elderly. Although many classification systems have been developed for them, the ambiguity in various definitions can potentially lead to misunderstandings. This paper aims to review the terminologies and current classification systems of odontoid fractures and propose a new, simplified anatomical classification. Given the descriptive variability of odontoid fractures in current classifications, we systematically reviewed the literature using PRISMA guidelines querying the National Library of Medicine PubMed database. The initial literature search yielded 175 publications. A total of seven reports met the inclusion criteria and were ultimately included for a full review. The classification systems previously used to categorize fractures of the odontoid process often need to be more transparent, imprecise, and incongruous. To simplify them, a new embryologically accurate system is proposed. A new embryological and anatomically-based system, combining the former systems' specific attributes, allows a more straightforward and adaptable classification of odontoid fractures.

The Classification of Axial Deformity in Patients with Basilar Invagination

OBJECTIVE

To summarize the variation types of the axis in patients with basilar invagination (BI), then propose a classification scheme of the axis deformity.

METHODS

From December 2013 to September 2020, 92 patients (male 42, female 50) who were diagnosed with BI were studied retrospectively. Based on the imaging data of CT, the width and height of the axis pedicle and the sagittal diameter of the lateral mass were measured in each patient. According to the development of axis pedicle and lateral mass, the types of axis variation were summarized, and then the classification scheme of axis deformity was put forward.

RESULTS

All cases were analyzed and axis deformities were divided into four types. Type I: the axis is basically normal (53 cases, 57.6%). Type II: axis lateral mass is dysplasia (eight cases, 8.7%), which includes two subtypes: type IIA, the axis unilateral lateral mass is dysplasia (three cases); type IIB, the axis bilateral lateral masses are all dysplasia (five cases). Type III: axis pedicle is dysplasia (11 cases, 12%), which is subdivided into two subtypes: type IIIA, the axis unilateral pedicle is dysplasia (six cases); type IIIB, the axis bilateral pedicles are all dysplasia (five cases). Type IV: axis pedicle and lateral mass are all dysplasia (20 cases, 21.7%), this type contains the following four subtypes: type IVA, the unilateral axis pedicle and unilateral lateral mass (contralateral or ipsilateral) are all hypoplasia (four cases); type IVB, the unilateral axis pedicle and bilateral lateral masses are all hypoplasia (five cases); type IVC, the bilateral axis pedicles and unilateral lateral mass are all dysplasia (seven cases); type IVD, the bilateral axis pedicles and bilateral lateral masses are all dysplasia (four cases). The left and right abnormal lateral mass sagittal diameter (Type II) was (7.23 ± 1.39) mm and (5.96 ± 1.37) mm, respectively, the left and right abnormal pedicle width (Type III) was (2.61 ± 1.01) mm and (3.23 ± 0.66) mm, respectively, left and right abnormal pedicle height (Type III) was (5.43 ± 2.19) mm and (4.92 ± 1.76) mm, respectively. Moreover, the classification scheme has good repeatability and credibility.

CONCLUSIONS

The classification about axis deformity could provide personalized guidance for axis screw placement in the BI and other upper cervical surgery, and axis screw placement errors would be effectively avoided.

Morphological variations in the transverse foramen of the axis in Japanese serows (Capricornis crispus)

The presence of transverse foramina in the axes of Japanese serows, a special national natural treasure in Japan, has been reported to be unstable, but other variations are unknown. In this study, we analysed the shape, cross-sectional area, length, and volume of the transverse foramen in the axes of 19 specimens using gross anatomy and computed tomography (CT) scan. There were four types in the transverse foramen: type 1, having the transverse foramina; type 2, having two cranial openings; type 3, sifting a caudal opening to the ventral side of the transverse process; and type 4, having no transverse foramina. Although the transverse foramina showed different types on the left and right sides in several specimens, there were no statistically significant differences in the length and volume. This variation may be related to running patterns of the vertebral artery penetrating the transverse foramina. Two goats without the transverse foramina were examined to infer a running pattern of the vertebral artery instead of Japanese serows. The vertebral artery in the goats branched in two directions (spinal and muscle), between the axis and the third cervical vertebra. This passage of the goat vertebral artery might be presumed in type 4 of Japanese serows. This study reveals the instability of the transverse foramina in the axes of Japanese serows and provides new data to compare the axes of other ruminants.

Analysis of Upper Cervical Spine Measurements in the Uninjured Pediatric Spine

BACKGROUND

Only a small number of studies have offered normative data for the upper cervical spine in children and with some variation in findings.

OBJECTIVE

The aim of this study was to determine normal values for upper cervical spine measurements used in the assessment of upper cervical spine trauma in the pediatric population.

METHODS

One-hundred computed tomographic images of the cervical spine of children aged ≤16 years were included for analysis. All children were cleared of spinal injury. Anterior atlanto-dens interval (ADI), posterior atlanto-dens interval (PADI), basion-dens interval (BDI), Powers ratio, condylar-C1 interval (CCI), and lateral mass interval (LMI) were measured on the relevant sagittal or coronal images. Measurements for CCI and LMI were taken on each side.

RESULTS

Mean age was 111 months (range 11-196 months). Sixty-two were male. Mean values (and ranges) of the measurements were as follows: BDI: 7.1 mm (3.6-12.2); ADI 2.8 mm (0.8-4.8); PADI 18.7 mm (14.1-23.2); Powers ratio 0.72 (0.59-1.0); CCI 2.0 and 2.0 (0.5-4.2); and LMI 3.2 and 3.3 mm (1.7-4.8). BDI (r = -0.488), ADI (r = -0.201), PADI (r = 0.264), and CCI (r = -0.468 and -0.454) all showed significant correlation with age. The Powers ratio was the most stable measurement across all age groups.

CONCLUSIONS

Normal values were reported from a local pediatric population with a wide age range. Most values correlate with age to a degree, and so normal values may vary throughout childhood. A multicenter study is desirable to advance knowledge in this field.

CLINICAL RELEVANCE

Current radiographic measures used to assess for possible ligamentous injury in the pediatric upper cervical spine correlate with age. Caution must be held when analyzing the upper cervical spine across a range of age groups in children.

LEVEL OF EVIDENCE: 4

Realignment Midfoot Osteotomy: A Preoperative Planning Method and Intraoperative Surgical Technique

Deformities of the midfoot are often treated with midfoot osteotomies. The goal of the midfoot osteotomy is to create a plantigrade forefoot to hindfoot relationship. Many different techniques are described for performing midfoot osteotomies. Our goal is to present an objective pre-operative planning method and an intra-operative technique for accurate multiplanar realignment and discuss our short-term results. We retrospectively reviewed 18 patients, 10 female (56%) and 8 male (44%), that underwent realignment midfoot osteotomies. The mean follow-up was 25 months (range, 4-120). The mean age at the time of surgery was 53 years (range, 21-76). Statistically significant improvement in radiographic alignment was found in the anteroposterior talo-first metatarsal angle (p = .002) and the mechanical axis deviation of the foot (p = .02). This study proved that our pre-operative and intra-operative planning technique provides accurate multiplanar radiographic realignment with good clinical results.

Precocious puberty and microbiota: The role of the sex hormone-gut microbiome axis

Puberty is a critical phase of life associated with physiological changes related to sexual maturation, and represents a complex process regulated by multiple endocrine and genetic controls. Puberty is driven by hormones, and it can impact the gut microbiome (GM). GM differences between sex emerge at puberty onset, confirming a relationship between microbiota and sex hormones. In this narrative review, we present an overview of precocious pubertal development and the changes in the GM in precocious puberty (PP) in order to consider the role of the sex hormone-gut microbiome axis from the perspective of pediatric endocrinology. Bidirectional interactions between the GM and sex hormones have been proposed in different studies. Although the evidence on the interaction between microbiota and sex hormones remains limited in pediatric patients, the evidence that GM alterations may occur in girls with central precocious puberty (CPP) represents an interesting finding for the prediction and prevention of PP. Deepening the understanding of the connection between the sex hormones and the role of microbiota changes can lead to the implementation of microbiota-targeted therapies in pubertal disorders by offering a pediatric endocrinology perspective.

Posterior First and Second Cervical Vertebrae Fusion by Screw Fixation Technique using the Modern Pre-fabricated Template Method on Cadaver Samples

Introduction

C1 lateral mass and C2 pedicular screws insertion are used for C1-C2 posterior fusion. Fluoroscopy Guided technique is routinely used for screw placement but it is associated with risk of injury to spinal cord and vertebral artery. 3D printing has developed rapidly in the fields of medicine. It is helpful in improving precise treatment and used for instrumentation in spine. We want to evaluate the accuracy of C1 lateral mass screws and C2 pedicle screws insertion by Pre-Fabricated Template made by three-dimensional (3D) printing.

Materials and methods

Five cervical samples were obtained from cadavers. Based on fine-cut CT scan 3D-images reconstructed and the path of the screws designed by special software. A template produced by 3D-printer from 3D images. After printing the templates, they were fixed on the relevant vertebra in the operation room and based on the template path, C1 lateral mass screw and C2 pedicular screws were inserted. Placement of the screws was evaluated using CT scans post-operatively.

Results

A total of 14 screws were inserted by above-mentioned method. After evaluation with CT scans none of the screws were entered in the spinal canal. Two screws had vertebral artery canal perforation with less than 50% breach. Violation was judged as noncritical and would probably not have resulted in injury to vertebral artery.

Conclusions

The accuracy of C1 lateral mass screw and C2 pedicle screw insertion is acceptable with pre-fabricated template and can provide a useful aid for screw placement.

The Relationship Between the Gut Microbiome-Immune System-Brain Axis and Major Depressive Disorder

Major depressive disorder (MDD) is a prominent cause of disability worldwide. Current antidepressant drugs produce full remission in only about one-third of MDD patients and there are no biomarkers to guide physicians in selecting the best treatment for individuals. There is an urgency to learn more about the etiology of MDD and to identify new targets that will lead to improved therapy and hopefully aid in predicting and preventing MDD. There has been extensive interest in the roles of the immune system and the gut microbiome in MDD and in how these systems interact. Gut microbes can contribute to the nature of immune responses, and a chronic inflammatory state may lead to increased responsiveness to stress and to development of MDD. The gut microbiome-immune system-brain axis is bidirectional, is sensitive to stress and is important in development of stress-related disorders such as MDD. Communication between the gut and brain involves the enteric nervous system (ENS), the autonomic nervous system (ANS), neuroendocrine signaling systems and the immune system, and all of these can interact with the gut microbiota. Preclinical studies and preliminary clinical investigations have reported improved mood with administration of probiotics and prebiotics, but large, carefully controlled clinical trials are now necessary to evaluate their effectiveness in treating MDD. The roles that several gut microbe-derived molecules such as neurotransmitters, short chain fatty acids and tryptophan play in MDD are reviewed briefly. Challenges and potential future directions associated with studying this important axis as it relates to MDD are discussed.

Neurodevelopment of the association cortices: Patterns, mechanisms, and implications for psychopathology

The human brain undergoes a prolonged period of cortical development that spans multiple decades. During childhood and adolescence, cortical development progresses from lower-order, primary and unimodal cortices with sensory and motor functions to higher-order, transmodal association cortices subserving executive, socioemotional, and mentalizing functions. The spatiotemporal patterning of cortical maturation thus proceeds in a hierarchical manner, conforming to an evolutionarily rooted, sensorimotor-to-association axis of cortical organization. This developmental program has been characterized by data derived from multimodal human neuroimaging and is linked to the hierarchical unfolding of plasticity-related neurobiological events. Critically, this developmental program serves to enhance feature variation between lower-order and higher-order regions, thus endowing the brain's association cortices with unique functional properties. However, accumulating evidence suggests that protracted plasticity within late-maturing association cortices, which represents a defining feature of the human developmental program, also confers risk for diverse developmental psychopathologies.

Integration between the cranial boundaries of the nasopharynx and the upper cervical vertebrae in Homo and Pan

The nasopharynx is an important anatomical structure involved in respiration. Its bony boundaries, including the basicranium and upper cervical vertebrae, may be subject to selective pressures and constraints related to respiratory function. Here, we investigate phenotypic integration, or covariation, between the face, the basicranial boundaries of the nasopharynx, and the atlas and axis to understand constraints affecting these structures. We collected three-dimensional coordinate data from a sample of 80 humans and 44 chimpanzees, and used two-block partial least squares to assess RV (a multivariate generalization of Pearson's r² ), r_PLS , the covariance ratio, and effect size for integration among structures. We find that integration is significant among some of these structures, and that integration between the basicranial nasopharynx and vertebrae and between the face and vertebrae is likely independent. We also find divergences in the pattern of integration between humans and chimpanzees suggesting greater constraints among the human face and nasopharynx, which we suggest are linked to divergent developmental trajectories in the two taxa. Evolutionary changes in human basicranial anatomy, coupled with human-like developmental trajectories, may have required that the face grow to compensate any variation in nasopharyngeal structure. However, we were unable to determine whether the nasopharynx or the face is more strongly integrated with the vertebrae, and therefore whether respiration or biomechanical considerations related to positional behavior may be more strongly tied to vertebral evolution. Future work should focus on greater sample sizes, soft tissue structures, and more diverse taxa to further clarify these findings.

The Combined Effect of Tropicamide and Phenylephrine on Corneal Astigmatism Axis

PURPOSE

To analyze astigmatism axis changes after tropicamide and phenylephrine combined instillation.

METHOD

One hundred and thirty-one eyes from 66 patients enrolled this cross-sectional study. An extensive ocular examination was carried out prior to tropicamide and phenylephrine instillation. Power and axis value from flat, steep, and mean keratometry were calculated using an Auto Kerato-Refractometer (AKR). Later, topography and tomography maps were evaluated with Pentacam HR® (Oculus, Wetzlar, Germany). Subsequently, a single drop of tropicamide 1% and phenylephrine hydrochloride 10% were instilled twice, with a five-minute gap between each instillation. After 30 minutes, the AKR and Pentacam HR® tests were repeated.

RESULTS

Incyclotorsion was found in 59 eyes (45.1%) and mean absolute incyclotorsion change was 3.91 ± 3.62 degrees (0.10 to 14.20). Excyclotorsion was found in 72 eyes (54.9%) and mean excyclotorsion change was 4.99 ± 5.94 degrees (0.20 to 36.20). We observed that 74.6% and 68.1% of eyes experienced incyclotorsion and excyclotorsion within 0 to 5 degrees, respectively. Fewer patients experienced incyclotorsion and excyclotorsion changes within 5 to 10 degrees, precisely 11.8% and 19.4%, respectively. Eyes that experienced over 10 degrees of incyclotorsion and excyclotorsion were 13.6% and 12.5%, respectively.

CONCLUSION

Astigmatism axis could change after combined tropicamide and phenylephrine instillation. Reference axis marking in astigmatism correction surgery should be performed under the same circumstances as the astigmatism axis has been measured.

Analysis of Nonunion in Conservatively Managed Anterior Tear Drop Fractures of C2 Vertebra

Many anterior C2 (2nd cervical vertebra) tear drop (TD) fractures can be successfully managed with conservative treatment. However, due to the occurrence of nonunion, large-sized or complex anterior C2 TD fractures undergo surgical treatment. To date, no surgical treatment guidelines are available about anterior C2 TD fractures. Therefore, we performed this study to investigate the factors that may affect nonunion for anterior C2 TD fractures and to suggest surgical treatment guidelines. Thirty-three patients with anterior C2 TD fractures, who underwent conservative treatment and had a minimum 1-year follow-up, were divided into union (N = 26) and nonunion (N = 7) groups. Their radiological and clinical data were analyzed retrospectively and compared between the two groups. The avulsion fracture ratio (29.5% vs. 43.3%, p < 0.05) and fracture displacement (3.6 mm vs. 5.1 mm, p < 0.05) were higher in the nonunion group compared to the union group. Incidence of associated C2 injury was higher in the nonunion group compared to the union group (15.4% vs. 57.1%, p < 0.05). Union status was negatively correlated with associated C2 injury (correlation coefficient, CC = -0.398, p < 0.05). Our results suggest that surgical treatment could be considered for anterior C2 TD fractures with an avulsion fracture ratio > 43%, fracture displacement > 5 mm, or associated C2 injury.

Comparison of Mechanical Axis of the Limb Versus Anatomical Axis of the Tibia for Assessment of Tibiotalar Alignment in End-Stage Ankle Arthritis

BACKGROUND

Coronal plane ankle joint alignment is typically assessed using the tibiotalar angle (TTA), which relies on the anatomical axis of the tibia (AAT) and the articular surface of the talus as landmarks. Often, the AAT differs from the mechanical axis of the lower limb (MAL). We set out to test our hypothesis that the TTA using the MAL would differ from the TTA measured using the AAT in patients with ankle osteoarthritis.

METHODS

Standardized standing long leg radiographs of 61 ankles with end-stage osteoarthritis were analyzed. We measured the MAL and the AAT. A line was drawn along the talar articular surface (TA) and the TTA was calculated using both the MAL (MAL-TA) and the AAT (AAT-TA). The mechanical axis of the tibia (MAT) was also recorded and the MAL-MAT angle calculated. The difference between MAL-TA and AAT-TA and its correlation with the MAL-MAT angle were assessed. Intra- and interobserver agreement were measured for MAL-TA and AAT-TA.

RESULTS

The mean MAL-TA was 91.4 degrees (95% CI, 88.5-94.4) and the mean AAT-TA was 91.2 degrees (95% CI, 88.6-93.9). The difference ranged from -8.1 to 7.8 degrees, and was greater than 2 and 3 degrees in 42% and 18% of the patients, respectively. The difference, as an absolute value, also strongly correlated with the MAL-MAT angle (r = 0.91, P < .001). Intra- and interobserver reliability were excellent for both MAL-TA (intraclass correlation coefficient [ICC], 0.93 and 0.91, respectively) and AAT-TA (ICC, 0.91 and 0.89, respectively).

CONCLUSION

We recommend that surgeons consider using the MAL-TA, which relies on long leg radiographs, especially with proximal deformity, to more accurately measure coronal plane ankle joint alignment.

LEVEL OF EVIDENCE

Level III, retrospective comparative study.

A morphological analysis of the cervical spine of the dolphin

Objective

Morphology of bones of cervical vertebrae of dolphin was studied. When compared to human vertebrae the structural modifications in terms of functional needs are evaluated.

Material

Morphological analysis of duly prepared bones of species D. delphis was carried out.

Result

The craniocervical junction and cervical spine of the dolphin (Delphinus delphis) has unique adaptations to allow for dorsoventrally undulating swimming movements as well as leaping out of water. The key differences from the human cervical spine include the absence of an odontoid process limiting rotatory movements, disproportionately short and wide vertebral bodies and a unilaterally elongated transverse process of the axis. Moreover, the cervical spine of the dolphin is disproportionally short compared to humans. These modifications give strength and stability to the cervical spine allowing maximal agility for flexion-extension movements of the lumbocaudal spine, which are keys for propulsion. The unilaterally elongated transverse process likely allows for rotatory spinning, suggesting possible lateral dominance of rotatory spin in this species.

Conclusions

Despite the skeletal adaptations, the cervical spine is strongly resonant of a mammalian heritage with a remarkably similar form and structure to house neurovascular contents and to allow muscular attachments.

The influence of sagittal spinopelvic alignment on patient discharge disposition following minimally invasive lumbar interbody fusion

Background

The aim of this study was to investigate the changes to spinopelvic sagittal alignment following minimally invasive (MIS) lumbar interbody fusion, and the influence of such changes on postoperative discharge disposition.

Methods

The Michigan Spine Surgery Improvement Collaborative was queried for all patients who underwent transforaminal lumbar interbody fusion (TLIF)or lateral lumbar interbody fusion (LLIF) procedures for degenerative spine disease. Several spinopelvic sagittal alignment parameters were measured, including sagittal vertical axis (SVA), lumbar lordosis, pelvic tilt, pelvic incidence, and pelvic incidence-lumbar lordosis mismatch. Primary outcome measure-discharge to a rehabilitation facility-was expressed as adjusted odds ratio (ORadj) following a multivariable logistical regression.

Results

Of the 83 patients in the study population, 11 (13.2%) were discharged to a rehabilitation facility. Preoperative SVA was equivalent. Postoperative SVA increased to 8.0 cm in the discharge-to-rehabilitation division versus a decrease to 3.6 cm in the discharge-to-home division (P<0.001). The odds of discharge to a rehabilitation facility increased by 25% for every 1-cm increase in postoperative sagittal balance (OR_adj =1.27, P=0.014). The strongest predictor of discharge to rehabilitation was increasing decade of life (OR_adj =3.13, P=0.201).

Conclusions

Correction of sagittal balance is associated with greater odds of discharge to home. These findings, coupled with the recognized implications of admission to a rehabilitation facility, will emphasize the importance of spine surgeons accounting for SVA into their surgical planning of MIS lumbar interbody fusions.

Digging into blindsnakes' morphology: Description of the skull, lower jaw, and cervical vertebrae of two Amerotyphlops (Hedges et al., 2014) (Serpentes, Typhlopidae) with comments on the typhlopoidean skull morphological diversity

Scolecophidians are small fossorial snakes that exhibit several osteological innovations, most of which driven by their extreme body miniaturization. Considering that data on skull morphology has proven to be relevant in terms of scolecophidian systematics and morphofunctional evolution, herein, we aim to describe in detail the skull, lower jaw, and cervical vertebrae of Amerotyphlops brongersmianus and A. reticulatus. Our results suggest that the investigated osteology of Amerotyphlops resembles several new world typhlopid species, with reduced interspecific variation in the basicranium, lower jaw and cervical vertebrae. Both species exhibit characters states that are typically conserved intragenerically amongst typhlopoids, such as the presence of a single parietal, paired supraoccipitals, and otooccipitals that are in contact medially, and the basioccipital participating in the formation of the foramen magnum. We discuss possible systematically important osteological skull variations among typhlopoids and provide a comprehensive comparison of these taxa based on literature and data gathered herein.

Fractures of C2 (Axis) Vertebra: Clinical Presentation and Management

BACKGROUND

Injuries of the upper cervical spine are a major cause of morbidity and mortality due to associated spinal cord and head injuries. The injury patterns of the upper cervical spine are numerous, and the neurologic sequelae are diverse. The axis (C2) is the most commonly fractured vertebra in the upper cervical spine; its unique anatomy and architecture pose difficulties in the diagnosis and the management of its fractures.

METHODS

All cases of acute spinal injuries at Prince Mohammed Bin Abdulaziz Hospital in Riyadh, Saudi Arabia, were screened for fractures of C2 vertebrae. These patients underwent computerized tomography (CT) imaging of the cervical spine with special attention paid to the cranio-cervical junction. Magnetic resonance imaging (MRI) and angiography of the neck were performed to exclude ligamentous tears and vascular injuries. Unstable fractures were fixed surgically. In the remaining cases, a conservative trial was given. All patients were followed up once every 3 months for a period of 1 year. During follow-up, some patients underwent additional CT imaging of the cervical spine to monitor the healing of fractures.

RESULTS

Out of 230 spinal trauma patients, 43.5% suffered from cervical spine injury. C2 fractures were recorded in 26% cases, and fractures of the C2 vertebral body, including pedicles, laminae, lateral masses, and articular processes, were found in many cases, followed by odontoid fractures (50%). No case of atlanto-axial or atlanto-occipital dislocation was recorded. Road traffic accidents were found to be responsible for 92% of cases. The majority of patients were young males, and 96% of patients had no neurological deficit. Only 15% of the patients required surgery for their unstable fractures. Half of the patients attended outpatient follow -up appointments, all of whom underwent CT scanning of the cervical spine 9 months after the accident or operation.

CONCLUSIONS

The axis (C2) is the most commonly affected vertebra in cervical spine trauma, and odontoid fractures make up 50% of all C2 fractures. C2 fractures rarely cause any neurological deficit or vascular injury, and the majority of affected patients can be managed conservatively; only a small proportion requires surgical intervention. Surgical intervention leads to early and complete healing.

Immersive Surgical Anatomy of the Craniocervical Junction

With the advent and increased usage of posterior, lateral, and anterior surgical approaches to the craniocervical junction (CCJ), it is essential to have a sound understanding of the osseous, ligamentous, and neurovascular layers of this region as well as their three-dimensional (3D) orientations and functional kinematics. Advances in 3D technology can be leveraged to develop a more nuanced and comprehensive understanding of the CCJ, classically depicted via dissections and sketches. As such, this study aims to illustrate - with the use of 3D technologies - the major anatomical landmarks of the CCJ in an innovative and informative way. Photogrammetry, structured light scanning, and 3D reconstruction of medical images were used to generate these high-resolution volumetric models. A clear knowledge of the critical anatomical structures and morphometrics of the CCJ is crucial for the diagnosis, classification, and treatment of pathologies in this transitional region.

Development and growth of the craniocervical junction with special reference to topographical relationship between the occipital basion, the anterior arch of atlas, and the odontoid process of axis: A study using human fetuses

The embryonic occipital bone and odontoid process of the axis are attached and connected by the notochord, but become separated in later development and growth. With special attention to the process of separation, we examined sagittal sections of the craniocervical junction in 18 human fetuses at 8-16 weeks and 22 fetuses at 31-37 weeks. At 8-9 weeks, the anterior arch of atlas was always seen overriding the occipital basal part. The odontoid process was close to the occipital with or without a transient joint cavity until 16 weeks. Near term, the top of the odontoid process was usually higher than the anterior arch, but the former was sometimes (7 of 22) at a level almost equal to or lower than the latter. The apical ligament was evident in a few specimens (5 of 22). A distance between the occipital basion and odontoid process was sometimes less than 1.5 mm (8 of 22) or less than half the thickness of the arch (10 of 22). A transient joint cavity between the basion and odontoid process was often (10 of 22). In three fetuses near term, the atlanto-occipital joint cavity was continuous with the median atlanto-axial joint cavity, and the anterior arch was overriding the occipital basal part. Therefore, rather than stage or age, individual differences were evident in the topographical relationship between the three bony elements at the craniocervical junction. An understanding of the embryology and normal development will aid in the correct interpretation of radiologic images of the pediatric cervical spine.

ASY1 acts as a dosage-dependent antagonist of telomere-led recombination and mediates crossover interference in Arabidopsis

During meiosis, interhomolog recombination produces crossovers and noncrossovers to create genetic diversity. Meiotic recombination frequency varies at multiple scales, with high subtelomeric recombination and suppressed centromeric recombination typical in many eukaryotes. During recombination, sister chromatids are tethered as loops to a polymerized chromosome axis, which, in plants, includes the ASY1 HORMA domain protein and REC8-cohesin complexes. Using chromatin immunoprecipitation, we show an ascending telomere-to-centromere gradient of ASY1 enrichment, which correlates strongly with REC8-cohesin ChIP-seq data. We mapped crossovers genome-wide in the absence of ASY1 and observe that telomere-led recombination becomes dominant. Surprisingly, asy1/+ heterozygotes also remodel crossovers toward subtelomeric regions at the expense of the pericentromeres. Telomeric recombination increases in asy1/+ occur in distal regions where ASY1 and REC8 ChIP enrichment are lowest in wild type. In wild type, the majority of crossovers show interference, meaning that they are more widely spaced along the chromosomes than expected by chance. To measure interference, we analyzed double crossover distances, MLH1 foci, and fluorescent pollen tetrads. Interestingly, while crossover interference is normal in asy1/+, it is undetectable in asy1 mutants, indicating that ASY1 is required to mediate crossover interference. Together, this is consistent with ASY1 antagonizing telomere-led recombination and promoting spaced crossover formation along the chromosomes via interference. These findings provide insight into the role of the meiotic axis in patterning recombination frequency within plant genomes.

Dynamic myelopathy as a result of C1 posterior arch aplasia and os odontoideum. A case report

The atlas (C1) and axis (C2) have distinct morphologies to support the skull and facilitate head rotation and neck flexion. Congenital defects of C1 posterior arch are rare. We present a case of a 59-year-old man with both an absent C1 posterior arch with concomitant os odontoideum. The patient presented with neck crepitus, moderate neck pain and progressive worsening upper limbs paraesthesia and pain. Computed tomography (CT) revealed non-union between the odontoid process and body of axis as well as absence of C1 posterior arch. An occiput C0–C3 fusion was performed. The patient’s symptoms improved significantly, and he is functioning well at 12 months. CT showed solid fusion without implant migration. Concomitant os odontoideum with aplastic C1 posterior arch is rare with limited evidence to guide management. Posterior fixation and fusion may be a potential solution to prevent dynamic compression, thereby preventing further myelopathy and related complications.

STRIPAK Limits Stem Cell Differentiation of a WNT Signaling Center to Control Planarian Axis Scaling

Regeneration involves regulating tissue proportionality across considerable size ranges through unknown mechanisms. In planarians, which scale reversibly over 40× through regeneration, we identify the Striatin-interacting phosphatase and kinase (STRIPAK) complex as a potent negative regulator of axis length. Inhibition of two proteins in the STRIPAK complex, mob4 and striatin, dramatically increased posterior length, through expansion of a posterior wnt1+ signaling center within midline muscle cells. wnt1 was required for tail expansion after mob4 inhibition and dynamically reestablishes proportionality after amputation in normal animals, indicating STRIPAK represses Wnt signaling for scaling. Regulation of wnt1 expansion was stem cell dependent, demonstrating that control of signaling-center production through stem cell differentiation underlies proportional growth in adult regenerative tissue.

Congenital Synostosis of Cervical Vertebrae: An Osteological Study and Review of the Literature

Introduction

The possible appearance of congenital fusion of the second cervical vertebra with adjacent cervical vertebrae, along with its epidemiology, embryological development, and clinical manifestations, was the aim of the current study.

Methods

The osteological material of 93 dried second cervical vertebrae of both sexes were examined in order to identify the likely presence of congenital fusion with the neighboring vertebrae.

Results

Among 93 axes, we identified one case of a congenitally fused second cervical vertebrae with the third and fourth cervical vertebrae, which accounted for a frequency of 1.08%. There was an incomplete fusion of the vertebral bodies and almost complete fusion of the laminae and facet joints.

Conclusion

The knowledge of such rare vertebral synostosis is crucial for the neurosurgeon, orthopedist, and physician dealing with the cervical spine, as well as the anesthetist when performing procedures, such as endotracheal intubation.

The Y-shaped trabecular bone structure in the odontoid process of the axis: a CT scan study in 54 healthy subjects and biomechanical considerations

OBJECTIVE

Odontoid process fractures are very common in both young and geriatric patients. The axial trabecular architecture of the dens appears to be crucial for physiological and biomechanical function of the C1-2 joint. The aim of this study is to demonstrate the presence of a Y-shaped trabecular structure of the dens on axial CT and to describe its anatomical and biomechanical implications.

METHODS

Fifty-four C2 odontoid processes in healthy subjects were prospectively examined for the presence of a Y-shaped trabecular structure at the odontocentral synchondrosis level with a dental cone beam CT scan. Length, width, and axial area of the odontoid process were measured in all subjects. In addition, measurements of the one-third right anterior area of the Y-shaped structure were taken.

RESULTS

The Y-shaped trabecular structure was found in 79.6% of cases. Length and width of the odontoid process were 13.5 ± 0.6 mm and 11.2 ± 0.9 mm, respectively. The mean area of the odontoid process at the odontocentral synchondrosis was 93.5 ± 4.3 mm2, whereas the mean one-third right anterior area of the odontoid process at the same level was 29.3 ± 2.5 mm2. The mean area of the odontoid process and its length and width were similar in men and women (p > 0.05). No significant difference was found in the mean area of the odontoid process in people older than 65 years (94 ± 4.2 mm2) compared to people younger than 65 years (93.3 ± 4.4 mm2; p > 0.05).

CONCLUSIONS

The authors identified a new anatomical entity, named the Y-shaped trabecular structure of the odontoid process, on axial CT scans. This structure appears to be the result of bone transformation induced by the elevated dynamic loading at the C1-2 level. The presence of the Y-shaped structure provides new insights into biomechanical responses of C2 under physiological loading and traumatic conditions.

Hypoglossal Nerve Palsy as a Rare Complication of C1-C2 Pott's Spine

Reporting a rare scenario of hypoglossal nerve palsy in craniovertebral tuberculosis. Two patients presented in outpatient department with chief complaints of pain in neck, restricted neck movements, gait changes, difficulty in speech and weakness in all the extremities. On the basis of clinicoradiological correlation, the patients were diagnosedwithtuberculosis of C1-C2 spine. They were started on antituberculosis therapy Category 1. The patients improved clinically and there was no worsening of symptoms, but they noticed tongue deviation and hypotrophy on one side of the tongue. C1-C2 tuberculosis along with cranial nerve palsy, especially hypoglossal nerve is one of the rarest presentations. Hypoglossal nerve arises from the medulla, exits through hypoglossal canal in the base of the skull and traverses neck to supply tongue musculature. Prevertebral fascia extends from superior mediastinum to base of the skull. Abscess in this area can cause either actual compression of the hypoglossal canal or C1 and base of the skull dissociation which can lead to compression of the canal.

Posterior Wall Punctures Between Long- and Short-Axis Techniques in a Phantom Intravenous Model

OBJECTIVES

To determine whether a long-axis, in-plane approach to ultrasound-guided vascular access produces fewer posterior wall punctures than a short-axis, out-of-plane approach when attempted by novices without prior ultrasound-guided procedural experience.

METHODS

Participants were randomized to perform either technique on a ballistic gel-based phantom in a randomized controlled trial. They were then crossed over to repeat the experiment using the alternative approach. The primary outcome was posterior wall puncture occurrences. Secondary outcomes included cannulation success, the time to cannulation, and provider preferences. These were formulated before data collection.

RESULTS

Forty participants completed the study. There were 6 posterior wall punctures in the short-axis, out-of-plane approach (15%) and 1 in the long-axis, in-plane approach (2.5%). A posterior wall puncture was less likely to occur when the long-axis approach was used (odds ratio, 0.15; 95% confidence interval, 0.02-0.91). There was no statistical difference in rates of successful cannulation and the time to cannulation. Eighty percent preferred the long-axis approach, whereas 85% stated that the long-axis approach provided better visualization of the needle tip throughout the procedure.

CONCLUSIONS

The long-axis, in-plane approach compared to the short-axis, out-of-plane approach for ultrasound-guided cannulation on a phantom resulted in fewer posterior wall punctures, better needle tip visibility, and higher preference among novices.

Treatment of Axis Ring Fractures: Recommendations of the Spine Section of the German Society for Orthopaedics and Trauma (DGOU)

STUDY DESIGN

Narrative literature review and expert recommendation.

OBJECTIVE

To establish treatment recommendations for axis ring fractures based on the knowledge of the experts of the Spine Section of the German Society for Orthopaedics and Trauma.

METHODS

This recommendation summarizes the knowledge of the experts of the Spine Section of the German Society for Orthopaedics and Trauma with regard to the treatment of axis ring fractures based on a narrative literature review.

RESULTS

Typical "hangman's fractures" with bilateral separation of the neural arch from C2 and atypical "hangman's fractures" with irregular fracture morphology are described. Computed tomography is the "gold" standard used to detect and analyse these fractures adequately. Furthermore, the detection of vertebral artery integrity is necessary. To classify axis ring fractures, the Levine-Edwards or Josten classification is recommended. In particular, the integrity of the C2/3 disc and the integrity of the anterior longitudinal ligament are used to determine the treatment strategy. While Levine-Edwards type I and type IIA (Josten type 1 and 2) fractures should be treated conservatively, Levine type II and type III (Josten type 3 and 4) fractures should be treated operatively. Levine-Edwards type II fractures will be predominately treated by anterior C2/3 fusion. Levine-Edwards type III fractures have to be primary reduced, if an anterior fusion is planned (anterior cervical discectomy and fusion [ACDF] C2/3). If a closed reduction of a type III fracture is impossible, an open reduction and posterior fixation/fusion is the treatment of choice.

CONCLUSION

Conservative treatment is predominantly reserved for Levine-Edwards I and IIA fractures. Operative treatment should be performed in case of Levine-Edwards II and III fractures.

Management of acute combined fractures of the atlas and axis: A retrospective study of two trauma centers

Background:

Management of combination fractures of the atlas and axis varies from nonoperative immobilization to selective early surgical intervention. In this study, we present our experience in managing these injuries.

Materials and Methods:

Electronic databases from two level 1 trauma centers were queried to identify all patients diagnosed with C1-C2 combination fractures from 2009 to present. Patient demographics, fracture characteristics, treatment modality, complications, Frankel scores, and fusion status were collected. Patients were separated into operative and nonoperative cohorts, and comparisons were made between the two groups.

Results:

Forty-eight patients were included, of which 19 received operative management and 29 were treated nonoperatively. The mean age was 76.1 and 75.3 years, respectively (P = 0.877). Frankel grade distribution was similar on presentation in both groups, with most being neurologically intact. C1 fractures of both the anterior and posterior arch were present in 41.2% patients undergoing fusions compared to 27.6% of patients treated nonoperatively. No significant differences in comorbidities, neurologic deficits, or radiographic measurements were observed across the two groups.

Conclusions:

This study demonstrates the variety of treatment strategies used for the management of combined C1-C2 fractures. Patients managed operatively tend to have both anterior and posterior C1 arch fractures, while patients managed nonoperatively tend to have either anterior or posterior arch fractures. In general, treatments should be tailored to patients’ needs depending on the stability of the fractures, neurological state, and medical comorbidities.

Sagittal Atlantoaxial Joint Inclination and Reduction Index Values for Diagnosis and Treatment of Irreducible Atlantoaxial Dislocation

BACKGROUND

Irreducible atlantoaxial dislocation (IAAD) is a disorder of atlantoaxial joint instability with various causes. The diagnostic criteria for IAAD are variable. The diagnosis of IAAD is mainly based on preoperative and intraoperative traction results, as well as the physician's experience, with no relatively uniform guidelines for the selection of treatment. This study evaluates sagittal atlantoaxial joint inclination (SAAJI) and reduction index (RI) values for diagnosis and treatment of IAAD.

MATERIALS AND METHODS

24 IAAD patients treated in our hospital from January 2008 to July 2014 were retrospectively analysed. Patients included were 13 males and 11 females, with a mean age of 43 years. The various causes for IAAD were atlantoaxial transverse ligament rupture (n=3), old dens fracture (n=15), occipitalization of the atlas (n=6). The patients were divided into two groups. group A underwent anterior release with posterior reduction and fixation; Group B underwent posterior reduction and fixation; 12 healthy individuals served as controls. SAAJI and atlas-dens interval (ADI) values before and after traction were measured, and RI was calculated. Imaging data were analyzed.

RESULTS

The mean SAAJI values were as follows: left, 5.6 ± 1.9° and right, 5.1 ± 2.1° in the control group; right, 39.5 ± 6.0° and left, 38.8 ± 5.8° in Group A; and right, 23.1 ± 7.0° and left, 23.9 ± 6.1° in Group B. There was no significant difference in the SAAJI values of the three groups (P < 0.05). The mean RIs in Groups A and B were 17.6 ± 9.3% and 34.4 ± 5.2%, respectively, and the difference was statistically significant (P < 0.05). There were obvious negative correlations between the SAAJI and RI values in Groups A and B.

CONCLUSIONS

SAAJI and RI can be used as important imaging indicators to determine the reversibility of IAAD. If the RI value is >27.9% and SAAJI value is <32.5°, reduction and fixation can be achieved by the posterior approach alone; otherwise, a combination of anterior and posterior approaches would be necessary.

Cervical myelopathy caused by invaginated laminae of the axis associated with occipitalizaion of the atlas: Case report and literature review

RATIONALE

In previous studies, few cases of cervical myelopathy caused by invaginated anomalous laminae of the axis have been reported, and none of them was combined with occipitalization of the atlas.

PATIENT CONCERNS

A 28-year-old male was brought to our hospital with motor and sensory impairments of the extremities after a car accident.

DIAGNOSES

MRI showed the spinal cord was markedly compressed at the C2/3 level. Reconstructed CT scans revealed an invaginated laminae of axis into the spinal canal as well as atlas assimilation.

INTERVENTIONS

The patient was successfully managed with surgical treatment by removal of the anomalous osseous structure as well as fixation and fusion.

OUTCOMES

The patient had a rapid recovery after the operation. He regained the normal strength of his 4 extremities and the numbness of his extremities disappeared. He returned to his normal work 3 months after the surgery without any symptoms.

LESSONS

Invaginated laminae of axis combined with occipitalization of the atlas is a rare deformity. MRI and reconstructed CT scans are useful for both diagnosing and surgical planning of this case. Surgical removal of the laminae results in a satisfactory outcome. The pathogenesis of this anomaly could be the fusion sequence error of the 4 chondrification centers in the embryological term.

The Gut Microbiome Feelings of the Brain: A Perspective for Non-Microbiologists

Objectives: To comprehensively review the scientific knowledge on the gut-brain axis. Methods: Various publications on the gut-brain axis, until 31 July 2017, were screened using the Medline, Google, and Cochrane Library databases. The search was performed using the following keywords: "gut-brain axis", "gut-microbiota-brain axis", "nutrition microbiome/microbiota", "enteric nervous system", "enteric glial cells/network", "gut-brain pathways", "microbiome immune system", "microbiome neuroendocrine system" and "intestinal/gut/enteric neuropeptides". Relevant articles were selected and reviewed. Results: Tremendous progress has been made in exploring the interactions between nutrients, the microbiome, and the intestinal, epithelium-enteric nervous, endocrine and immune systems and the brain. The basis of the gut-brain axis comprises of an array of multichannel sensing and trafficking pathways that are suggested to convey the enteric signals to the brain. These are mediated by neuroanatomy (represented by the vagal and spinal afferent neurons), the neuroendocrine-hypothalamic-pituitary-adrenal (HPA) axis (represented by the gut hormones), immune routes (represented by multiple cytokines), microbially-derived neurotransmitters, and finally the gate keepers of the intestinal and brain barriers. Their mutual and harmonious but intricate interaction is essential for human life and brain performance. However, a failure in the interaction leads to a number of inflammatory-, autoimmune-, neurodegenerative-, metabolic-, mood-, behavioral-, cognitive-, autism-spectrum-, stress- and pain-related disorders. The limited availability of information on the mechanisms, pathways and cause-and-effect relationships hinders us from translating and implementing the knowledge from the bench to the clinic. Implications: Further understanding of this intricate field might potentially shed light on novel preventive and therapeutic strategies to combat these disorders. Nutritional approaches, microbiome manipulations, enteric and brain barrier reinforcement and sensing and trafficking modulation might improve physical and mental health outcomes.

The outcome of eosinophilic granuloma involving unilateral atlantoaxial joint: A case report and literature review

RATIONALE

Solitary eosinophilic granuloma (EG), the most benign, common form of Langerhans cell histiocytosis, has a self-limiting process and is associated with a good prognosis. Immobilization is recommended as the first treatment strategy for solitary EG, although the treatment protocols are still controversial. Radiotherapy and surgery are secondary treatment choices. Lesions of the upper cervical spine react differently to treatment because of their specific anatomical and motor features.

PATIENT CONCERNS

We discuss the case of a 29-year-old man with axis EG who underwent immobilization, radiotherapy, and finally surgery.

DIAGNOSIS

Eosinophilic granuloma (EG).

INTERVENTIONS

An initial conservative protocol, including immobilization with a collar and radiotherapy, effectively relieved his neck pain, whereas torticollis secondary to atlantoaxial subluxation was not improved. Therefore, he underwent tumor resection through the anterior approach and spinal reconstruction, fixation, and fusion through the posterior approach.

OUTCOMES

The deformity was well corrected and follow-up was satisfactory.

LESSONS

Upon review of the literature, we found that EG lesions affecting the axis have more risk factors for instability or deformity, and they have particular anatomical and motor characteristics; thus, they require more consideration and attention in terms of treatment, prognosis, and follow-up.

Deletion of 2.7 kb near HOXD3 in an Arabian horse with occipitoatlantoaxial malformation

In the horse, the term occipitoatlantoaxial malformation (OAAM) is used to describe a developmental defect in which the first cervical vertebra (atlas) resembles the base of the skull (occiput) and the second cervical vertebra (axis) resembles the atlas. Affected individuals demonstrate an abnormal posture and varying degrees of ataxia. The homeobox (HOX) gene cluster is involved in the development of both the axial and appendicular skeleton. Hoxd3-null mice demonstrate a strikingly similar phenotype to Arabian foals with OAAM. Whole-genome sequencing was performed in an OAAM-affected horse (OAAM1) and seven unaffected Arabian horses. Visual inspection of the raw reads within the region of HOXD3 identified a 2.7-kb deletion located 4.4 kb downstream of the end of HOXD4 and 8.2 kb upstream of the start of HOXD3. A genotyping assay revealed that both parents of OAAM1 were heterozygous for the deletion. Additional genotyping identified two of 162 heterozygote Arabians, and the deletion was not present in 371 horses of other breeds. Comparative genomics studies have revealed that this region is highly conserved across species and that the entire genomic region between Hoxd4 and Hoxd3 is transcribed in mice. Two additional Arabian foals diagnosed with OAAM (OAAM 2 and 3) were genotyped and did not have the 2.7-kb deletion. Closer examination of the phenotype in these cases revealed notable variation. OAAM3 also had facial malformations and a patent ductus arteriosus, and the actual malformation at the craniocervical junction differed. Genetic heterogeneity may exist across the HOXD locus in Arabian foals with OAAM.

"Soft that molds the hard:" Geometric morphometry of lateral atlantoaxial joints focusing on the role of cartilage in changing the contour of bony articular surfaces

Purpose:

The existing literature on lateral atlantoaxial joints is predominantly on bony facets and is unable to explain various C1-2 motions observed. Geometric morphometry of facets would help us in understanding the role of cartilages in C1-2 biomechanics/kinematics.

Objective:

Anthropometric measurements (bone and cartilage) of the atlantoaxial joint and to assess the role of cartilages in joint biomechanics.

Materials and Methods:

The authors studied 10 cadaveric atlantoaxial lateral joints with the articular cartilage in situ and after removing it, using three-dimensional laser scanner. The data were compared using geometric morphometry with emphasis on surface contours of articulating surfaces.

Results:

The bony inferior articular facet of atlas is concave in both sagittal and coronal plane. The bony superior articular facet of axis is convex in sagittal plane and is concave (laterally) and convex medially in the coronal plane. The bony articulating surfaces were nonconcordant. The articular cartilages of both C1 and C2 are biconvex in both planes and are thicker than the concavities of bony articulating surfaces.

Conclusion:

The biconvex structure of cartilage converts the surface morphology of C1-C2 bony facets from concave on concavo-convex to convex on convex. This reduces the contact point making the six degrees of freedom of motion possible and also makes the joint gyroscopic.

Comparing an Atomic Model or Structure to a Corresponding Cryo-electron Microscopy Image at the Central Axis of a Helix

Three-dimensional density maps of biological specimens from cryo-electron microscopy (cryo-EM) can be interpreted in the form of atomic models that are modeled into the density, or they can be compared to known atomic structures. When the central axis of a helix is detectable in a cryo-EM density map, it is possible to quantify the agreement between this central axis and a central axis calculated from the atomic model or structure. We propose a novel arc-length association method to compare the two axes reliably. This method was applied to 79 helices in simulated density maps and six case studies using cryo-EM maps at 6.4-7.7 Å resolution. The arc-length association method is then compared to three existing measures that evaluate the separation of two helical axes: a two-way distance between point sets, the length difference between two axes, and the individual amino acid detection accuracy. The results show that our proposed method sensitively distinguishes lateral and longitudinal discrepancies between the two axes, which makes the method particularly suitable for the systematic investigation of cryo-EM map-model pairs.

C-2 arteriovenous fistula presenting as a pathologic hangman's fracture: case report

The authors report on an 81-year-old woman with a pathologic hangman's fracture secondary to a complex arteriovenous fistula (AVF). The patient presented with severe, unremitting neck pain and was found to have fractures bilaterally through the pars interarticularis of C-2 with significant anterior subluxation of C-2 over C-3 along with widening of the left transverse foramen. Due to an abnormally appearing left vertebral artery (VA) on CT angiography, the patient underwent conventional angiography, which revealed a complex AVF stemming from the left VA at the level of C-2 with dilated posterior cervical veins and a large venous varix. Given the radiographic evidence of bone remodeling and the chronicity of the AVF, it is believed that the C-2 vertebra was weakened over time by the pulsatile and compressive force of the vascular malformation eventually leading to fracture with minimal stress. Coil embolization of the AVF was performed followed by surgical fixation of C-1 to C-4. This case highlights the importance of investigating an underlying disease process in patients who present with significant spinal fractures in the absence of trauma.

Morphometric multislice computed tomography examination of the craniovertebral junction in neck flexion and extension

BACKGROUND

Detailed study of the craniovertebral junction (CVJ) is necessary to completely understand the mechanism of its flexion and extension.

MATERIALS AND METHODS

One cadaver head was sectioned in the sagittal plane. Also, in 22 volunteers, examined using the multislice computed tomography (MSCT), 14 parameters and 2 angles were measured in the neutral position, flexion and extension.

RESULTS

The obtained measurements showed the anterior part of the occiput to move inferiorly in flexion, and the anterior atlas arch and the tip of the dens to get closer to the basion. At the same time, the opisthion moves superiorly, but the cervical spine bends anteriorly. Consequently, the dens-opisthion diameter and the opisthion-posterior atlas arch distance slightly decrease in length, whilst the arches of the atlas (C1), axis (C2) and C3 vertebra become more distant. Following extension, the posterior part of the occiput moves inferiorly, so that the basion-dens tip, the basion-axis arch, and the basion-posterior atlas arch distances increase in length. In contrast, the distances of the C1-C3 arches decrease in length. The angle between the foramen magnum and the dens tip decreases 1.620 on average in flexion, but increases 3.230 on average in extension. The angle between the axis body and the opisthion also decreases in flexion (mean, 3.360) and increases in extension (mean, 6.570). Among the congenital anomalies, a partial agenesis of the posterior atlas arch was revealed (4.5%), as well as an anterior dehiscence of the C1 foramen transversarium (13.6%).

CONCLUSIONS

The mentioned measurements improved our understanding of the CVJ biomechanics. The obtained data can be useful in the evaluation of the CVJ instability caused by trauma, congenital anomalies and certain spine diseases.

Upper Cervical Epidural Abscess in Clinical Practice: Diagnosis and Management

Study Design Narrative review. Objective Upper cervical epidural abscess (UCEA) is a rare surgical emergency. Despite increasing incidence, uncertainty remains as to how it should initially be managed. Risk factors for UCEA include immunocompromised hosts, diabetes mellitus, and intravenous drug use. Our objective is to provide a comprehensive overview of the literature including the history, clinical manifestations, diagnosis, and management of UCEA. Methods Using PubMed, studies published prior to 2015 were analyzed. We used the keywords "Upper cervical epidural abscess," "C1 osteomyelitis," "C2 osteomyelitis," "C1 epidural abscess," "C2 epidural abscess." We excluded cases with tuberculosis. Results The review addresses epidemiology, etiology, imaging, microbiology, and diagnosis of this condition. We also address the nonoperative and operative management options and the relative indications for each as reviewed in the literature. Conclusion A high index of suspicion is required to diagnose this rare condition with magnetic resonance imaging being the imaging modality of choice. There has been a shift toward surgical management of this condition in recent times, with favorable outcomes.

Wnt, Ptk7, and FGFRL expression gradients control trunk positional identity in planarian regeneration

Mechanisms enabling positional identity re-establishment are likely critical for tissue regeneration. Planarians use Wnt/beta-catenin signaling to polarize the termini of their anteroposterior axis, but little is known about how regeneration signaling restores regionalization along body or organ axes. We identify three genes expressed constitutively in overlapping body-wide transcriptional gradients that control trunk-tail positional identity in regeneration. ptk7 encodes a trunk-expressed kinase-dead Wnt co-receptor, wntP-2 encodes a posterior-expressed Wnt ligand, and ndl-3 encodes an anterior-expressed homolog of conserved FGFRL/nou-darake decoy receptors. ptk7 and wntP-2 maintain and allow appropriate regeneration of trunk tissue position independently of canonical Wnt signaling and with suppression of ndl-3 expression in the posterior. These results suggest that restoration of regional identity in regeneration involves the interpretation and re-establishment of axis-wide transcriptional gradients of signaling molecules.

Congenital absence of the posterior arch of the atlas with concomitant fusion to the axis: a case report

We present a 52-year-old man with congenital absence of the posterior arch of the atlas and concomitant fusion of the posterior tubercle of the atlas to the spinal process of the axis. He had normal reflexes and no motor deficit. He underwent C3-C7 laminoplasty and achieved good outcome.