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We designed a prospective multicenter cohort study to clarify a long-term, > 10-year prevalence and aggravation of cervical spine instabilities in rheumatoid arthritis (RA). In 2001-2002, 634 outpatients were enrolled, and 233 (36.8%) were followed for > 10 years. Cervical spine instability was defined as atlantoaxial subluxation (AAS, > 3-mm atlantodental interval), vertical subluxation (VS, < 13-mm Ranawat value), and subaxial subluxation (SAS, ≥ 2-mm irreducible vertebral translation). The aggravation was determined as ≥ 2 mm decrease of the Ranawat value in VS, ≥ 2-mm increase of slippage in SAS, and these new developments. The prevalence of VS and SAS increased during both the initial and last > 5 years (all, p ≤ 0.049). While VS aggravation was associated with pre-existing AAS (p = 0.007) and VS (p = 0.002), SAS aggravation correlated with pre-existing VS (p = 0.002). Multivariable analysis found hand mutilating changes (odds ratio [OR] = 4.048, p = 0.008), RA duration ≥ 5 years (OR = 3.711, p = 0.013), C-reactive protein (CRP) level ≥ 3.8 mg/dL (OR = 2.187, p = 0.044), and previous joint surgery (OR = 2.147, p = 0.021) as predictors for VS aggravation. Pre-existing VS (OR = 2.252, p = 0.024) and CRP ≥ 1.0 mg/dL (OR = 2.139, p = 0.013) were disclosed as predictors for SAS aggravation. Low disease activity and clinical remission before the development of VS and advanced peripheral joint destruction are essential to prevent progressive cervical spine instability in RA., (© 2024. The Author(s).)

Purpose: This study aimed to investigate the association between unilateral high-riding vertebral artery (HRVA) and morphological changes in the atlantoaxial joint (AAJ) and to determine whether unilateral HRVA is a risk factor for atlantoaxial osteoarthritis (AAOA)., Methods: We conducted a retrospective analysis of 2496 patients admitted to our medical center between January 2020 and December 2022 who underwent CT imaging of the cervical spine. Two hundred and seventy-two patients with unilateral HRVA (HRVA group) were identified and a respective 2:1 age- and sex-matched control group without HRVA was built. Morphological parameters, including C2 lateral mass settlement (C2 LMS), C1/2 coronal inclination (C1/2 CI), lateral atlanto-dental interval (LADI), and C1/2 relative rotation angle (C1/2 RRA) were measured. The degree of AAOA was recorded. Risk factors associated with AAOA were identified using univariate and multivariable logistic regression analyses., Results: The study included 61.4% women, and the overall average age of the study population was 48.7 years. The morphological parameters (C2 LMS, C1/2 CI, and LADI) in AAJ were asymmetric between the HRVA and the non-HRVA sides in the HRVA group (p < 0.001). These differences in parameters (d-C2 LMS, d-C1/2 CI, and d-LADI) between the HRVA and the non-HRVA sides, and C1/2 RRA were significantly larger than those in the control group. Eighty-three of 816 patients (10.2%) with AAOA had larger values of d-C2 LMS, d-C1/2 CI, d-LADI, and C1/2 RRA compared with the patients without AAOA (p < 0.05). The multivariable logistic regression analysis indicated that unilateral HRVA [adjusted odds ratio (OR) = 2.6, 95% CI: 1.1-6.3, p = 0.029], age in the sixth decade or older (adjusted OR = 30.2, 95% CI: 16.1-56.9, p < 0.001), women (adjusted OR = 2.1, 95% CI: 1.0-5.6, P = 0.034) were independent risk factors for AAOA., Conclusion: Unilateral HRVA was associated with asymmetric morphological changes of nonuniform settlement of C2 lateral mass, lateral slip of atlas, and atlantoaxial rotation displacement. Besides age ≥ 60 years and females, unilateral HRVA is an independent risk factor for AAOA., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Background: Nablus mask-like facial syndrome (NMFLS) is an extremely rare genetic syndrome characterized by facial dysmorphia as well as developmental delay. In the present report we describe a potential association between non-traumatic atlanto-occipital dislocation and NMFLS in an 11-year old female lacking typical facial features of NMFLS., Case Description: An 11-year-old female with autism presented with symptoms of persistent headache and vomiting as well as neck stiffness. Further investigation and CT imaging revealed congenital malformation of the skull base and craniocervical junction with complete posterior subluxation of the left occipital condyle. MRI findings later corroborated the findings on CT., Conclusions: The patient was successfully treated with occipitocervical fusion. The findings in this case suggest the possibility that atlanto-occipital instability and generalized occipitocervical may be associated with NMFLS., Competing Interests: Declaration of Competing interest report no conflicts of interest. The authors alone are responsible for the content and writing of the article., (Copyright © 2024 The Authors. Published by Elsevier Masson SAS.. All rights reserved.)

Background: Cervical subluxation is a broad class of injuries in which there are degrees of misalignment of vertebral bodies in relationship to adjacent vertebra. Atlantoaxial rotatory subluxation (AARS) is a subtype of cervical subluxation resulting from exaggerated rotation of the C1-C2 complex. Inflammatory, infectious, post-surgical, and traumatic etiologies are recognized and well-described. AARS is predominantly seen in children and occurs rarely in adults., Case Report: We submit the case of an otherwise healthy adult male patient presenting to the emergency department with strangulation-induced C1-C2 subluxation with a rotational component that was treated at the bedside by neurosurgery with closed reduction. Why Should an Emergency Physician Be Aware of This? Clinicians must consider a broad range of serious pathologies in a patient presenting with torticollis, especially in the setting of strangulation. Although extremely rare in adults, AARS must be considered in the differential diagnosis, as early identification increases the likelihood of successful nonoperative treatment., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Published by Elsevier Inc.)

Objectives: In rheumatoid arthritis, neck pain can be caused by inflammatory reactions or cervical lesions, but the prevalence and associated factors have not been well studied. This study aimed to investigate the prevalence of neck pain in patients with rheumatoid arthritis and elucidate the related factors., Methods: This study included 146 patients with rheumatoid arthritis. Neck pain, quality of life, and levels of anxiety and depression were evaluated using a questionnaire. Cervical lesions and spinal alignment were evaluated using plain radiograph and magnetic resonance imaging. Factors associated with neck pain were analysed using a logistic regression model., Results: Fifty-six per cent of the patients had neck pain, and the quality of life scores were significantly worse in these patients. Multivariate analysis revealed age, C7 sagittal vertical axis, upper cervical lesion, and endplate erosion as factors associated with neck pain in patients with rheumatoid arthritis., Conclusions: More than half the patients with rheumatoid arthritis suffer from neck pain, and neck pain affects the quality of life and activities of daily living. Neck pain was associated with upper cervical lesion and endplate erosion suggesting the importance of radiological examination in patients with rheumatoid arthritis and neck pain., (© Japan College of Rheumatology 2022. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Atlantoaxial rotatory subluxation is an important differential diagnosis in young children with torticollis. The condition rarely results in neurological deficits. Radiological examinations such as computer tomography (CT) and magnetic resonance imaging (MRI) are useful to determine the diagnosis. It is important for doctors in all areas of healthcare to be aware of the condition, as persistent problems or surgery can be avoided by early detection and treatment.

The craniovertebral junction (CVJ) is an anatomically complex region of the axial skeleton that provides protection of the brainstem and the upper cervical spinal cord. Structural malformation of the CVJ gives rise to life-threatening neurological deficits, such as quadriplegia and dyspnea. Unfortunately, genetic studies on human subjects with CVJ malformation are limited and the pathogenesis remains largely elusive. In this study, we recruited 93 individuals with CVJ malformation and performed exome sequencing. Manual interpretation of the data identified three pathogenic variants in genes associated with Mendelian diseases, including CSNK2A1, MSX2, and DDX3X. In addition, the contribution of copy number variations (CNVs) to CVJ malformation was investigated and three pathogenic CNVs were identified in three affected individuals. To further dissect the complex mutational architecture of CVJ malformation, we performed a gene-based rare variant association analysis utilizing 4371 in-house exomes as control. Rare variants in LGI4 (carrier rate = 3.26%, p = 3.3 × 10 -5 ) and BEST1 (carrier rate = 5.43%, p = 5.77 × 10 -6 ) were identified to be associated with CVJ malformation. Furthermore, gene set analyses revealed that extracellular matrix- and RHO GTPase-associated biological pathways were found to be involved in the etiology of CVJ malformation. Overall, we comprehensively dissected the genetic underpinnings of CVJ malformation and identified several novel disease-associated genes and biological pathways., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Objective: Investigating the causal relationship between rheumatoid arthritis (RA) and atlantoaxial subluxation (AAS) and identifying and quantifying the role of C-reactive protein (CRP) as a potential mediator., Methods: Using summary-level data from a genome-wide association study (GWAS), a two-sample Mendelian randomization (MR) analysis of genetically predicted rheumatoid arthritis (14,361 cases, and 43,923 controls) and AAS (141 cases, 227,388 controls) was performed. Furthermore, we used two-step MR to quantitate the proportion of the effect of c-reactive protein-mediated RA on AAS., Results: MR analysis identified higher genetically predicted rheumatoid arthritis (primary MR analysis odds ratio (OR) 0.61/SD increase, 95% confidence interval (CI) 1.36-1.90) increased risk of AAS. There was no strong evidence that genetically predicted AAS had an effect on rheumatoid arthritis risk (OR 1.001, 95% CI 0.97-1.03). The proportion of genetically predicted rheumatoid arthritis mediated by C-reactive protein was 3.7% (95%CI 0.1%-7.3%)., Conclusion: In conclusion, our study identified a causal relationship between RA and AAS, with a small proportion of the effect mediated by CRP, but a majority of the effect of RA on AAS remains unclear. Further research is needed on additional risk factors as potential mediators. In clinical practice, lesions of the upper cervical spine in RA patients need to be given more attention., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Yuan, Xiong, Zhang, Feng, Zhang, Wang and Tang.)

Backgroundand Objectives: To date, imaging characterization of non-rheumatic retro-odontoid pseudotumors (NRROPs) has been lacking; therefore, NRROPs have been confused with atlantoaxial joint involvement of rheumatoid arthritis (RA). It is important to differentiate these two disease because the treatment strategies may differ. The purpose of this study is to characterize imaging findings of NRROPs and compare them with those of RA. Material and Methods: From January 2015 to December 2019, 27 patients (14 women and 13 men) with NRROPs and 19 patients (15 women and 4 men) with RA were enrolled in this study. We evaluated various imaging findings, including atlantoaxial instability (AAI), and measured the maximum diameter of preodontoid and retro-odontoid spaces with magnetic resonance imaging (MRI) and computed tomography (CT). Results: Statistical significance was considered for p < 0.05. AAI was detected in eight patients with NRROPs and in all patients with RA (p < 0.0001). Seventeen patients with NRROPs and six patients with RA showed spinal cord compression (p = 0.047). Compressive myelopathy was observed in 14 patients with NRROPs and in 4 patients with RA (p = 0.048). Subaxial degeneration was observed in 25 patients with NRROPs and in 9 patients with RA (p = 0.001). Moreover, C2-3 disc abnormalities were observed in 11 patients with NRROPs and in 2 patients with RA (p = 0.02). Axial and longitudinal diameter of retro-odontoid soft tissue and preodontoid and retro-odontoid spaces showed significant differences between NRROP and RA patients (p < 0.0001). Furthermore, CT AAI measurements were differed significantly between NRROP and RA patients (p < 0.05). Conclusions: NRROPs showed prominent retro-odontoid soft tissue thickening, causing compressive myelopathy and a high frequency of subaxial and C2-3 degeneration without AAI.

Tenosynovial giant cell tumor (TGCT) is a benign condition that arises from tendon sheaths, synovium, or bursae and is classified according to the site of involvement (intra-articular versus extra-articular) and pattern of growth (localized versus diffuse). The diffuse form tends to present as peri-articular masses and are locally aggressive. It usually presents as a mono-articular process affecting larger joints. Spinal involvement is extremely rare, particularly the cervical spine. In this case report, we present a pediatric case of spinal TGCT involving the C1-C2 joint which was incidentally detected in a 13-year-old girl undergoing surveillance for medulloblastoma recurrence. Although spinal TGCT is a benign condition, it remains a diagnostic challenge, which specific to our case can raise the concern for malignancy or metastasis. We also described a percutaneous biopsy approach using a spring-loaded blunt tip coaxial needle to avoid inadvertent vascular injury. The imaging features of spinal TGCT and biopsy approach for atlantoaxial lesion are discussed together with a comprehensive review of the literature., (© 2021. ISS.)

Objective: To determine cutoff values for the diagnosis of atlantoaxial instability (AAI) based on cross-sectional imaging in small-breed dogs., Study Design: Retrospective multicenter study., Sample Population: Client-owned dogs (n = 123) and 28 cadavers., Methods: Dogs were assigned to three groups: a control group, a "potentially unstable" group, and an AAI-affected group, according to imaging findings and clinical signs. The ventral compression index (VCI), cranial translation ratio (CTR), C1-C2 overlap, C1-C2 angle, atlantoaxial distance, basion-dens interval, dens-to-axis length ratio (DALR), power ratio, and clivus canal angles were measured on CT or T2-weighted magnetic resonance (MR) images. Receiver operating characteristic (ROC) analysis was performed to define cutoff values in flexed (≥25°) and extended (<25°) head positions., Results: Cutoff values for the VCI of ≥0.16 in extended and ≥0.2 in flexed head positions were diagnostic for AAI (sensitivity of 100% and 100%, specificity of 94.54% and 96.67%, respectively). Cutoff values for the other measurements were defined with a lower sensitivity (75%-96%) and specificity (70%-97%). A combination of the measurements did not increase the sensitivity and specificity compared with the VCI as single measurement., Conclusion: Cutoff values for several imaging measurements were established with good sensitivity and specificity. The VCI, defined as the ratio between the ventral and dorsal atlantodental interval, had the highest sensitivity and specificity in both head positions., Clinical Significance: The use of defined cutoff values allows an objective diagnosis of AAI in small-breed dogs. The decision for surgical intervention, however, should remain based on a combination of clinical and imaging findings., (© 2022 The Authors. Veterinary Surgery published by Wiley Periodicals LLC on behalf of American College of Veterinary Surgeons.)

Objective: A retro-odontoid pseudotumor (ROP) is commonly associated with atlantoaxial instability or rheumatoid arthritis. However, ROP in the absence of atlantoaxial instability or rheumatoid arthritis, which is termed idiopathic ROP (IROP), is a rare condition. The pathomechanisms and optimal treatment strategies for IROP remain controversial. The aim of the present study was to evaluate the radiographic and clinical characteristics of IROP patients and to assess the efficiency of atlantoaxial/occipitocervical fusion on IROP regression., Methods: Data from 5 patients diagnosed with IROP were retrospectively reviewed. Posterior atlantoaxial or occipitocervical fixation and fusion were performed in 4 patients and C1 posterior arch resection alone in 1 patient. The patients' features, surgical procedures, and complications were recorded. The retro-odontoid soft tissue thickness was measured on preoperative and postoperative magnetic resonance imaging to evaluate IROP regression., Results: The mean follow-up time was 37 months. ROP regression was achieved in patients who received atlantoaxial/occipitocervical fusion, but not for the patient with C1 posterior resection alone. There were no observed neurovascular complications associated with surgery., Conclusions: IROP was related to a restricted range of motion of the subaxial spine. Upper cervical fixation is an optional treatment that produces IROP regression over time. By contrast, direct removal of the IROP is unnecessary., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Objective: Although the spontaneous regression of pseudotumors after posterior fusion has been reported, the predictive factors remain unclear. We examined the radiological features that predict for the regression of retro-odontoid pseudotumors after posterior fusion, with a specific focus on cyst formation., Methods: We included 28 patients with a diagnosis of retro-odontoid pseudotumor using preoperative magnetic resonance imaging. The radiographic parameters and pseudotumor thickness were measured pre- and postoperatively. The regression rate for each pseudotumor was calculated. The presence of a cyst around the retro-odontoid pseudotumor was investigated. If present, the cyst thickness was measured. To elucidate the predictors for the postoperative regression of pseudotumors, the patients were divided into 2 cohorts: the regression group with a regression rate >40% and the no-regression group with a regression rate of <40%. Multivariate logistic regression analysis, including the demographic data and preoperative radiographic parameters as independent variables, was performed., Results: The mean pseudotumor size had decreased significantly from 8.8 ± 3.6 mm preoperatively to 5.3 ± 2.0 mm postoperatively (P < 0.0001). The mean regression rate was 35.9% during a magnetic resonance imaging follow-up period of 8.6 months (range, 6-12 months). Cystic lesions were noted in 10 patients (35.7%) preoperatively. The mean cyst size was 4.7 ± 1.9 mm. All cysts were located dorsal to the pseudotumors and were involved at the maximum spinal compression levels. Nevertheless, all the cysts had disappeared postoperatively. Multivariate logistic regression analysis revealed that the pseudotumor regression group had had a significantly greater proportion of cysts (57.1% vs. 14.3%; odds ratio, 11.7; P = 0.013)., Conclusions: The presence of cystic lesions protruding from retro-odontoid pseudotumors might serve as a predictive factor for the spontaneous regression of pseudotumors after posterior fusion., (Copyright © 2021. Published by Elsevier Inc.)

Abstract: To introduce a novel technique of using individualized 3D printing occipitocervical fusion instrument (3D-OCF) for the treatment of upper cervical deformity with atlantoaxial joint dislocation.The surgery for deformity of the craniocervical junction area is a challenge in the field of spine. If the surgical deviation is too large to injure the spinal cord or vertebral artery, it will cause catastrophic damage to the patient. Therefore, it is controversial whether these patients should undergo surgical treatment. We provide a novel surgical approach for the challenging upper cervical surgery through 3D-OCF and a typical patient.We present a 54-year-old female patient, who suffered from dizziness and numbness in her limbs for 8 months. After the patient was admitted, we performed the three-dimensional CT scan, modeled using Mimics software 17.0, and designed customized occipitocervical fusion instrument. Besides, we repeatedly perform simulated surgery based on 3D-printed models before surgery.The operative time was 142 minutes and the intraoperative blood loss was 700 mL. X-ray showed reduction of atlantoaxial dislocation and accurate position of internal fixation. The patient's symptoms were significantly relieved: the sensation of dizziness and numbness of limbs was obviously relieved, and the sense of banding in chest, abdomen, and ankle was disappeared. At the last follow-up, imaging showed that 3D-OCF had bone-integration and Syringomyelia was disappeared. The patient's cervical JOA (Japanese Orthopaedic Association) score increased from 10 points to 17 points.Individualized 3D-OCF can improve the safety and accuracy of upper cervical surgery, reduce the operative time and the number of fluoroscopy. Our study provides a novel surgical approach for the challenging upper cervical surgery., Competing Interests: The authors have no conflicts of interest to disclose., (Copyright © 2021 the Author(s). Published by Wolters Kluwer Health, Inc.)

The objective of this study is to suggest clinical and subclinical atlantoaxial (AA) instability as a cause for dorsal AA ligament hypertrophy responsible for clinical signs in dogs with dens abnormalities. Clinical information from five dogs with malformed dens and dorsal spinal cord compression at the AA junction was collected. All dogs had neck pain, associated with tetraparesis in three cases. Radiological examination revealed hypoplastic dens in two dogs and a defect in its ossification in the other three. Stress views were able to demonstrate obvious AA instability only in two cases, but it was suspected in the other owing to response to surgical fixation of the joint and the presence of a dorsal compressive band, which was considered an enlarged dorsal AA ligament. Surgical and histopathological examination of compressive tissue confirmed hypertrophy of the ligament. Long-term prognosis in the four operated cases, either by dorsal decompression and ventral fixation or by ventral fixation alone, was excellent. A malformed dens can cause subclinical instability, unnoted in dynamic studies. As instability may lead to hypertrophy of joint ligaments, soft tissue changes (specifically dorsal AA ligament hypertrophy) points out this instability and the need for joint fixation if surgical management is required., (© 2021 by American Animal Hospital Association.)

Background: The literature seems fractured for the management of craniovertebral junction (CVJ)-tuberculosis (TB). Presently, non-surgical management has been in vogue for neurologically intact patients. On the contrary, severely disabled cases of CVJ-TB continue to attract discussion, tilted towards surgical intervention. We present our experience with the non-surgical management of CVJ-TB tailored to their neurological status., Methods: Authors managed 37 cases (2004-2019; age 1-57 years, mean 36 years) of CVJ-TB, of which eighteen (18/37, 48.6%) were severely disabled (Nurick grade ≥ 3) with a mean follow-up of 84 months (48-192 months). Irrespective of the clinical status and radiological findings, all patients were managed on medical management only. Needle aspiration established pathology in 23 (62.2%) cases, while 9 (24.3%) cases required drainage of an abscess. All patients received 18 months of anti-tubercular therapy (ATT). In patients with Nurick grade ≥ 3 and documented AAD, we applied halo vest for 12 months to achieve cervical immobilization. Only hard cervical collar for 3 months was prescribed in patients with no documented AAD., Results: All minimally disabled cases (Nurick grade ≤ 2, n = 19) responded favorably (n = 18) to ATT, except for an infant, who succumbed to irreversible hypoxic brain damage due to the obstructed aero-digestive gateway. Of the severely disabled cases (Nurick grade ≥ 3, n = 18), 16 cases had favorable outcomes with only external orthosis (12) and 18-month ATT. One patient succumbed to multiple cerebral infarcts, while one required realignment surgery at CVJ due to fusion in malaligned position., Conclusion: The authors conclude that the disability grading of CVJ-TB is pertinent only for assessing the functional disability of patients at presentation, with minimal relevance in deciding its management strategy. Irrespective of neurological disability, almost all patients respond favorably to external immobilization and ATT.

Objective: Atlantoaxial rotatory fixation (AARF) is an acquired fixed abnormality of C1-2 joint rotation associated with torticollis in childhood. If the condition is left uncorrected, patients are at risk for developing C1-2 fusion with permanent limitation in the cervical range of movement, cosmetic deformity, and impact on quality of life. The management of AARF and the modality of nonsurgical treatment are poorly defined in both primary care and specialized care settings, and the optimal strategy is not clear. This systematic review aims to examine the available evidence to answer key questions relating to the nonsurgical management of AARF., Methods: A systematic review was performed using the following databases: PubMed, MEDLINE, Healthcare Management Information Consortium (HMIC), EMCare, Embase, Cumulative Index to Nursing and Allied Health Literature (CINAHL), British Nursing Index (BNI), and Allied and Complementary Medicine Database (AMED). Search criteria were created and checked independently among the authors. All articles with a radiological diagnosis of AARF and primary outcome data that met the study inclusion criteria were included and analyzed by the authors., Results: Search results did not yield any level I evidence such as a meta-analysis or randomized controlled trial. The initial search yielded 724 articles, 228 of which were screened following application of the core exclusion criteria. A total of 37 studies met the full criteria for inclusion in this review, consisting of 4 prospective studies and 33 retrospective case reviews. No articles directly compared outcomes between modalities of nonsurgical management. Six studies compared the outcome of AARF based on duration of symptoms before initiation of treatment. Comparative analysis of studies was hindered by the wide variety of treatment modalities described and the heterogeneity of outcome data., Conclusions: The authors did not identify any level I evidence comparing different nonsurgical management approaches for AARF. There were few prospective studies, and most studies were uncontrolled, nonrandomized case series. Favorable outcomes were often reported regardless of treatment methods, with early treatment of AARF tending to yield better outcomes independent of the treatment modality. There is a lack of high-quality data, and further research is required to determine the optimal nonsurgical treatment strategy.

Pediatric stroke presents with a variety of signs and symptoms. Correct modality of imaging is essential in decreasing the time from symptom onset to appropriate management. Evaluation of pediatric stroke should include both blood work as well as imaging in a parallel rather than a sequential matter. We report a case of a child with a bow hunter's stroke that was challenging to diagnose. This type of stroke happens when the vertebral artery is occluded at the atlantoaxial or subaxial level during neck rotation. This case demonstrates that workup of stroke should be comprehensive to include all mechanical and anatomic possibilities before investigating rarer hypercoagulable disorders.

Introduction: Recently, a novel hypothesis has been proposed concerning the origin of craniovertebral junction (CVJ) abnormalities. Commonly found in patients with these entities, atlantoaxial instability has been suspected to cause both Chiari malformation type I and basilar invagination, which renders the tried and tested surgical decompression strategy ineffective. In turn, C1-2 fusion is proposed as a single solution for all CVJ abnormalities, and a revised definition of atlantoaxial instability sees patients both with and without radiographic evidence of instability undergo fusion, instead relying on the intraoperative assessment of the atlantoaxial joints to confirm instability., Methods: The authors conducted a comprehensive narrative review of literature and evidence covering this recently emerged hypothesis. The proposed pathomechanisms are discussed and contextualized with published literature., Conclusion: The existing evidence is evaluated for supporting or opposing sole posterior C1-2 fusion in patients with CVJ abnormalities and compared with reported outcomes for conventional surgical strategies such as posterior fossa decompression, occipitocervical fusion, and anterior decompression. At present, there is insufficient evidence supporting the hypothesis of atlantoaxial instability being the common progenitor for CVJ abnormalities. Abolishing tried and tested surgical procedures in favor of a single universal approach would thus be unwarranted.

Objective: Assessment of transverse ligament (TL) competence in patients with suspected atlantoaxial instability is performed via indirect radiograph measurements or direct TL visualization on magnetic resonance imaging (MRI). Interpretation of these images can be limited by unique patient anatomy or imaging technique variability. We report a novel technique for evaluating TL competence using flexion-extension computed tomography (feCT) scan with 3-dimensional (3D) segmentation and quantitative analysis., Methods: feCT scans of 11 patients were segmented to create 3D surface models. Six patients with atlantoaxial pathology were evaluated for possible instability based on clinical examination and imaging findings. The other 5 patients had no clinical or imaging evidence of atlantoaxial injury. Dynamic atlantodental interval (ADI) was calculated using point-to-point voxel changes between flexion and extension 3D models. Magnitude and direction of ADI changes were quantified and compared with available cervical spine flexion-extension radiograph and/or MRI findings., Results: In the 5 patients without evidence of atlantoaxial injury, 94.3% of ADI vector changes were <3.0 mm. In the 3 patients with atlantoaxial pathology but TL competence, 92.4% of ADI vector changes were <3.0 mm. In the 3 patients with atlantoaxial pathology and TL incompetence, only 49.1% of ADI vector changes were <3.0 mm. In addition to the significant atlantoaxial subluxation in these 3 patients, there was significant rotational motion compared with the patients with an intact TL., Conclusions: 3D segmentation and quantitative analysis of feCT scan allow objective indirect assessment of TL integrity. Results are consistent with MRI findings and offer additional biomechanical information regarding the direction and distribution of atlantoaxial motion., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Calcium pyrophosphate dihydrate deposition (CPPD) disease, also known as pseudogout, in which crystals are deposited in the joints and/or soft tissues, leads to a variety of articular and periarticular disorders. Herein we report a 67-year-old female patient with neck pain who was diagnosed as CPPD disease of both the atlantoaxial joint and right C4-C5 facet joint with radiological findings. The combined use of computed tomography and magnetic resonance imaging can be helpful in establishing a diagnosis and providing the correct treatment.

Objective: Pannus formation in the atlanto-axial joint is a well-recognized complication of rheumatoid arthritis (RA). Occasionally, atlanto-axial pannus is reported when patients without a history of RA undergo magnetic resonance imaging (MRI) of the cervical spine. We sought to further characterize these patients., Methods: The Partners HealthCare Research Patient Data Registry was free-text searched for "atlanto-axial" AND "pannus" in cervical spine MRI reports from 2001 to 2015. Cases with MRI reports describing pannus were reviewed. Clinical data were extracted by chart review in cases with confirmed atlanto-axial pannus (n = 105)., Results: Twenty-nine patients (27.6%) had RA, all of whom except one carried this diagnosis at the time of the MRI scan. Only 1 of 77 patients without a history of RA was subsequently diagnosed with RA (1.3%, 95% CI 0.1-7.0%, median followup 3.6 yrs). Non-RA patients were significantly older (median age 79 vs 63 yrs, p < 0.0001), less frequently female (55% vs 86%, p = 0.0032), and more likely to have undergone prior cervical spine surgery (18% vs 0%, p = 0.016) compared with RA patients. Thirty-four non-RA patients (44.7%) either had a clinical diagnosis of calcium pyrophosphate dihydrate disease (CPPD) or imaging evidence for tissue calcification. There were no significant differences in age or sex between the CPPD subgroup and other non-RA patients. Twenty-eight patients (26.7%) underwent cervical spine surgery., Conclusion: Patients without RA diagnosis and incidental atlanto-axial pannus on cervical spine MRI are unlikely to have previously unrecognized RA. Degenerative disease and tissue calcification may contribute to pannus formation in these patients.

Objective: To determine a flexed position for radiographic diagnosis of atlantoaxial instability (AAI) and to identify radiographic measurement cutoffs to differentiate affected dogs from neurologically healthy toy breeds., Study Design: Retrospective case series and prospective case controls., Animals: Thirty-nine client-owned toy breed dogs in which AAI had been diagnosed and 20 neurologically healthy client-owned toy breed dogs., Methods: Medical records from three institutions were retrospectively reviewed to identify dogs affected with AAI. Flexed lateral images were reviewed, and measurements were obtained by using anatomic landmarks. Radiography was performed with control dogs to obtain the same measurements., Results: Flexed lateral radiographs of thirty dogs affected with AAI were found to be positioned at a mean of 51° flexion. When flexed lateral radiographs were evaluated with a cutoff value for atlas to axis angle (AAA) >10°, evaluation of all breeds represented revealed a 90% sensitivity and 90% specificity. When this cutoff was evaluated in Yorkshire terriers, Chihuahuas, and mixes of these breeds, the sensitivity was 92%, and the specificity was 92%. When the control sample was positioned at 51° ± 10°, only two of the dogs were within the AAA cutoff value of >10°. There was no difference between the measurements obtained by using the flexed lateral view (mean = 50.9°) and the exaggerated flexed lateral view (mean = 38.9°) in the control sample., Conclusion: This study established objective measurements for the positioning and diagnosis of AAI on flexed lateral radiographs in toy breed dogs., Clinical Significance: Atlantoaxial instability can be objectively diagnosed in sedated or anesthetized toy breed dogs when applying 51° flexion to cervical radiographs., (© 2019 The American College of Veterinary Surgeons.)

Objective: The craniocervical junction permits a certain amount of mobility for the cervical spine. The biomechanical properties of occipital bone-atlas joint mainly depend on the bony structure, and atlas-axis joint biomechanical properties mainly depend on ligamentous structure. The underlying etiologic factor of Chiari malformation (CM) is debatable. Nowadays, some researchers argue that stabilization difference is one of the suspicious factors for etiopathogenesis. We aim to analyze the ligamentous morphometric differences of CM., Methods: Magnetic resonance images of 93 adult healthy subjects (n = 93) without any craniocervical junction development abnormalities and 25 (n = 25) adult patients with craniocervical junction development abnormalities (Arnold CM) were evaluated. Length, width, and length-width ratios of ligaments were evaluated., Results: Length of transverse ligament (mean: 23 ± 3.6 [range: 12.1-31.4]) in the normal population was significantly longer than transverse ligament length in CM patients (mean: 21.3 ± 2.5 [range: 17.2-24.9]). Length of alar ligament (mean: 10.7 ± 2 [range: 5.1-15.4]) in the normal population was significantly longer than alar ligament length in CM patients (mean: 8.8 ± 3.8 [range: 1.1-16.6]) (P = 0.007)., Conclusions: Craniocervical ligaments play an important role in maintaining stability and motion capacity of this region. This study promoted better understanding of craniocervical junction anomalies and provided data that facilitate performing more precise surgical treatment., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Objective: Occipitalization of the atlas (OA) often is associated with atlantoaxial dislocation and basilar invagination. The purpose of this study is to determine the biomechanical difference between normal and OA conditions in the craniovertebral junction and to further explore the rationale for development of atlantoaxial dislocation and basilar invagination using the finite element model (FEM)., Methods: A ligamentous, nonlinear, sliding-contact, 3-dimensional FEM of the occipitoatlantoaxial complex was generated. Validation of the model was accomplished by comparing kinematic predictions with experimental data. We defined the atlantooccipital joint as a tie contact to simulate the OA deformity. The range of motion and the value of the maximum Von Mises stress were compared between the intact and OA models., Results: We found all of the predicted data in the intact FEM fell within 1 standard deviation of the cadaver data for all 6 loadings. The OA simulation significantly reduced the overall range of motion of the occipitoatlantoaxial complex at all loadings. The maximum Von Mises stress was predicted to increase at the transverse ligament and the superior articular facet of the axis for all the flexion, extension, lateral bending, and axial rotation loadings., Conclusions: The OA could result in hypermobility of the atlantoaxial segment and cause overstress in the transverse ligament and the lateral atlantoaxial joints. These changes explain the pathogenesis of atlantoaxial dislocation and basilar invagination associated with OA. Follow-up should be scheduled regularly due to the nature of the dynamic development of atlantoaxial dislocation and basilar invagination., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Objective: To perform a radiological analysis of the degeneration of C1-C2 joints after C1-C2 transarticular fixation (TAF) and compare the long-term results of a routine Magerl technique (RMT) to a posterior transarticular C1-C2 stand-alone screw instrumentation (SAS) application., Methods: A total of 40 patients (26 men and 14 women) were included in the present retrospective observational cohort study. The mean follow-up period was 61.7 months (range, 11-118). The mean patient age at the baseline examination was 48.4 years (range, 22-82). Of the 40 patients, 11 were included in the RMT group and 29 in the SAS group., Results: The structure of 80 atlantoaxial joints was analyzed, with grade 4 degenerative changes observed in 57 joints (71.3%). Of the 40 analyzed atlanto-odontoid joints, grade 4 degenerative changes were revealed in 18 joints (45%). C1-C2 bone fusion was observed in 38 patients (95%) and stable fibrous fusion in 2 patients (5%). No cases of C1-C2 nonunion were revealed. No statistically significant differences in the frequency of C1-C2 fracture consolidation or C1-C2 fusion were revealed between the RMT and SAS groups., Conclusions: The application of cortical lag screws in TAF might result in stable atlantoaxial joint fusion formation without joint curettage. Atlanto-odontoid joint fusion was also observed after C1-C2 TAF. The application of cortical lag screws for bilateral fixation using the SAS technique resulted in C1-C2 fusion in 93.1% of cases, comparable to the results with the Magerl technique., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Background: Surgical treatment is mainly used for atlantoaxial tuberculosis with neurological damage. However, the anatomic structure around the atlantoaxial joint is complex, and the position of vertebral body is deep, which increases the difficulty of the operation and it is challenging for the surgeon to develop surgical strategy. The purpose of this study was to evaluate the clinical outcomes of one-stage combined anterior and posterior surgical treatment approach for atlantoaxial tuberculosis with neurological impairment., Methods: From January 2005 to January 2015, 12 patients suffering from atlantoaxial tuberculosis with neurological impairment were surgically treated by one-stage combined anterior and posterior approach. Preoperative CT scanning and MRI imaging showed unilateral or bilateral lateral mass destruction of the atlas, and varying destruction degrees of odontoid process, loss of atlantoaxial stability, and tuberculosis focus into the spinal canal resulting in the corresponding spinal cord compression in all patients. The preoperative neurological classifications were Class C for 4 cases, D for 8 cases according to the American Spinal Injury Association (ASIA) system. Quadruple sensitive anti-TB drug treatment was used in all 12 patients preoperative and postoperative. Patients' clinical symptoms and neurological function recovery were evaluated by comparing the Visual Analogue Scale (VAS) score, Neck Disability Index (NDI), Japanese Orthopedic Association (JOA) score and ASIA grading before operation and at the final follow-up., Results: Mean surgical duration was 263.3 ± 43.6 min. Intraoperative blood loss was averagely 529.2 ± 169.8 ml. The average fusion period was 7.3 ± 1.5 months. No instrumentation loosening, migration or breakage was observed during the follow-up of 6.5 ± 2.9 years. The VAS, NDI and JOA scores were significantly changed to 1.00 ± 0.95, 9.50 ± 3.34 and 15.42 ± 1.44 at last follow-up (P < 0.05). The neurological function of all 12 patients was recovered to Class E according to the ASIA grading system., Conclusion: In the treatment of atlantoaxial tuberculosis with neurological impairment, one-stage combined anterior and posterior surgical approach have the ability to complete debridement and decompression, and reconstruction of the stability of the upper cervical spine.

Case: Spine injuries are rare in children, but when they do occur, the synchondrosis of C2 may be involved. A 5-year-old boy presented to our clinic complaining of neck pain for 6 weeks, which started after wrestling with peers. He had slight upper extremity weakness, clonus, and diminished reflexes. Imaging, including computed tomography and magnetic resonance imaging scans, showed a fracture dislocation through the synchondrosis of the odontoid. The patient was initially treated with admission to the hospital, awake halo placement, and gradual traction over a few days. Subsequently, he was taken for transoral reduction and posterior instrumented fusion of C1-C3 using a combination of sublaminar suture, screws, and rods. Most recently, he was doing well over 2 years later, with no residual neurologic symptoms., Conclusions: The case presented demonstrates one option for an otherwise nonreducible odontoid synchondrosis fracture with complete atlantoaxial dislocation: transoral reduction and open posterior instrumentation. This proved to be a practical technique and provided a good clinical result in this case. These injuries are rare, but when they do occur, the examination can be surprisingly subtle given the severity of the injury. Plain films should be scrutinized carefully and advanced imaging obtained when necessary to confirm the diagnosis.

Objective: To assess the involvement of the atlantoaxial joint in patients with early rheumatoid arthritis (ERA) and to elucidate the risk profile for the individual patient., Materials and Methods: Consecutive ERA patients (disease duration < 12 months) were included in our study. A cervical spine magnetic resonance imaging (MRI) and X-rays (cervical spine, hands, wrists, and feet) were performed in all patients. The MRI features were correlated with clinical, radiological, and biochemical variables., Results: Fifty patients (13 men and 37 women) with a mean age of 58.2 years (range, 36-79 years) were included in the study. In 12 (24%) patients were detectable MRI findings suggestive of the craniovertebral junction involvement. Compared with patients without cervical involvement, the patients with atlantoaxial synovitis showed a significantly higher anti-citrullinated protein antibodies (ACPA) titer [mean 200.25 UI (SD 262.44) vs. mean 22.05 (SD 40.21) (p < 0.001)]; a worse Disease Activity Score 44 joints (DAS44) [mean 5.72 (SD 0.44) vs. mean 4.52 (SD 0.53) (p < 0.001)]; a worse Health Assessment Questionnaire Disability Index (HAQ-DI) [mean 1.55 (SD 0.37) vs. mean 1.09 (SD 0.33) (p < 0.001)], and a higher Simple Erosion Narrowing Score (SENS) [mean 15.83 (SD 4.52) vs. mean 7.71 (SD 3.43) (p < 0.001)]. The multivariate analysis revealed a meaningful relationship between atlantoaxial synovitis and ACPA, DAS44, and the presence of an erosive disease., Conclusions: The craniovertebral junction is frequently involved in ERA patients. ACPA, high disease activity, and erosive disease at baseline are predictors of atlantoaxial involvement.

Case: We report a unique case of compressive myelopathy caused by late kyphosis angulation of a previously operated dens base fracture nonunion challenged by age-related ankyloses of the lateral articulations C1 to C2 and a solid posterior fusion mass., Conclusions: Posterior column shortening such as commonly practiced for progressive kyphosis or myelopathy may be precluded at the atlantoaxial level for potential vascular risk to the vertebral artery. A standard anterior cervical approach and the application of basic surgical spine care principles lead to a simple solution in the unique and highly complex anatomy of our case.

Introduction: Atlanto-axial rotatory fixation (AARF) is a rare complication of ventriculo-peritoneal shunt (VPS) surgery., Case Presentation: The authors present a unique case of AARF developing early after VP shunting, with persistent torticollis, a "cock-robin" head position, and a thick fibrous band along the catheter path. Due to refractoriness to conservative treatments, AARF, which can be an early-onset complication of VPS surgery, was resolved by removing the distal catheter along with the fibrous band encasing it., Conclusion: Surgical removal of the fibrous band might be enough to solve such complication with no need of further surgical fusion procedures.

Background: Grisel's syndrome is a non-traumatic subluxation of the atlantoaxial joints, which is caused by an inflammatory process involving the upper neck. Torticollis, neck pain, and reduced neck mobility are the main clinical signs of presentation. Predisposing factors are trauma, hyperlaxity of the transverse and alar ligaments of the atlantoaxial joints, and surgical interventions carried out in this area. Several viral and bacterial pathogens have been reported as causative events of Grisel's syndrome, including Epstein-Barr virus, Kawasaki disease, Streptococcus pyogenes, Staphylococcus aureus, and other infectious agents. Grisel's syndrome linked to Mycoplasma pneumoniae infection as the trigger has not previously been reported. Mycoplasma pneumoniae is a small prokaryotic microbe and a frequent etiologic factor of respiratory tract infections and, less frequently, of extrapulmonary body organs. The recognition of the Grisel's syndrome is based on clinical and neuroradiological investigations, and early diagnosis and specific treatment are crucial to the successful outcome of the disease., Results: We report the case of an 8-year-old girl with Grisel's syndrome caused by an upper respiratory tract infection due to Mycoplasma pneumoniae. Diagnostic suspicion and treatment of Grisel's syndrome were established quickly by anamnestic and clinical data and confirmed by radiological findings. The girl was immediately treated with specific antibiotic therapy and cervical immobilization, thus preventing the most dangerous complications of the disorder., Conclusion: Mycoplasma pneumoniae, among the other infectious agents, may be cause of scute torticollis and Gresel's syndrome.

This study investigated cerebral ventricle size and concurrent craniocervical junction abnormality in relation to atlantooccipital overlapping (AOO) in dogs with atlantoaxial instability (AAI). A total of 61 dogs were treated with atlantoaxial ventral fixation. Medical records of each dog, including magnetic resonance (MR) and computed tomography (CT) images, were retrospectively reviewed. CT images were assessed for the presence of AOO and the dogs were then assigned to either an AOO group or a non-AOO group accordingly. CT images were also evaluated to determine the foramen magnum (FM) index. Syringomyelia, cerebellar compression, dorsal compression, and the degree of enlargement of each cerebral ventricle were evaluated using MR images. Of the 61 dogs, 23 had AOO and 38 did not. Furthermore, the ventricle/brain height ratio, the fourth ventricle height/cerebellum length ratio, and the fourth ventricle width/cerebellum length ratio were significantly higher in the AOO group than in the non-AOO group. However, the FM index, third ventricle/brain height ratio, and incidence of syringomyelia did not differ significantly between the two groups. Dogs with concurrent AOO exhibited significantly more dilatation of the lateral and fourth ventricles.

A 5-year-old boy with a chromosome-9 abnormality and multiple external and visceral malformations was found in cardiopulmonary arrest during a regular visit to the hospital; he did not respond to cardiopulmonary resuscitation and died. An odontoid process fracture and calcification and fibrosis of the muscles around the superior cervical vertebra were observed during the autopsy. Postmortem computed tomography revealed an anterior dislocation of the atlas; odontoid synchondrosis fracture; and delayed, incomplete bony fusion of the odontoid process relative to his age. The cause of his death was a superior spinal cord injury. The tissue surrounding the upper cervical spine presented with myositis ossificans, suggesting a prior injury. He experienced a minor traffic accident 3 months before his death. It was concluded that the odontoid synchondrosis fracture occurred during the accident based on the incomplete bony fusion and atlantoaxial instability, which were consistent with the findings of myositis ossificans. Delayed fatal dislocation may then have occurred under the influence of a minor external force. Odontoid process abnormalities and atlantoaxial instability are common in patients with trisomy 21 and other congenital diseases; however, the condition's association with chromosome-9 abnormalities has not been reported. In children with various chromosomal abnormalities, periodic assessment of instability and morphology of the cervical spine, and a lowered examination threshold for the children at risk, could prove useful in the prevention injuries leading to fatality, and provide additional information to rule out abuse., (Copyright © 2018 Elsevier Ltd and Faculty of Forensic and Legal Medicine. All rights reserved.)

Objective: The implications of diagnosis and treatment of central or axial atlantoaxial dislocation (CAAD) as a cause of symptoms of cervical myelopathy are evaluated., Methods: This is a report of a series of 5 patients who presented with the primary symptoms of spasticity and motor weakness and paresthesias in all the limbs. There was no evidence of any significant compression of the dural tube or neural structures at the craniovertebral junction. There was no craniovertebral junction instability when assessed by classically described radiologic parameters. CAAD was diagnosed based on our recently discussed parameter of facetal alignment, corroborative clinical and radiologic evidence, and direct observation of atlantoaxial instability by manual manipulation of the bones of the region. All patients underwent atlantoaxial fixation., Results: There was remarkable improvement in the clinical symptoms in the immediate postoperative period and during the follow-up period of 12-24 months (average, 16 months). All patients have continued to have progressive clinical recovery. Clinical assessments were done using Goel clinical evaluation scale, Japanese Orthopedic Association score, and visual analog scale., Conclusions: Identification and treatment of CAAD can have a significant management impact on patients where the cause of spastic quadriparesis is otherwise undiagnosed., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Purpose: Occipitocervical instrumentation is infrequently required for stabilization of the axial and subaxial cervical spine in very young children. However, when it is necessary, unique surgical considerations arise in children when compared with similar procedures in adults., Methods: The authors reviewed literature describing fusion of the occipitocervical junction (OCJ) in toddlers and share their experience with eight cases of young children (age less than or equal to 4 years) receiving occiput to axial or subaxial spine instrumentation and fixation. Diagnoses and indications included severe or secondary Chiari malformation, skeletal dysplastic syndromes, Klippel-Feil syndrome, Pierre Robin syndrome, Gordon syndrome, hemivertebra and atlantal occipitalization, basilar impression, and iatrogenic causes., Results: All patients underwent occipital bone to cervical spine instrumentation and fixation at different levels. Constructs extended from the occiput to C2 and T1 utilizing various permutations of titanium rods, autologous rib autografts, Mersilene sutures, and combinations of autografts with bone matrix materials. All patients were placed in rigid cervical bracing or halo fixation postoperatively. No postoperative neurological deficits or intraoperative vascular injuries occurred., Conclusion: Instrumented arthrodesis can be a treatment option in very young children to address the non-traumatic craniocervical instability while reducing the need for prolonged external halo vest immobilization. Factors affecting fusion are addressed with respect to preoperative, intraoperative, and postoperative decision-making that may be unique to the toddler population.

In addition to involvement of small peripheral joints, the cervical spine is the second most affected body region in rheumatoid arthritis (RA). Due to improvement of pharmaceutical treatment in recent years, new data show that there is a decreasing prevalence of cervical involvement; however, depending on the severity of cervical lesions surgical treatment still plays an important role. The sequelae of involvement of the cervical spine are craniocervical and atlantoaxial instability, which can cause severe pain, neural deficits and even death. Multimodal conservative treatment can lead to an alleviation of pain but in cases of therapy-resistant pain or neural deficits surgical treatment alone is essential to improve patient outcome. For isolated atlantoaxial instability (AAS), atlantoaxial fusion by posterior C1-2 fixation according to Harms and Goel is the method of choice. Posterior stabilization including C0 should be avoided whenever possible due to substantial limitations in range of movement.

Atlanto-axial instability (AAI) is a congenital or developmental condition that leads to instability/subluxation of the atlantoaxial joint. This study is performed to determine anatomic feasibility of trajectory L and help select an optimal screw trajectory in treating patients with AAI with a narrow C1 posterior arch. Sixty patients who underwent cervical three dimensional-computed tomography (3D-CT) were chosen from the hospital's picture archiving and communication system (PACS). Aquilion Multi 64 helical CT was used to perform CT examinations and measurements on patients. Based on CT images, the trajectory L and M for each C1 pedicle were established. Posterior arch height was measured on C1 coronal image. The medullary cavity width along trajectory M was narrower than trajectory L. The medullary cavity width that was less than 3.5 mm was found in 12.5% pedicles along trajectory M and 2.5% along trajectory L. The posterior arch height along trajectory L was significantly higher than that of trajectory M. Posterior arch height that was less than 3.5 mm was found in 74.2% pedicles along trajectory M and only 16.7% along trajectory L. The pedicle length along trajectory L was significantly longer than trajectory M. Trajectory angles for C1 pedicles had an average of 9.08° ± 4.66° along trajectory L and 14.53° ± 4.03° along trajectory M. The Optimal entry point of trajectory L was 5.4 mm medial to trajectory M. Based on our results, this study suggests that C1 pedicle screw trajectory with lateral inclination yielded a good outcome in the treatment of AAI., (Copyright © 2018 Kaohsiung Medical University. Published by Elsevier Taiwan LLC. All rights reserved.)

Introduction: Grisel's syndrome consists in rotational subluxation of C1-C2 following ENT infection or surgery. There is no consensus on management. We present 2 cases requiring surgical treatment in our center., Case Reports: Two 10-year-old patients presented torticollis with cervical pain resistant to medical treatment, with onset a few months after tonsillectomy. In both cases, radiological assessment, comprising CT scan and MRI, showed Fielding-Hawkins type-3 C1-C2 rotational subluxation, without ligament lesion. After failure of conservative treatment, posterior reaming, realignment, C1-C2 arthrodesis using lateral masses and pars interarticularis screws and bone graft achieved good fusion and immediate spinal stability in all planes of the atlantoaxial complex., Discussion: Grisel's syndrome consists in non-traumatic subluxation of the atlantoaxial joint with intact atlantoaxial ligaments. Initial pharyngeal inflammation spreads to the prevertebral fascia via direct connections between the periodontoidal venous plexus and pharyngovertebral veins, inducing fasciitis that leads to abnormal relaxation of the atlantoaxial ligaments and reactional muscle contraction with ankylosis. This phenomenon, appearing gradually and insidiously over a period of a few weeks, creates a frozen joint with ankylosis. Medical treatment with NSAIDs, muscle relaxants, and immobilization is usually sufficient; cervical traction may be needed. Surgical treatment by C1-C2 arthrodesis is indicated in case of failure of medical management or onset of neurologic signs., Conclusion: Close collaboration between pediatricians, ENT surgeons and neurosurgeons is essential for early diagnosis and management, which is the main prognostic factor for successful medical treatment, avoiding surgery., (Copyright © 2018 Elsevier Masson SAS. All rights reserved.)

Study Design: This is a meta-analysis., Objective: To establish rates of (1) neurological complications, (2) bony-related complications, (3) complications delaying recovery, (4) reoperation, and (5) fatalities following posterior cervical arthrodesis in Down syndrome (DS) patients with atlantoaxial subluxation. To determine if presenting symptoms had any relationship to postoperative complications., Summary of Background Data: Posterior arthrodesis is commonly utilized to correct cervical instability secondary to atlantoaxial instability in DS patients. However, there has never been a global evaluation of postoperative complications associated with posterior cervical spinal arthrodesis in DS patients., Methods: A comprehensive search of Medline/PubMed, EMBASE, and Ovid databases between January 1980 and July 2017 was utilized to identify DS patients with atlantoaxial subluxation who underwent posterior cervical arthrodesis. Data were sorted by neurological complications, complications delaying recovery, bony-related complications, reoperations, and fatalities. Patients were sorted into 2 groups based on presentation with or without neurological deficits., Results: Twelve studies met inclusion criteria, including 128 DS patients. Mean age was 13.8 years (range: 6.7-32.7 y; 47.8% male). Mean follow-up was 31.7 months (range: 14.9-77 mo). All patients underwent primary posterior cervical arthrodesis with an average of 2.5 vertebrae fused. A total of 39.6% of patients had bony-related complications [95% confidence interval (CI), 31.4%-48.5%], 23.3% had neurological deficits (95% CI, 16.6%-31.6%), and 26.4% experienced complications delaying recovery (95% CI, 19.4%-34.9%). The reoperation rate was 34.9% (95% CI, 25.5%-45.6%). The mortality rate was 3.9% (95% CI, 1.5%-9.7%). Neurological complications were 4-fold (P<0.05) and reoperation was 5.5-fold (P<0.05) more likely in patients presenting with neurological deficits compared with those without., Conclusions: This study detailed global complication rates of posterior arthrodesis for DS patients, identifying bony-related complications and reoperations among the most common. Patients presenting with neurological symptoms and cervical instability have increased postoperative rates of neurological complications and reoperations than patients with instability alone. Further investigation into how postoperative complications effect patient independence is warranted.

Klippel-Feil syndrome (KFS) is defined as congenital fusion of two or more cervical vertebrae resulting from a segmentation failure in the developing spine. According to Samartzis et al., the most commonly fused segments are found at C2/3 (74.1%) and C6/7 (70.4%). In patients with C2/3 fusion, especially when there is additional C1 occipitalization, several secondary anomalies including atlantoaxial dislocation (AAD), basilar invagination (BI), Chiari malformation, and syringomyelia can be identified. In this report, we present a case of a 12-year-old patient with C2/3 and occipitalization and a "Full-Spectrum" presentation of associated CVJ abnormalities including C0/1 fusion, AAD, BI, Chiari malformation, syringomyelia, myelopathy and cranial neuropathy received neurological decompression of the cervico-medullary junction by posterior reduction of the AAD and reconstruction of her CVJ using an unconventional hybrid construct due to a high-riding right vertebral artery in C2. To our knowledge, her "Full-Spectrum" presentation may include the most categories of concomitant abnormalities in the literature. In addition, She received neurological decompression of the cervico-medullary junction using an unconventional hybrid construct due to a high-riding vertebral artery in C2. Three months after the surgery, all of her symptoms recovered significantly. Neither Chiari malformation nor syringomyelia could be identified by MRI two years after the surgery. At the last follow-up (4 years), the patient became completely asymptomatic., (Copyright © 2018 Elsevier Ltd. All rights reserved.)