C2 pedicle screw insertion assisted by mobilization of the vertebral artery in cases with high-riding vertebral artery.

Objective: To describe the feasibility, safety and efficacy of mobilization of the vertebral artery for C2 pedicle screws in cases with the high-riding vertebral artery (HRVA).. Methods: During the period January 2020 to September 2022, fifteen patients underwent posterior occipitocervical fixation in our department. All patients had unilateral HRVA on at least one side that prohibited the insertion of C2 pedicle screws. There were 2 males and 13 females aged 47 ± 11.9 years (range: 17-64 years). After the correction of the vertical dislocation during the operation, the C2 pedicle screw insertion and occipitocervical fixation and fusion were performed using the vertebral artery mobilization technique. A routine three-dimensional reconstructed CT examination was executed to confirm the trajectory of C2 pedicle screws post-operation, and a CT angiography examination was performed when necessary. Neurological function was assessed using the Japanese Orthopedic Association (JOA) scale. The preoperative and postoperative JOA score and the main radiological measurements, including anterior atlantodental interval (ADI), the distance of odontoid tip above Chamberlain line, and clivus-canal angle (CCA), were collected and compared by paired t-test. Results: All 15 patients had atlas assimilation, among which 12 patients had C2-C3 fusion (Klippel-Feil syndrome). Mobilization of the HRVA was successfully completed, and C2 pedicle screws were then fulfilled after the vertebral artery was protected. There was no injury to the vertebral artery during the operation. Meanwhile, no severe surgical complications such as cerebral infarction or aggravated neurological dysfunction occurred during the perioperative period. Satisfactory C2 pedicle screw placement and reduction were reached in all 15 patients. All the patients achieved bone fusion 6 months after surgery. No looseness and shift of internal fixation or reduction loss was observed during the follow-up period. Compared to the preoperative, the postoperative JOA score and the main radiological measurements were remarkably improved and statistically significant. Conclusions: C2 pedicle screw insertion assisted by mobilization of the vertebral artery is safe and considerably effective, providing a choice for internal fixation in cases with high-riding vertebral arteries.

Clinical effect and prognosis of transoral or endoscope-assisted transoral release for irreducible atlantoaxial dislocation: A retrospective cohort study.

Background: The clinical applications of endoscope-assisted transoral release for irreducible atlantoaxial dislocations are limited. This study aimed to investigate the clinical effect and prognostic factors of traditional and endoscope-assisted transoral release, as well as posterior reduction and fixation, in treating irreducible atlantoaxial dislocations. Materials and methods: We conducted a retrospective study on 59 patients with irreducible atlantoaxial dislocation who underwent either traditional or endoscope-assisted transoral release, posterior fixation, and fusion between January 2018 and January 2023. Various data, including surgical time, blood loss, drainage volume, oral intake, hospital stay, complications, and neurological status (assessed by the Japanese Orthopedic Association [JOA] score and Oswestry Disability Index [ODI]), were recorded. Imaging parameters such as the atlantodontoid interval (ADI), space available for the cord (SAC), and cervicomedullary angle (CMA) were analyzed and compared. In addition, the correlation between ODI, JOA and patient age, course of disease, preoperative ADI, SAC and CMA were analyzed. Results: No significant differences were observed in age, sex, BMI, preoperative ADI, preoperative SAC, or preoperative CMA. All patients achieved excellent reduction with no significant differences between the two groups. Patients in the endoscopic group experienced significantly reduced blood loss, earlier oral intake, and shorter hospital stays compared to those in the open group (P < 0.05). The ODI and JOA scores improved significantly in both groups at 1, 6, 12, 18, and 24 months postoperatively (P < 0.05). Postoperative ADI, SAC, and CMA values in both groups were significantly better than preoperative values (P < 0.001). The patient age, course of disease and the preoperative ADI were negatively correlated with the postoperative ODI and the JOA improvement ratio (P < 0.01), and the preoperative SAC and preoperative CMA had positive correlations with the postoperative ODI and the JOA improvement ratio (P < 0.01) at 6, 12 and 24 months postoperatively. Conclusion: Patient age, course of disease, preoperative ADI, SAC and CMA are correlated with the operative prognosis of irreducible atlantoaxial dislocation. The endoscope-assisted transoral approach, compared to the traditional transoral approach, is minimally invasive, resulting in less operative blood loss, earlier oral intake and a shorter length of hospital stay, which could be offered as an alternative for irreducible atlantoaxial dislocation.

Clival Osteomyelitis in an Adult Patient: A Case Report.

Clival osteomyelitis is an uncommon skull base infection that mostly affects elderly diabetics and is frequently caused by malignant otitis externa or paranasal sinus infections. It manifests as severe otalgia, fever, auditory fullness, and purulent otorrhea. Clinical history, physical examination, test data, radiographic findings, and pathogen identification all contribute to a diagnosis. Treatment consists of extended intravenous broad-spectrum antibiotics, with severe cases necessitating surgical debridement. We present a case of a 20-year-old girl with bilateral ear discharge, nasal blockage, and purulent rhinorrhea, as well as a dull neck ache increased by extension. An MRI revealed osteomyelitis in the clivus and right atlanto-occipital joint. The clival abscess was drained transnasally using endoscopic techniques. Microbiological tests revealed Streptococcus intermedius. The post-operative recovery was uneventful, with extended antibiotic therapy. Early identification and treatment are critical for preventing serious consequences, as illustrated in this case, where surgical and antibiotic care improves patient outcomes.

[Comparative study of computer-assisted and robot-assisted atlantoaxial pedicle screw implantation for reversible atlantoaxial dislocation].

Objective: To investigate the effectiveness of computer-assisted and robot-assisted atlantoaxial pedicle screw implantation for the treatment of reversible atlantoaxial dislocation (AAD). Methods: The clinical data of 42 patients with reversible AAD admitted between January 2020 and June 2023 and met the selection criteria were retrospectively analyzed, of whom 23 patients were treated with computer-assisted surgery (computer group) and 19 patients were treated with Mazor X spinal robot-assisted surgery (robot group). There was no significant difference in gender, age, T value of bone mineral density, body mass index, etiology, and preoperative Japanese Orthopaedic Association (JOA) score, Neck Dysfunction Index (NDI) between the two groups ( P>0.05). The operation time, screw implantation time, intraoperative blood loss, hand and wrist radiation exposure, and complications were recorded and compared between the two groups. Gertzbein classification was used to evaluate the accuracy of screw implantation. JOA score and NDI were used to evaluate the function before operation, at 3 days after operation, and at last follow-up. At last follow-up, the status of screws and bone fusion were observed by neck three-dimensional CT. Results: The operation time and hand and wrist radiation exposure of the computer group were significantly longer than those of the robot group ( P<0.05), and there was no significant difference in the screw implantation time and intraoperative blood loss between the two groups ( P>0.05). All patients were followed up 11-24 months, with an average of 19.6 months. There was no significant difference in the follow-up time between the two groups ( P>0.05). There was no significant difference in the accuracy of screw implantation between the two groups ( P>0.05). Except for 1 case of incision infection in the computer group, which improved after antibiotic treatment, there was no complication such as nerve and vertebral artery injury, screw loosening, or breakage in the two groups. The JOA score and NDI significantly improved in both groups at 3 days after operation and at last follow-up ( P<0.05) compared to those before operation, but there was no significant difference between the two groups ( P>0.05). At last follow-up, 21 patients (91.3%) in the computer group and 18 patients (94.7%) in the robot group achieved satisfactory atlantoaxial fusion, and there was no significant difference in the fusion rate between the two groups ( P>0.05). Conclusion: Computer-assisted or robot-assisted atlantoaxial pedicle screw implantation is safe and effective, and robotic navigation shortens operation time and reduces radiation exposure.

[Effectiveness comparison of robot-assisted and traditional freehand technology in treatment of atlantoaxial dislocation].

Objective: To compare the effectiveness of robot-assisted and traditional freehand screw placement in the treatment of atlantoaxial dislocation. Methods: The clinical data of 55 patients with atlantoaxial dislocation who met the selection criteria between January 2021 and January 2024 were retrospectively analyzed. According to different screw placement methods, they were divided into the traditional group (using the traditional freedhand screw placement, 31 cases) and the robot group (using the Mazor X robot-assisted screw placement, 24 cases). There was no significant difference in gender, age, body mass index, etiology, and preoperative visual analogue scale (VAS) score, cervical spine Japanese Orthopaedic Association (JOA) score between the two groups ( P>0.05). The operation time, intraoperative blood loss, operation cost, and intraoperative complications were recorded and compared between the two groups. The VAS score and cervical spine JOA score were used to evaluate the improvement of pain and cervical spinal cord function before operation and at 1 month after operation. CT examination was performed at 3 days after operation, and the accuracy of screw placement was evaluated according to Neo grading criteria. Results: All the 55 patients successfully completed the operation. The operation time, intraoperative blood loss, and operation cost in the robot group were significantly higher than those in the traditional group ( P<0.05). A total of 220 C 1 and C 2 pedicle screws were inserted in the two groups, and 94 were inserted in the robot group, with an accuracy rate of 95.7%, among them, 2 were inserted by traditional freehand screw placement due to bleeding caused by intraoperative slip. And 126 pedicle screws were inserted in the traditional group, with an accuracy rate of 87.3%, which was significantly lower than that in the robot group ( P<0.05). There were 1 case of venous plexus injury in the robot group and 3 cases in the traditional group, which improved after pressure hemostasis treatment. No other intraoperative complication such as vertebral artery injury or spinal cord injury occurred in both groups. All patients were followed up 4-16 months with an average of 6.6 months, and there was no significant difference in the follow-up time between the two groups ( P>0.05). Postoperative neck pain significantly relieved in both groups, and neurological symptoms relieved to varying degrees. The VAS score and cervicle spine JOA score of both groups significantly improved at 1 month after operation when compared with preoperative scores ( P<0.05), and there was no significant difference in the score change between the two groups ( P>0.05). Conclusion: In the treatment of atlantoaxial dislocation, the accuracy of robot-assisted screw placement is superior to the traditional freedhand screw placement.

Cervico-occipital junction infectious osteoarthritis complicated with atlantoaxial dislocation, cervical abscesses and epiduritis: A case report and review of the literature.

Craniocervical junction infections are considered a rare condition and can be associated with degradation of the odontoid ligaments and, the risk of a subsequent atlantoaxial subluxation or dislocation. Osteomyelitis at this level is often seen in immunocompromised patients with, intravenous drug use or infective endocarditis. Atlantoaxial subluxation associated with pharyngeal infection or its surrounding tissues is called Grisel's syndrome. We report the case of a 29-year-old man diagnosed with infectious cervico-occipital osteoarthritis complicated by atlantoaxial dislocation, abscesses located in the retropharyngeal space, and the prevertebral space as well as upper cervical epiduritis. Our purpose is to highlight the role of radiologists in diagnosing this rare yet deadly condition.

The Establishment of a Novel Upper Cervical Complex Fracture Classification System.

BACKGROUND CONTEXT: Upper cervical complex fractures are associated with high rates of neurological damage and mortality. The Dickman's classification is widely used in the diagnosis of upper cervical complex fractures. However, it falls short of covering the full spectrum of complex fractures. This limitation hinders effective diagnosis and treatment of these injuries. PURPOSE: To address the diagnostic gap in upper cervical complex fractures, the study introduces a novel classification system for these injuries, assessing its reliability and usability. STUDY DESIGN: Proposal of a new classification system for upper cervical complex fractures. PATIENT SAMPLE: The study comprised the clinical data of 242 patients with upper cervical complex fractures, including 32 patients treated at our hospital, along with an additional 210 cases from the literature. OUTCOME MEASURES: The inter-observer and intra-observer reliability (kappa coefficient, κ) of this classification system were investigated by 3 spine surgeons. The three researchers independently re-evaluated the upper cervical complex fracture classification system 3 months later. METHODS: The proposed classification categorizes upper cervical complex fractures into three main types: Type I combines odontoid and Hangman's fractures into two subtypes; Type II merges C1 with odontoid/Hangman's fractures into three subtypes; and Type III encompasses a combination of C1, odontoid, and Hangman's fractures, divided into two subtypes. Meanwhile, a questionnaire was administered in 15 assessors to evaluate the system's ease of use and clinical applicability. RESULTS: A total of 45 cases (18.6%) unclassifiable by Dickman's classification were successfully categorized using our system. The mean κ value of inter-observer reliability was 0.783, indicating substantial reliability. The mean κ value of intra-observer reliability was 0.862, indicating almost perfect reliability. Meanwhile, thirteen assessors (87.7%) stated that the classification system is easy to remember, easy to apply, and they expressed intentions to apply it in clinical practice in the future. CONCLUSIONS: This system not only offers high confidence and reproducibility but also serves as a precise guide for clinicians in formulating treatment plans. Future prospective applications are warranted to further evaluate this classification system.

The role of clivus and atlanto-occipital lateral mass height in basilar invagination with or without atlas occipitalization.

Basilar invagination (BI) is a common deformity. This study aimed to quantitatively evaluate the height of clivus and atlanto-occipital lateral mass (LM) in patients with BI with or without atlas occipitalization (AOZ). We evaluated 166 images of patients with BI and of controls. Seventy-one participants were control subjects (group A), 68 had BI with AOZ (group B), and 27 had BI without AOZ (group C). Parameters were defined and measured for comparisons across the groups. Multiple linear regression analysis was used to test the relationship between Chamberlain's line violation (CLV) and the clivus height ratio or atlanto-occipital LM height. Based on the degree of AOZ, the lateral masses in group B were classified as follows: segmentation, incomplete AOZ, complete AOZ. From groups A to C, there was a decreasing trend in the clivus height and clivus height ratio. There was a linear negative correlation between the clivus height ratio and CLV in the three groups. Generally, the atlanto-occipital LM height followed the order of group B < group C < group A. The atlanto-occipital LM height was included only in the equations of groups B. There were no cases of atlantoaxial dislocation (AAD) in group C. There was a decreasing trend in LM height from the segmentation type to the complete AOZ type in group B. BI can be divided into three categories: AOZ causes LM height loss; Clivus height loss; Both clivus and LM height loss. The clivus height ratio was found to play a decisive role in both controls and BI group, while the atlanto-occipital LM height loss caused by AOZ could be a secondary factor in patients with BI and AOZ. AOZ may be a necessary factor for AAD in patients with congenital BI. The degree of AOZ is associated with LM height in group B.

Clinical and MR Predictors of Retro-Odontoid Pseudotumor Regression Following Posterior Fixation in Patients with Atlantoaxial Instability.

Purpose: To identify clinical and MR predictors of retro-odontoid pseudotumor (ROP) regression after posterior fixation in patients with atlantoaxial instability. Materials and Methods: We included patients who had undergone posterior fixation for atlantoaxial instability and preoperative and postoperative MR imaging. Patients were classified into two groups according to the degree of ROP regression after posterior fixation: regression (≥ 10% reduction) and no regression (< 10% reduction). Mann-Whitney and Fisher's exact tests were performed to identify the clinical (age and sex) and MR predictors (preoperative ROP thickness, ROP type, MR signal homogeneity of the ROP, spinal cord signal change, spinal cord atrophy, ossified posterior longitudinal ligament, os odontoideum, and atlantodental interval) associated with ROP regression. Results: We retrospectively assessed 11 consecutive patients (7 female; median age, 66 years [range, 31-84 years]). Posterior fixation induced ROP regression in eight (72.7%) patients. Older age and greater preoperative ROP thickness significantly correlated with ROP regression (p = 0.024 and 0.012, respectively). All patients with preoperative ROP thickness > 5 mm exhibited ROP regression. The other variables were not significantly associated with ROP regression. Conclusion: Older age and thicker preoperative ROP are associated with ROP regression after posterior fixation in patients with atlantoaxial instability.

Digital anatomical features of morphological development in the atlantoaxial synchondroses in children aged 1 to 6 years old: a retrospective study of CT images.

OBJECTIVE: To investigate the anatomical indexes and anatomical positional indexes of the atlantoaxial synchondroses in normal Chinese Han children aged 1-6 years, and to analyze the changing law of the atlantoaxial cartilage union with the growth and development of age and its influence on the atlantoaxial ossification in children. METHODS: A retrospective collection of CT imaging of 160 cases of normal cervical spine in children aged 1 to 6 years old was conducted. The cases were divided into six age groups, with each group representing a one-year age range. Measure the morphological anatomical indicators and anatomical positional indicators of the atlantoaxial synchondroses. Record and statistically analyze the measurements of each indicator. RESULTS: Measurements were taken on various parameters of the atlantoaxial synchondroses. TD, SD, height, area, and perimeter all gradually decreased among the groups. Distance between bilateral atlantal anterolateral synchondroses increased gradually from Group A to Group F, while the angle formed along the long axis in the cross-section showed a decreasing trend. Distance between the axoid dentolateral synchondroses and between the neurocentral synchondroses increased gradually from Group A to Group F, with the angle value in the cross-section showing a gradual decrease, and distance from the odontoid apex increasing from Group A to Group F. CONCLUSIONS: The atlantoaxial synchondroses gradually decrease in size with age, and ossification levels increase with age, with faster ossification occurring during a 1-2 years-old period. The anterolateral synchondroses, dentolateral synchondroses, and neurocentral synchondroses all gradually ossify towards the lateral direction with increasing age.

Efficacy and Safety of Shi Cervical Rotational Manipulation in Patients With Atlantoaxial Joint Subluxation: Protocol for a Randomized Controlled Trial.

BACKGROUND: The clinical diagnosis of atlantoaxial joint subluxation (AJS) in traditional Chinese medicine (TCM) is characterized by an unequal distance between the lateral mass of the atlas and the odontoid process on imaging, resulting in neck pain accompanied by symptoms such as dizziness, headache, and limited cervical mobility. In Shanghai, Shi cervical rotational manipulation (SCRM) is a commonly employed TCM manual therapy for treating this condition. Nevertheless, there is a lack of evidence-based medical information regarding the clinical efficacy and safety of this technique. OBJECTIVE: The principal aim of this study is to evaluate the efficacy and safety of SCRM in patients diagnosed with AJS. METHODS: This study is a prospective randomized controlled clinical trial that will be conducted at a single center and that has a follow-up period of 24 weeks. A total of 96 patients diagnosed with AJS will be recruited from outpatient and inpatient clinics at Shanghai Baoshan Hospital of Integrated Traditional Chinese and Western Medicine. These patients will be randomly assigned to either the experimental group (SCRM) or the comparison group (basic cervical manipulation [BCM]). Treatment sessions consisting of SCRM or BCM will be administered twice a week for a duration of 4 weeks. Clinical monitoring indicators include the presence or absence of clinical symptoms as recorded on a symptom recording form, cervical imaging examination findings using cervical computed tomography, degree of neck pain measured by a visual analog scale (VAS), cervical range of motion assessed through cervical mobility measurement, degree of vertigo evaluated using the Vertigo Symptoms Scale-Chinese Version (VSS-C), and adverse events that may occur during the follow-up period. The time points for data collection and follow-up are baseline and postintervention (weeks 4, 8, 12, 16, 20, and 24). RESULTS: This paper presents an overview of the reasoning and structure of a prospective randomized controlled trial with the objective of investigating the clinical efficacy and safety of SCRM in patients with AJS by assessing improvements in clinical symptoms, neck pain severity, and vertigo severity and evaluating changes in cervical imaging findings. Recruitment was started in March 2023. By the end of May 2024, 76 patients were included in this project. The last follow-up data are predicted to be collected by the end of February 2025. CONCLUSIONS: This investigation will yield dependable evidence regarding the efficacy and safety of SCRM in patients with AJS. TRIAL REGISTRATION: Chinese Clinical Trial Registry ChiCTR2300068510; https://www.chictr.org.cn/showprojEN.html?proj=186883. INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID): DERR1-10.2196/57865.

Treatment of Klippel-Feil syndrome with symptomatic atlantoaxial instability in a 7-year-old boy : A case report.

Klippel-Feil syndrome (KFS) is a congenital deformity of the cervical spine. Clinical symptoms of KFS are reduced range of motion, short neck and low hairline. In adult KFS patients the deformity can lead to adjacent segmental instability with spinal canal stenosis, radiculopathy and myelopathy. This article reports about the diagnostics and treatment management of juvenile KFS patient with myelopathy due to instability of the C1/C2 segment, subsequent stenosis through the posterior arch of C1 and symptomatic myelopathy. This 7­year-old boy could be successfully treated with C1 decompression and computer tomography (CT) guided C1/C2 stabilization with pedicle screws under intraoperative neuromonitoring.

[Grisel's syndrome : about two cases of a atlantoaxial (C1-C2) subluxation]. / Le syndrome de Grisel : à propos de deux cas de subluxation C1-C2.

Grisel's syndrome is a non-traumatic atlantoaxial (C1-C2) subluxation and one of the causes of torticollis in children. The subluxation occurs in the context of an infection in the ENT ("Ear Nose and Throat") region or following surgery. Diagnosis is based on clinical examination and radiological assessment. Treatment is typically medical and conservative, with surgical interventions reserved for recurrences and late presentations. We discuss here two cases of C1-C2 subluxation. The first case involves a 10-year-old child with subluxation following a rhinopharyngitis. This presentation is the classical manifestation of Grisel's syndrome. Prompt management led to correction of the subluxation using medical treatment and a soft Philadelphia collar. The second case involves a 34-year-old adult who developed posterior headaches after sphenoidotomy surgery. Grisel's syndrome is less common in adults, leading to clinical challenges and delayed diagnosis (> 1 month). Reduction combined with a halo vest treatment failed, and the patient required cervical arthrodesis.

Le syndrome de Grisel est une subluxation atlanto-axoïdienne (C1-C2) non traumatique et l'une des causes de torticolis chez l'enfant. La subluxation survient dans le cadre d'une infection de la sphère ORL ou à la suite d'une chirurgie. Le diagnostic est basé sur la clinique et l'examen radiologique. Le traitement est le plus souvent médical et conservateur. Les prises en charge chirurgicales sont limitées aux récidives et aux présentations tardives.Nous discutons ici deux cas de subluxation C1-C2. La première chez un enfant de 10 ans faisait suite à une rhinopharyngite. Cette présentation correspond à la présentation typique du syndrome de Grisel. Une prise en charge rapide a permis une correction de cette subluxation à l'aide d'un traitement médical et d'une minerve souple de type Philadelphia. Le second cas concerne une adulte de 34 ans qui a présenté des céphalées postérieures à la suite d'une chirurgie de sphénoïdotomie. Le syndrome Grisel est moins fréquent chez l'adulte, ce qui a engendré une errance clinique et un diagnostic retardé (> 1 mois). La réduction associée à un traitement par haloveste a échoué et la patiente a nécessité une arthrodèse cervicale.

Atlantoaxial Instability in the Course of Rheumatoid Arthritis in Relation to Selected Parameters of Sagittal Balance.

Background: Atlantoaxial instability is the most common cervical instability in patients with rheumatoid arthritis (RA). Its course may differ in different patients and may have different degrees of severity and symptoms. Methods: There are a number of studies on systemic factors associated with the development of this instability, but there are few publications in the scientific literature on the influence of biomechanical factors on the development of cervical instability. One of the areas that allows the study of biomechanical factors influencing spine pathologies is the analysis of sagittal balance using radiological parameters. The study of radiological parameters of sagittal balance has contributed to understanding the pathology of selected spine diseases and is currently an indispensable tool in planning surgical treatment. Results: The presented study, conducted on a group of RA patients with cervical instability, was performed to look for a relationship between C1-C2 instability and sagittal balance parameters. Conclusions: Among the examined selected parameters, a statistically relationship between C1-C2 instability and the Cobb angle C1-C7 and OD-HA parameters has been found. This confirms the need for further in-depth research on this areas.

Morphometric analysis of atlas lateral mass in Down syndrome cases with relevance to surgical intervention.

PURPOSE: Surgical stabilization of the Atlas vertebrae is indicated for severe atlantoaxial instability (AAI) in patients with Down syndrome (DS). This study aims to evaluate the morphological characteristics of the Atlas lateral mass (ALM) in patients with DS with regard to safe instrumentation for surgical stabilization and to compare them with non-syndromic group. METHODS: This multicenter, retrospective, case-control study included age- and sex-matched patients with and without DS aged > 7 years with a cervical computed tomography (CT) scan. After three-dimensional CT reconstruction, nine parameters were evaluated for both groups. All included measurements were performed by a neuroradiologist who was blinded to clinical data. RESULTS: Forty-three of 3,275 patients with DS were included in this study. Matching number of consecutive patients without DS were identified (mean age: 16 years). Patients with DS were significantly shorter than those without DS. Seven of nine parameters related to ALM were significantly lower in patients with DS than in those in the control group, including anterior wall height (AH), posterior wall height (PH), their ratio, and arch-ALM angle. On adjusting data for patient height, patients with DS had a smaller PH, lower PH/AH ratio, and steeper arch-ALM angle than the control group. CONCLUSIONS: Patients with DS had a smaller posterior ALM wall and a steeper arch-ALM angle than the control group without DS. This information is important for surgical planning of safe posterior ALM exposure and safe instrumentation for surgical stabilization in patients with DS.

Influence of the type of atlantoaxial dislocation secondary to os odontoideum on sagittal alignment and balance of the subaxial cervical spine after posterior atlantoaxial fusion.

OBJECTIVE: This retrospective study aims to investigate the effect of the type of atlantoaxial dislocation due to os odontoideum on the sagittal alignment and balance of the cervical spine after posterior atlantoaxial fusion. METHODS: Data of 48 consecutive patients who underwent posterior C1-C2 fusion to treat atlantoaxial dislocation/instability due to os odontoideum were retrospectively reviewed. Radiographic variables, namely the T1 slope (T1S), C1-C2 angle, C2-C7 angle, C1-C2 sagittal vertical axis (SVA), C2-C7 SVA, and modified atlas-dens interval (MADI), were measured preoperatively, immediate postoperatively, and at final follow-up. Patients were divided into three groups based on the preoperative MADI. Differences within and between groups in radiographic variables and relationships between the investigated variables were analyzed. RESULTS: The MADI was correlated with the preoperative to postoperative changes in the C1-C2 angle (r = 0.776, P < 0.05) and C2-C7 angle (r = - 0.357, P < 0.05). In the group with anterior atlantoaxial dislocation, the C1-C2 angle and C2-C7 SVA were significantly enlarged at final follow-up (P < 0.05), while the C2-C7 angle was significantly reduced (P < 0.05). The changes in C1-C2 angle and C2-C7 angle were opposite between the posterior group and the anterior dislocation group. CONCLUSION: The direction/type of atlantoaxial subluxation correlates with the changes in lower cervical curvature after atlantoaxial fusion. Patients with atlantoaxial posterior dislocation and atlantoaxial instability are less likely than those with atlantoaxial anterior dislocation to develop loss of lordosis after posterior atlantoaxial fusion.

Atlantoaxial subluxation and Down syndrome: A cross-sectional analysis.

Background: Atlantoaxial subluxation (AAS) is a diagnosis describing misalignment of the C1 vertebra relative to C2. Excessive translation of this joint, located adjacent to the medullary brain stem, can lead to devastating neurological consequences. A higher prevalence of AAS within the Down syndrome (DS) population has been well-established. This study aims to establish a prevalence rate of DS in patients hospitalized for AAS and compare outcomes between AAS patients with and without DS. Methods: This study utilized the National Inpatient Sample (NIS) provided by the Healthcare Cost and Utilization Project (HCUP). In accordance with HCUP 2023 Clinical Classifications Software Refined files, data were queried using the International Classification of Diseases 10th Edition codes for DS and AAS. Demographics, comorbidities, hospital course, and outcomes were examined and compared using binary and linear multivariate regression. IBM SPSS software was used for data analysis. Results: Of the 213,095 patients in the NIS database admitted between 2016 and 2020 with AAS as their primary diagnosis, 7.2% were DS patients. DS patients were significantly younger (26.56 ± 20.81 vs. 49.39 ± 27.63, P < 0.01), less likely to be female (33.30% vs. 52.10%), and had fewer comorbidities (diabetes mellitus, hypertension, and hyperlipidemia) than non-DS patients. There was no significant difference in likelihood to undergo surgical fusion between DS patients and non-DS patients with AAS. Conclusion: This large-scale study using NIS data determined that 7.2% of all patients admitted to hospitals for AAS are DS patients. The analysis of demographics, hospital course, and outcomes can influence the development of treatment protocols for AAS in the DS population.

Early Extrusion of an Anterior Odontoid Screw: A Case Report.

Odontoid fractures in the elderly typically require surgical intervention due to poor adaptability to conservative treatment. Anterior screw fixation, despite its high fusion rates under specific conditions, may lead to complications such as screw extrusion, as demonstrated in the case discussed, necessitating subsequent posterior cervical fusion. This study aimed to describe early extrusion of an anterior odontoid screw and the importance of caution and thorough postoperative assessment in elderly patients undergoing anterior screw fixation for odontoid fracture. A 73-year-old female patient with a history of ground-level fall and subsequent cervical pain was diagnosed with an odontoid type II fracture and underwent odontoid screw placement in June 2023. However, in August, follow-up imaging revealed screw displacement and a fracture of the posterior arch of the C1 vertebral, which was initially overlooked. After seeking a second opinion, a new surgical approach was decided, involving removal and replacement of the odontoid screw, posterior and posterolateral C1-C2 spinal instrumentation, arthrodesis, and fusion with the use of morselized allograft. The patient was discharged on postoperative day 3 with mild cervical pain, wearing a soft collar, and neurologically intact. Given the current literature, odontoid screw extrusion rates are still small but can come with enormous potential complications. Also, the present case is a reminder to always double-check preoperative imaging and recognize early failure/malpositioning of hardware.

Grisel's Syndrome After COVID-19 in a Pediatric Patient: A Case Report.

An eight-year-old female presenting with posterior neck pain and torticollis who had been diagnosed with coronavirus disease 2019 (COVID-19) three weeks earlier was radiographed and diagnosed with atlantoaxial rotatory fixation (AARF). Following treatment with non-steroidal anti-inflammatory drugs (NSAIDs), the posterior neck pain improved, and the torticollis was cured. Symptoms returned after two weeks, and computed tomography showed a 3.94 mm atlantodental interval and axis rotation. The patient was diagnosed with AARF relapse; symptoms resolved spontaneously prior to subsequent examination, and no further relapses were observed. This case highlights the need for clinicians to be aware that AARF may develop after COVID-19. Treatment options should be carefully considered.