Vertebral Artery Dissection in the Setting of Unstable Os Odontoideum: A Case Report.

CASE: A healthy 5-year-old boy presented with a gradual onset of headaches and acute global right-sided weakness over 10 days. The work-up revealed unstable os odontoideum leading to multiple posterior circulation infarcts with vertebral artery dissection. He underwent antiplatelet therapy, cervical collar immobilization, and delayed occiput to C2 posterior spinal fusion and instrumentation with iliac crest autograft. At 2-year follow-up, the patient had a solid fusion mass, appropriate cervical alignment, and was without neurologic sequelae. CONCLUSION: This case adds to a sparse body of literature in the management of vertebral artery dissection with vertebrobasilar insufficiency secondary to unstable os odontoideum.

Posterior Reduction and Intra-Articular Cage Fusion With a C2 Nerve Root Preservation Technique for Treating Posterior Atlantoaxial Dislocation Secondary to Os Odontoideum.

BACKGROUND AND OBJECTIVES: Posterior C1-C2 interlaminae compression fusion with iliac bone graft may lead to donor site complications and recurrent C1 posterior dislocation for posterior atlantoaxial dislocation (AAD) secondary to os odontoideum. C1-C2 intra-articular fusion often needs C2 nerve ganglion transection to facilitate exposing and manipulating the facet joint, leading to bleeding from the venous plexus and suboccipital numbness or pain. Therefore, this study was conducted to evaluate the outcomes of posterior C1-C2 intra-articular fusion with a C2 nerve root preservation technique in the treatment of posterior AAD secondary to os odontoideum. METHODS: Data of the 11 patients who underwent C1-C2 posterior intra-articular fusion because of posterior AAD secondary to os odontoideum were retrospectively reviewed. Posterior reduction was performed using C1 transarch lateral mass screws and C2 pedicle screws. Intra-articular fusion was performed using a polyetheretherketone cage filled with autologous bone from the caudal edge of the C1 posterior arch and cranial edge of the C2 laminar. Outcomes were evaluated by using the Japanese Orthopaedics Association score, Neck Disability Index, and visual analog scale for neck pain. Bone fusion was evaluated by using computed tomography and 3-dimensional reconstruction. RESULTS: The average follow-up duration was 43.9 ± 9.5 months. All patients achieved good reduction and bone fusion, without transection of the C2 nerve roots. The mean bone fusion time was 4.3 ± 1.1 months. There was no complication related to the surgical approach and instrumentation. Function of the spinal cord manifested by the Japanese Orthopaedics Association score significantly improved ( P < .05). The Neck Disability Index score and visual analog scale for neck pain markedly decreased (all P < .05). CONCLUSION: Posterior reduction and intra-articular cage fusion with a C2 nerve root preservation technique was a promising treatment of posterior AAD secondary to os odontoideum.

What is the C2 pedicle, pars interarticularis, and isthmus? Anatomical study and review of the literature regarding these confusing terms with proposal of new nomenclature.

INTRODUCTION: The atypical anatomy of the C2 vertebra has led to terminological discrepancies within reports and studies in the literature regarding the location of its pedicle, pars interarticularis, and isthmus. These discrepancies not only limit the power of morphometric analyses, but they also confuse technical reports regarding operations involving C2, and thus confuse our ability to properly communicate this anatomy. Herein, we examine the variations in nomenclature regarding the pedicle, pars interarticularis, and isthmus of C2, and via an anatomical study, propose new terminology. METHODS: The articular surface and underlying superior and inferior articular processes and adjacent transverse processes were removed from 15 C2 vertebrae (30 sides). Specifically, the areas regarded as the pedicle, pars interarticularis, and isthmus were evaluated. Morphometrics were performed. RESULTS: Our results indicate that, anatomically, C2 has no "isthmus" and that a pars interarticularis for C2, when present, is very short. Deconstruction of the attached parts allowed for visualization of a bony arch extending from the anterior most aspect of the lamina to the body of C2. The arch is composed almost entirely of trabecular bone and without its attached parts, e.g., transverse process, really has no cortical bone laterally. CONCLUSIONS: We propose a more accurate terminology, the pedicle, for pars/pedicle screw placement of C2. Such a term more accurately describes this unique structure of the C2 vertebra and would alleviate terminological confusion in the future literature on this topic.

The Relationship Between Cervical Sagittal Balance and Type of Atlantoaxial Dislocation Secondary to Os Odontoideum.

OBJECTIVE: To analyze the effect of cervical sagittal balance on the direction and type of atlantoaxial dislocation. METHODS: Data of 55 patients seen at our hospital for atlantoaxial instability/dislocation caused by os odontoideum were reviewed. Radiographic variables, including T1 slope (T1S), C1-C2 angle, C2-C7 angle, C1-C2 sagittal vertical axis (SVA), C2-C7 SVA, and atlanto-dens interval (ADI), were measured preoperatively. Patients were divided into three groups according to ADI: anterior atlantoaxial dislocation, atlantoaxial instability, and posterior atlantoaxial dislocation. Differences within and between groups in radiographic variables and relationships between the investigated variables were analyzed. RESULTS: ADI was strongly negatively associated with C1-C2 angle (r = -0.805, P < 0.05); whereas ADI had a medium-strength positive relationship with C2-C7 angle (r = 0.425, P < 0.05) and a medium-strength negative relationship with C2-C7 SVA (r = -0.411, P < 0.05). However, ADI was not significantly correlated with T1 slope (r = -0.092, P > 0.05). CONCLUSIONS: The type and direction of atlantoaxial dislocation is closely associated with cervical sagittal balance. C2-C7 SVA is an important factor in assessing the direction of atlantoaxial subluxation secondary to os odontoideum. ADI decreases with increasing C2-C7 SVA. The larger the C2-C7 SVA, the more likely the atlantoaxial dislocation is to be posterior.

Axial superior facet slope may determine anterior or posterior atlantoaxial displacement secondary to os odontoideum and compensatory mechanisms of the atlantooccipital joint and subaxial cervical spine.

OBJECTIVE: To introduce novel parameters in determining directions of os odontoideum (OO) with atlantoaxial displacement (AAD) and compensations of cervical sagittal alignment after displacement. METHODS: Analysis was performed on 96 cases receiving surgeries for upper cervical myelopathy caused by OO with AAD from 2011 to 2021. Twenty-four patients were included in the OO group and divided into the OO-anterior displacement (AD) group and the OO-posterior displacement (PD) group by displacement. Seventy-two patients were included as the control (Ctrl) group and divided into Ctrl-positive (Ctrl-P) group and Ctrl-negative (Ctrl-N) group by axial superior facet slope (ASFS) in a neutral position. ASFS, the sum of C2 slope (C2S) and axial superior facet endplate angle (ASFEA), was measured and calculated by combining cervical supine CT with standing X-ray. Cervical sagittal parameters were measured to analyse the atlantoaxial facet and compensations after AAD. RESULTS: Atlas inferior facet angle (AIFA), ASFS, and ASFEA in Ctrl-P significantly differed from OO-AD.C0-C1, C1-C2, C0-C2, C2-C7, C2-C7 SVA, and C2S in Ctrl-P significant differed from the OO-AD group. C2-C7 SVA and C2S in Ctrl-N significantly were smaller than the OO-PD group. C1-C2 correlated with C0-C1 and C2-C7 negatively in the OO group. Slight kyphosis of C1-C2 in OO-AD was compared with lordosis of C1-C2 in Ctrl-P, inducing increased extension of C0-C1 and C2-C7. Mildly increased lordosis of C1-C2 in OO-PD was compared with C1-C2 in Ctrl-N, triggering augmented flexion of C0-C1 and C2-C7. CONCLUSION: ASFS was vital in determining directions of OO with AAD and explaining compensations. ASFS and ASFEA could provide pre- and intraoperative guidelines. KEY POINTS: • ASFS may determine the directions and compensatory mechanisms of AAD secondary to OO. • ASFS could be achieved by the sum of ASFEA and C2S.

Two-Surgeon Multidisciplinary Approach to Pediatric Cervical Spinal Fusion: A Single-Institution Series and Review of the Literature.

BACKGROUND: A collaborative 2-surgeon approach is becoming increasingly popular in surgery but is not widely used for pediatric cervical spine fusions. The goal of this study is to present a large single-institution experience with pediatric cervical spinal fusion using a multidisciplinary 2-surgeon team, including a neurosurgeon and an orthopedic surgeon. This team-based approach has not been previously reported in the pediatric cervical spine literature. METHODS: A single-institution review of pediatric cervical spine instrumentation and fusion performed by a surgical team composed of neurosurgery and orthopedics during 2002-2020 was performed. Demographics, presenting symptoms and indications, surgical characteristics, and outcomes were recorded. Particular focus was given to describe the primary surgical responsibility of the orthopedic surgeon and the neurosurgeon. RESULTS: A total of 112 patients (54% male) with an average age of 12.1 (range 2-26) years met the inclusion criteria. The most common indications for surgery were os odontoideum with instability (n=21) and trauma (n=18). Syndromes were present in 44 (39%) cases. Fifty-five (49%) patients presented with preoperative neurological deficits (26 motor, 12 sensory, and 17 combined deficits). At the time of the last clinical follow-up, 44 (80%) of these patients had stabilization or resolution of their neurological deficit. There was 1 new postoperative neural deficit (1%). The average time between surgery and successful radiologic arthrodesis was 13.2±10.6 mo. A total of 15 (13%) patients experienced complications within 90 days of surgery (2 intraoperative, 6 during admission, and 7 after discharge). CONCLUSIONS: A multidisciplinary 2-surgeon approach to pediatric cervical spine instrumentation and fusion provides a safe treatment option for complex pediatric cervical cases. It is hoped that this study could provide a model for other pediatric spine groups interested in implementing a multi-specialty 2-surgeon team to perform complex pediatric cervical spine fusions. LEVEL OF EVIDENCE: Level IV-case series.

MR documented craniocervical ligamentous injury at age 18 months: delayed formation of OS odontoideum. Complex management issues. Case-based review.

OBJECTIVE: There are two separate theories regarding the genesis of os odontoideum: congenital and post-traumatic. Trauma documentation in the past has been the presence of a normal odontoid process at the time of initial childhood injury and subsequent development of the os odontoideum. True MR documentation of craniocervical injury in early childhood and subsequent os odontoideum formation has been very rare. METHODS: An 18-month-old sustained craniocervical ligamentous injury documented on MRI with transient neurological deficit. Chiari I abnormality was also recorded. Subsequent serial imaging of craniocervical region showed the formation of os odontoideum and instability. He became symptomatic from the os odontoideum and the Chiari I abnormality. The patient underwent decompression and intradural procedure for Chiari I abnormality and occipitocervical fusion. Postoperative course was complicated by the failure of fusion and redo. He later required transoral ventral medullary decompression. He recovered. RESULTS: This is an MR documented craniocervical ligamentous injury with sequential formation of os odontoideum with accompanying changes in the atlas. Despite a subsequent successful dorsal occipitocervical fusion, he became symptomatic requiring transoral decompression. CONCLUSIONS: Os odontoideum here is recognized as a traumatic origin with the presence of congenital Chiari I abnormality as a separate entity. The changes of the anterior arch of C1 as well as the os formation were serially documented and give credence to blood supply changes in the os and atlas as a result of the trauma. The recognized treatment of dorsal occipitocervical fusion failed in this case requiring also a ventral decompression of the medulla.

Posterior Atlantoaxial Screw Placement in a Portuguese Population: A Morphometric Analysis Based on Computed Tomography Scan Measurements / Colocação de parafusos atlantoaxiais posteriores em uma população portuguesa: Uma análise morfométrica baseada em medidas de tomografia computadorizada

Abstract Objective The present study aims to evaluate the screw length and trajectory angles for posterior atlantoaxial fixation in a Portuguese population, through the study of cervical computed tomography (CT) scans. Methods Cervical CT scans of 50 adults were measured according to predefined screw trajectories of C1-C2 transarticular (C1C2TA), C1 lateral mass (C1LM), C2 pedicle (C2P), C2 pars and C2 laminar (C2L) screws. For each of these trajectories, screw length and angles were measured and compared between males and females. Results For the C1C2TA screw trajectory, the mean length, medial, and cranial angles were 34.12 ± 3.19 mm, 6.24° ± 3.06, and 59.25° ± 5.68, respectively, and for the C1LM screw trajectory, they were 27.12 ± 2.15 mm, 15.82° ± 5.07, and 13.53° ± 4.80, respectively. The mean length, medial, and cranial angles for the C2P screw trajectory were 23.44 ± 2.49 mm, 27.40° ± 4.88, and 30.41° ± 7.27, respectively; and for the C2 pars screw trajectory, they were 16.84 ± 2.08 mm, 20.09° ± 6.83, and 47.53° ± 6,97. The mean length, lateral, and cranial angles for the C2L screw trajectory were 29.10 ± 2.48 mm, 49.80° ± 4.71, and 21.56° ± 7.76, respectively. There were no gender differences except for the lengths of the C1C2TA (p= 0,020) and C2L (p= 0,001) screws, which were greater in males than in females. Conclusion The present study provides anatomical references for the posterior atlantoaxial fixation in a Portuguese population. These detailed data are essential to aid spine surgeons to achieve safe and effective screw placement.

Resumo Objetivo O presente estudo tem como objetivo avaliar o comprimento e os ângulos de trajetória do parafuso para fixação atlantoaxial posterior em uma população portuguesa por meio do estudo de tomografia computadorizada (TC) cervical. Métodos Tomografias computadorizadas cervicais de 50 adultos foram analisadas quanto às trajetórias pré-definidas dos parafusos transarticulares C1-C2 (C1C2TA), na massa lateral de C1 (C1LM), no pedículo de C2 (C2P) e na pars de C2 e C2 laminar (C2L). O comprimento e os ângulos dos parafusos em cada uma destas trajetórias foram medidos e comparados entre homens e mulheres. Resultados O comprimento médio e ângulos medial e cranial da trajetória do parafuso C1C2TA foram de 34,12 ± 3,19 mm, 6,24° ± 3,06 e 59,25° ± 5,68, respectivamente; as medidas da trajetória do parafuso C1LM foram 27,12 ± 2,15 mm, 15,82° ± 5,07 e 13,53° ± 4,80. O comprimento médio e os ângulos medial e cranial da trajetória do parafuso C2P foram de 23,44 ± 2,49 mm, 27,40° ± 4,88 e 30,41° ± 7,27, respectivamente; as medidas da trajetória do parafuso da pars de C2 foram 16,84 ± 2,08 mm, 20,09° ± 6,83 e 47,53° ± 6,97. O comprimento médio e ângulos lateral e cranial da trajetória do parafuso C2L foram de 29,10 ± 2,48 mm, 49,80° ± 4,71 e 21,56° ± 7,76, respectivamente. Não houve diferenças entre os gêneros, à exceção do comprimento dos parafusos C1C2TA (p= 0,020) e C2L (p= 0,001), que foi maior no sexo masculino do que no feminino. Conclusão O presente estudo fornece referências anatômicas para a fixação atlantoaxial posterior em uma população portuguesa. Estes dados detalhados são essenciais para ajudar os cirurgiões de coluna a colocar os parafusos de maneira segura e eficaz.

Analysis of surgical strategies and efficacy in the treatment of Os odontoideum with atlantoaxial dislocation.

BACKGROUND: There are many classification systems for atlantoaxial dislocation (AAD). Among these systems, the definitions of irreducible AAD remain vague, and its treatments are not unified. OBJECTIVE: To explore the surgical strategies and efficacy for the treatment of os odontoideum (OO) with AAD. METHODS: The clinical data of 56 OO patients with AAD who underwent surgery from January 2017 to June 2021 were retrospectively analyzed. AAD was classified into four types, Type I and type II were treated with posterior fixation and fusion. Type III received posterior fixation and fusion after irreducible dislocations were converted to reducible dislocations by translateral mass release or transoral release. Type IV required transoral release for conversion into reducible dislocations before posterior fixation and fusion. The operation time, blood loss, and complications were recorded. The preoperative and postoperative neurological function changes were assessed using the Japanese Orthopedic Association (JOA) score. Postoperative fusion status was assessed by X-ray. RESULTS: There were 40 cases of type I-II, 14 cases of type III, and two cases of type IV AAD. The operation times of single posterior fixation and fusion, combined translateral mass release and combined transoral release were 130.52 ± 37.12 min, 151.11 ± 16.91 min and 188.57 ± 44.13 min, the blood loss were 162.63 ± 58.27 mL, 235.56 ± 59.94 mL, 414.29 ± 33.91 mL, respectively. One patient with type III died, one with type III underwent revision surgery due to infection, and three patients with type I had further neurological deterioration after operation. fifty-five patients were followed up for 12-24 months. The follow-up results showed that enough decompression was achieved and that fixation and fusion were effective. The JOA score increased from 9.58 ± 1.84 points preoperative to 13.09 ± 2.68 points at 3 months after operation, 14.07 ± 2.83 points at 6 months and 14.25 ± 2.34 at 12 months after operation, all significant differences compared with preoperative results (P < 0.05). CONCLUSION: OO patients with irreducible AAD can be treated by translateral mass release or transoral release combined with posterior fixation and fusion, while some of those with bony fusion can be treated by transoral release combined with posterior fixation and fusion.

New Subtype of Atlantoaxial Rotatory Fixation (Type IIIa).

OBJECTIVE: Some atlantoaxial rotatory fixations (AARFs) cannot be classified according to the Fielding and Hawkins classification. This study aimed to introduce a new subtype of AARF (type IIIa AARF) with a C1 anterior displacement >5 mm, but with one lateral mass being displaced anteriorly and another posteriorly. METHODS: Data from 10 cases of AARF with anterior C1 displacement of >5 mm were retrospectively reviewed. The exclusion criteria were as follows: 1) type I, II, or IV AARF according to the Fielding and Hawkins classification; 2) cases caused by trauma, tumor, or infection; 3) AARF with os odontoideum or odontoid fracture; and 4）age ≥18 years. Imaging features were analyzed. The atlanto-dental interval was measured to evaluate C1 anterior displacement. RESULTS: Three cases that did not match type III AARF were classified under type IIIa AARF. They had the following common imaging features: 1) atlanto-dental interval of >5 mm, being similar to type III AARF; 2) one lateral mass of C1 displaced anteriorly and the other posteriorly (the most important feature distinguishing the type from type III AARF in which both C1 lateral masses displaced anteriorly); and 3) C1-C2 separation angle (mean 44.2 ± 2.9°) being larger than that in type III AARF. CONCLUSIONS: AARF with anterior C1 displacement of >5 mm, but with one lateral mass displaced anteriorly and the other posteriorly, was defined as type IIIa AARF. It should not be confused with type III AARF because these 2 types differ in biomechanics and imaging parameters.

Angle class II/2nd division: is there an alignment? / Classe II/2ª divisão de Angle: existe alinhamento?

Introduction: Interdisciplinary investigative study of the stomatognathic-cervical complex, necessary to understand the structure and biomechanics of this system in Angle Class I and II / 2nd Division participants. Objective: To evaluate alignment and position of cranial cervical structures on radiographs and their functional relationship with the stomatognathic system. Material and method: Trans Oral and Profile radiographs were submitted to biomechanical analysis, considered the linear and angular measurement of Atlas and Axis through the application included in the radiogram software. Result: We observed a significant difference in the angular measurements of vertical alignment between the Skull, Axis, and the Mandible (p = <0.001), and in the left joint between the Atlas and the Axis (AE: p = 0.011; SEA: p = 0.042). Among the linear measures of the distances between the Atlas and the Axis, the AOD distance presented statistics quite close to the level of significance (p = 0.0502), but above. There was no statistically significant difference in the other measures. Conclusion: In this study, the alignment between the Atlas and Axis cervical vertebrae and the mandible and angles of the atlanto-occipital joints are altered in Class II / 2nd Division participants. There is no difference in the size and distance of the Atlas and the Axis between the Classes.

Introdução: Estudo interdisciplinar investigativo do complexo cérvico-estomatognático, necessário para compreender a estrutura e a biomecânica desse sistema em participantes Classe I e II/2ª Divisão de Angle. Objetivo: Avaliar o alinhamento e a posição das estruturas crânio cervicais nas radiografias de participantes Classe I e II/2ª Divisão de Angle e sua relação funcional com o sistema estomatognático. Material e método: As imagens digitais Trans Oral e Perfil de participantes com maloclusão Classe I e II/2ª Divisão de Angle foram submetidas à medição linear e angular do crânio, mandíbula, Atlas e do Áxis através do software Advantage Workstation 4.6 (AW4.6 ext. 04). Resultado: Houve diferença significativa nas medidas angulares de alinhamento vertical entre o Crânio, Áxis e a Mandíbula (p = <0,001), e da articulação esquerda entre o Atlas e o Áxis (AE: p = 0,011; AAE: p = 0,042). Das medidas lineares das distâncias entre o Atlas e o Áxis, a distância AOD apresentou estatística bastante próxima do nível de significância (p=0,0502), porém acima. Não houve diferença significativamente estatística nas demais medidas avaliadas. Conclusão: Neste estudo, o alinhamento entre as vértebras cervicais Atlas e Áxis e a mandíbula e os ângulos das articulações atlanto occipitais se mostraram alterados nos participantes Classe II/2ª Divisão de Angle. Não há diferença significativa no tamanho e distância do Atlas e do Áxis entre as Classes.

Surgical Management Of Irreducible Atlanto-Axial Dislocation With OS Odontoideum And Klippel-Feil Syndrome.

Klippel-Feil syndrome (KFS) is the congenital fusion of two or more cervical vertebrae which is often associated with various other abnormalities in the cervical spine. Involvement the upper cervical segments leads to atlanto-axial instability which manifests as progressive neurological symptoms due to compression on the spinal cord. These cases pose a surgical challenge due the abnormal and unique anatomy of each patient. A 37-year-old patient presented with neck pain and cervical myelopathy due to a posterior subluxation of C2-3 fused segment over C4-6 fused segment. The patient had an os odontoideum, incomplete posterior arch of C1, anomalous course of vertebral artery and C3 hemi-vertebra. The patient was successfully managed with transoral odontoidectomy and occipeto-cervical fusion. Irreducible atlanto-axial dislocation in a patient with an abnormal upper cervical spine anatomy may require transoral decompression followed by posterior fusion.

Incidental Os Odontoideum in an Adolescent Athlete With Sports-Related Concussion.

ABSTRACT: Sports-related concussion (SRC) is a frequent injury in the adolescent population with presentation including a wide array of signs and symptoms. There are no universally agreed upon guidelines for when to pursue advanced imaging, such as magnetic resonance imaging (MRI), in the workup of SRCs in the adolescent population. Our experience indicates that MRI rarely contributes to management. This case report highlights a rare finding of os odontoideum on MRI imaging in an adolescent female soccer player in the setting of treatment of an SRC that altered the course of her clinical management.

Transnasal Endoscopic and Transoral Approaches in the Biopsies of Ventral Atlas and Axis Vertebrae: A Comprehensive Retrospective Study for Preprocedural Scheme, Biopsy Procedure, Core Technique Analysis, Diagnostic Yield and Clinical Outcome.

OBJECTIVE: This study aims to describe and analyze the transoral and transnasal approaches for pathologies of the ventral atlas and axis vertebrae, which are considered technically challenging regions for diagnostic biopsy. METHODS: A series of transnasal endoscopic approach (TNA) and transoral approach (TOA) biopsies for the pathologies of the first and second cervical vertebrae were conducted and retrospectively analyzed from July 2014 to May 2021. The depth of the biopsy trajectory was measured on computed tomography images for all nine patients (eight males and one female with an average age of 58.11 ± 11.60 years), as were the coronal, sagittal, and vertical biopsy safe ranges. The characteristics of each lesion, including radiographic features, blood supply, and destruction of anterior or posterior vertebral body edges, were evaluated to guide the biopsy. Four biopsy core techniques (BCTs), including "lesion perforating", "aspiration", "cutting-and-scraping" and "biopsy forceps utilization" were elaborated in this study. The biopsy procedures and periprocedural precautions were demonstrated. Patient demographics, clinical data, lesion characteristics, diagnostic yield, and complications were recorded for each case. RESULTS: Eight TOA biopsies for the axis vertebral body and one TNA biopsy for the atlas anterior arch were successfully performed and yielded adequate pathologies. All biopsies were organized based on the preprocedural radiographic measurements, which showed that the average length of biopsy trajectory and coronal, sagittal, and vertical safe biopsy ranges were 85.00 ± 5.88, 20.63 ± 4.75, 16.25 ± 1.49, and 24.63 ± 2.26 mm, respectively, and these corresponding data were 95, 36, 9, and 26 mm in the TNA patient. Six osteolytic lesions (66.7%), one osteoblastic lesion (11.1%), and two mixed lesions (22.2%) were observed, among which seven lesions had a rich blood supply. Biopsy forceps and core needles were utilized to obtain samples in six and three patients, respectively. All the TNA and TOA biopsies were performed with cooperative application of multiple BCTs under compound anatomic and stereotactic navigations. Intraprocedural or postprocedural complications occurred in no patients who underwent the biopsy in the follow-up period (1-39 months). No significant differences were found between the preprocedural and postprocedural blood indexes and visual analogue scale scores. CONCLUSION: With a sophisticated preprocedural arrangement, cooperative application of BCTs, and careful periprocedural precautions, transnasal endoscopic and transoral biopsies are two feasible, efficient, and well-tolerated procedures that achieve satisfactory diagnostic yield, complication rate, and clinical outcome.

Traumatic spondylolisthesis of axis: clinical and imaging experience at a level one trauma center.

PURPOSE: Traumatic spondylolisthesis of the axis (TSA) with bilateral pars interarticularis fracture (a pattern also known as Hangman's fractures) accounts for 4-5% of all cervical fractures. Various classification systems have been described to assist therapeutic decision-making. The goal is to reassess the utility of these classifications for treatment strategy and evaluate additional imaging associations. METHODS: This is an IRB approved, retrospective analysis of patients with imaging diagnosis of TSA from 2016 to 2019. Consensus reads were performed classifying TSA into various Levine and Edwards subtypes and typical vs. atypical fractures. Other imaging findings such as additional cervical fractures, traumatic brain injury, spinal cord injury, and vertebral artery injury were recorded. Treatment strategy and outcome were reviewed from clinical charts. Fisher exact test was used for statistical analysis. RESULTS: A total of 58 patients were included, with a mean age of 62.7 ± 25 years, and male to female ratio of 1:1.2. Motor vehicle collision was the most common cause of TSA. Type I and III injuries were the most and the least common injuries, respectively. Patients with type I injuries were found to have good healing rates with conservative management (p < 0.001) while type IIa and III injuries were managed with surgical stabilization (p = 0.04 and p = 0.01, respectively). No statistical difference was observed in the treatment strategy for type II fractures (p = 0.12) and its prediction of the associated injuries. Atypical fractures were not found to have a higher incidence of SCI (p = 0.31). A further analysis revealed significantly higher-grade vertebral artery injuries (grades III and IV according to Biffl grading) in patients with type IIa and III injuries (p = 0.001) and an 11-fold increased risk of TBI compared to type I and type II fractures (p = 0.013). CONCLUSION: TSA fracture types were not associated with any clinical outcome. Levine and Edwards type II classification itself is not enough to guide the treatment plan and does not account for associated injuries. Additional imaging markers may be needed.

Isolated atlas-duplication as a manifestation of persistent proatlas: a case report.

PURPOSE: Atlas-duplication is an exceedingly rare dysplasia of the craniocervical junction. To the best of our knowledge, only two cases of atlas-duplication have been reported and these were associated with complete anterior rachischisis and os odontoideum. We aimed to report a case of isolated atlas-duplication of incidental finding and without attributable symptoms which makes it unique. METHODS: Following a normal coronarography for a suspected myocardial infarction, a 60-year-old-man with no significant medical history developed a transient ischemic attack that justified brain computed-tomography angiography. RESULTS: There was no evidence for cerebral ischemic lesion, intracranial occlusion or significant artery disease. Bone analysis revealed eight cervical vertebral segments with an additional vertebral level located between the occiput and the atlas. This vertebra presented all the morphological characteristics of an atlas vertebra except for hypoplasia of the left transverse process. An incomplete anterior rachischisis was associated, and there was no other abnormality of craniocervical junction. The clinical examination revealed no neck pain, no limitation of joint amplitude and no neurological deficit. Apart from preventive treatment of ischemic stroke, no orthopedic or surgical treatment was undertaken. After 1.5 years of radiological monitoring, the patient remains symptom-free. CONCLUSIONS: Atlas-duplication is an exceedingly rare dysplasia of the craniocervical junction that may be found isolated and incidentally. If this variation does not necessarily warrant specific treatment, brain CT angiography is recommended to detect anatomical variations of the vertebral arteries.

The Results of Interfacetal Fusion Using Local Bone Combined With an Atlantoaxial Instrumentation.

BACKGROUND: Many studies have described different C1-2 fusion techniques that have evolved over time. We introduced an easy and effective C1-2 fusion technique using local bone chips combined with atlantoaxial instrumentation. OBJECTIVE: To identify the efficacy of interfacetal fusion using local bone combined with atlantoaxial instrumentation by assessment of clinical outcomes and fusion rate. METHODS: We retrospectively reviewed the data from 25 patients who underwent atlantoaxial stabilization surgery using C1-2 pedicle screws and interfacetal bone fusion by a single surgeon between March 2012 and December 2019. RESULTS: The demographics were 15 men and 10 women with a mean age of 57.6 years (range, 27-85 years) at the time of surgery. Three patients underwent surgery for myelopathy due to os odontoideum, 9 for C1-2 instability, 9 for trauma, 3 for rheumatoid arthritis, and 1 for bony spur, C1-2. At 3 months postsurgery, 3 and 21 patients showed 2-point and 1-point improvements in the Nurick grade, respectively. There was no difference in the Nurick score in 1 patient. Seven patients had a computed tomography scan at 1 year after surgery, which revealed a bridging trabecular bone. No movement was observed in the x-ray flexion/extension view at 1 year after surgery in all patients. In addition, no patients complained of postoperative occipital neuralgia. CONCLUSION: This study showed that interfacetal fusion with C1-2 pedicle screws using the free-hand technique was efficient and simple.

Asymmetry of the C2 pars interarticularis: a clinical anatomical study with relevance to screw placement.

PURPOSE: Potential asymmetries of the C2 posterior elements pose a problem for the spine surgeon seeking to make the best choice for spinal stabilization while reducing morbidity. METHODS: A digital caliper was used to measure the pars interarticularis height and length on left and right sides of 25 adult C2 vertebrae. The pars interarticularis was defined as the bone between the posterior most aspect of the superior articular process and the anterior most aspect of the inferior articular process of C2. Also, the C2 vertebrae from 49 patients were scanned by CT. Parasagittal images were reviewed and using the same definitions as were used for the skeletal specimens, the length and the height of the C2 pars interarticularis from both the left and right sides were measured using CT. The image slices were acquired at 3 mm intervals. The pars interarticularis height was determined on sagittal CT reconstruction, while the pars interarticularis length was calculated on the basis of the axial images. RESULTS: The lengths and the heights of the left and right pars interarticularis were compared using CTs of patients and skeletal specimens. No significant differences were found in the length and height measurements of the CT images on both sides. However, in the skeletal specimens, the left and right pars interarticularis did not differ significantly in length but differed significantly in height (p = 0.003). The mean height of the left pars interarticularis was approximately two times larger than the right in the skeletal specimens. Absolute differences were calculated between the side with the greater length and height and the side with the lesser length and height irrespective of their left-right orientations. For CT measurements, most differences in length and height between the greater pars interarticularis and lesser pars interarticularis occurred between 0 and 1 mm with each successive disparity interval yielding lower numbers. Skeletal measurements revealed a similar length disparity distribution to the CT measurements. However, height measurements in the skeletal specimens varied widely. Eight pars interarticularis specimens demonstrated a height difference between 0 and 1 mm. No dry bone pars interarticularis specimens demonstrated a height difference between 1 and 2 mm. The pars interarticularis of nine specimens demonstrated a height difference between 2 and 3 mm. Two demonstrated a height difference between 3 and 4 mm. Four demonstrated a height difference between 4 and 5 mm and two demonstrated a height difference greater than 5 mm. The greater pars interarticularis lengths and heights were combined and compared to their lesser counterparts on CT and skeletal measurements. In all measurements of this type, significant differences were found in the pars interarticularis length and height, whether measured through CT or via digital calipers. CONCLUSION: Asymmetry between the left and right C2 pars interarticularis as shown in the present study can alter surgical planning. Therefore, knowledge of this anatomical finding might be useful to spine surgeons.

The relationship between atlas hypoplasia and os odontoideum in children with Down syndrome: a preliminary case report.

The purpose of this study was to evaluate the relationship of os odontoideum and the size of atlas among children with Down syndrome. Understanding the risk of developing myelopathy in asymptomatic cases is important in children with Down syndrome. Children with os odontoideum are considered to be at high risk of developing myelopathy because of instability; however, in cases that are complicated by atlas hypoplasia, the risk remains the same, regardless of instability. This retrospective case-control study assessed atlas hypoplasia in children with Down syndrome with or without os odontoideum. We retrospectively assessed the records of 59 patients (36 males and 23 females) with Down syndrome who underwent spinal X-ray evaluations at our hospital. The average age at examination was 5.0 years (range, 4-7). We evaluated the following radiologically: the presence of os odontoideum; atlas-dens interval; space available for the spinal cord at the atlas level (C1SAC); instability index; sagittal atlas diameter (SAD) as an index of atlas hypoplasia and C5 level SAC (C5SAC), adjusted for child growth. Os odontoideum was present in seven cases (12%). Between the groups with and without os odontoideum, there was no significant difference in age (mean, 5.2 vs. 5.0 years) or male/female ratio (57 vs. 62% males). The SAD/C5SAC (mean, 1.6 vs. 1.9) was significantly smaller in the group with os odontoideum than in those without os odontoideum. The instability index was not significantly different between the two groups. Children with Down syndrome and os odontoideum have small SAD. Evaluations for atlas hypoplasia are necessary.