Análise biomecânica das fixações atlantoaxiais: estudo experimental / Análise biomecânica das fixações atlantoaxiais: estudo experimental

Introdução: o tratamento cirúrgico de pacientes com fraturas do processo odontoide tem sido controverso. As principais técnicas cirúrgicas para o segmento C1-C2 incluem além da artrodese cervical (aramagem tipo Gallie, parafusos transarticulares e aramagem tipo 88), a fixação direta com parafuso no processo odontoide. Objetivo: comparar a estabilidade mecânica destes quatro tipos de osteossínteses do segmento atlantoaxial (C1-C2). Metodologia: vinte segmentos atlantoaxiais de cadáveres humanos adultos foram preparados com fraturas do tipo 2 de Anderson e D'Alonso e divididos em quatro grupos: aramagem tipo Gallie (aG); parafusos transarticulares (pT); parafuso no processo odontoide (pD); aramagem tipo 88 (a88). Os corpos de prova foram submetidos a esforços de flexocompressão em máquina universal de ensaios mecânicos para análise de resistência, elasticidade e deformações. Resultados:na fase de acomodação, os parafusos no processo odontoide apresentaram pouquíssima mobilidade com cargas baixas. Na fase de elasticidade, não houve diferença significativa entre as construções testadas. Com relação à resistência máxima suportada pelas construções, houve uma diferença estatisticamente significativa a favor da aramagem tipo Gallie. Conclusão: nossos testes mostraram que em relação à acomodação houve diferença significativa entre a aramagem tipo Gallie e o parafuso no processo odontoide; e quanto à resistência máxima, entre a aramagem tipo Gallie e o parafuso transarticular.

Introduction: the surgical treatment of patients with fractures of the odontoid process has been controversial. The main surgical techniques for C1-C2 are: Gallie wiring, transarticular screw, direct odontoid process screw and 88 posterior laminar wiring. Objective: to compare the mechanical stability of these four types of atlantoaxial segment osteosynthesis (C1/C2). Methodology: twenty atlantoaxial segments of adult human cadavers were prepared with Anderson and D'Alonso type II fractures and divided into four groups: Gallie wiring; transarticular screw; odontoid process screw; 88 wiring. After being fixed with each osteosynthesis technique, they were submitted to flexocompression efforts in a universal mechanical testing machine for analysis of strength, elasticity and deformations. Results: in the accommodation phase, the odontoid process screws showed very little mobility with low loads. In the elasticity phase, there was no significant difference between the constructions tested. With regard to the maximum resistance supported by the constructions, there was a statistically significant difference in favor of Gallie wiring. Conclusion: Our tests showed a significant difference between Gallie wiring and odontoid process screw in accommodation; and between the Gallie wiring and the transarticular screw in maximum resistance test

Traction for the treatment of traumatic atlantoaxial subluxation in adults / 中国骨伤

OBJECTIVE@#To observe the application of modified traction therapy in traumatic atlantoaxial subluxation in adults.@*METHODS@#The clinical data of 31 patients with atlantoaxial subluxation treated from March 2018 to June 2019 were restropectively analyzed. There were 15 males and 16 females, aged from 18 to 68 years old with an average of 39 years old, including 10 cases of 18-40 years, 15 cases of 41-60 years, 6 cases of 51-68 years. The main manifestations of the patients were limited neck movement, pain, and atlantoaxial CT scan showed different degrees of atlantoaxial subluxation. Three dimensional multifunctional traction bed was used for traction for 2 min, relaxation for 10 s. The traction angle starts from the rearward extension of 5°-10° and weight from 3-6 kg. The weight increased by 1 kg every two days until the symptoms were improved. Traction time was 30 min twice a day and 10 days for a course of treatment. One course of treatment was performed in patients with 1-2 mm left and right equal width of atlantoaxial space, and two courses of treatment were performed in patients with 3-4 mm left and right equal width of atlantoaxial space, and the course of treatment could be increased to 3 months in especially patients with serious problems, such as 4 mm left and right equal width of atlantoaxial space and no improvement after conventional treatment. The criteria to evaluate the clinical effect was cure:no pain in the neck, normal range of neck movement, CT showed normal atlantoaxial space and odontoid process was in the middle, patients with normal neck movement were followed up 1 month after the end of treatment;improvement:neck pain was significantly improved and CT showed that the left and right atlantoaxial space was less than 1 mm in equal width.@*RESULTS@#Among the 31 patients, 17 cases were cured by one course of treatment, 11 cases were cured by 2 courses of treatment, and 2 caseswere improved.@*CONCLUSION@#The modified traction therapy has obvious effect on adult traumatic atlantoaxial subluxation, especially the subluxation of 3-4 mm equal width in left and right atlantoaxial space, and this method is safe and reliable with good efficacy and the patients without discomfort.

Retro-odontoid pseudotumor: a poorly recognized alteration of the craniocervical junction

SUMMARY INTRODUCTION Retro-odontoid pseudotumor (ROP) is a rare disease that affects the atlantoaxial joint and, in general, is associated with local biomechanical alterations that may or may not cause instability. METHODS Descriptive study of the literature available in databases MEDLINE/PubMed, LILACS, and Scopus. The research was conducted in April 2019. DISCUSSION ROP is, possibly, a syndromic designation that encompasses a significant variety of diseases of the atlantoaxial joint. There are different pathophysiological mechanisms implicated in its genesis. The patients, almost in their entirety, present with severe myelopathy, and most of them are treated surgically, with the posterior decompression being the most commonly used method, with or without arthrodesis. Evolution is usually favorable. CONCLUSION The ROP is still poorly recognized as a differential diagnosis between the diseases of the cranial-cervical junction. The information available in the literature analyzed was based mainly on the study of reports or case series; therefore, it is insufficient to define conducts with a high level of scientific evidence.

RESUMO INTRODUÇÃO O pseudotumor retro-odontoide (PRO) é uma patologia rara que acomete a articulação atlantoaxial e, em geral, está associada a alterações biomecânicas locais que podem ou não causar instabilidade. METODOLOGIA Estudo descritivo da literatura disponível nas bases de dados Medline/PubMed, Lilacs e Scopus. A pesquisa foi realizada em abril de 2019. DISCUSSÃO O PRO é, possivelmente, uma designação sindrômica que abrange uma variedade significativa de doenças da articulação atlantoaxial. Existem diferentes mecanismos fisiopatológicos implicados em sua gênese. Os pacientes, quase em sua totalidade, apresentam quadro de mielopatia grave e a maioria deles é tratada cirurgicamente, sendo a descompressão posterior o método mais utilizado, com ou sem artrodese. A evolução costuma ser favorável. CONCLUSÃO O PRO ainda é pouco reconhecido como diagnóstico diferencial entre as doenças da junção crânio-cervical. As informações disponíveis na literatura analisada foram baseadas principalmente no estudo de relatos ou séries de casos, sendo, portanto, insuficientes para definir condutas com alto nível de evidência científica.

One stage temporary atlantoaxial segmental fixation and reduction for Grauer type IIB dens fractures in teenagers / 中国骨伤

OBJECTIVE@#To assess the clinical results of one stage temporary atlantoaxial segmental fixation and reduction for Grauer type IIB dens fractures in teenagers.@*METHODS@#From February 2009 to April 2015, 19 teenagers with Grauer type IIB dens fractures not amenable to anteiror screw fixation were enrolled and treated using one stage temporary atlantoaxial segmental fixation and reduction without fusion. There were 14 males and 5 females, aged from 14 to 32 years with an average of (24.6±5.0 ) years. The internal fixation was removed after bone healing confirmed by CT scan. At the last follow-up (at least 1 year after internal fixation removal), dynamic CT was used to assess the atlantoaxial rotation activity. Visual analogue scale (VAS) was recorded before the first operation, before the second operation (removal of internal fixation) and at the last follow-up. Neck Disability Index(NDI) was used to evaluate the efficacy before the second operation (removal of internal fixation) and the last follow-up.@*RESULTS@#After operation, 2 patients developed the symptoms of occipital nerve stimulation such as numbness and pain in the occipitocervical region, and were treated with drugs such as dehydration and neurotrophic drugs, and the symptoms were relieved after 1 to 2 months. All the internal fixations were removed and all the patients were followed up more than 1 year, with time ranging from 18 to 25 months and an average of (21.47±2.41) months. The time of bone fusion after operation was 6 to 10 months with the mean of(8.21±1.27) months. Secondary surgical removal of internal fixation were performed immediately after fracture healing without internal fixation failure. The symptoms of neck pain improved significantly after operation, VAS score decreased from 6.74±0.65 before operation to 0.42±0.51 at the last follow-up after the second operation (removal of internal fixation), with statistically significant differences(<0.01). The NDI value decreased from (10.58±2.04)% before the second operation (removal of internal fixation) to (3.79±2.23)% at the last follow-up after the second operation (removal of internal fixation), with statistically significant difference(<0.01). At the last follow-up after the second operation (removal of internal fixation), dynamic CT showed that the unilateral rotation of the atlantoaxial spine reached (15.73±5.57)° to the left, (15.55±5.78)° to the right, and the overall rotation of the atlantoaxial spine was (31.28±10.71)°.@*CONCLUSIONS@#One stage temporary atlantoaxial segmental fixation and reduction for the treatment of Grauer type IIB dens fractures not amenable to anteiror screw fixation in teenagers can avoid the loss of atlantoaxial rotation function caused by atlantoaxial fusion, and to some extent retain the rotation activity of atlanto-axial joint.

Trigeminal Neuralgia Resulting from Delayed Cervical Cord Compression after Acute Traumatic Fracture of Odontoid Process / 대한신경손상학회지

Trigeminal neuralgia is caused by compression of trigeminal nerve root and it leads to demyelination gradually. It was almost idiopathic and occurred unexpected. The upper cervical spinal cord contains the spinal trigeminal tract and nucleus. Fibers with cell bodies in the trigeminal ganglion enter in the upper pons and descend caudally to C2 level. We experienced a rare patient with facial pain, which was paroxysmal attack with severe pain after a clear event, cervical spinal injury (C2). So, this case reminds us of a possible cause of trigeminal neuralgia after a trauma of the head and neck.

Basilar invagination associated with chiari malformation type I: A literature review

Basilar invagination (BI) and Chiari malformation type I (CM-I) are very important anomalies that introduce instability and compression in the occipitocervical transition region and have complex clinical characteristics. These anomalies vary according to the affected structures. The present study revises current knowledge regarding the anatomy, anatomo-physiology, clinical manifestations, and radiological findings of these entities and the associated surgical treatment approaches. A bibliographic survey was performed through a search in the Medline, PubMed, SciELO, Science and LILACS databases. When associated, these craniovertebral malformations result in neurological deficits due to neural parenchyma compression; however, the presence of microtraumas due to repetitive lesions caused by the bulb and cervical marrow instability has been highlighted as a determinant dysfunction. Surgical treatment is controversial and has many technical variations. Surgery is also challenging due to the complex anatomical characteristics and biomechanics of this region. Nevertheless, advances have been achieved in our understanding of related mechanisms, and compression and atlantoaxial instability are considered key elements when selecting the surgical approach.

Síndrome de la apófisis odontoides coronada, una manifestación inusual de dolor cervical: presentación de un caso / Crowned Dens Syndrome, An Unusual Manifestation of Cervical Pain: A Case Report

Las enfermedades por depósito de cristales de pirofosfato dihidratado de calcio o hidroxiapatita se pueden manifestar en cualquier articulación y cuando se acumulan en la columna cervical pueden causar dolor. El síndrome de la apófisis odontoides coronada es una rara condición clínica que consiste en la calcificación en forma de corona de los ligamentos que rodean a la apófisis odontoides. Se describe el caso de un hombre de 70 años de edad con una semana de cervicalgia, cefalea y fiebre, que ingresa por sospecha de patología neurológica. Se realiza TC de cráneo que documenta calcificaciones lentiformes del ligamento transverso del atlas. Se instaura manejo con corticosteroides y antiinflamatorios no esteroideos, con mejoría. Una adecuada anamnesis, junto con estudio por imagen, evita procedimientos innecesarios y permite incluir esta entidad en el diagnóstico diferencial del dolor cervical agudo.

The calcium pyrophosphate dehydrate (CPPD) or hydroxyapatite (HA) crystal deposition disease can manifest in any joint and when it comprises the cervical spine can lead to pain. Crowned dens syndrome is a rare clinical condition that is featured by crown-like calcification of ligaments around the odontoid process. We describe the case of a 70-year-old man with cervical pain, headache and fever for over a week in whom a neurological condition was suspected. A CT scan revealed lentiform calcifications of the transverse ligament of the atlas. Treatment with steroids and non-steroidal anti-inflammatory improve the symptoms. A proper clinical history and imaging studies avoid unnecessary procedures and can let this entity to be included as a differential diagnosis in acute cervical pain.

Torticollis and Atlantoaxial Rotatory Subluxation after Chiropractic Therapy

Torticollis is an abnormal, asymmetric head or neck position which usually caused by imbalance of paracervical muscles. The traumatic torticollis can be caused by following events; atlantoaxial rotatory subluxation, atlantoaxial dislocation, cervical vertebral fractures, and injury to the cervical musculature. Especially, acute traumatic atlantoaxial rotatory subluxation usually presents limitation of cervical range of motion without pain or neurologic deficit. We report a case of a 58 year-old man who developed the acute atlantoaxial rotatory subluxation right after the chiropractic therapy, which induced the limitation of cervical range of motion to 52.5% of normal range. The magnetic resonance image revealed the facture of the odontoid process and the partial injury in transverse ligaments of the atlas. He underwent intramuscular botulinum toxin injection and 10 days of continuous cervical traction 15 hours a day using a 5 kg weight. The range of the cervical motion restored up to 90.2% of normal range.

Una causa infrecuente de dolor de cuello. Síndrome de la apófisis odontoides coronada / An infrequent cause of neck pain. Crowned dens síndrome

Resumen En la práctica clínica habitual existe un crecimiento en la demanda asistencial de servicios de urgencias. El dolor cervical es una patología muy frecuente que compete a diversos profesionales sanitarios. El síndrome de apófisis odontoides coronada, es una patología muy poco frecuente, que hace parte del espectro de las enfermedades por microcristales de pirofosfato cálcico, ocasionando una calcificación de ligamentos del proceso de odontoides cervical, llevando a una clínica de cervicalgia, fiebre y rigidez de nuca. Esta patología entra en el diagnóstico diferencial con patologías potencialmente graves. En muchas ocasiones lleva a procedimientos y gastos farmacológicos innecesarios, principalmente por el desconocimiento que la transforma en una patología infradiag-nosticada. (Acta Med Colomb 2018; 43: 230-232).

Abstract In the usual clinical practice there is a growth in the demand for emergency services. Cervical pain is a very common pathology that concerns various health professionals. The crowned den syndrome is a very rare pathology, which is part of the spectrum of microcrystalline diseases of calcium pyrophosphate, causing a calcification of ligaments of the cervical odontoid process, leading to clinical signs of neck pain, fever and neck stiffness. This pathology enters into the differential diagnosis with potentially serious pathologies. In many cases it leads to unnecessary pharmacological procedures and expenses, mainly due to the ignorance that turns it into an infra diagnosed pathology. (Acta Med Colomb 2018; 43: 230-232).

Reduction and internal fixation of complex fractures of the odontoid by the transoral approach / Redução e osteossíntese de fratura complexa do odontoide por via transoral / Reducción y fijación interna de fracturas complejas de la odontoides por la vía transoral

ABSTRACT Type II odontoid fractures with irreducible posterior displacement are uncommon, and can cause spinal cord compression, respiratory failure and even death. Treatment is usually surgical, with transoral decompression and posterior fusion or with reduction and fusion of C1-C2 by the transoral approach. We describe a case of type II odontoid fracture with irreducible posterior atlantoaxial dislocation that was treated exclusively by the transoral approach with osteosynthesis of the odontoid, thus preserving functional segmental mobility. Level of Evidence III; therapeutic study.

RESUMO As fraturas do odontoide tipo II com deslocamento posterior irredutível não são comuns e podem causar compressão medular, insuficiência respiratória e até óbito. O tratamento habitualmente é cirúrgico, com descompressão transoral e fusão posterior, ou com a redução e fusão C1-C2 pela via transoral. Descrevemos um caso de fratura do odontoide tipo II, com deslocamento atlantoaxial posterior irredutível, que foi tratado exclusivamente por via transoral, com a osteossíntese do odontoide, preservando, assim, a mobilidade funcional segmentar. Nível de Evidência III; Estudo terapêutico

RESUMEN Las fracturas tipo II de la odontoides con desplazamiento posterior irreductible son poco comunes y pueden causar compresión de la médula espinal, insuficiencia respiratoria e incluso la muerte. El tratamiento suele ser quirúrgico con descompresión transoral y fusión posterior o con reducción y fusión de C1-C2 por vía transoral. Se describe un caso de fractura tipo II de la odontoides con luxación atlantoaxial posterior irreductible que fue tratada exclusivamente por vía transoral con osteosíntesis de la odontoides, preservando así la movilidad segmentaria funcional. Nivel de Evidencia III; Estudio terapéutico.

Anterior fixation of odontoid fractures: results / Fixação anterior de fraturas do processo odontoide: resultados

ABSTRACT Objective: To evaluate the clinical and radiological outcomes of the surgical treatment in patients diagnosed with odontoid fracture who underwent open reduction and internal fixation (ORIF) with screws. Methods: This was a retrospective study with nine patients. Pain (visual analog scale [VAS]) and neurological status (Frankel scale) were assessed. The neck disability index (NDI) and the post-operative cervical range of motion were calculated. The cervical spine was radiologically evaluated (X-ray and CT) pre- and postoperatively. Results: The mean age of patients was 70 years. All patients presented type IIb (Grauer classification) fractures, with a mean deviation of 2.95 mm. Two patients had subaxial lesions. The mean follow-up was 30 months. The mean time from trauma to surgery was seven days. The pre-operative Frankel score was E in all except one patient (B), in whom a post-operative improvement from B to D was observed. Post-operative pain was 2/10 (VAS). A total of 77% of patients presented a mild or moderate disability (NDI). Six patients regained full range of cervical movement, and bone union required approximately 14 weeks. Pseudarthrosis complications were observed in two patients (77% union rate), one patient presented screw repositioning and one case, dysphonia. Conclusion: Delayed diagnosis is still an issue in the treatment of odontoid fractures, especially in elderly patients. Concomitant lesions, especially in younger patients, are not uncommon. The literature presents high fusion rates with ORIF (≥80%), which was also observed in the present study. However, surgical success depends on proper patient selection and strict knowledge of the technique. This pathology presents a reserved functional prognosis in the medium-term, especially in the elderly.

RESUMO Objetivo: Avaliar os resultados clínicos e radiológicos do tratamento cirúrgico em pacientes com diagnóstico de fratura do processo odontoide submetidos a redução aberta e fixação interna (RAFI) com parafusos. Métodos: Estudo retrospectivo com nove pacientes. Avaliada a dor (escala visual analógica [EVA]) e o estado neurológico (escala de Frankel). O Neck Disability Index (NDI) e a amplitude de movimento cervical pós-operatória foram calculados. A coluna cervical foi avaliada radiologicamente (raios X e TC) nos períodos pré- e pós-operatório. Resultados: A idade média dos pacientes foi de 70 anos. Todos apresentaram fraturas do tipo IIb (classificação de Grauer), com desvio médio de 2,95 mm. Dois apresentaram lesões subaxiais. O seguimento médio foi de 30 meses. O tempo médio entre trauma e cirurgia foi de sete dias. O escore pré-operatório de Frankel foi E em todos, exceto em um paciente (B), no qual se observou uma melhoria pós-operatória de B para D. A dor pós-operatória foi 2/10 (EVA). Apresentaram incapacidade leve ou moderada (NDI) 77% pacientes. Seis pacientes recuperaram toda a amplitude de movimento cervical; a consolidação óssea levou aproximadamente 14 semanas. Foram observadas complicações de pseudartrose em dois pacientes (taxa de consolidação: 77%), um paciente necessitou reposicionamento do parafuso e um paciente, disfonia. Conclusão: O diagnóstico tardio ainda é um problema no tratamento de fraturas do odontoide, especialmente em pacientes idosos. As lesões concomitantes, especialmente em pacientes mais jovens, não são incomuns. A literatura apresenta altas taxas de consolidação com RAFI (≥ 80%), o que também foi observado no presente estudo. No entanto, o sucesso cirúrgico depende da seleção adequada do paciente e do conhecimento rigoroso da técnica. Essa patologia apresenta um prognóstico funcional reservado em médio prazo, especialmente em idosos.

Age-Related Prevalence of Periodontoid Calcification and Its Associations with Acute Cervical Pain

STUDY DESIGN: Prospective study. PURPOSE: To assess the prevalence of periodontoid calcification and its associations with acute cervical pain. OVERVIEW OF LITERATURE: Calcium pyrophosphate dihydrate (CPPD) deposition disease is a common rheumatological disorder that occurs especially in elderly patients. Although CPPD crystals induce acute arthritis, these crystals are not usually symptomatic. Calcification surrounding the odontoid process (periodontoid calcification) has been reported to induce inflammation, resulting in acute neck pain. This disease is called crowned dens syndrome. Whether calcification induces inflammation or whether the crystals are symptomatic remains unclear. METHODS: The prevalence of periodontoid calcification at the atlas transverse ligament was examined by computed tomography of the upper cervical spine in patients suspected of brain disease but no cervical pain (control group, n=296), patients with pseudogout of the peripheral joints but no cervical pain (arthritis group, n=41), and patients with acute neck pain (neck pain group, n=22). Next, the correlation between the prevalence of periodontoid calcification and symptoms was analyzed. RESULTS: In the control group, 40 patients (13.5%) showed periodontoid calcification with no significant difference in the prevalence with gender. The prevalence of calcification increased significantly with age (p=0.002). In the arthritis group, 26 patients (63.4%) reported periodontoid calcification. In the neck pain group, 14 patients (63.6%) reported periodontoid calcification. Multiple logistic regression analysis by age and group revealed that higher age, inclusion in the arthritis group, and inclusion in the neck pain group significantly affected the prevalence of calcification. CONCLUSIONS: Our results cumulatively suggest that periodontoid calcification is an aging-related reaction and that calcification per se does not always cause neck pain. Periodontoid calcification was observed more frequently in patients with pseudogout of the peripheral joints and in those with acute neck pain than in asymptomatic control patients.

Acute neck pain due to crowned dens syndrome: A case report

Crowned dens syndrome (CDS) is a cause of neck pain characterized by calcium deposition in the periodontoid tissues. Clinical features of the syndrome are acute onset of neck pain and headache with fever. Computed tomographic imaging is necessary for diagnosis. The prognosis of CDS is excellent. Symptoms disappear within several weeks and calcifications may be absorbed. We report a case of CDS with acute onset of severe neck pain, facial pain, and pharyngeal pain provoked by swallowing.

Safe Margin beyond Dens Tips to Ventral Dura in Anterior Odontoid Screw Fixation: Analysis of Three-Dimensional Computed Tomography Scan of Odontoid Process

OBJECTIVE: Anterior odontoid screw fixation is a safe and effective method for the treatment of odontoid fractures. The surgical technique is recommended for perforation of the apical cortex of the dens by the lag screw. However, overpenetration of the apical cortex may lead to potentially serious complications such as damages of adjacent vascular and neural structures. The purpose of this study was to assess the role of three-dimensional computed tomography (CT) scan to evaluate the safe margin beyond dens tip to ventral dura for anterior odontoid screw fixation.METHODS: We retrospectively analyzed the three-dimensional CT scans of the cervical spines in 55 consecutive patients at our trauma center. The patients included 38 males and 17 females aged between 22 and 73 years (mean age±standard deviation, 45.8±14.2 years). Using sagittal images of 3-dimensional CT scan, the safe margins beyond dens tip to ventral dura as well as the appropriate screw length were measured.RESULTS: The mean width of the apical dens tip was 9.6±1.1 mm. The mean lengths from the screw entry point to the apical dens tip and posterior end of dens tip were 39.2±2.6 mm and 36.6±2.4 mm. The safe margin beyond apical dens tip to ventral dura was 7.7±1.7 mm. However, the safe margin beyond the posterior end of dens tip to ventral dura was decreased to 2.1±3.2 mm, which was statistically significant (p < 0.01). There were no significant differences of safe margins beyond dens tip to ventral dura with patient gender and age.CONCLUSION: Extension by several millimeters beyond the dens tip is safe, if the trajectory of anterior odontoid screw is targeted at the apical dens tip. However, if the trajectory of the screw is targeted to the posterior end of dens tip, extension beyond dens tip may lead to damage immediately adjacent to the vental dura mater.

Safe Margin beyond Dens Tips to Ventral Dura in Anterior Odontoid Screw Fixation: Analysis of Three-Dimensional Computed Tomography Scan of Odontoid Process

OBJECTIVE: Anterior odontoid screw fixation is a safe and effective method for the treatment of odontoid fractures. The surgical technique is recommended for perforation of the apical cortex of the dens by the lag screw. However, overpenetration of the apical cortex may lead to potentially serious complications such as damages of adjacent vascular and neural structures. The purpose of this study was to assess the role of three-dimensional computed tomography (CT) scan to evaluate the safe margin beyond dens tip to ventral dura for anterior odontoid screw fixation. METHODS: We retrospectively analyzed the three-dimensional CT scans of the cervical spines in 55 consecutive patients at our trauma center. The patients included 38 males and 17 females aged between 22 and 73 years (mean age±standard deviation, 45.8±14.2 years). Using sagittal images of 3-dimensional CT scan, the safe margins beyond dens tip to ventral dura as well as the appropriate screw length were measured. RESULTS: The mean width of the apical dens tip was 9.6±1.1 mm. The mean lengths from the screw entry point to the apical dens tip and posterior end of dens tip were 39.2±2.6 mm and 36.6±2.4 mm. The safe margin beyond apical dens tip to ventral dura was 7.7±1.7 mm. However, the safe margin beyond the posterior end of dens tip to ventral dura was decreased to 2.1±3.2 mm, which was statistically significant (p < 0.01). There were no significant differences of safe margins beyond dens tip to ventral dura with patient gender and age. CONCLUSION: Extension by several millimeters beyond the dens tip is safe, if the trajectory of anterior odontoid screw is targeted at the apical dens tip. However, if the trajectory of the screw is targeted to the posterior end of dens tip, extension beyond dens tip may lead to damage immediately adjacent to the vental dura mater.

Cranio-vertebral transition assessment by magnetic resonance imaging in a sample of a northeast Brazilian population / Avaliação da transição crânio-vertebral por ressonância magnética em uma amostra da população do nordeste brasileiro

ABSTRACT Platybasia and basilar invagination are important alterations of the cranial-vertebral transition. Neuroimaging-based platybasia parameters include the Welcker basal angle, distance between the apex of the odontoid and Chamberlain's line, and the clivus-canal angle. This study aimed to measure and correlate these parameters in a sample from northeast Brazil. Methods Cross-sectional analysis of craniometric parameters from individuals submitted to magnetic resonance at an outpatient imaging center between 2011 and 2012. Results Of 181 analyzed cases, the Welcker basal angle averaged 128.96º (SD 6.51), median distance between apex of the odontoid and Chamberlain's line was 2.27 mm (IQR -1.23-4.47) and the median clivus-canal angle was 150.5º (IQR 143.2-157.3). The Welcker basal angle was inversely correlated to the clivus-canal angle, and correlated to the distance between the apex of the odontoid and Chamberlain's line. Conclusion There was a tendency to platibasia, basilar invagination and narrowing of the cranio-vertebral transition.

RESUMO Platibasia e invaginação basilar são importantes alterações da transição craniovertebral. Existem parâmetros importantes obtidos pela neuroimagem, como o ângulo basal de Welcker, distância do ápice do odontoide à linha de Chamberlain e o ângulo clivo-canal. Este estudo procurou medir e correlacioná-los em uma amostra do Nordeste Brasileiro. Métodos Estudo transversal com medidas de indivíduos submetidos a ressonância magnética craniana em um centro de diagnóstico por imagem entre 2011 e 2012. Resultados Dos 181 casos analisados, o ângulo basal de Welcker teve média 128.96º (DP 6.51), a distância do ápice do odontoide à linha de Chamberlain obteve mediana 2.27 mm (IIQ -1.23-4.47) e o ângulo clivo-canal mediano foi 150.5º (IIQ 143.2-157.3). O ângulo basal de Welcker foi inversamente correlacionado com o ângulo clivo-canal e diretamente correlacionado com a distância do ápice do odontoide à linha de Chamberlain. Conclusão Houve uma tendência a platibasia, invaginação basilar e estreitamento da transição craniovertebral, que poderiam ser influenciados pela natureza multirracial e por fatores antropológicos da população estudada.

Odontoid process hypoplasia and bipartite atlas associated with atlanto-axial instability / Hipoplasia do processo odontóide e atlas bipartido associado a instabilidade atlanto-axial / Hipoplasia de la apófisis odontoide y atlas bipartito asociado con inestabilidad atlantoaxial

ABSTRACT Surgical treatment of craniocervical junction pathology has evolved considerably in recent years with the implementation of short fixation techniques rather than long occipito-cervical fixation (sub-axial). It is often difficult and sometimes misleading to determine the particular bone and vascular features (high riding vertebral artery, for instance) using only the conventional images in three orthogonal planes (axial, sagittal and coronal). The authors describe a rare clinical case of congenital malformation of the craniovertebral junction consisting of hypoplasia/agenesis of the odontoid process and bipartite atlas associated with atlantoaxial instability which was diagnosed late in life in a patient with a previous history of rheumatologic disease. The authors refer to the diagnostic process, including new imaging techniques, and three-dimensional multiplanar reconstruction. The authors also discuss the surgical technique and possible alternatives.

RESUMO O tratamento cirúrgico da patologia da charneira crânio-cervical tem evoluído consideravelmente nos últimos anos com a implementação de técnicas de fixação curta em detrimento de longas fixações occipito-cervicais (sub-axiais). Frequentemente é difícil e por vezes enganador determinar as variações ósseas e vasculares (artéria vertebral high-riding p.e.) apenas pelas imagens convencionais em três planos ortogonais (axial, sagital e coronal). Os autores descrevem um caso clínico raro de malformação congénita da charneira crânio-cervical constituída por hipoplasia/agenésia da odontoide e atlas bipartido, associado a instabilidade atlanto-axial e diagnosticado tardiamente em doente com antecedentes reumáticos prévios. Descreve-se o processo diagnóstico, incluindo novas técnicas de imagiologia e de reconstrução multiplanar tridimensional. Discute-se a técnica cirúrgica utilizada e possíveis alternativas.

RESUMEN El tratamiento quirúrgico de la patología de la región craneocervical ha evolucionado considerablemente en los últimos años con la aplicación de técnicas de fijación cortas en lugar de fijación occipito-cervical larga (sub-axial). A menudo es difícil y hasta engañoso determinar las características óseos y vasculares (arteria vertebral high-riding, por ejemplo) usando sólo imágenes convencionales en tres planos ortogonales (axial, sagital y coronal). Los autores describen un caso clínico poco frecuente de malformación congénita de la unión craneocervical que consiste en la hipoplasia/agenesia de la apófisis odontoides y atlas bipartito, asociado con la inestabilidad atlantoaxial, diagnosticado tardiamente en pacientes con enfermedades reumatológicas previas. Los autores relatan el proceso de diagnóstico, incluyendo nuevas técnicas de imagen y la reconstrucción multiplanar tridimensional. Los autores también discuten la técnica quirúrgica y las posibles alternativas.

Retro-Odontoid Pseudotumor without Atlantoaxial Subluxation or Rheumatic Arthritis / 대한신경손상학회지

We present a case of retro-odontoid pseudotumor (ROP) without rheumatoid arthritis (RA) or atlantoaxial subluxation (AAS). A 76-year-old woman presented with paresthesia and weakness of both lower and upper extremities. She had no laboratory or physical findings of RA. Dynamic X-ray showed no AAS and magnetic resonance imaging (MRI) showed a retro-odontoid mass compressing the spinal cord. Transdural mass debulking and biopsy were performed via minimal left suboccipital craniectomy and C1 hemilaminectomy. Two months after surgery, her symptoms were aggravated. Follow-up MRI visualized mass re-growth and spinal cord compression due to the mass and AAS. Posterior C1-2 fixation was performed without further decompression. Twelve months after posterior fixation, no symptoms were apparent and follow-up MRI showed complete resolution of the ROP with C1-2 bony fusion. The ROP with C1-2 instability might be completely resolved only C1-2 fusion without decompression. Furthermore, we speculated that osteoarthritis of C1-2 itself causes a partial tear or degradation of the transverse ligament, that induced formation of ROP.

Irreducible Atlanto-Axial Dislocation in Neglected Odontoid Fracture Treated with Single Stage Anterior Release and Posterior Instrumented Fusion

It is a well-know fact that type 2 odontoid fractures frequently go into nonunion. If left untreated, patients may develop irreducible atlantoaxial dislocation (AAD). We describe the surgical management of two patients with neglected odontoid fractures and irreducible AAD treated with single stage anterior release followed by posterior instrumented fusion. Both patients presented with history of neglected trauma and progressive myelopathy. Traction under anesthesia failed to achieve reduction of AAD. Anterior release was done by trans-oral approach in one patient and retrophayngeal approach in the other. Posterior fixation was performed with transarticular screws in both the patients. Both patients had full neurological recovery and demonstrated fusion at follow-up. Anterior release followed by posterior instrumented correction may be an effective alternative to the traditional means of treating irreducible dislocations associated with neglected odontoid fractures.

Acute Pseudogout of the Neck: "Crowned Dens" Revisited

Calcium pyrophosphate dihydrate crystal deposition disease is associated with an acute mono- or pauciarthritis, termed "pseudogout" in elderly patients, involving a large joint (including the knees, ankles) or a chronic arthropathy manifesting as mild joint pain and stiffness. Pseudogout is a crystal-deposition disease of peripheral joints, usually encountered in elderly patients. However, acute presentation of pseudogout around the odontoid process comprises a "crowned-dens" appearance, and requires contemplation of differential diagnoses. We recently experienced a case of pseudogout in the cervical spine presenting with fever and acute neck pain that was successfully treated with a colchicine and low-dose oral steroid. We reported this case with a review of the relevant literature.