Navigated Anterior Full-Endoscopic Transcervical Approach Odontoidectomy for Traumatic Posterior Atlantoaxial Dislocation Without Odontoid Fracture.

BACKGROUND AND IMPORTANCE: Complete posterior atlantoaxial dislocation (PAAD) with an unfractured odontoid process is a rare condition where a dislocated but intact odontoid process is positioned ventrally to the anterior arch of C1. This lesion is related to transverse and alar ligament rupture secondary to hyperextension and rotatory traumatic injury and is often associated with neurological deficit. The treatment strategy remains controversial, and in many cases, odontoidectomy is required. Traditional approaches for odontoidectomy (transnasal and transoral) are technically demanding and are related to several complications. This article describes a 360° reduction and stabilization technique through a navigated anterior full-endoscopic transcervical approach (nAFETA) as a novel technique for odontoidectomy and C1-C2 anterior transarticular fixation supplemented with posterior fusion. CLINICAL PRESENTATION: A 21-year-old man presented to the emergency room by ambulance after a motorcycle accident. On evaluation, incomplete ASIA B spinal cord injury was documented. Imaging revealed a complete PAAD. We performed a two-staged procedure, a nAFETA odontoidectomy plus C1-C2 anterior transarticular fixation followed by posterior C1-C2 wired fusion. At a 2-year follow-up, the patient had a 10-point Oswestry Disability Index score and neurological improvement to ASIA E. CONCLUSION: PAAD can be successfully treated through minimally invasive nAFETA. Noteworthy, the risks of the transoral and endonasal routes were avoided through this approach. In addition, nAFETA allows anterior transarticular fixation during the same procedure providing spinal stability. Further studies are required to expand the use of nAFETA in this field.

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

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

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.

[Os odontoideum. Presentation in adult age]. / Os odontoideum. Presentación en edad adulta.

The Os odontoideum is a variable oval or round ossicle with a smooth cortical border, which partially corresponds to the odontoid process, without having continuity with the rest of C2 bone. The multifactorial etiology causes instability and clinically translates into pain and compression data into neural structures. The treatment of choice is surgical and techniques have been developed that focus on preserving the stability of the segment. We present the case of a 23-year-old female patient, who begins to suffer at 8 years of age, refers to moderate to severe cervicalgia, which develops with paresthesias in the left hemisphere and later paresis of the left thoracic limb. Physical examination showed hypoaesthesia of the left hemisphere, as well as paresis of the left thoracic limb. Extension studies demonstrate chronic axonal lesion from C1 to C3, predominantly left, imaging studies showing axial instability and magnetic resonance bulbar compression. The patient receives surgical treatment consisting of posterior fixation C1-C2, evolving satisfactorily.

Os odontoideum es un osículo oval o redondo de tamaño variable con un borde cortical liso, que se corresponde parcialmente con la apófisis odontoides, sin tener continuidad ósea con el resto de C2. La etiología es multifactorial, causa inestabilidad y clínicamente se traduce en dolor y datos de compresión a las estructuras neurales. El tratamiento de elección es quirúrgico y se han desarrollado técnicas que se enfocan en conservar la estabilidad del segmento. Presentamos el caso de una mujer de 23 años, inicia padecimiento a los ocho años, refiere cervicalgia moderada a intensa, que evoluciona con parestesias en hemicuerpo izquierdo y posteriormente paresia de miembro torácico izquierdo. A la exploración física se evidencia hipoestesia de hemicuerpo izquierdo, así como paresia de miembro torácico izquierdo. Los estudios de extensión demuestran lesión axonal crónica de C1 a C3, de predominio izquierdo, los estudios de imagen evidencian inestabilidad axial y la resonancia magnética compresión bulbar. La paciente recibe tratamiento quirúrgico consistente en fijación posterior C1-C2, evolucionando satisfactoriamente.

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.

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.

Diagnostic accuracy of classical radiological measurements for basilar invagination of type B at MRI.

OBJECTIVE: To evaluate the diagnostic accuracy of classical measurements for basilar invagination (BI) of type B at MRI. METHODS: This study used head MRIs from 31 participants with BI type B and 96 controls. The radiological criterion for BI was the odontoid process invagination using the obex as reference. It based on the independent prospective reading of two neuroradiologists. Concordance between the two neuroradiologists was analysed through the KAPPA index, and the discrepancy was resolved in a consensus meeting. A third examiner measured in two occasions (double blind) the distance of the odontoid apex to Chamberlain's line (DOCL) and McGregor's line (DOMG), clivus canal angle (CCA), Welcker's basal angle (WBA), and Boogaard's angle (BOA). Intra-examiner reproducibility of the measurements was evaluated with the intraclass correlation coefficient and the diagnostic accuracy by ROC curve. All analyses were at 95% confidence interval. RESULTS: Agreement between the two neuroradiologists was statistically relevant (KAPPA = .91; P = .0001). The intra-examiner reproducibilities were .98 (DOCL), .97 (DOMG), .96 (CCA), .94 (WBA), and .95 (BOA) (P < .05). The areas under the ROC curve were .963 (DOCL), .940 (DOMG), .880 (CCA), .867 (WBA), and .951 (BOA) (P < .05). The cut-off criteria were ≥ 7 mm (DOCL), ≥ 8 mm (DOMG), ≤ 145° (CCA), ≥ 142° (WBA), and ≥ 136° (BOA). The diagnostic accuracies were .904 (DOCL), .870 (DOMG), .844 (CCA), .810 (WBA), and .899 (BOA). CONCLUSION: The DOCL and BOA presented the highest diagnostic accuracy for BI type B. These slides can be retrieved under Electronic Supplementary Material.

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.

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.

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.

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).

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.

Elongated odontoid process in late Holocene skeletal remains from B6 archaeological site, Mendoza, Argentina.

The odontoid process of the axis can be affected by congenital or acquired pathologies. While abnormalities such as os odontoideum, agenesis, and fractures are reported in archaeological remains, the abnormality of an elongated length of the odontoid process has not been described in the paleopathological literature. The aim of this paper is to evaluate two individuals with elongated odontoid processes from a skeletal assemblage from the B6 archaeological site (Mendoza, Argentina), and to discuss the possible etiologies of the condition, with particular attention given to the relation to trauma and Crowned Dens Syndrome (CDS), a condition characterized by the ossification of ligaments of the odontoid process of the second cervical vertebra.

Feasibility of anterior screw fixation in children: a tomographic study.

PURPOSE: Morphology measures of the odontoid process in children under 12 years old were carried out to demonstrate the viability of anterior internal fixation in this population once their active profile may not be compatible with successful conservative treatment. METHODS: During a 6-month period, 36 tomographic examinations of the cervical spine region that provided visualization of the odontoid process were selected. Group 1 included children between 6 and 9 years of age, and group 2 contained children from 9 to 12 years of age. There were 23 (63.8%) male patients and 13 (36.2%) female patients. Patients diagnosed with a tumor, an infection, fracture non-union, or congenital malformation were excluded. Exams were ordered as part of a protocol applied to non-specific neck pain and pediatric trauma entries. The following parameters were analyzed: (1) screw attack angle, (2) height of the odontoid process, and (3) minimal transverse diameter of the odontoid process. RESULTS: In Groups 1 and 2, the average values of the screw attack angle were 55.9° ± 2.3° and 54.8° ± 4.5°, respectively; the average heights of the odontoid process were 26.58 ± 3.28 and 29.48 ± 3 mm, respectively, and the average minimal transverse diameter of the odontoid process were 6.57 ± 1.08 and 6.23 ± 0.88 mm, respectively. The minimal transverse diameter of the odontoid process was statistically higher in males than that in females, regardless of age (p = 0.007). CONCLUSION: In both groups, the minimal transverse diameter of the odontoid process allowed for the use of one 3.5-4.5 mm screw for anterior internal fixation. These slides can be retrieved under Electronic Supplementary Material.

Cranio-vertebral transition assessment by magnetic resonance imaging in a sample of a northeast Brazilian population.

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.

Radiological evolution of peri-odontoid pannus in a patient with Chiari I malformation: a case-based review.

INTRODUCTION: The Chiari I malformation (CIM) is commonly encountered by neurosurgeons and can have different etiologies and clinical presentations. CASE REPORT: We report a CIM patient who presented with symptoms of ventral brain stem compression and was found to have a large peri-odontoid pannus. Posterior fossa decompression was performed with a planned second-stage odontoidectomy. However, at the 6-month follow-up, postoperative images demonstrated a mostly resolved pannus and improvement of the brain stem compression symptoms, and the patient progressed uneventfully without the need for odontoidectomy. CONCLUSIONS: This case illustrates the resolution of a significant and symptomatic peri-odontoid pannus in a patient with CIM without craniocervical fusion or odontoidectomy. Such a case indicates that not all peri-odontoid pannus formations in CIM patients are due to hypermobility at the craniocervical junction.

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.

Fractura combinada del atlas y del axis con morfología poco frecuente / Combined fracture of atlas and axis with infrequent

Fundamento: las lesiones combinadas del atlas y el axis son los traumatismos más frecuentes de la columna cervical en el adulto mayor, con una incidencia que se acerca al 70 por ciento. Su diagnóstico demanda de estudios imaginológicos de avanzada y las opciones de tratamiento van del conservador a complejas intervenciones para restablecer la estabilidad de la región occipitocervical.Objetivo: presentar una lesión combinada de la primera y segunda vértebra cervical con una forma poco frecuente de fractura de odontoides.Caso clínico: paciente de 79 años de edad, que después de la caída de un caballo, sufre trauma craneal variedad posterior, seguido de cervicobraquialgia bilateral con parestesias. El examen físico no demostró signos de compresión radicular ni cordonal. Las imágenes de tomografía axial computarizada con reconstrucciones tridimensionales evidenciaron una fractura bilateral y simétrica del arco posterior del atlas, asociado a una fractura longitudinal y oblicua del odontoides próxima a su istmo. No se observó luxación, por lo que se conservó la estabilidad del raquis cervical superior. Se trató de manera conservadora con una órtesis externa y tuvo una evolución favorable.Conclusiones: para el diagnóstico de las lesiones traumáticas atlantoaxiales es imprescindible el uso de la tomografía axial computarizada, asociada o no con la resonancia magnética nuclear. La estabilidad de esta región en correspondencia con el estado neurológico del paciente, son los factores más importantes para decidir la mejor opción de tratamiento(AU)

Background: combined lesions of atlas and axis are the most common cervical spine traumas in elderly people, with an incidence of about 70 percent. The diagnosis demands the use of advance radiologic procedures and the treatment options runs through conservative to complex surgical interventions to restore the stability of the occipito-cervical region.Objective: to present a combined lesion of the first and second cervical vertebra as a less frequent shape of odontoid fracture.Clinical case: a 79-year-old patient who suffered a posterior cranial trauma followed by bilateral cervicobrachialgia and paresthesias after a horse fall. At physical exploration no signs of radicular or cordonal compression were demonstrated. Computarized axial tomography with tridimentional reconstructions showed a bilateral and symmetrical fracture of the posterior arch of the atlas, associated with longitudinal and oblique fracture of odontoid next to the isthmus. No dislocation was observed that is why the upper cervical spine stability was preserved. Conservative treatment was achieved by an external orthesis with a favourable evolution.Conclusions: for atlantoaxial traumatic lesions diagnosis, the use of computerized axial tomography is important associated or not with nuclear magnetic resonance. The stability of this region in correspondence with neurological status are the most important factors to select the best treatment choice(AU)