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OBJECTIVE: To evaluate the effect of the basilar invagination (BI) type B on cervical spine. METHODS: The research protocol used head magnetic resonance imaging (MRI) exams from 41 participants with BI type B and 158 controls. The criterion for BI was the distance of the odontoid apex to Chamberlain's line (DOCL) equal to or greater than 7 mm. The clivus length (CLI), clivus canal angle (CCA), Welcker's basal angle (WBA), Boogaard's angle (BOA), upper cervical lordosis angle (UCL), and total cervical lordosis angle (CL) were evaluated. The descriptive analysis, group comparisons, and correlations between skull base and cervical spine parameters were performed at the 95% CI. RESULTS: Participants with BI type B showed shorter clivus length (CLI: 25.7 ± 7.3 mm); greater angulation of the skull base (WBA: 126.5 ± 10.4); greater inclination foramen magnum (BOA: 151.5 ± 14.5); decrease in the value of the CCA (131.6 ± 15); and greater angulations of UCL (17.9 ± 13.8) and CL (29.7 ± 19.9) in comparison to the control group (P < 0.05). Clivus length and CCA correlated inversely with UCL and CL, while BOA correlated directly with UCL and CL. The WBA did not correlate with CL (P < 0.05). CONCLUSIONS: The deformation of skull base in the BI of type B caused, on average, a hyperlordosis of almost 30° in the C2-C6 segment. This change was approximately 17° in the C2-C4, with the clivus hypoplasia being a risk factor for cervical hyperlordosis.

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Basilar invagination (BI) is characterized by rostral dislocation of the cervical spine toward the skull base. The craniometrics of the skull base have shown significant differences among craniocervical junction malformations. The sphenoid bone is the center of the skull base; however, no study has evaluated this bone in cases of BI. This was a cross-sectional study of MRI databanks from two institutions of the author's practice between 1985 and 2020. The craniometrics of the sphenoid bone were measured in BI patients and controls. Fifty-eight MRIs were selected, including 28 BI patients and 30 controls. The mean sphenoid crest-clivus length was 32.66 ± 4.7 mm in the BI group and 29.98 ± 3.0 mm in the control group (p = 0.01). The mean sphenoid planum-top of Dorsum sellae length was 28.53 ± 3.7 mm in the BI group and 26.45 ± 3.2 mm in the control group (p = 0.02). The mean tuberculum sellae-sphenoid floor height was 18.52 ± 4.4 mm in the BI group and 21.32 ± 2.9 mm in the control group (p = 0.00). The mean sella turcica-sphenoid floor height was 10.35 ± 3.8 mm in the BI group and 12.24 ± 3.5 mm in the control group (p = 0.05). The mean clivus length was 29.81 ± 6.3 mm in the BI group and 40.86 ± 4.2 mm in the control group (p = 0.00). The mean sphenoid length was 58.34 ± 7.4 mm in the BI group and 67.31 ± 6.0 mm in the control group (p = 0.00). The mean sphenoid angle was 116.33 ± 8.7° in the BI group and 112.36 ± 6.9° in the control group (p = 0.05). The BI sphenoid bone has shorter vertical dimensions and longer horizontal measures. This morphology promotes a flattening of the sphenoid angle. The sphenoid bone is significantly altered in BI, favoring the congenital hypothesis in the pathophysiology of this disease.

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OBJECTIVE: To analyze the anatomical changes of the IV ventricle and cisterna magna in the Chiari malformation I (CMI) and basilar invagination (type B). METHODS: This is a controlled study with 161 exams of magnetic resonance imaging (MRI) of adults grouped into control (n = 37), basilar invagination (BI; n = 31), Chiari malformation I (CMI; n = 37), and CMI+BI (n = 56). The MRIs were analyzed using the visualization software Osirix (Pixmeo, Bernex, Geneva, version 3.8.2). The morphometric variables were: distance from the obex to the McRae line; length of the IV ventricle floor; and the area and volume of the cisterna magna. The univariate ANOVA followed by Tukey's post-hoc test was applied to evaluate the difference between the groups. The difference between sexes was evaluated by the t test for each group. RESULTS: Alterations in the cisterna magna and IV ventricle were more evident only in the CMI and CMI+BI groups. For both sexes, the CMI and CMI+BI groups showed: a reduction in the CSF space (P < 0.001), cisterna magna with volume reduction (P < 0.001), low position of the obex (P < 0.001), and IV ventricle more elongated (male P = 0.007 and female P < 0.001). The BI group had no significant change in the analysis by sex. CONCLUSIONS: The CMI (isolated and associated with BI) showed a low obex position and elongation of the IV ventricle due to traction towards the spinal canal. The reduction of cisterna magna volume added to the occupation of the cerebellar tonsils can impact in the cerebrospinal fluid dynamics. The BI when isolated was not related to alterations in the parameters of cerebrospinal fluid spaces studied.

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CONTEXT: Spinal-generated movement disorders are a complex group of medical conditions, frequently misdiagnosed, originating in the spinal cord or from combined peripheral and central nervous system involvement. In this case report, we describe a novel form of position-dependent dyskinesia due to severe craniocervical malformation. FINDINGS: An 83-year-old woman with basilar invagination at the C2 vertebra above the line of Chamberlain, occipitocervical lordosis, platybasia with a short clivus, ankylosis of the C1-C2 complex and fusion of the C1 arch developed an unusual pattern of position-dependent left arm dyskinesia triggered by bending her neck forward with simultaneous contact of the flexed elbow with a flat surface. Symptoms did not improve with anticonvulsants and she progressed and died suddenly. CONCLUSION/CLINICAL RELEVANCE: A newly described form of position-dependent arm dyskinesia can be associated with severe craniocervical malformation.

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OBJECTIVE: The present study aims to perform a reproducibility study of the clivus-canal angle (CCA), Welcker's basal angle (WBA), and the distance from the odontoid process to Chamberlain's line (DOCL) on magnetic resonance imaging (MRI). MATERIALS AND METHODS: Two medical students and two radiologists respectively evaluated 100 and 50 consecutive MRI scans of adult skulls, selected randomly. Each examiner, working independently and blinded to the previous results, performed readings for each patient on two different occasions. Measurements were performed in T1-weighted sequences acquired in the midsagittal plane. The levels of intraobserver reproducibility and interobserver agreement were evaluated by calculating the intraclass correlation coefficients (ICCs) and the corresponding 95% confidence intervals. RESULTS: The mean values obtained by the examiners were 150º for the CCA, 130º for the WBA, and 2.5 mm for the DOCL. The ICC for interobserver agreement was 0.980, 0.935, and 0.967, for the CCA, WBA, and DOCL, respectively, for the students, compared with 0.977, 0.941, and 0.982, respectively, for the radiologists, and 0.980, 0.992, and 0.990, respectively, for all of the examiners together. In the analysis of intraobserver agreement, the ICC ranged from 0.929 to 0.959 for the CCA, from 0.918 to 0.964 for the WBA, and from 0.918 to 0.981 for the DOCL. CONCLUSION: The measurement of the CCA, WBA, and DOCL appears to show excellent intraobserver reproducibility and interobserver agreement on MRI.

OBJETIVO: Realizar um estudo de reprodutibilidade do ângulo clivocanal (ACC), ângulo basal de Welcker (ABW) e distância do odontoide à linha de Chamberlain (DOLC) em ressonância magnética (RM). MATERIAIS E MÉTODOS: Quatro examinadores, dois graduandos de medicina e dois radiologistas, avaliaram, respectivamente, 100 e 50 indivíduos adultos submetidos a RM de crânio, consecutiva e aleatoriamente. Cada um realizou duas leituras para cada paciente em diferentes ocasiões, de forma cega e independente. As análises de concordância intraobservador e interobservador foram realizadas pelo coeficiente de correlação intraclasse (CCI), com intervalo de confiança de 95%. RESULTADOS: As medidas médias, considerando todos os examinadores, foram: ACC = 150º, ABW = 130º, DOLC = 2,5 mm. A análise interobservador entre os estudantes revelou CCI de 0,980, 0,935 e 0,967 para ACC, ABW e DOLC, respectivamente, e para os radiologistas, CCI de 0,977, 0,941 e 0,982, respectivamente. A análise interobservador entre estudantes e radiologistas revelou CCI de 0,980, 0,992 e 0,990, respectivamente. Em relação à análise intraobservador, as medidas do ACC tiveram CCI variando entre 0,929 e 0,959, ABW entre 0,918 e 0,964 e DOLC entre 0,918 e 0,981. CONCLUSÃO: ACC, ABW e DOLC obtiveram excelentes reprodutibilidades intraobservador e interobservador na RM.

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Abstract Objective: The present study aims to perform a reproducibility study of the clivus-canal angle (CCA), Welcker's basal angle (WBA), and the distance from the odontoid process to Chamberlain's line (DOCL) on magnetic resonance imaging (MRI). Materials and Methods: Two medical students and two radiologists respectively evaluated 100 and 50 consecutive MRI scans of adult skulls, selected randomly. Each examiner, working independently and blinded to the previous results, performed readings for each patient on two different occasions. Measurements were performed in T1-weighted sequences acquired in the midsagittal plane. The levels of intraobserver reproducibility and interobserver agreement were evaluated by calculating the intraclass correlation coefficients (ICCs) and the corresponding 95% confidence intervals. Results: The mean values obtained by the examiners were 150° for the CCA, 130° for the WBA, and 2.5 mm for the DOCL. The ICC for interobserver agreement was 0.980, 0.935, and 0.967, for the CCA, WBA, and DOCL, respectively, for the students, compared with 0.977, 0.941, and 0.982, respectively, for the radiologists, and 0.980, 0.992, and 0.990, respectively, for all of the examiners together. In the analysis of intraobserver agreement, the ICC ranged from 0.929 to 0.959 for the CCA, from 0.918 to 0.964 for the WBA, and from 0.918 to 0.981 for the DOCL. Conclusion: The measurement of the CCA, WBA, and DOCL appears to show excellent intraobserver reproducibility and interobserver agreement on MRI.

Resumo Objetivo: Realizar um estudo de reprodutibilidade do ângulo clivocanal (ACC), ângulo basal de Welcker (ABW) e distância do odontoide à linha de Chamberlain (DOLC) em ressonância magnética (RM). Materiais e Métodos: Quatro examinadores, dois graduandos de medicina e dois radiologistas, avaliaram, respectivamente, 100 e 50 indivíduos adultos submetidos a RM de crânio, consecutiva e aleatoriamente. Cada um realizou duas leituras para cada paciente em diferentes ocasiões, de forma cega e independente. As análises de concordância intraobservador e interobservador foram realizadas pelo coeficiente de correlação intraclasse (CCI), com intervalo de confiança de 95%. Resultados: As medidas médias, considerando todos os examinadores, foram: ACC = 150°, ABW = 130°, DOLC = 2,5 mm. A análise interobservador entre os estudantes revelou CCI de 0,980, 0,935 e 0,967 para ACC, ABW e DOLC, respectivamente, e para os radiologistas, CCI de 0,977, 0,941 e 0,982, respectivamente. A análise interobservador entre estudantes e radiologistas revelou CCI de 0,980, 0,992 e 0,990, respectivamente. Em relação à análise intraobservador, as medidas do ACC tiveram CCI variando entre 0,929 e 0,959, ABW entre 0,918 e 0,964 e DOLC entre 0,918 e 0,981. Conclusão: ACC, ABW e DOLC obtiveram excelentes reprodutibilidades intraobservador e interobservador na RM.

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BACKGROUND: The craniovertebral junction is an anatomically well-defined transitional zone located between the skull and the cervical spine. Multiple malformations can affect this region with the most prominent being basilar invagination (BI) and Chiari malformation (CM). Despite numerous studies, the origin, pathophysiology, and classification of these pathologies remain controversial. The objective of this study was to evaluate the implication of cranial base flexion angle and clivus length in the development of these conditions. METHODS: Midline tomography and magnetic resonance imaging of normal subjects and patients diagnosed with BI (types I and II) and Chiari malformation were evaluated. A craniometric study of the skull base was performed. Linear and angular measurements were used for comparisons between groups. RESULTS: 109 images from patients with craniovertebral junction malformation and controls were evaluated. Seventeen had BI-I, 26 had BI-II, 36 had CM, and 30 were normal subjects. Demographic data for the two groups were not significantly different. Craniometric analysis of images revealed a gradation in linear and angular variables from controls to CM, BI-I, and BI-II patients. Clivus length was significantly smaller in BI-II patients compared with other groups, while basal angle was greater. Moderate or strong correlations were noted among all variables analyzed. CONCLUSION: Data suggest that clivus length and basal angle may play a role in pathophysiology of BI and CM.

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Biomodels are produced using three-dimensional printers and their use in complex spine surgeries can be quite helpful, especially when complex anatomy is faced. In this case report, we presented a 14-year-old patient who had rigid congenital cervical scoliosis and basilar invagination and abnormalities on a neurological examination. This patient underwent atlantoaxial facet distraction and C1 C2 fusion while using a biomodel of his craniocervical junction in pre-operative planning and also as an anatomical reference per-operatively. Using biomodel in this case helped in achieving favorable surgical outcomes without any perioperative complications. Postoperative assessments including coronal deformity, basilar invagination, and neurological examination showed significant improvements and we recommend using biomodels in complex atlantoaxial distraction procedure to achieve favorable surgical outcomes with minimum complications.

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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.

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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.

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INTRODUCTION: Congenital disorders of the craniovertebral junction (CVJ) include a wide range of conditions, such as Chiari malformation (CM), basilar Invagination (BI), and atlantoaxial dislocation (AAD). The objective of this paper is to critically review the literature related to the management of congenital CVJ disorders focusing on: the significant developments in the past (from anterior open ventral decompression to modern CVJ realignment); the diagnosis of CVJ instability; the role of atlantoaxial fixation without posterior fossa decompression in patients with tonsillar herniation and no evidence of CVJ instability; use of C1-2 inter-articular spacers and use of C1-2 interarticular spacers with intra-operative manipulations to correct BI with AAD along with its deformity. MATERIALS AND METHODS: We performed a review of articles showing up on PubMed database without time restriction. Articles were included according to the purpose of our review and selected by two authors (AFJ and PSC). RESULTS: CVJ instability may be inferred when there is atlantoaxial abnormal motion seen on dynamic studies, facet joint subluxation or severe symptomatic CVJ kyphosis; routine fixation of patients with CM without clear CCJ instability, while based on an interesting hypothesis, still requires further studies; use of C1-2 inter-articular spacers for re-establishing CVJ alignment is probably the most effective surgery for posterior CVJ realignment and reduction of AAD and BI, potentially avoiding the need for an open or endoscopic anterior odontoidectomy (AO); current development of deformity correcting surgeries and the measurement of joint indices to plan surgery have provided new strategies for treatment. CONCLUSION: We present a critical review of important new concepts involved in the surgical treatment of CVJ congenital disease.

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BACKGROUND: Basilar invagination (BI) is an abnormality characterized by a superior projection at the craniovertebral junction (CVJ). The high prevalence of BI in Northeastern Brazil associated with brachycephaly, which is measured by the cranial index (CI), has been widely reported by several neurosurgeons and radiologists from that region since the 1950s. However, strong evidence for this relationship is still pending. The aim of this study is to investigate whether there is a relationship between BI and CI in a sample with participants from Northeastern Brazil. METHODS: The study used magnetic resonance images (MRIs) from 34 patients with BI and 92 controls. These participants had the CI correlated with radiological measurements used in BI diagnosis: Welcker's basal angle (WBA), clivus-canal angle (CCA), apex distance of the odontoid process to Chamberlain's line (DOCL), and Boogaard's angle (BOA). Craniometry was performed using the software Osirix, version 3.9.2 and statistical analysis by SPSS. We used Pearson's test for correlation analysis and the ROC curve was used for depicting CI accuracy related to BI diagnosis. All tests were calculated at the 95% confidence interval. RESULTS: The BI group showed a moderate correlation between CI and CVJ measurements (P < 0.05). The control group had a weak correlation between CI and DOCL, and no statistical significance was verified for other correlations (P > 0.05). The area under the ROC was 0.659 and a CI greater than 86 had a specificity of approximately 80% for BI (P = 0.002). CONCLUSIONS: The results indicated a greater cephalic projection of the CVJ in patients with high CI in the BI group. Moreover, a CI above 86 has a good diagnosis specificity for BI, showing evidence of a relationship between hyperbrachycephaly and CVJ anomalies in Northeastern Brazil.

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Down syndrome (DS) occurs when an individual has a full or partial extra copy of chromosome 21 and is the most common of all malformation syndromes. Associating with numerous pathologies like anterior atlantoaxial subluxation (AAAS) which is an increase in the space between the anterior arch of the first cervical vertebra (C1) and the odontoid process of the second vertebra (C2), most of the time its asymptomatic, only 1-2% to all the 30% who may have the AAAS and DS develop clinical symptoms. In this occasion, we present the case of a patient with SD and Juvenile chronic arthritis (JCA) who has atlantoaxial subluxation of approximately 11mm, basilar impression and platybasia with severe medullary compression in 2 points, requiring surgical management by the Neurological Surgery Service in Bucaramanga-Colombia.

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Chiari malformation (CM) and basilar invagination (BI) are mesodermal malformations with disproportion between the content and volume of posterior fossa capacity and overcrowding of neural structures at the level of foramen magnum. Several alternatives for posterior approaches are available, including extradural (ED), extra-arachnoidal, and intradural (ID) approaches. The objectives are to evaluate the effect of several surgical techniques for posterior fossa decompression (PFD) in the outcomes of patients with CCJM and to evaluate complications in the techniques reported. A systematic review of the literature on the effects of PFD surgery was performed using the MEDLINE (via PubMed) database and the Cochrane Central Register of Controlled Trials. The PRISMA statement and MOOSE recommendations were followed. Five hundred and thirty-nine (539) articles were initially selected by publication title. After abstract analysis, 70 articles were selected for full-text analysis, and 43 were excluded. Ultimately, 27 studies were evaluated. The success rate (SR) with ED techniques was 0.76 versus 0.81 in EA technique and 0.83 in IA technique. All posterior fossa decompression techniques were very successful. Results from observational studies were similar to that of the randomized trial. The main complications were CSF fistulas, most common in patients with IA approach. The overall mortality rate was 1%.

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In the present article, we describe a technique of direct intraoperative reduction of congenital atlantoaxial subluxation associated with severe basilar invagination and atlas assimilation. It consists of a wide dissection of the craniovertebral junction, exposing the region between the superior facet of C2 and the occiput (described as a "pseudoarticulation" by some authors). After exposure, a self-rotating small dissector or Kobe is used bilaterally, pushing C2 anteriorly and inferiorly, with reduction of the dislocation, followed by craniovertebral fixation. The technique is safe and eliminates the need for an anterior approach to the odontoid reduction, as well as the need to dissect the C1­2 joint.

Neste artigo, descrevemos a técnica de redução intraoperatória direta de subluxação atlantoaxial congênita associada a invaginação basilar grave e assimilação do atlas. Ela consiste em ampla dissecção da junção craniovertebral, expondo a região entre a face superior da C2 e o osso occipital (descrita como uma "pseudoarticulação" por alguns autores). Após exposição, um descolador pequeno ou Kobe é usado bilateralmente com rotação própria, deslocando C2 anterior e inferiormente, com redução da luxação, seguido de fixação craniovertebral. A técnica é segura e elimina a necessidade de uma abordagem anterior para a ressecção do odontoide, além de evitar a dissecação da junta C1­C2.

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AIM: To evaluate the role of dynamic computed tomography (CT) scan imaging in diagnosing craniovertebral junction (CVJ) instability in patients with congenital CVJ malformations. METHODS: Patients with symptomatic congenital CVJ malformations who underwent posterior fossa decompression and had a preoperative dynamic CT scan in flexion and extended position were included in this study. Measurements of the following craniometrical parameters were taken in flexed and extended neck position: Atlanto-dental interval (ADI), distance of the odontoid tip to the Chamberlain's line, and the clivus-canal angle (CCA). Assessment of the facet joints congruence was also performed in both positions. Comparison of the values obtained in flexion and extension were compared using a paired Student's t-test. RESULTS: A total of ten patients with a mean age of 37.9 years were included. In flexion imaging, the mean ADI was 1.76 mm, the mean CCA was 125.4° and the mean distance of the odontoid tip to the Chamberlain's line was + 9.62 mm. In extension, the mean ADI was 1.46 mm (P = 0.29), the mean CCA was 142.2° (P < 0.01) and the mean distance of the odontoid tip to the Chamberlain's line was + 7.11 mm (P < 0.05). Four patients (40%) had facetary subluxation demonstrated in dynamic imaging, two of them with mobile subluxation (both underwent CVJ fixation). The other two patients with a fixed subluxation were not initially fixed. One patient with atlantoaxial assimilation and C23 fusion without initial facet subluxation developed a latter CVJ instability diagnosed with a dynamic CT scan. Patients with basilar invagination had a lower CCA variation compared to the whole group. CONCLUSION: Craniometrical parameters, as well as the visualization of the facets location, may change significantly according to the neck position. Dynamic imaging can provide additional useful information to the diagnosis of CVJ instability. Future studies addressing the relationship between craniometrical changes and neck position are necessary.

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We describe a Basilar Invagination (BI) case with craniocervical instability and many previous failure surgeries and poor wound coverage. The patient had been submitted to a large posterior fossa craniectomy (which greatly limited the availability of an adequate area for bone fixation) and showed a poor quality of the surgical wound in the posterior craniocervical region. We performed an occipito-cervical fixation, using the bone overlying the torculla as a point of cranial fixation. Craniocervical realignment was achieved by the use of distractive maneuvers with occipital rods, followed by coverage of the hardware via a pedicled longitudinal trapeze myocutaneous flap. We used local ribs removed from the region where the myocutaneous flap was harvested as autologous bone grafts for craniocervical fusion. Post-operatively, the patient was placed in a halo-vest for three months. The patient improved substantially after the procedure, recovered some muscular strength and experienced total relief of her pain. We hereby discuss the surgical strategy used for treating this complex case in details, with illustrative pictures.

Descrevemos caso de paciente com diagnóstico de invaginação basilar e instabilidade crânio cervical com múltiplas cirurgias prévias e deiscência de ferida operatória. Devido a falha de osso na escama occipital, assim como da cobertura cutânea adequada, realizamos realinhamento craniocervical, com descompressão indireta anterior, fixação occipitocervical na região da tórcula e cobertura da pele com flap miocutâneo longitudinal pediculado de trapézio. As costelas removidas da região do retalho miocutâneo foram transferidas para serem usadas como enxerto autólogo de osso para fusão craniocervical. No pós-operatório, a paciente utilizou um halo-vest por 3 meses. No presente artigo, apresentamos nuances ilustrados de manobras para realinhamento craniocervical por via posterior na invaginação basilar, bem como estratégias para otimizar a artrodese e o fechamento cutâneo.

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OBJECT: The goal of this study was to compare the indications, benefits, and complications between the endoscopic endonasal approach (EEA) and the microscopic transoral approach to perform an odontoidectomy. Transoral approaches have been standard for odontoidectomy procedures; however, the potential benefits of the EEA might be demonstrated to be a more innocuous technique. The authors present their experience with 12 consecutive cases that required odontoidectomy and posterior instrumentation. METHODS: Twelve consecutive cases of craniovertebral junction instability with or without basilar invagination were diagnosed at the National Institute of Neurology and Neurosurgery in Mexico City, Mexico, between January 2009 and January 2013. The EEA was used for 5 cases in which the odontoid process was above the nasopalatine line, and was compared with 7 cases in which the odontoid process was beneath the nasopalatine line; these were treated using the transoral microscopic approach (TMA). Odontoidectomy was performed after occipital-cervical or cervical posterior augmentation with lateral mass and translaminar screws. One case was previously fused (Oc-C4 fusion). The senior author performed all surgeries. American Spinal Injury Association scores were documented before surgical treatment and after at least 6 months of follow-up. RESULTS: Neurological improvement after odontoidectomy was similar for both groups. From the transoral group, 2 patients had postoperative dysphonia, 1 patient presented with dysphagia, and 1 patient had intraoperative CSF leakage. The endoscopic procedure required longer surgical time, less time to extubation and oral feeding, a shorter hospital stay, and no complications in this series. CONCLUSIONS: Endoscopic endonasal odontoidectomy is a feasible, safe, and well-tolerated procedure. In this small series there was no difference in the outcome between the EEA and the TMA; however, fewer complications were documented with the endonasal technique.

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INTRODUCTION: Basilar invagination (BI) is a congenital craniocervical junction (CCJ) anomaly represented by a prolapsed spine into the skull-base that can result in severe neurological impairment. MATERIALS AND METHODS: In this paper, we retrospective evaluate the surgical treatment of 26 patients surgically treated for symptomatic BI. BI was classified according to instability and neural abnormalities findings. Clinical outcome was evaluated using the Nürick grade system. RESULTS: A total of 26 patients were included in this paper. Their age ranged from 15 to 67 years old (mean 38). Of which, 10 patients were male (38%) and 16 (62%) were female. All patients had some degree of tonsillar herniation, with 25 patients treated with foramen magnum decompression. Nine patients required a craniocervical fixation. Six patients had undergone prior surgery and required a new surgical procedure for progression of neurological symptoms associated with new compression or instability. Most of patients with neurological symptoms secondary to brainstem compression had some improvement during the follow-up. There was mortality in this series, 1 month after surgery, associated with a late removal of the tracheal cannula. CONCLUSIONS: Management of BI requires can provide improvements in neurological outcomes, but requires analysis of the neural and bony anatomy of the CCJ, as well as occult instability. The complexity and heterogeneous presentation requires attention to occult instability on examination and attention to airway problems secondary to concomitant facial malformations.