Craniovertebral Junction Deformity Diagnosed by Computed Tomography: A Case Report.

Craniovertebral junction (CVJ) deformities, including basilar invagination and atlanto-occipital assimilation, present significant challenges in diagnosis and management due to their complex nature and impact on neurological function. We report a case of a 28-year-old female who experienced neck pain, weakness, tingling in the upper limbs, restricted neck movements, occipital headaches, and intermittent dizziness. These symptoms progressively worsened over six months, markedly affecting her quality of life. Neurological examination revealed reduced motor power in the upper limbs and a diminished bicipital tendon reflex, while other assessments remained normal. Cervical spine CT imaging was done which revealed basilar invagination and atlanto-occipital assimilation. This case underscores the importance of recognizing and managing CVJ deformities, highlighting the need for a multidisciplinary approach to address anatomical and associated neurological symptoms. Early and accurate diagnosis and a tailored treatment strategy are crucial for improving patient outcomes.

Atlanto-occipital assimilation: A pictorial review of a commonly missed pathology.

Atlanto-occipital assimilation is a congenital craniovertebral junction malformation where the partial or complete fusion of the atlas and occiput occurs. Atlanto-occipital assimilation can be associated with numerous complications, including basilar invagination, atlantoaxial subluxation, Chiari malformation, congenital vertebral bodies fusion, and cord compression. As a result, vigilant identification and accurate reporting of atlanto-occipital assimilation are essential. The purpose of this review article is to discuss the numerous complications and associations of atlanto-occipital assimilation, such that an accurate diagnosis could be made for this commonly missed pathology.

Atlanto-occipital Assimilation with Basilar Invagination and Atlanto-occipital Dislocation Treated by Occipitocervical Fixation: A Rare Case Report.

Introduction: Atlanto-occipital assimilation is the most common osseous anomaly of the cervical-occipital junction. The incidence rate of occipitalization has been reported 1.42.5/1000 children. Most of the patients are asymptomatic initially. Clinical features usually appear after 3rd decade depending on the level and degree of spinal cord compression with surrounding vital structures such as vertebral artery involvement. Hence, early definitive diagnosis and subsequent successful treatment are necessary in such cases to prevent life-threatening complications. Case Report: A 16-year-old male presented with neck pain and progressive weakness of the bilateral lower limb since the past 2 months suffering from difficulty in walking, giddiness, and numbness of his fingertips. Hoffman's sign was positive. Plain cervical spine radiography (AP and lateral) is falsely suggestive of the absence of an atlas. MRI revealed the tip of the dens projecting 1314 mm above the Chamberlains line suggestive of basilar invagination. Occipito-cervical fixation was planned with an occipital plate, laminar, pedicle screw, and rods. Occipital plate fixed with screws (6,8 mm). C2 vertebra fixation with pedicle screw and laminar screws and C3 vertebra with a lateral mass screw under C-arm guidance. The patient mobilized with a walker from post-operative day 2 and then he ambulated unaided. Conclusion: Different types of atlanto-occipital assimilation have been reported. Treatment modality completely depends on neurological symptoms and instability.Although, different surgical options are available, occipito-cervical fixation with occipital plate, screws, and rod fixation is the most superior surgical technique for atlanto-occipital assimilation with atlanto-occipital instability.

Intraoperative discovery of a radiographically occult subependymoma obstructing the obex in a patient with a Chiari malformation - A rare case.

Background: Chiari (type I) malformations are typically congenital. Occasionally, however, tonsillar herniation can arise secondary to cerebrospinal fluid leakage, posterior fossa or intraventricular mass lesions, or other etiologies. We present the first-ever case of an intramedullary subependymoma at the cervicomedullary junction associated with vertebral bone abnormalities and an acquired secondary Chiari malformation. Case Description: A 60-year-old woman presented with a 3-year history of occipital, tussive headaches. Preoperative imaging was negative for mass lesions but demonstrated a Chiari malformation. She was recommended posterior fossa decompression with tonsillar shrinkage. During surgery, an intramedullary mass was incidentally observed, obstructing the obex at the cervicomedullary junction. Histopathological analysis of the resected lesion revealed a diagnosis of subependymoma. Conclusion: Subependymomas can sometimes present a diagnostic challenge due to their subtle appearance in neuroimaging. Only rarely are such masses associated with an acquired Chiari malformation. No such case has previously been reported. We present a literature review on acquired Chiari malformations and discuss their management.

Traumatic posterior dislocation of atlanto-axial joint with anterior arch fracture in the patient of atlanto-occipital assimilation: A case report.

INTRODUCTION AND IMPORTANCE: Traumatic atlanto-axial dislocation (AAD) is relatively uncommon and can pose life-threatening risks. In this case, we describe a patient with a combination of AAD, an anterior arch fracture of the atlas, and a rare congenital anomaly known as atlanto-occipital assimilation (AOA). CASE PRESENTATION: A 70-year-old man presented with posterior neck pain and right-sided torticollis following an accident that collision with a car while riding an electric scooter. Radiographic findings confirmed posterior AAD with anterior arch fracture of C1 in the inherent setting of AOA. The patient showed no neurologic deficit, so a closed reduction technique using Gardner-Wells tongs was attempted in an awakened state, and successful reduction could achieve without a neurologic deficit. After about three months of rigid brace application, head and neck motion was allowed, and no recurrence of dislocation or cervical pain occurred during the follow-up period of about one year. CLINICAL DISCUSSION: Because the posterior AAD is usually accompanied by anterior arch fracture of atlas, the transverse atlantal ligament remained intact. So nonoperative management after manual reduction was possible. The presence of a C1 anterior arch fracture observed in our case can be regarded as an indicator predicting the success of closed reduction of AAD. CONCLUSION: Our case highlighted the successful nonoperative management of traumatic posterior AAD with an accompanying anterior arch fracture of the atlas in a peculiar inherent combination of AOA through the closed reduction technique and rigid cervical brace application.

Cervical Myelopathy Caused by Non-Rheumatic Retro-Odontoid Pseudotumor: An Investigation of Underlying Mechanisms and Optimal Surgical Strategy.

STUDY DESIGN: Retrospective case-control study. OBJECTIVE: This study aimed to identify the underlying pathologies of non-rheumatic retro-odontoid pseudotumors (NRPs), which would help establish an appropriate surgical strategy for myelopathy caused by NRP. METHODS: We identified 35 patients with myelopathy caused by NRP who underwent surgery between 2006 and 2017. An age- and sex-matched control group of 70 subjects was selected from patients with degenerative cervical myelopathy. Radiographic risk factors for NRP were compared between cases and controls. We also assessed surgical outcomes following occipital-cervical (O-C) fusion, atlantoaxial (C1-2) fusion, or C1 laminectomy. RESULTS: Patients with NRP had significantly lower C1 sagittal inner diameter, C2-7 range of motion (ROM), C2-7 Cobb angle, and C7 tilt, as well as significantly higher C1-2 ROM, atlantodental interval (ADI), and C1-2 to O-C7 ROM ratio. Multivariate regression analysis revealed that ADI, C2-7 ROM, and C7 tilt were independent risk factors for NRP. Neurological recovery and pseudotumor size reduction were comparable among surgical procedures, whereas post-operative cervical spine function was significantly lower in the O-C fusion group than in the other groups. CONCLUSION: Non-rheumatic retro-odontoid pseudotumor was associated with an increase in ADI, suggesting that spinal arthrodesis surgery is a reasonable strategy for NRP. C1-2 fusion is preferable over O-C fusion because of the high prevalence of ankylosis in the subaxial cervical spine. Given that 29% of patients with NRP have C1 hypoplasia, such cases can be treated by posterior decompression alone. Our study highlights the need to select appropriate surgical procedures based on the underlying pathology in each case.

Successful non-operative management for atlanto-occipital dislocation resulting in spinal cord contusion in a patient with atlanto-occipital assimilation and severe Chiari I malformation.

BACKGROUND: Atlanto-occipital dislocation (AOD) is a rare, highly morbid, and highly lethal injury that results from high-energy trauma and almost universally requires operative management for satisfactory outcomes. It can be difficult to identify the severity of injury at the time of presentation, and when diagnosis is delayed outcomes worsen significantly. Anatomic anomalies of the craniovertebral junction may further complicate its detection. When such anomalies are present either singly or in combination, they are known to cause space constraints which may increase the likelihood of spinal cord injury. Given that such anomalies and AOD are rare, few examples of patients with both are reported in the literature. Furthermore, it is not clear in what way patient management may be impacted in this context. CASE DESCRIPTION: We will present a unique case of an 18-year-old patient with traumatic AOD and an intact neurologic examination who was found to have atlanto-occipital assimilation (AOA), platybasia, basilar invagination, and severe Chiari I malformation, who was treated effectively with non-operative management. CONCLUSION: Our case demonstrates the successful application of a non-operative treatment strategy in a carefully selected patient with AOD in the context of AOA.

Cough Syncope, a Rare Presenting Symptom of Chiari I Malformation and Atlanto-Occipital Assimilation.

Chiari I malformation and atlanto-occipital assimilation are both fairly uncommon conditions. Symptoms usually present during adolescence or adulthood, typically consisting of headache or neck pain. Cough-associated syncope is an unusual presenting symptom. The diagnosis of this condition in a pulmonology department is even rarer. We report the case of a 62-year-old male referred to our pulmonology department due to complaints of cough-associated syncope. After several examinations, a pharyngeal CT scan incidentally showed low positioning of the cerebellar tonsils. Cerebral MRI confirmed the diagnosis of Chiari I malformation and atlanto-occipital assimilation and the patient was effectively treated with surgical decompression. LEARNING POINTS: Chiari I malformation (CMI) and atlanto-occipital assimilation are both fairly rare conditions. The prevalence of CMI is estimated to range between 1/1,000 to 1/5,000 individuals and the incidence of atlanto-occipital assimilation varies from 0.08 to 3.6%.The most frequent clinical presentation is a paroxysmal headache or neck pain. Cough syncope is an unusual form of presentation, described in few cases.It is important to bear CMI in mind in the differential diagnosis of cough syncope, since there is an effective treatment that improves the patient's symptoms and quality of life.

Chiari I malformation associated with atlanto-occipital assimilation presenting as orthopnea and cough syncope: a case report and review of literature.

Although it is not uncommon for patients with Chiari I malformations to present with respiratory complaints, cough syncope is a rare presenting symptom. We report an adult patient who harbored both a Chiari I malformation and atlanto-occipital assimilation who complained of cough syncope, orthopnea, and central sleep apnea. The patient underwent decompressive craniectomy of the posterior fossa and cervical level 2 laminectomy. However, due to a possible initial underappreciation of the profound narrowing of the foramen magnum as a result of these concomitant pathologies, the patient may have had continued impaired cerebrospinal fluid flow, leading to a symptomatic pseudomeningocele and requiring a more extensive decompression that included a cervical level 3 laminectomy as well as a temporary lumbar drain. On 2-year follow-up, he has remained asymptomatic.

Chiari I malformation associated with atlanto-occipital assimilation presenting as orthopnea and cough syncope.

Although it is not uncommon for patients with Chiari I malformations to present with respiratory complaints, cough syncope is a rare presenting symptom. We report an adult patient who had both a Chiari I malformation and atlanto-occipital assimilation, and complained of cough syncope, orthopnea, and central sleep apnea. The patient underwent decompressive craniectomy of the posterior fossa and a cervical level 2 laminectomy. However, due to an initial under-appreciation of the profound narrowing of the foramen magnum as a result of these concomitant pathologies, the patient had continued impaired cerebrospinal fluid flow, leading to a symptomatic pseudomeningocele and required a more extensive decompression that included a cervical level 3 laminectomy as well as a temporary lumbar drain. On 2 year follow-up, he remained asymptomatic.

Morphological changes of the atlantoaxial facet joint and three-dimensional characteristics of atlantoaxial dislocation in patients with atlanto-occipital assimilation / 中华神经医学杂志

Objective To explore the morphological changes of the atlantoaxial facet joint and the three-dimensional characteristics of joint dislocation in patients with atlanto-occipital assimilation accompanied by atlantoaxial dislocation. Methods Thirty-six patients with atlanto-occipital assimilation and concurrent atlantoaxial dislocation underwent spiral CT scanning of the craniovertebral junction, and the imaging data in DICOM format were transferred to the three-dimensional visualization workstation to construct the three-dimensional model of the craniovertebral junction. The characteristics of atlantoaxial dislocation in association with the bony malformation were studied in the reconstructed model. Results Multiple anomalies of the atlantoaxiai facet joint were found in these patients, including joint dislocation involving 57 sides in the 36 patients, skeletal deformity in 61 sides, and facet separation in 11 sides. Three-dimensional classification identified 3 types of atlantoaxial dislocation in these patients, namely symmetrical type (14 cases, 39%) representing the approximately symmetrical joint dislocation and/or skeletal distortion, rotational type (13 cases, 36%) representing apparently asymmetrical joint dislocation and/or skeletal deformity, and separate type (9 cases, 25%) with separation of the joint facets. Conclusion In patients with atlanto-occipital assimilation, multiple factors including developmental anomaly, secondary skeletal deformity and ligament extension and fatigue interact as the fundamental causes ofatlantoaxial dislocation. The CT-based three-dimensional model of the craniovertebrai junction allows visualization of the atlantoaxial facet joint and atlantoaxial dislocation to provide important evidence for surgical planning and decision on the internal fixation approaches.

Atlanto-occipital Assimilation Associated with Basilar Invagination, C1-2 Instability, C2-3 Block Vertebra,and C3-4 Retrolisthesis : A Case Report / 대한정형외과학회잡지

Congenital atlanto-occipital assimilation is frequently accompanied by basilar invagination and C1-2 instability. Occipitocervical fusion is required if these conditions cause neurological symptoms. Recently posterior fusion using occipitocervical screw fixation in the extension position has been introduced for the simultaneous decompression of the cervicomedullary junction compressed by basilar invagination, a reduction of atlantoaxial subluxation, and rigid fixation. However, it is a technically demanding procedure, and there is no domestic report of an experience with this procedure. We report a case of a patient with C2-3 block vertebra and C3-4 retrolisthesis in addition to congenital atlanto-occipital assimilation, basilar invagination and C1-2 instability. The patient underwent posterior fusion using occipitocervical screw fixation in the extension position.

Atlanto-occipital Assimilation Can be Misdiagnosed as Atlantoaxial Dislocation: A Case Report

We present a rare case that atlanto-occipital assimilation can be misdiagnosed as C1-2 anterior subluxation. This is a lack of familiarity in orthopedic surgeon that was not used to manage the upper cervical spine injury. So the treatment of this entity need to get careful diagnosis and attention.