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Background: Biallelic mutations in the non-coding RNA gene RMRP cause Cartilage-hair hypoplasia (CHH), a rare skeletal dysplasia in which the main phenotypic characteristic is severe progressive growth retardation. Objective: This study compared the cranial dimensions of individuals with CHH to healthy subjects. Methods: Lateral skull radiographs of 17 patients with CHH (age range 10 to 59 years) and 34 healthy individuals (age range 10 to 54 years) were analyzed for relative position of the jaws to skull base, craniofacial height and depth, as well as vertical growth pattern of the lower jaw, anterior cranial base angle, and the relationship between the cervical spine and skull base. Results: We found that the length of the upper and lower jaws, and clivus were significantly decreased in patients with CHH as compared to the controls. Anterior cranial base angle was large in patients with CHH. Basilar invagination was not found. Conclusion: This study found no severe craniofacial involvement of patients with CHH, except for the short jaws. Unexpectedly, mandibular deficiency did not lead to skeletal class II malocclusion. Clinical Impact: Although the jaws were shorter in patients with CHH, they were proportional to each other. A short posterior cranial base was not associated with craniocervical junction pathology. [ABSTRACT FROM AUTHOR]

Objective To examine the morphological characteristics of the bone structure in the posterior cranial fossa in adult patients with Chiari malformation type Ⅰ (CMⅠ) without basilar invagination. Methods Thirty-eight adult patients with CMⅠ without basilar invagination treated in our department between January, 2018 and June, 2020 were enrolled in this study as the observation group, and 38 gender- and age-matched healthy adults served as the control group. The differences in the linear and angular variables in the posterior cranial fossa were analyzed between the 2 groups based on thin-slice CT data. Results Compared with the control subjects, the patients with CMⅠ showed significantly decreased clivus length (P < 0.001), supra-occipital length (P < 0.01), occipital length (P < 0.01), Klaus height index (P < 0.001), posterior compressive value (P < 0.01), tentorial angle (P < 0.05) and sagittal area of the bony posterior cranial fossa (P < 0.001) and significantly increased odontoid compressive value (P < 0.01), odontoid and soft tissue compressive value (P < 0.01), anterior compressive value (P < 0.01) and basal angle (P < 0.01). Conclusion In adult patients with CMⅠ patients but without basilar invagination, the clivus and occipital bone are shortened and elevated with co-existing ventral cervicomedullary compression by the posterior margin of the odontoid process.

Abstract Background The revision surgery of basilar invagination (BI) with irreducible atlantoaxial dislocation (IAAD) after a previous occipitocervical fusion (OCF) is challenging. Transoral revision surgery has more advantages than a combined anterior and posterior approach in addressing this pathology. The C-JAWS is a cervical compressive staple that has been used in the lower cervical spine with many advantages. Up to now, there is no report on the application of C-JAWS in the atlantoaxial joint. We therefore present this report to investigate the clinical outcomes of transoral intraarticular cage distraction and C-JAWS fixation for revision of BI with IAAD. Methods From June 2011 to June 2015, 9 patients with BI and IAAD were revised by this technique after previous posterior OCF in our department. Plain cervical radiographs, computed tomographic scans and magnetic resonance imaging were obtained pre- and postoperatively to assess the degree of atlantoaxial dislocation and compression of the cervical cord. The Japanese Orthopedic Association (JOA) score was used to evaluate the neurological function. Results The revision surgeries were successfully performed in all patients. The average follow-up duration was 18.9 ± 7.3 months (range 9–30 months). The postoperative atlas-dens interval (ADI), cervicomedullary angle (CMA), distance between the top of the odontoid process and the Chamberlain line (CL) and JOA score were significantly improved in all patients (P

Abstract Background Although the single-stage posterior realignment craniovertebral junction (CVJ) surgery could treat most of the basilar invagination (BI) and atlantoaxial dislocation (AAD), there are still some cases with incomplete decompression of the spinal cord, which remains a technique challenging situation. Methods Eleven patients were included with remained myelopathic symptoms after posterior correction due to incomplete decompression of the spinal cord. Transoral odontoidectomy assisted by image-guided navigation and intraoperative CT was performed. Clinical assessment and image measurements were performed preoperatively and at the most recent follow-up. Results Eleven patients were followed up for an average of 47 months. Symptoms were alleviated in 10 of 11 patients (90.9%). One patient died of an unknown reason 1 week after the transoral approach. The clinical and radiological parameters pre- and postoperatively were reported. Conclusion Transoral odontoidectomy as a salvage surgery is safe and effective for properly selected BI and AAD patients after inadequate indirect decompression from posterior distraction and fixation. Image-guided navigation and intraoperative CT can provide precise information and accurate localization during operation, thus enabling complete resection of the odontoid process and decompression of the spinal cord.

Craniovertebral junction (CVJ) deformity is a challenging pathology that can result in progressive deformity, myelopathy, severe neck pain, and functional disability, such as difficulty swallowing. Surgical management of CVJ deformity is complex for anatomical reasons; given the discreet relationships involved in the surrounding neurovascular structures and intricate biochemical issues, access to this region is relatively difficult. Evaluation of the reducibility, CVJ alignment, and direction of the mechanical compression may determine surgical strategy. If CVJ deformity is reducible, posterior in situ fixation may be a viable solution. If the deformity is rigid and the C1–2 facet is fixed, osteotomy may be necessary to make the C1–2 facet joint reducible. C1–2 facet release with vertical reduction technique could be useful, especially when the C1–2 facet joint is the primary pathology of CVJ kyphotic deformity or basilar invagination. The indications for transoral surgery are becoming as narrow as a treatment for CVJ deformity. In this article, we will discuss CVJ alignment and various strategies for the management of CVJ deformity and possible ways to prevent complications and improve surgical outcomes.

INTRODUCTION: To evaluate craniometric measurements and accompanying additional pathologies in cases with basilar invagination on radiological imaging. METHODS: Between January 2010 and April 2020, cervical CT, cervical MRI and brain MRI with 18,190 examinations were analyzed retrospectively. If the extension of the odontoid to the cranial using the Chamberlain line was greater than 5 mm, that was called basilar invagination. The association of pathologies such as platybasia, Chiari malformation, Klippel-Feil Syndrome and occipital bone dysplasia in cases with basilar invagination were investigated. Frequency of detection of basilar invagination on radiological images and demographic data of the cases were examined. Welcher's basal angle measurements were made with the modified basal angle for the platybasia. RESULTS: Basilar invagination was detected in 64 cases, more frequently in women (73.44%). The incidence of basilar invagination on radiological examinations was 0.35%. The average age of cases with basilar invagination was 37.09 +- 14.23 (age range 7 - 64). The distance to reach the Chamberlain line cranial axis of the dens axis was measured as 10.61 +- 5.02 mm. Modified basal angle mean was 123.77 +- 6.76 degrees, and Welcher's basal angle mean was 138.79 +- 7.06 degrees in cases with basilar invagination. The most common finding accompanying basilar invagination was the platybasia (89.06%), followed by Chiari type 1 malformation, Klippel-Feil syndrome, and atlantooccipital assimilation, respectively. Only 22.8% of the cases detected with a modified basal angle measurement were able to detect the presence of Welcher's basal angle measurement. DISCUSSION AND CONCLUSION: Although basilar invagination is a rare craniocervical junction pathology, it may be associated with other pathologies such as platybasia and Chiari type 1 malformation.

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.

Background: Relationship of atlantoaxial instability with Chiari formation is further analyzed in the report. Objective: The outcome of 25 patients who had failed conventional treatment for Chiari formation that included foramen magnum decompression surgery and were treated by atlantoaxial fixation is analyzed. Materials and Methods: During the period January 2010 to November 2019, we treated 25 patients who had undergone conventionally described surgical procedures; all included foramen magnum decompression for Chiari formation. None of the patients had any craniovertebral junction anomaly. All patients had syringomyelia. All patients had worsened in their neurological condition following surgery either in the immediate or in the delayed postoperative phase. Atlantoaxial instability was diagnosed on the basis of facetal alignment and on the basis of direct observation of joint status by bone manipulation during surgery. The patients were treated by atlantoaxial fixation. Goel clinical grading scale and Japanese Orthopedic Association Score assessed the clinical status both before and after surgery. Results: Following surgery, all patients improved in the clinical condition. The improvement began in the immediate postoperative period and progressed. During the follow-up period that ranged from 4 to 123 months, “significant” neurological recovery and amelioration of presenting symptoms were observed. During the period of follow-up, reduction in the size of syrinx was observed in 14 out of 18 cases where postoperative magnetic resonance imaging was possible. Conclusions: Clinical results reinforce the belief that atlantoaxial instability is the nodal point of pathogenesis of Chiari formation. Atlantoaxial fixation is the treatment.

Introduction: The prevalence of Chiari malformation type I (CM-I) has been estimated as up to 1% of the general population. The majority of patients are asymptomatic and usually do not need treatment. Symptomatic patients, and some asymptomatic patients with associated conditions, may benefit from further assessment and treatment. Research question: The aim of this review was to describe the clinical and radiological assessment of patients presenting with a CM-I. Material and methods: A literature search was performed using the PubMed and Embase databases focused on clinical assessment and imaging techniques used to diagnose CM-I. Results: Following a complete clinical evaluation in patients with symptomatic CM-I and/or radiologically significant CM-I (tonsillar impaction, resulting tonsillar asymmetry and loss of CSF spaces), MRI of the brain and whole spine enables an assessment of the CM-I and potential associated or causative conditions. These include hydrocephalus, syringomyelia, spinal dysraphism, and tethered cord. Flow and Cine MRI can provide information on CSF dynamics at the craniocervical junction, and help in surgical decision-making. Hypermobility or instability at the upper cervical and craniocervical junction is less common and can be measured with CT imaging and flexion/extension or upright MRI. Discussion and conclusion: The majority of CM-I detected are incidental findings on MRI imaging of brain or spine, and do not require intervention. Once a radiological diagnosis and concern has been raised, clinical assessment by an appropriate specialist is required. A MRI brain and cervical spine is indicated in all radiologically labelled CM-I. In symptomatic patients or cases of radiologically significant CM-I, MRI of the brain and entire spine is indicated. Further investigations should be tailored to individuals’ needs.

BackgroundBiallelic mutations in the non-coding RNA gene RMRP cause Cartilage-hair hypoplasia (CHH), a rare skeletal dysplasia in which the main phenotypic characteristic is severe progressive growth retardation.ObjectiveThis study compared the cranial dimensions of individuals with CHH to healthy subjects.MethodsLateral skull radiographs of 17 patients with CHH (age range 10 to 59 years) and 34 healthy individuals (age range 10 to 54 years) were analyzed for relative position of the jaws to skull base, craniofacial height and depth, as well as vertical growth pattern of the lower jaw, anterior cranial base angle, and the relationship between the cervical spine and skull base.ResultsWe found that the length of the upper and lower jaws, and clivus were significantly decreased in patients with CHH as compared to the controls. Anterior cranial base angle was large in patients with CHH. Basilar invagination was not found.ConclusionThis study found no severe craniofacial involvement of patients with CHH, except for the short jaws. Unexpectedly, mandibular deficiency did not lead to skeletal class II malocclusion.Clinical ImpactAlthough the jaws were shorter in patients with CHH, they were proportional to each other. A short posterior cranial base was not associated with craniocervical junction pathology.

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., (Copyright © 2024 Elsevier Inc. All rights reserved.)

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., Competing Interests: Human subjects: Consent was obtained or waived by all participants in this study. Conflicts of interest: In compliance with the ICMJE uniform disclosure form, all authors declare the following: Payment/services info: All authors have declared that no financial support was received from any organization for the submitted work. Financial relationships: All authors have declared that they have no financial relationships at present or within the previous three years with any organizations that might have an interest in the submitted work. Other relationships: All authors have declared that there are no other relationships or activities that could appear to have influenced the submitted work., (Copyright © 2024, Kumari et al.)

Objective: To describe the feasibility, safety and efficacy of mobilization of the vertebral artery for C2 pedicle screws in cases with the high-riding vertebral artery (HRVA).
., Methods: During the period January 2020 to September 2022, fifteen patients underwent posterior occipitocervical fixation in our department. All patients had unilateral HRVA on at least one side that prohibited the insertion of C2 pedicle screws. There were 2 males and 13 females aged 47 ± 11.9 years (range: 17-64 years). After the correction of the vertical dislocation during the operation, the C2 pedicle screw insertion and occipitocervical fixation and fusion were performed using the vertebral artery mobilization technique. A routine three-dimensional reconstructed CT examination was executed to confirm the trajectory of C2 pedicle screws post-operation, and a CT angiography examination was performed when necessary. Neurological function was assessed using the Japanese Orthopedic Association (JOA) scale. The preoperative and postoperative JOA score and the main radiological measurements, including anterior atlantodental interval (ADI), the distance of odontoid tip above Chamberlain line, and clivus-canal angle (CCA), were collected and compared by paired t -test., Results: All 15 patients had atlas assimilation, among which 12 patients had C2-C3 fusion (Klippel-Feil syndrome). Mobilization of the HRVA was successfully completed, and C2 pedicle screws were then fulfilled after the vertebral artery was protected. There was no injury to the vertebral artery during the operation. Meanwhile, no severe surgical complications such as cerebral infarction or aggravated neurological dysfunction occurred during the perioperative period. Satisfactory C2 pedicle screw placement and reduction were reached in all 15 patients. All the patients achieved bone fusion 6 months after surgery. No looseness and shift of internal fixation or reduction loss was observed during the follow-up period. Compared to the preoperative, the postoperative JOA score and the main radiological measurements were remarkably improved and statistically significant., Conclusions: C2 pedicle screw insertion assisted by mobilization of the vertebral artery is safe and considerably effective, providing a choice for internal fixation in cases with high-riding vertebral arteries., Competing Interests: The authors declare that they have no conflict of interest., (© 2024 The Authors.)

Atlantoaxial fixation rather than any form of decompressive surgery is necessary and optimal form of surgical treatment (give that image of craniovertebral junction osteophytes/bone formation at spinal ligament). J Neurosurg Spine 2013;19:672-7. 18 Goel A. "Only fixation" as rationale treatment for spinal canal stenosis. [Extracted from the article]

Study Design: Retrospective study.Objective: To evaluate the morphologic features of the subaixal cervical spine in patients with basilar invagination (BI) and provide information for the accurate screw placement in this region.Summary Of Background Data: BI is a congenital anomaly, comprising a wide range of abnormal structures. The screw fixation can be required in situation that BI is combined with subaxial cervical spine pathologies. However, there are no literatures specifically addressed the subaxial cervical morphology of BI.Method: A total of 42 BI patients were included in this retrospective study. Forty-two patients without head or cervical disease were matched for sexes and ages. Information on radiographic features of the subaxial cervical spine was collected and compared systematically.Results: There were no differences in the age and sex between the BI and control group. The BI group manifested a wider pedicle and laminar than the control group at all cervical levels, except for the pedicle of C6 and C7, and the laminar of C3 and C6. In addition, the BI group had a wider lateral mass from C3 to C5 than the control group. There were no differences in most measurements of the length of pedicle, laminar, and lateral mass.Conclusion: BI patients have a wider pedicle and laminar than the general population in the subaxial cervical spine, but the same size in length of pedicle, laminar, and lateral mass.Level of Evidence: 4. [ABSTRACT FROM AUTHOR]

Background: Basilar invagination (BI) is a complex condition characterized by prolapse of the odontoid into the brain stem/upper cervical cord. This lesion is often associated with Chiari malformations, and rheumatoid arthritis (RA). Treatment options for BI typically include cervical traction, an isolated anterior transoral odontoidectomy, anterior endonasal odontoidectomy, an isolated posterior fusion, or combined anterior/posterior surgical approach. Case Description: A 45-year-old female with a Chiari I malformation and RA underwent a combined posterior C0-C5 posterior decompression/fusion, followed by an anterior odontoidectomy (i.e. endoscopic/endonasal under neuronavigation). Postoperatively, the patient's symptoms and neurological signs resolved. Conclusion: BI in was successfully managed with a combined posterior C0-C5 decompression/fusion followed by an anterior endoscopic/endonasal odontoidectomy performed under neuronavigation. [ABSTRACT FROM AUTHOR]

A review of related publications in the literature suggests that cervical spinal degeneration has more often been identified and surgically treated in the lower cervical spine, less frequently in the upper cervical spine, and only rarely in the craniovertebral junction. Symptoms are "longstanding" and secondary alterations in the craniovertebral junction and subaxial cervical spine can be prominent. J Craniovertebr Junction Spine 2017;8:88-90. 6 Goel A, Dandpat S, Shah A, Rai S, Vutha R. Muscle weakness-related spinal instability is the cause of cervical spinal degeneration and spinal stabilization is the treatment: An experience with 215 cases surgically treated over 7 years. [Extracted from the article]

Introduction: Craniovertebral junction is the “zone of transition” between the skull and cervical spine so its detailed discussion is lacking in so many standard textbooks addressing these regions. These anomalies are especially common in the Indian subcontinent. Accurate diagnosis, probable aetiology and pre-treatment evaluation considerably affect the prognosis of patients. The aim of this study was to classify various Craniovertebral junction disorders according to their aetiology and to correlate the imaging findings with the clinical profile of the patients and histopathology whenever possible. Methods: This prospective observational study was done in our department over the period of one year from August 2016 to July 2017. 57 North Indian patients from all age groups and both sex, who had imaging features suggesting craniovertebral junction pathology were selected for the study. Results: Our study group comprised 34 males and 23 females with a male to female ratio of 1.47: 1. The most common age group was 11-20 years and the most common aetiology being developmental followed by infective, autoimmune and inflammatory disorders. Conclusions: CVJ abnormalities are a group of treatable neurological disorders, and are approached with much caution by clinicians. Thus, it is crucial that radiologists should be able to make a precise diagnosis, categorize them into etiological groups, and give precise anatomical information on MDCT and/or MRI, as this information ultimately helps determine the management of such abnormalities and their prognosis.

Objective: An abnormally decreased clivoaxial angle (CXA) is used during the clinical evaluation for corrective skull base surgery. Published normal ranges of CXA using x-ray, computed tomography, or magnetic resonance imaging (MRI) vary dramatically, especially with neck flexion or extension. The aim of this study was to use high-resolution MRI to determine the normal range of CXA in various neck positions using a reproducible measurement technique. Methods: The CXA was measured in 10 healthy volunteers on sagittal T2 SPACE c-spine MRI in supine and prone positions and with the neck both neck and extended. CXA is strictly defined as the angle between a line along the inferior third of the dorsal clival cortex and a line from the superior/posterior cortex of the dens to the posterior/inferior corner of the C2 body. Statistical analysis was performed in all positions and included mean CXA, range, standard deviation (SD), inter-reader agreement, and group comparisons. Results: The mean CXA overall was 156.92° (SD =4.23°; range 134–179°). The mean value for extension CXA was 169.20° (SD =5.81°), and the mean value for flexion CXA was 144.73° (SD =5.71°), the difference being statistically significant (p <0.0001) regardless of supine or prone position. Concordant correlations of reader measurements showed substantial agreement in the supine position at 0.96, with lower agreement in the prone position at 0.87. Conclusions: We report normal ranges for CXA in various neck positions based on 3D T2-weighted MRI, using a reproducible measurement method. There was a significant difference in the CXA values between neck extended and neck flexed positions but not between supine and prone positions. [ABSTRACT FROM AUTHOR]

Atlas assimilation (AA) may be associated with atlantoaxial dislocation, Chiari malformation (CM), and basilar invagination. The importance of AA in the context of craniocervical junction (CVJ) anomalies is unclear. Considering this context, this study's objective is to discuss the role of AA in the management of CVJ anomalies, especially in CM. A comprehensive literature review was performed. In addition, some illustrative cases were discussed on the basis of our review. Finally, we propose a theoretic algorithm to evaluate patients with AA and CM. AA is a proatlas segmentation anomaly that may be complete or incomplete. It may be totally asymptomatic or symptomatic as the result of transferred shifted forces onto the C1-2 joints, leading to clear instability (atlantoaxial dislocation) or mild C1-2 instability. Cautious surgical planning may be required due to associated vertebral artery anomalies. AA with concomitant C2-C3 segmentation failure is highly associated with late C1-C2 instability. CVJ decompression failure was reported in patients with CM and a low clivus canal angle (<130−135 degrees). Patients with assimilated anterior C1 arches usually have evident AAD. CM patients with AA generally have type 1 BI or type 2 BI and are reported with higher rates of CVJ instabilities when compared with those "pure" CM. Dynamic examinations may provide additional evidence of atlantoaxial instability. Although AA per se is not considered an unstable configuration, further and detailed evaluations of patients with CM associated with AA are necessary. Some associated unstable configurations required concomitant CVJ fixation. [ABSTRACT FROM AUTHOR]

Severe stenotic aortic valve poses serious anesthetic challenges because of the fixed cardiac output and complex hemodynamics. The challenges magnify in the presence of a difficult airway which not only puts the airway at risk but also disturbs the hemodynamics, which can negatively impact the patient outcome. Moreover, prone positioning, intraoperative hemodynamics, recovery, and extubation are equally challenging for management. This case report highlights the perioperative management of a child with severe uncorrected aortic stenosis and Klippel–Feil syndrome posted for cervical spinal stabilization under anesthesia. [ABSTRACT FROM AUTHOR]

Background: Basilar invagination (BI) can be defined as the insinuation of the content of the craniovertebral junction through the foramen magnum toward the posterior fossa. BI is a prevalent condition in Northeast Brazil. The present study describes the changes in the clivus-canal angle (CCA) in the postoperative period in patients with symptomatic BI operated by a posterior approach, using a simple technique of indirect reduction of the odontoid associated with occipitocervical fixation. Methods: Patients underwent radiological evaluations by magnetic resonance imaging in the pre and postoperative periods, where the height of the odontoid tip was measured in relation to the Chamberlain line and the ACC. All patients underwent posterior occipitocervical fixation with specific maneuvers of distraction and extension of the cephalic segment with the aid of a head clamp with three fixation points for anterior reduction of the odontoid. Results: Among the 8 patients evaluated in the series, all had increased ACC in the postoperative period, with a mean of 14.81 ± 1.54°, and statistically significant difference between the pre and postoperative periods (P < 0.05). Conclusion: The indirect surgical reduction of the odontoid process by a posterior approach through the manipulation (distraction-extension) of a "Mayfield" type of head clamp followed by occipitocervical fixation proved to be effective in improving the ACC, being easily reproducible. [ABSTRACT FROM AUTHOR]

Introduction: Craniovertebral junction is the "zone of transition" between the skull and cervical spine so its detailed discussion is lacking in so many standard textbooks addressing these regions. These anomalies are especially common in the Indian subcontinent. Accurate diagnosis, probable aetiology and pre-treatment evaluation considerably affect the prognosis of patients. The aim of this study was to classify various Craniovertebral junction disorders according to their aetiology and to correlate the imaging findings with the clinical profile of the patients and histopathology whenever possible. Methods: This prospective observational study was done in our department over the period of one year from August 2016 to July 2017. 57 North Indian patients from all age groups and both sex, who had imaging features suggesting craniovertebral junction pathology were selected for the study. Results: Our study group comprised 34 males and 23 females with a male to female ratio of 1.47: 1. The most common age group was 11-20 years and the most common aetiology being developmental followed by infective, autoimmune and inflammatory disorders. Conclusions: CVJ abnormalities are a group of treatable neurological disorders, and are approached with much caution by clinicians. Thus, it is crucial that radiologists should be able to make a precise diagnosis, categorize them into etiological groups, and give precise anatomical information on MDCT and/or MRI, as this information ultimately helps determine the management of such abnormalities and their prognosis. [ABSTRACT FROM AUTHOR]

Purpose: To introduce a novel surgical protocol for safe and accurate placement of C1 lateral mass screws in patients with atlas assimilation, basilar invagination and atlantoaxial instability, and to categorize the screw accuracy and perioperative complications regarding this technique in a large case series. Methods: Between January 2015 and January 2020, patients who had atlas assimilation, basilar invagination and atlantoaxial instability, and underwent atlantoaxial fixation using C1 lateral mass screws were reviewed. C1 lateral mass screws were placed with a novel surgical protocol following a series key steps, including posterior para-odontoid ligament release, panoramic exposure of the invaginated lateral mass, and diligent protection of the abnormal VA. Screw accuracy and related complications were specifically evaluated. Results: A total of 434 C1 lateral mass screws were placed. Fifteen screws (3.5%) were classified as unacceptable, 54 screws (12.4%) were classified as acceptable, and 365 screws (84.1%) were classified as ideal. Overall, 96.5% of screws were deemed safe. There were no cases of vascular injury or permanent neurological defects. One patient with an unacceptable screw presented with hypoglossal nerve paralysis and recovered after an immediate revision surgery. Thirty-seven patients complained about occipital neuralgia and were successfully managed with medication. Conclusion: Placement of C1 lateral mass screws in patients with atlas assimilation, basilar invagination and atlantoaxial instability following this surgical protocol is safe and accurate. Thorough para-odontoid ligamental release, wide exposure of the invaginated lateral mass, and diligent protection of the vertebral artery are critical to maximize the chances of successful screw placement. [ABSTRACT FROM AUTHOR]

This article from Neurology India discusses a case of Arnold-Chiari Malformation 1.5 in a 29-year-old male patient. The patient presented with difficulty walking and unsteadiness, and upon examination, mild ataxia was observed. Magnetic resonance imaging (MRI) revealed herniation of the cerebellar tonsils below the level of the foramen magnum, along with displacement of the brainstem and fourth ventricle. The article explains that Chiari 1.5 refers to tonsillar herniation seen in Chiari 1 malformation, in addition to caudal displacement of the brainstem and fourth ventricle. The article emphasizes the importance of differentiating Chiari 1.5 from Chiari I malformation for appropriate treatment. [Extracted from the article]

Crania vertebral junction abnormalities such as at lantoaxial dislocation with or without basilar invagination with or without association chiari malformation may cause a high cervical myelopathy occasionally mechanical factor such as inadequate canal decompression torticollis and scoliosis may lead to lack of implement. A 30 years old male patient was admitted in the neuro ward with presenting complaint of weakness in right leg since 9 month, pain in neck region since 9 month, difficulty during walking and unable to climb stairs, tingling sensation in right hand since 9 month. After undergoing certain primary therapeutic investigation likeBlood investigation, MRI, x-ray, patientwas diagnosed with a Cranio Vertebral Function Anomaly. He was initially treated with antibiotics, penicillin, Analgesic, antacid, antiemetic, and intravenous fluid along with alternative therapies i.e. gropping exercises of upper limb, bed mobility training, bed side sitting, breathing exercise and dynamic quads. Patient showed progressive during hospitalization. [ABSTRACT FROM AUTHOR]

In the scenario of chronic, subtle or potential and less frequently manifest atlantoaxial instability, there are a number of secondary so-called "pathological" musculoskeletal, spinal structural, or neural alterations that include basilar invagination, Chiari formation, syringomyelia, Klippel-Feil alteration, assimilation of atlas, C2-3 fusion, os-odontoideum, bifid arch of atlas, platybasia, short neck, and torticollis.[[1]],[[2]],[[3]],[[4]],[[5]],[[6]],[[7]],[[8]],[[9]],[[10]],[[11]],[[12]] Whenever any of these radiologically identifiable alterations are present discretely or in the cohort, they are indicative of atlantoaxial instability and suggest the need for atlantoaxial stabilization. External syringomyelia - is it an evidence of focal spinal instability? World Neurosurg 2016;95:375-82. 4 Goel A, Sathe P, Shah A. Atlantoaxial fixation for basilar invagination without obvious atlantoaxial instability (Group B Basilar Invagination): Outcome analysis of 63 surgically treated cases. [Extracted from the article]

Background Data: Atlantoaxial fixation, unlike subaxial spine, is still challenging due to complex topographical anatomy. Nowadays, atlas lateral mass screws and transpedicular axis screws fixation is a well-accepted technique for the management of atlantoaxial instability due to their rigid fixation and higher fusion rate. However, in complex cases like basilar invagination, further reduction and proper bony alignment are needed. Study Design: A retrospective descriptive clinical case series. Objective: The aim of this study was to assess the safety and efficiency of bilateral posterior atlantoaxial facet joint distraction and insertion of spacer in reducing complex cases of atlantoaxial instability. Patients and Methods: Out of 17 patients with atlantoaxial instability, five patients underwent posterior fixation and atlantoaxial facet joint distraction and insertion of spacer for reduction of irreducible atlantoaxial dislocation. Clinical results were evaluated by using the criteria of Japanese Orthopaedic Association Scoring System for Cervical Myelopathy (JOA score). The surgical technique, results, and morbidity and mortality were assessed. Results: There were 3 females and 2 males; the age ranged from 10–50 years. The cause of significant instability was trauma (2 patients), while each of the 3 other patients suffered from Down syndrome, rheumatoid arthritis, and posttuberculous infection. All 5 patients had pyramidal tract compression manifestations. At the end of follow-up (mean 18 months), the average preoperative JOA score improved from 13.2±1 to 15.9±0.2 (P=0.04) and the average recovery rate was 69±12 % SD. Postoperative CT scans showed that the mean atlantodens interval improved from 6.2±1.6 to 1.8±0.8 (P=0.04) and the mean clivus-canal angle increased from 119.8±3.7° to 135.2±7°(P=0.04). The average extra time and blood loss of bilateral facet distraction and grafting were about 65 ml (P=0.004) and 72.5 ml, respectively. There was no mortality, vertebral artery injury, CSF leak, or construct failure. Conclusions: Bilateral posterior atlantoaxial facet joint distraction and placement of spacer is a safe and effective adjunct procedure for reduction of complex atlantoaxial instability. (2019ESJ184)

Objective Endoscopic approaches to the craniovertebral junction (CVJ) have been established as viable and effective surgical treatments in the past decade. One of the major complications is leakage of the cerebrospinal fluid (CSF). This study aimed to investigate the efficacy and feasibility of suture closure at the nasopharyngeal mucosa upon durotomy. Methods A series of consecutive patients who underwent different endoscopic approaches to the CVJ were retrospectively reviewed. The pathologies, surgical corridors, neurological and functional outcomes, radiological evaluations, and complications were analyzed. Different strategies of repair for the intraoperative CSF leakage were described and compared. Results A total of 22 patients covering 13 years were analyzed. There were 12, 2, and 8 patients who underwent transnasal, transoral, and combined approaches, respectively. There were 8 patients (36.4%) who experienced intraoperative CSF leakage, and were grouped into 2: 4 in the nonsuture (NS) group and 4 in the suture-repaired (SR) group. The NS group had 3 (75%) persistent CSF leakages postoperation that caused 1 mortality, whereas patients of the SR group had only 1 minor CSF rhinorrhea that healed spontaneously within days. Conclusion In this series of 22 patients who required anterior endoscopic resection of pathologies at the CVJ, there was 1 (4.5%) serious complication related to CSF leakage. For patients who had no durotomy, the mucosal incision at the nasopharynx usually healed rapidly and there were few procedure-related complications. For patients with intraoperative CSF leakage, suture closure was technically challenging but could significantly lower the risks of postoperative complications.

Objective The technique of distraction, compression, extension, and reduction (DCER) is effective to reduce, realign, and relieve cranio-spinal compression through posterior only approach. Methods Study included all patients with atlantoaxial dislocation and basilar invagination (BI) with occipitalized C1 arch. Study techniques included Nurick grading, computed tomography scan to study atlanto-dental interval, BI, hyper-lordosis, and neck tilt. Sagittal inclination (SI), coronal inclination (CI), cranio-cervical tilt, presence of pseudo-joints, and anomalous vertebral artery were also noted. Patients underwent DCER with/without joint remodeling or extra-articular distraction (EAD) based on the SI being 160° respectively. In cases with pseudo-joints, joint remodeling was performed in type I and EAD in type II. Customized ‘bullet shaped’ PSC spacers (n=124) and prototype of the universal craniovertebral junction reducer (UCVJR, n=36) were useful. Results A total of 148 patients with average age 27.25±17.43 years, ranging from 3 to 71 years (87 males) were operated. Nurick’s grading improved from 3.14±1.872 to 1.22±1.17 (p

The author discusses the novel form of central or axial atlantoaxial instability and analyses its clinical significance. High degree of clinical and radiological understanding of the region is mandatory to diagnose and then treat such atlantoaxial instability. Evaluation of alignment of facets of atlas and axis and observations on direct manipulation of facets of atlas and axis forms the basis of diagnosis. The treatment of clinical entities like basilar invagination, Chiari formation, syringomyelia and myelopathy related to cervical spinal degeneration, spinal deformities, ossified posterior longitudinal ligament, and Hirayama disease can be influenced by the understanding of central or axial atlantoaxial instability.

Objective Surgery is indicated for basilar invagination (BI) in symptomatic patients. In many patients, symptoms and signs occur due to an upward-migrated and malaligned odontoid with fixed or mobile atlantoaxial instability. Posterior distraction and fixation of the atlantoaxial joints has evolved to become the standard of care, but has some inherent morbidity. In this study, we propose that the unilateral anterior submandibular retropharyngeal approach with customized wedge-shaped titanium cages inserted into both atlantoaxial joints and anterior atlantoaxial fixation with a plate screw construct is a safer and easier option in many cases of BI. Methods From February 2014 to February 2019, 52 patients (age range, 15–78 years; 40 males and 12 females) with symptomatic BI with atlantoaxial dislocation and minimal sagittal facetal inclination and only mild Chiari malformation without syringomyelia were offered anterior submandibular retropharyngeal atlantoaxial distraction and fixation surgery. Results Neurological improvement occurred in 80% of patients, while the neurological status of 20% remained unchanged. No patients worsened, and no major complications or mortality was observed. Conclusion In properly selected cases of symptomatic BI, anterior wedge cage distraction with anterior atlantoaxial fixation is a safe and simple option.

Chiari I malformation is characterized by the downward displacement of cerebellar tonsils through the foramen magnum. While discussing the treatment options for Chiari I malformation, the points of focus include: (1) Has the well-established procedure of posterior fossa decompression become outdated and has been replaced by posterior C1–2 stabilization in every case? (2) In case posterior stabilization is required, should a C1–2 stabilization, rather than an occipitocervical fusion, be the only procedure recommended? The review of literature revealed that when there is bony instability like atlantoaxial dislocation (AAD), occipito-atlanto-axial facet joint asymmetry or basilar invagination (BI) associated with Chiari I malformation, one should address the anterior bony compression as well as perform stabilization. This takes care of the compromised canal at the foramen magnum and re-establishes the cerebrospinal fluid flow along the craniospinal axis; and also provides treatment for CVJ instability. In the cases with a pure Chiari I malformation without AAD or BI and with completely symmetrical C1–2 joints, however, posterior fossa decompression with or without duroplasty is sufficient to bring about neurological improvement. The latter subset of cases with pure Chiari I malformation have, thus, shown significant (>70%) rates of neurological improvement with posterior fossa decompression alone. A C1–2 posterior stabilization is a more stable construct due to the strong bony purchase provided by the C1–2 lateral masses and the short lever arm of the construct. However, in the cases with significant bleeding from paravertebral venous plexus; a very high BI, condylar hypoplasia and occipitalized atlas; gross C1–2 rotation or vertical C1–2 joints with unilateral C1 or C2 facet hypoplasia, as well as the presence of subaxial scoliosis; maldevelopment of the lateral masses and facet joints (as in very young patients); or, the artery lying just posterior to the C1–2 facet joint capsule (being endangered by the C1–2 stabilization procedure), it may be safer to perform an occipitocervical rather than a C1–2 fusion.

Rotatory atlantoaxial instability can manifest as an acute episode following subtle or minor injury or even following a gentle tap on head in young children and can manifest as a painless deformity of the head. Goel technique of direct surgical opening of the atlantoaxial facet joint, manual manipulation of the facets can lead to reduction of rotatory atlantoaxial dislocation and recovery from torticollis. Torticollis can be a protective natural phenomenon in response to atlantoaxial instability and related basilar invagination. Only atlantoaxial fixation can lead to immediate postoperative reduction of torticollis. Spasmodic torticollis related to muscle hyperactivity is unrelated to atlantoaxial instability.

The author reviews the various types of cervical fusion that are associated with instability of the craniovertebral junction. Assimilation of the atlas, C2–3 fusion, the Klippel-Feil abnormality, and pancervical fusion are amongst the more common types of bone abnormalities. It is conceptualised that these types of cervical fusion are not related to any kind of embryological dysgenesis or fault, but instead emerge due to longstanding muscle spasms of the neck in response to atlantoaxial instability. Such bone fusions could be secondary protective responses to longstanding atlantoaxial instability.

Amyotrophic lateral sclerosis (ALS) is characterized by progressive onset motor deficits with heterogenous presentations ranging from dysarthria to foot drop. Approximately 20% of the patients present with focal bulbar symptoms, in which some may remain restricted to bulbar region (isolated bulbar palsy), and the remaining eventually spreads to involve other body regions (classical ALS). Without accompanying upper and lower motor neurons signs elsewhere, differential diagnoses for isolated bulbar symptoms are extensive, include ALS variants as well as potentially treatable mimics. Therefore, it is important to take heed on every possible aetiology that may disrupt the hypoglossal nucleus, nerve, or lingual muscle itself. Herein, we illustrated a rare presentation of Group A basilar invagination, which mimicked bulbar-onset ALS.

Objectives: Craniovertebral junction (CVJ) abnormalities constitute a group of treatable neurological disorders, especially in the Indian subcontinent. Thus, it is essential that clinicians should be able to make a precise diagnosis of abnormalities and rule out important mimickers on multidetector computed tomography (MDCT) as this information ultimately helps determine the management, prognosis, and quality of life of patients. CVJ is the most complex part of the cervical region. Congenital malformations of this region can cause serious neurological deficit and require a surgical intervention. The present study was undertaken to know the embryological basis of the CVJ and to identify commonly observed congenital CVJ abnormalities, their frequency, and mode of presentation. Materials and Methods: Diagnosed cases of CVJ anomalies on dynamic MDCT head were reviewed at a tertiary care center between January 2014 to December 2019. Type of anomaly, clinical presentation, and associated malformations were recorded. Different types of variations were expressed in terms of percentage. Results: Congenital anomalies were seen in 42 cases. Fifteen types of anomalies were detected. Anomalies were either singly or in combination. The CVJ anomalies were more common in young adults (28%), almost equal in both sexes. The most common anomaly was basilar invagination (52.3%), followed by atlanto-occipital assimilation (33.3%), and Arnold-Chiari malformation is the most common soft tissue anomaly. In fourteen cases, additional anomalies of other vertebrae were present. The most common symptoms were weakness of extremities, neck pain, paresthesia, torticollis, and gait disturbances. About 28 patients got improved, 8 patients had residual deficit as that of preoperative status, and 4 patients got deteriorated after surgery, at 1-month follow-up. About 34 patients had improved, 5 remained static, and 3 patients got worsened at the end of 3-month follow-up. About 37 patients had improved, 4 patients remained static, and 2 patients got deteriorated at 6 months of follow-up. The patients with increased atlantodens interval 3-5 mm showed 77% improvement after surgery. Conclusion: Congenital CVJ anomalies, though rare, are fatal. CVJ abnormalities constitute an important group of treatable neurological disorders with diagnostic dilemma. The atlantodental interval is the most important preoperative prognostic marker. Dynamic CT imaging can provide additional useful information to the diagnosis of CVJ instability. To prevent long-term neurological problems, early diagnosis and treatment of congenital bony CVJ anomalies is important. [ABSTRACT FROM AUTHOR]

Objective: The conventional criteria for defining the basilar invagination (BI) focus on the relationship of odontoid tip to basion and opisthion, landmarks that are intrinsically variable especially in presence of occipitalised atlas. A universal single reference line is proposed that helps in unequivocally establishing the diagnosis of BI, may be relevant in establishing both Goel types A and B BI, as well as in differentiating a 'very high' from 'regular' BI. Methods: Study design - case-control study. In 268 patients (group I with BI [n = 89] including Goel type A BI [n = 66], Goel type B BI [n = 23], and group II controls [n = 179]), the perpendicular distance between odontoid tip and line subtended between posterior tip of hard palate-internal occipital protuberance (P-IOP line) was measured. Logistic regression analysis determined factors influencing the proposed parameter (p < 0.05). Results: In patients with a 'very high' BI (n = 5), the odontoid tip intersected/or was above the P-IOP line. In patients with a 'regular' BI (n = 84), the odontoid tip was 6.56 ± 3.9mm below the P-IOP line; while in controls, this distance was 12.53 ± 4.28 mm (p < 0.01). In Goel type A BI, the distance was 7.01 ± 3.78 mm and in type B BI, it was 5.07 ± 4.19 mm (p = 0.004). Receiver-operating characteristic curve analysis identified 9.0 mm (8.92-9.15 mm) as the cut-point for diagnosing BI using the odontoid tip-P-IOP line distance as reference. Conclusion: The odontoid tip either intersecting the P-IOP line (very high BI) or being < 9 mm below the P-IOP line (Goel types A and B BI) is recommended as highly applicable criteria to establish the diagnosis of BI. This parameter may be useful in establishing the diagnosis in all varieties of BI. [ABSTRACT FROM AUTHOR]

The article discusses the concept of central or axial atlantoaxial instability (CAAD) and its diagnosis using dynamic imaging. CAAD is characterized by musculoskeletal and neural alterations, which can include basilar invagination, Chiari formation, syringomyelia, and other conditions. The authors propose that these alterations are adaptive or protective in nature and can potentially be reversed with atlantoaxial stabilization. The article also classifies different types of atlantoaxial facetal instability and highlights the utility of dynamic imaging in diagnosing and confirming atlantoaxial instability. The authors suggest that dynamic imaging can be a valuable tool in cases where conventional parameters fail to detect instability. [Extracted from the article]

Malformations in the craniocervical junction (CCJ) are rare in the pediatric population but often need surgical treatment. We present a pediatric case series of patients treated with a 2-stage surgical approach with a halo vest and occipitocervical fusion and review complications and outcomes. A retrospective analysis of a single-center case series was performed. Pediatric patients affected by congenital craniocervical junction anomalies and treated with a 2-stage approach were included. A halo vest was implanted in the first surgery, and ambulatory progressive reduction was performed. When a favorable anatomic situation was observed, arthrodesis was performed. Safety analysis was undertaken by analyzing the incidence of complications in both procedures. Effectivity analysis was carried out analyzing radiologic and clinical outcome (Goel grade and modified Japanese Orthopaedic Association score). Student t test was used for statistical analysis. Sixteen cases were included. Mean age of patients was 9.38 years. Safety analysis showed 2 halo loosenings, 1 pin infection, 2 wound infections, 1 cerebrospinal fluid leak, and 2 delayed broken rods. No major complications were observed. Radiologic analysis showed an improvement in the tip of the odontoid process to the McRae line distance (from −3.26 mm to −6.16 mm), atlantodental interval (from 3.05 mm to 1.88 mm), clival-canal angle (from 134.61° to 144.38°), and cervical kyphosis (from 6.39° to 1.54°). Clinical analysis also showed improvement in mean Goel grade (from 1.75 to 1.44) and modified Japanese Orthopaedic Association score (from 15.12 to 16.41). The 2-stage approach was a suitable and effective treatment for craniocervical junction anomalies in pediatric patients. [ABSTRACT FROM AUTHOR]

To evaluate the results of surgery for congenital craniovertebral junction (CVJ) anomalies with atlantoaxial dislocation (AAD)/basilar invagination (BI) and compare the results of transoral odontoidectomy and posterior fusion (TOO+PF) with only posterior fusion (PF) in patients with irreducible AAD/BI. All 94 patients with congenital CVJ anomalies with AAD/BI operated on during the 3-year study period (June 2013–May 2016) were included. Of these patients, 55 had irreducible AAD/BI and the remaining 39 had reducible AAD/BI. TOO+PF was restricted to patients (34/94; 36.2%) with irreducible AAD/BI when reduction and realignment by intraoperative C1-C2 facet joint manipulation were considered technically difficult and risky. The remaining patients with irreducible AAD/BI and all the patients with reducible AAD/BI (60/94; 63.8%) were managed with only posterior fusion. Poor preoperative Nurick grade, preoperative dyspnea/lower cranial nerve deficits, and syringomyelia were associated with significantly higher incidence of postoperative pulmonary complications. Follow-up ≥3 months (final follow-up) was available for 87 patients. Good outcome (Nurick grade 0–3) at final follow-up was noted in 90% (45/50) of the patients with irreducible AAD/BI and 91.9% (34/37) of the patients with reducible AAD/BI. Preoperative poor Nurick grade (4–5) was the only factor associated with poor outcome. No significant difference in perioperative complications, outcome, and fusion was noted between patients who underwent TOO+PF or only PF for irreducible AAD/BI. Many of the patients with congenital AAD/BI showed remarkable recovery after surgery. Preoperative poor Nurick grade (4–5) is associated with poor outcome. TOO+PF is a safe alternative treatment option for irreducible AAD/BI when only PF techniques are technically difficult/risky. [ABSTRACT FROM AUTHOR]

Background: To compare clinical effect and safety between posterior fossa decompression with duraplasty (PFDD) and posterior fossa decompression without duraplasty (PFD) in treatment of Chiari type I malformation and basilar impression.Methods: A comprehensive computer search was conducted from 2000 to 2019. The quality assessment was performed by the QUADAS-2 tool. The clinical value of comparison between PFDD and PFD was evaluated by using the pooled estimate of sensitivity and specificity. In addition, sensitivity analysis and bias analysis were applied to ensure the accuracy of the results.Results: Finally, 468 patients were enrolled in 6 studies and ultimately met the eligibility criteria. The PFDD and PFD groups were 282 and 186, respectively. The meta-analysis showed no significant difference in the Chicago Chiari Outcome Scale (COSS score) (MD = 0.14, 95% CI [-0.23, 0.50], P = 0.47; P = heterogeneity = 0.86, I2 = 0%). Meanwhile, Significant difference existed in length of stay (MD = -1.08, 95% CI [-1.32, -0.84], P = 0.001; heterogeneity P < 0.000001, I2 = 85%) and complications (OR = 0.35, 95%CI [0.20, 0.62], P = 0.0003; P for Heterogeneity = 0.04, I2 = 56%).Conclusion: PFD is a more efficient and safer therapy than PFDD in the treatment of Chiari type I malformation with basilar impression. [ABSTRACT FROM AUTHOR]

A Prospective Study. To assess results of posterior occipito-cervical decompression and fusion operated with intra-operative traction/manipulation and instrumented reduction in cases of Basilar Invagination(BI). Total 22 patients of 8–65 years with diagnosed BI were operated for posterior occipito-cervical fusion by intra-operative traction/manipulation and instrumented reduction. Fusion was done using autologous bone graft taken from iliac crest. Immediate post-operative, first month and then every 3 months' follow-up examination were done for minimum period of 2 years. 22 patients (10 males,12 females) with mean age of 23.9 years having BI were included. 11 patients had C1 occipitalization, 4 had platybasia and 9 had atlanto-axial dislocation (AAD). 1 patient with os odontoideum with kyphotic deformity expired on 4th postoperative day due to respiratory insufficiency (mortality rate 4.54%). Neurological improvement by at least by one grade according to RANAWAT's and/or NURICK'S scale was observed in 17/21 patients (80.95%). 3 patients remained static and 1 had neuro-worsening. Mean mJOA score of 13.14 improved to 16.24. All had reduction of dens below foramen magnum according to McRae, chamberlain line and Ranawat index. Bone graft fused in all patients as confirmed with CT scan and dynamic X-rays. 1 wound dehiscence and 1 asymptomatic implant loosening were seen on follow-up. Surgical treatment of BI with intra-operative traction/manipulation, instrumented reduction and posterior occipito-cervical fusion can achieve good correction of radiology, functional performance and clinical neurology as well as excellent fusion rates without adverse effects of trans-oral surgery. [ABSTRACT FROM AUTHOR]

Introduction of a posterior spacer for atlantoaxial joint distraction followed by posterior stabilization is a commonly performed procedure for irreducible atlantoaxial dislocation. We present a unique case in which posterior distraction was associated with increased risk of injury to the vertebral artery (VA) owing to its anomalous course, and hence a novel anterior distraction technique was used. A 45-year-old woman presented with severe neck pain for 1 month with gait imbalance and history of occipital headache for 1 year. Clinical examination revealed upper motor neuron–type findings. Hoffmann sign was positive bilaterally. Clinically, the patient had Nurick grade 4 cervical myelopathy. Magnetic resonance imaging showed basilar invagination along with Arnold-Chiari malformation and syrinx formation at C3-C4 vertebral levels. CT angiography revealed anomalous VAs directly overlying the atlanto-occipital joint. Owing to the anomalous route of the VA and unfavorable slope of facet joints, a 2-step anterior reduction followed by posterior stabilization surgery was planned. We achieved complete reduction using a 10-mm titanium cage inserted via a retropharyngeal approach. Following anterior reduction, instrumented in situ occipitocervical fusion was performed using a plate and screw construct. At 2-year follow-up, the patient is ambulating independently without gait imbalance and with successful radiologic fusion. The craniovertebral junction has a unique pathoanatomy, and the course of the vertebral artery is variable. Appropriate investigations, including computed tomography angiography, with adequate surgical planning will provide a desirable long-term outcome. Our novel technique has the potential to add a new dimension to the management of irreducible atlantoaxial dislocation. [ABSTRACT FROM AUTHOR]

We present a report of two patients having the association of omovertebra, Sprengel's deformity of the shoulder and Klippel–Feil abnormality with craniovertebral junctional instability. Our literature survey did not locate any report of such association. Significance of bone alterations is analyzed. Two young patients presented with neck pain, torticollis, webbed neck, and spastic quadriparesis. In both patients, the investigations revealed basilar invagination, Klippel–Feil abnormality and Sprengel's deformity of the shoulder. Apart from these relatively common associations, both the patients had omovertebral bone that extended from the transverse process of C5 vertebra to scapula. Following atlantoaxial stabilization surgery, the patients rapidly recovered from all symptoms. Musculoskeletal abnormalities at the craniovertebral junction that include Klippel–Feil abnormality, Sprengel's shoulder, and omovertebra are secondary alterations to primary atlantoaxial instability. [ABSTRACT FROM AUTHOR]