Craniovertebral Junction Surgery Research Articles

Anatomy of anterior craniovertebral junction in endoscopic transnasal approach

Modern achievements in endoscopic technologies ensure extending the indications for endoscopic transnasal approach in skull base surgery. Knowledge on topographic anatomy of craniovertebral junction is a prerequisite for surgical interventions in this area. Transnasal endoscopic surgery of craniovertebral junction is a relatively new field. Therefore, this manuscript and similar anatomical studies are extremely important for neurosurgeons.

Combined transoral exoscope and OArm-assisted approach for craniovertebral junction surgery: Light and shadows in single-center experience with improving technologies.

Background:The introduction of recent innovations in the field of intraoperative imaging and neuronavigation, such as OArm Stealth Station, allows to obtain crucial intraoperative data by performing safer and controlled surgical procedures. As part of the improvement of surgical visual magnification and wide expansion of surgical corridors, the 3D-4K exoscope (EX) represents nowadays an interesting and useful tool. Transoral approach (TOA) represents the historical gold standard direct microsurgical route to ventral craniovertebral junction (CVJ).Methods:We herein report a preliminary experience on 6 cases of 33 patients operated by TOA concerning the simultaneous application of OArm with Stealth Navigation system (Medtronic, Memphis, TN) and imaging system along with the 3D-4K EXs in TOA for the treatment of CVJ pathologies.Results:Neither intraoperative neurophysiological changes nor postoperative infections occurred, but a neurological improvement was evident in all the patients. A complete decompression along with stable instrumentation and fusion of the CVJ was accomplished in all cases at the maximum follow-up (mean: 16.8 months).Conclusions:With EX, the role of surgeon become self-sufficient with a better individual surgical freedom compared to endoscopic surgery and excellent 3D vision and magnification. OArm allows an absolutely reliable intraoperative support for a more effective CVJ decompression. Nevertheless, with OArm-assisted neuronavigation, it can be difficult to navigate C1 lateral masses and C2 isthmi, and to convert 3D into 2D real-time navigation, it can become quite complicate. Finally, the association of EX and OArm appears more time consuming compared to the old fashion one.

Endonasal Endoscopic and Transoral Approaches to the Craniovertebral Junction and the Clival Region: A Comparative Anatomical Study

Anterior craniovertebral junction (CVJ) surgery has continued to be one of the most debated neurosurgical topics. The transoral approach (TOA) has been considered the choice for this region. However, it has some limitations and a not negligible degree of surgery-related morbidity. With the advent of endoscopy, the endoscopic endonasal approach (EEA) was developed, which minimized morbidity and improved exposure. To the best of our knowledge, despite the extensive reported data, a comparative anatomical study has not been performed and no definitive consensus has been reached on the indications for both approaches. We compared the TOA and EEA to the CVJ using the previously described operability score (OS), calculated at 4 different targets: the C1 tubercle (C1), the lowest exposed point of the odontoid process (C2), the basion (BS) and the middle clivus (MC). The higher the OS for the selected targets, the more favorable the approach. The TOA had higher OSs at the MC, C1, and C2 targets, and the EEA showed greater OSs at MC and C1. The TOA and EEA had similar OSs at the BS. These results have shown that the OS is more favorable at C1-C2 using the TOA and the OSs at the MC and BS were similar. The OS is an effective method to compare surgical approaches. The present study demonstrated the maximal exposure capability of the 2approaches. The TOA seemed to be superior for lower targets and the EEA for upper targets. Because of the strong variability in the CVJ anatomy and pathological features, we suggest considering the OS as a further tool to better define the best surgical approach.

Anatomical study of the ventral neurovascular structures and hypoglossal canal for the surgery of the upper cervical spine

The aim of this study is to evaluate the anatomical relationship between the bony structures and ventral neurovascular structures around craniovertebral junction (CVJ).Eleven fresh-frozen cadaveric specimens were dissected around CVJ. The anatomical relationships were evaluated between C1 bony structures (midline, lateral margin of the C1 lateral mass (LM) and C1 transverse process (TP)) and ventral neurovascular structure such as ICA and HN. Morphometric evaluation of occipital condyle was also performed.The diameter of the HN and the ICA was 2.4 ± 0.5 mm and 5.1 ± 0.2 mm. The ICA was located lateral to the C1 LM in 44.4% (ICA Group 1) and in front of lateral half of the C1 LM in 55.6% (ICA Group 2). The HN was located lateral to the C1 LM in 85% (HN Group 1) and in front of lateral half of the C1 LM in 15% (HN Group 2). HN Group 2 was significantly more common in ICA Group 2 (p < 0.05, OR = 2.00, 95% CI: 1.07–3.71). There was significant correlation between ICA and HN in terms of the distance from the midline, C1 LM and TP (r = 0.67, 0.87 and 0.76 respectively, P < 0.01).In conclusion, the HN location is related with ICA location and the medially located ICA is a risk factor of the HN located ventral to the C1 LM. These results demonstrate the vulnerability of the neurovascular structures during CVJ surgery and suggest that preoperative 3D-CTA or enhanced CT scan can be useful in guiding surgical technique.

Safe and bloodless exposure of the third segment of the vertebral artery: a step-by-step overview based on over 50 personal cases.

Craniovertebral junction surgery usually requires the exposure of the third segment of the vertebral artery (V3). However, the complexity of musculature, a relatively high incidence of anomalies in the course of the vertebral artery (VA), and the presence of a rich venous plexus in this region make the V3 exposure challenging with a high risk of serious complications while taking down the suboccipital muscles in a single layer. A muscle dissection in interfascial layers, however, overcomes the drawbacks inherent in a blind dissection of the V3 as each of the muscles represents substantial landmark aiding subsequent step of the procedure and thus helping identify underlying anatomical structure early and safely. Moreover, along with a bloodless VA dissection off its surrounding venous plexus, it permits a safe and comfortable V3 exposure during the surgically demanding procedures.

A Review of a New Clinical Entity of 'Central Atlantoaxial Instability': Expanding Horizons of Craniovertebral Junction Surgery.

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.

Intraoperative Neurophysiological Monitoring for Craniovertebral Junction Surgery.

Craniovertebral junction (CVJ) surgery encompasses a wide spectrum of neurosurgical procedures ranging from transoral approaches for CVJ bone anomalies to surgery for intramedullary tumours. Intraoperative neurophysiological monitoring (IONM) has been increasingly used in recent years because of its ability to prevent neurological complications during surgery. In CVJ surgery the risk of neurological injuries is related first to the positioning of the patient and then to the surgical procedure. Application of IONM during the positioning of the patient permits fast recognition of impending causes of neurological injury. During surgery, continuous IONM permits real-time assessment of the functional integrity of the spinal tracts and provides useful feedback during surgical manoeuvres. The applications of IONM are mainly related to intradural procedures, but wider application of these techniques during surgery for CVJ instability and degenerative disorders has recently been described, leading also to better understanding of the pathophysiology of spinal cord injuries. In this paper we review and discuss the principal IONM techniques used during surgery around the CVJ.

Management of Anaesthesia.

Surgical treatment of the craniovertebral junction (CVJ) requires excellent management by the anaesthetist. Patients undergoing this type of surgery have a wide range of concomitant diseases. Therefore, before proceeding to CVJ surgery, it is recommended to analyse the clinical aspects of the patient that could complicate the outcome of the surgical procedure.In this paper we aim to establish what constitutes the best surgical and anaesthesia management of these patients. We consider airway management, trying to identify the gold standard for the patient. We also consider the most appropriate intraoperative approach to guarantee the best management of the patient.

Significance of Multimodal Intraoperative Monitoring During Surgery in Patients with Craniovertebral Junction Pathology

Although many studies have investigated the benefits of multimodal intraoperative monitoring (MIOM) during cervical spine surgery, the benefits of MIOM in craniovertebral junction (CVJ) surgery remain unclear. The objectives of the present study were to report our clinical experience in CVJ surgery with the use of MIOM and to identify risk factors that could affect MIOM changes during surgery of CVJ pathology. We reviewed the MIOM records of 146 patients who had undergone high cervical spinal surgery. The patients were grouped by the MIOM data recorded during surgery; the patients were included in either the MIOM or non-MIOM change group. The analyzed risk factors included demographic, myelopathy, preoperative Japanese Orthopedic Association (JOA) score, spinal cord diameter, and surgical factors. Univariate and multivariate analyses were performed to identify the risk factors for changes in MIOM data during surgery and postoperative neurological deficits. Our results revealed that the incidence of postoperative neurological complications was 4.1% after CVJ surgery; this rate was significantly greater in the MIOM change group than in the non-MIOM change group (21.7% vs. 0.8%; P < 0.01). Multiple regression analysis revealed that preoperative myelopathy, preoperative JOA score, and congenital anomaly/tumor were independently associated with MIOM changes during surgery. Postoperative neurological complications are not uncommon after CVJ surgery, and the incidence was significantly greater in the MIOM change group. Preoperative myelopathy, preoperative JOA score, and CVJ pathology related to congenital anomaly or tumor were independent risk factors for changes in MIOM data during surgery.

Top 50 most-cited articles on craniovertebral junction surgery.

Background:Craniovertebral junction is a complex anatomical location posing unique challenges to the surgical management of its pathologies. We aimed to identify the fifty most-cited articles that are dedicated to this field.Methods:A keyword search using the Thomson Reuters Web of Knowledge was conducted to identify articles relevant to the field of craniovertebral junction surgery. The articles were reviewed based on title, abstract, and methods, if necessary, and then ranked based on the total number of citations to identify the fifty most-cited articles. Characteristics of the articles were determined and analyzed.Results:The earliest top-cited article was published in 1948. When stratified by decade, 1990s was the most productive with 16 articles. The most-cited article was by Anderson and Dalonzo on a classification of odontoid fractures. By citation rate, the most-cited article was by Herms and Melcher who described Goel's technique of atlantoaxial fixation using C1 lateral mass screws and C2 pedicle screws with rod fixation. Atlantoaxial fixation was the most common topic. The United States, Barrow Neurological Institute, and VH Sonntag were the most represented country, institute, and author, respectively. The significant majority of articles were designed as case series providing level IV evidence.Conclusion:Using citation analysis, we have provided a list of the most-cited articles representing important contributions of various authors from many institutions across the world to the field of craniovertebral junction surgery.

Pediatric Craniovertebral Junction Surgery.

The craniovertebral junction (CVJ) has attracted more attention in pediatric medicine in recent years due to the progress in surgical technologies allowing a direct approach to the CVJ in children. The CVJ is the site of numerous pathologies, most originating in bone anomalies resulting from abnormal CVJ development. Before discussing the surgical approaches to CVJ, three points should be borne in mind: first, that developmental anatomy demonstrates age-dependent mechanisms and the pathophysiology of pediatric CVJ anomalies; second, that CT-based dynamic simulations have improved our knowledge of functional anatomy, enabling us to locate CVJ lesions with greater certainty; and third, understanding the complex structure of the pediatric CVJ also clarifies the surgical anatomy. This review begins with a description of the embryonic developmental process of the CVJ, comprising ossification and resegmentation of the somite. From the clinical perspective, pediatric CVJ lesions can be divided into three categories: developmental bony anomalies with or without instability, stenotic CVJ lesions, and others. After discussing surgery and management based on this classification, the author describes surgical outcomes on his hands, and finally proceeds to address controversial issues specific for pediatric CVJ surgery. The lessons, which the author has gleaned from his experience in pediatric CVJ surgery, are also presented briefly in this review. Recent technological progress has facilitated pediatric surgery of the CVJ. However, it is important to recognize that we are still far from reliably and consistently obtaining satisfactory results. Further progress in this area awaits contributions of the coming generations of pediatric surgeons.

Three-dimensional models: an emerging investigational revolution for craniovertebral junction surgery.

Complex craniovertebral junctional anomalies can be daunting to treat surgically, and preoperative information regarding the osseous abnormalities, course of the vertebral arteries, size of the pedicles, and location of the transverse foramina is invaluable to surgeons operating on these challenging cases. The authors present their experience with the emerging technology of 3D model acquisition for surgery in 11 cases of complex craniovertebral junction region anomalies. For each case, a 3D printed model was made from thin CT scans using a 64-slice CT scanner. The inclination of the joints, the presence of false articulations, the size of the pedicles, and the course of the vertebral arteries were studied preoperatively on the 3D models. The sizes of the plates and screws to be used and the angle of insertion of the screws were calculated based on the data from the models. The model was scaled to actual size and was kept beside the operating surgeon in its anatomical position during surgery. The potential uses of the models and their advantages over conventional radiological investigations are discussed. The authors conclude that 3D models can be an invaluable aid during surgery for complex craniovertebral junction anomalies. The information available from a real life-size model supersedes the information available from 3D CT reconstructions and can also be superior to virtual simulation. The models are both cost effective and easy to build and the authors suggest that they may form the basis of investigations in the near future for craniovertebral junction surgery.

Craniovertebral Junction Instability: A Review of Facts about Facets.

Craniovertebral junction surgery involves an appropriate philosophical, biomechanical and anatomical understanding apart from high degree of technical skill and ability of controlling venous and arterial bleeding. The author presents his 30-year experience with treating complex craniovertebral junction instability related surgical issues. The facets of atlas and axis form the primary site of movements at the craniovertebral junction. All craniovertebral junction instability is essentially localized to the atlantoaxial facet joint. Direct manipulation and fixation of the facets forms the basis of treatment for instability.

Posterior occipitocervical (C0–3) fusion using polyaxial occipital condyle to cervical spine screw and rod fixation: a radiographic and cadaveric analysis

Numerous conditions affect the occipitocervical junction requiring treatment with occipitocervical fixation. In this paper the authors present their technique of craniocervical fixation achieved with the cephalad extension of posterior C1-3 polyaxial screw and rods to polyaxial screws placed in the occipital condyles. They retrospectively analyzed occipital condyle morphology obtained from CT analyses of 40 patients with normal cervical spines, evaluated occipital condyle screw placement feasibility in 4 cadavers, and provided a case report of a 70-year-old woman with rheumatoid arthritis, basilar invagination, and atlantoaxial instability who was treated with this novel technique. Based on radiographic analysis of occipital condyle anatomy, they concluded that on average a 3.5-mm-diameter x 20- to 30-mm-long screw can be safely placed at an angle of 20-33 degrees from the sagittal plane. Overall, measuring the condylar heights (mean [+/- SD] 10.8 +/- 1.5 mm, range 8.1-15.0 mm), widths (mean 11.1 +/- 1.4 mm, range 8.5-14.2 mm), lengths (20.3 +/- 2.1 mm, range 15.4-24.6 mm), and angles (mean 32.8 +/- 5.2 degrees , range 20.2-45.8 degrees) by using CT studies is an accurate and precise method. This finding correlates with the results of prior anatomical studies of occipital condyles and is important in the planning of craniovertebral junction surgery.

The effect of posterior bridging of C-1 on craniovertebral junction surgery

The groove for the vertebral artery (VA) may be bridged on C-1, forming a canal through which the artery passes. Because this variant may significantly affect the commonly performed C-1 posterior laminectomy, the authors studied the incidence and radiological appearance of this anatomical feature in surgical specimens. Anatomical measurements were performed using a Vernier caliper (accurate to 0.1 mm) on 166 dry C-1 vertebrae. In addition, a convenience sample of 172 cervical x-ray films was evaluated. Partial osseous bridging was detected in eight (4.8%), and a complete osseous bridge, forming the canalis arteriae vertebralis (canal for the VA), was seen unilaterally (eight on the left and two on the right) in 10 (6%) and bilaterally in eight (4.8%) of the dry vertebrae. On lateral radiography, a complete bone bridge was observed on nine (5.2%) and a partial bridge on 10 (5.8%) of the 172 studies. The discovery of a common variant may necessitate an immediate change in surgical management, and this anomaly could even increase the rate of surgery-related complications. The VA canal, present in the C-1 vertebra in approximately 5% of the specimens evaluated, was a variant that may be protective against VA injury. Knowledge of this variant may help the surgeon undertaking procedures in the C-1 region.

Anesthetic Management of CVJ Surgical Procedures, Particularly Transoral Procedures

Anesthesia for craniovertebral junction surgery is complex and highly specialized. In addition to the basics of safe anesthesia delivery, the anesthetic management should include safe performance of fiberoptic intubation and avoidance of airway trauma, proper positioning of the patient, maintenance of physiological hemodynamics and body chemistry during surgery, extreme vigilance to safeguard the airway during the procedure, and proper ventilatory and nutritional management in surgical intensive care postoperatively.

Morphometric analysis of human occipital condyle

Objective: The human occipital condyle is the unique bony structure connecting the cranium and the vertebral column. The progress in neuroimaging techniques has increased interest for aggressive craniovertebral surgery. Such surgery requires the knowledge regarding anatomical aspects of the craniovertebral junction. The aim of the present study is to analyze the occipital condyle morphometrically. Material and methods: 404 occipital condyles of 202 dry skulls were used for this study. Twenty-seven parameters were measured, including length, width and height of occipital condyle, the distances between the occipital condyle and hypoglossal canal, as well as some important condyle-related angles. Results: The length, width and the height of the occipital condyle were found to be 23.4, 10.6, and 9.2 mm, respectively. The anterior and posterior intercondylar distances are 21.0 and 41.6 mm, respectively. Sagittal intercondylar angle was 59.3°. The intracranial orifice of the hypoglossal canal was found in the junction of the second and third quarter on the condyle in more than 55% of specimens. The shape of occipital condyles was classified into eight types as followings—type 1: oval-like condyle; type 2: kidney-like condyle; type 3: S-like condyle; type 4: eight-like condyle; type 5: triangle condyle; type 6: ring-like condyle; type 7: two-portioned condyle and type 8: deformed condyle. The most common type was type 1 (50%), whereas the most unusual type was type 7 (0.8%). Conclusion: It is concluded that the occipital condyle may present various shapes, length, width, and orientation, requiring a careful radiological analysis before craniovertebral junction surgery.

Anatomical and computed tomographic analysis of C1 vertebra

Craniovertebral junction surgery requires knowledge regarding the anatomy of this region, particularly the C1 vertebra. Both C1 laminectomy and C1-2 instrumentation necessitate preoperative information about bony landmarks and the vertebral artery. This study compares the results obtained from anatomic and computed tomographic measurements of C1 bony landmarks. 31 C1 cervical vertebrae were measured; the C1 AP diameter, and C1 transverse diameter, the facet diameter, the distance between the anterior tubercle and the anterior aspect of the C1 lateral mass on a lateral view, the distance between the midline and the vertebral artery groove on the outer cortex of the posterior arch of C1 anatomically and computed tomographically. Anatomic measurements were performed by an anatomist using a Vernier caliper accurate to 0.1 mm, whereas the computed tomographic measurements were performed by a radiologist on bone window computed tomography (CT). The mean values and the differences between two measurement modalities were analysed using a paired t-test. There was no statistical difference between the results obtained by anatomical and radiological measurements for six parameters. There was, however, a statistically significant difference between two modalities regarding the distance between the midline and vertebral artery groove on the outer cortex of posterior arch of C1, while slightly different, the difference is within 1 mm and, therefore, not clinically significant. It is concluded that CT reflects most anatomical details of bony landmarks of C1.