Atlantoaxial joint distraction for treatment of basilar invagination secondary to rheumatoid arthritis

We present our experience of treating two cases of rheumatoid arthritis involving the craniovertebral junction and having marked basilar invagination by an alternative treatment method. In both the cases, the facets were osteoporotic and were not suitable for screw implantation. The patients were 66 and 72 years of age and both patients were females. Both the patients presented with complaints of progressively increasing spastic quadriparesis. Surgery involved attempts to reduce the basilar invagination and restore the height of the 'collapsed' lateral mass by manual distraction of the facets of the atlas and axis and forced impaction of titanium spacers in the joint in addition to bone graft harvested from the iliac crest. The procedure also provided stabilization of the region. No other fixation procedure involving wires, screws, plate and rods was carried out simultaneously. Following surgery both the patients showed symptomatic improvement and partial restoration of craniovertebral alignments. Follow-up is of 2 and 24 months. Distraction of the facets of atlas and axis and impaction of metal implant and bone graft in the facet joint can assist in reduction of basilar invagination and fixation of the region in selected cases of rheumatoid arthritis involving the craniovertebral junction.     

Craniovertebral realignment for basilar invagination and atlantoaxial dislocation secondary to rheumatoid arthritis

OBJECTIVE: We present our experience of treating nine consecutive cases of rheumatoid arthritis involving the craniovertebral junction by atlantoaxial joint manipulation and attempts towards restoration of craniovertebral region alignments. MATERIAL AND RESULTS: Between November 2001 and March 2004, nine cases of rheumatoid arthritis involving the craniovertebral junction were treated in our department of neurosurgery. Six patients had basilar invagination and 'fixed' atlantoaxial dislocation and three patients had a retroodontoid process pannus and mobile and incompletely reducible atlantoaxial dislocation. The patients ranged from 24 to 74 years in age. Six patients were males and three were females. Neck pain and spastic quadriparesis were the most prominent symptoms. Surgery involved attempts to reduce the atlantoaxial dislocation and basilar invagination by manual distraction of the facets of the atlas and axis. Reduction of the atlantoaxial dislocation and of basilar invagination and stabilization of the region was achieved by placement of bone graft and metal spacers within the joint and direct inter-articular plate and screw method of atlantoaxial fixation. Following surgery all the patients showed symptomatic improvement and restoration of craniovertebral alignments. Follow-up ranged from four to 48 months (average 28 months). CONCLUSION: Manipulation of the atlantoaxial joints and restoring the anatomical craniovertebral alignments in selected cases of rheumatoid arthritis involving the craniovertebral junction leads to remarkable and sustained clinical recovery.     

应用C1-2螺钉棒系统行后路复位、固定和融合治疗合并寰-枢椎脱位的颅底凹陷症

目的探讨应用C1-2螺钉棒内固定系统行后路复位、固定和融合治疗寰枢椎脱位的手术疗效。方法 2013年4月至2013年10月,对30例我科收治的合并寰枢椎脱位的颅底凹陷症患者采用寰椎侧块螺钉和枢椎椎弓根峡部螺钉(或下关节突螺钉、颈3椎弓根螺钉)棒内固定系统进行复位、固定并取髂后上嵴松质骨植骨融合。通过术后3D-CT评判复位程度,JOA评分评判临床疗效,并探讨影响手术效果的因素。结果 30例患者中26例达到完全复位,4例为部分复位。其中25例完成了3个月以上随访,CT显示植骨愈合良好,未出现植骨的吸收及内固定的松动。结论 C1-2椎弓根钉棒内固定系统对治疗合并寰枢椎脱位的颅颈交界区畸形可以获得满意的疗效,安全可行。     

基于HyperMesh建立颅底陷入合并寰枕融合畸形的三维有限元模型

目的 探讨建立颅底陷入合并寰枕融合畸形的三维有限元模型的方法。方法 采集1例颅底陷入合并寰枕融合畸形患者的颅颈交界区的CT薄层扫描数据,利用Mimics软件对CT数据进行处理,生成三维几何表面模型,并导出点云;采用逆向工程软件Imageware处理点云数据,生成三维曲面;采用四面体与六面体混合分网的思路,利用HyperMesh对曲面模型先分块再分网,最后导出网格模型;将网格模型导入有限元软件Abaqus,进行韧带添加、材料赋值、接触定义、边界约束等,得到寰枕融合畸形三维有限元模型。结果 建立的有限元模型包含474 162个单元和235 524个节点,外观逼真,几何相似性较好,可根据不同实验目的进行加载分析,对复杂载荷条件进行仿真计算。结论 利用HyperMesh等软件的前处理功能建立的颅底陷入合并寰枕融合三维有限元模型,可为颅颈交界区畸形的生物力学研究提供基础,可为上颈椎畸形有限元模型的建立提供参考。     

Imaging the craniocervical junction

INTRODUCTION: The craniovertebral junction (CVJ) comprises the occiput, atlas, and axis. Radiographic evaluation of this region involves knowledge of only a few anatomical landmarks, as well as basic normal measurements and relationships to perform CVJ craniometry. Occipital bone anomalies and atlanto-occipital non-segmentation typically produce basilar invagination. Atlas anomalies predominantly involve the posterior arch, while the os odontoideum accounts for the majority of axis anomalies. RESULTS AND DISCUSSION: A number of syndromes are associated with CVJ pathology, the most notable being Klippel-Feil and Down syndromes, achondroplasia, the mucopolysaccharidoses, and osteogenesis imperfecta. Skull-base softening associated with some of these syndromes results in acquired basilar invagination or basilar impression. In this article, we present a detailed review of essential anatomy and craniometry needed for radiographic assessment of the CVJ and illustrate various congenital anomalies of the occiput, atlas, and axis. The common syndromes affecting this region are also discussed and illustrated.     

Techniques in the treatment of craniovertebral instability

The techniques of craniovertebral region stabilization introduced and used by the senior author over the last 20 years are summarized. The lateral masses of atlas and axis are strong and largely cancellous in nature and can be used for direct implantation of screws. Opening up of the joint and placement of bone graft within the joint stabilizes the region and provides a large area for bone fusion. Distraction of the facets provides an opportunity to treat a range of congenital craniovertebral anomalies. The technique of exposure of the lateral mass of the atlas and axis and the atlantoaxial joint is technically relatively complex and needs precise understanding of anatomy of the vertebral artery and training with cadavers.     

Surgical Treatment of Craniovertebral Junction Instability : Clinical Outcomes and Effectiveness in Personal Experience

Objective

Craniovertebral junction (CVJ) consists of the occipital bone that surrounds the foramen magnum, the atlas and the axis vertebrae. The mortality and morbidity is high for irreducible CVJ lesion with cervico-medullary compression. In a clinical retrospective study, the authors reviewed clinical and radiographic results of occipitocervical fusion using a various methods in 32 patients with CVJ instability.

Methods

Thirty-two CVJ lesions (18 male and 14 female) were treated in our department for 12 years. Instability resulted from trauma (14 cases), rheumatoid arthritis (8 cases), assimilation of atlas (4 cases), tumor (2 cases), basilar invagination (2 cases) and miscellaneous (2 cases). Thirty-two patients were internally fixed with 7 anterior and posterior decompression with occipitocervical fusion, 15 posterior decompression and occipitocervical fusion with wire-rod, 5 C1-2 transarticular screw fixation, and 5 C1 lateral mass-C2 transpedicular screw. Outcome (mean follow-up period, 38 months) was based on clinical and radiographic review. The clinical outcome was assessed by Japanese Orthopedic Association (JOA) score.

Results

Nine neurologically intact patients remained same after surgery. Among 23 patients with cervical myelopathy, clinical improvement was noted in 18 cases (78.3%). One patient died 2 months after the surgery because of pneumonia and sepsis. Fusion was achieved in 27 patients (93%) at last follow-up. No patient developed evidence of new, recurrent, or progressive instability.

Conclusion

The authors conclude that early occipitocervical fusion to be recommended in case of reducible CVJ lesion and the appropriate decompression and occipitocervical fusion are recommended in case of irreducible craniovertebral junction lesion.     

Vertical reduction using atlantoaxial facet spacer in basilar invagination with atlantoaxial instability

Although posterior segmental fixation technique is becoming increasingly popular, surgical treatment of craniovertebral junctional disorders is still challenging because of its complex anatomy and surrounding critical neurovascular structures. Basilar invagination is major pathology of craniovertebral junction that has been a subject of clinical interest because of its various clinical presentations and difficulty of treatment. Most authors recommend a posterior occipitocervical fixation following transoral decompression or posterior decompression and occipitocervical fixation. However, both surgical modalities inadvertently sacrifice C0-1 and C1-2 joint motion. We report two cases of basilar invagination reduced by the vertical distraction between C1-2 facet joint. We reduced the C1-2 joint in an anatomical position and fused the joint with iliac bone graft and C1-2 segmental fixation using the polyaxial screws and rods C-1 lateral mass and the C-2 pedicle.     

Rigid variety occiput/C1–C2–C3 internal fixation in pediatric population

Purpose

The purpose of this study was to review our experience of rigid internal fixation of craniovertebral junction in pediatric population. A new technique of reduction of basilar invagination with atlantoaxial dislocation is described. To the best of our knowledge and available scientific literature, this technique has not yet been described in younger patients.

Methods

We have managed 27 children by rigid variety of occiput/C1–C2–C3 internal fixation of various craniovertebral junction pathologies. All patients were subjected to thin cuts of computed tomography with 3D reconstruction for selecting appropriate rigid construct. Eight children had occiput-C2, 3 had occiput-C2–C3, and 16 had C1-C2 hardware constuct. One patient of C1–C2-plate fixation had section of C2 nerve root ganglia. Basilar invagination with atlantoaxial dislocation was reduced by new distraction/compression techniques.

Results

Improvement in clinical features and correction of deformity with solid hardware construct were seen in all patients. Follow-up period ranged from 5–72 months. One patient was lost to follow-up, and one case died of compression of vertebral artery at C1 lateral mass. Patients of myelopathy had recovery rate of 90.9 %. Hardware failure was seen in one patient, and wound infection was observed in two cases.

Conclusions

Rigid variety of occiput/C1–C2 internal fixation is a safe and effective method in the management of variety of craniovertebral pathologies in pediatric population. This new technique of reduction of basilar invagination with atlantoaxilal dislocation from posterior approach may alleviate the need of high morbity associated with surgical procedure like transoral odontoidectomy in younger patients.     

Vertical atlantoaxial dislocation as a cause of failure of midline fixation

We report an 11-year-old girl who had previously undergone an operation for basilar invagination involving a foramen magnum decompression and midline wire fixation. After improving initially, her neurological condition worsened again. Repeated investigations showed a firm midline craniovertebral fixation and bone fusion. However, she was found to have a vertical mobile and reducible atlantoaxial dislocation. Treatment of the vertical dislocation by lateral mass fixation resulted in lasting relief from her symptoms. Vertical instability at the atlantoaxial joints needs to be identified and appropriately treated as it may be a cause of failure of midline fixation.     

Fusions at the craniovertebral junction

INTRODUCTION: The surgical management of craniovertebral junction instability in pediatric patients has unique challenges. While the indications for internal fixation in children are similar to those of adults, the data concerning techniques, complications, and outcomes of spinal instrumentation comes from experience with adult patients. Diminutive osseous and ligamentous structures and anatomical variations associated with syndromic craniovertebral abnormalities frequently complicates the approaches and limits the use of internal fixation in children. Cervical arthrodesis in the pediatric age group has the potential for limiting growth potential and causing secondary deformity. Recent advances in image analysis have enabled preoperative planning which is critical to evaluate the size of instrumentation and its relation to the patient's anatomy. Newer techniques have recently evolved and have been incorporated in the management of pediatric patients with requirement for craniocervical stabilization. MATERIALS AND METHODS: Over 750 craniovertebral junction fusions have been reviewed in children. The indications for atlantoaxial arthrodesis were: (a) absent odontoid process, dystopic os odontoideum, absent posterior arch of C1; (b) Morquio's syndrome, Goldenhar's syndrome, Conradi's syndrome, and spondyloepiphyseal dysplasia. The acquired abnormalities of trauma, postinfectious instability, and Down's syndrome completed the indication in children. The indications for occipitocervical fusion were: (a) anterior and posterior bifid C1 arches with instability, absent occipital condyles; b) severe reducible basilar invagination, unstable dystopic os odontoideum, and unilateral atlas assimilation; (c) acquired phenomenon with traumatic occipitocervical dislocation, complex craniovertebral junction fractures of C1 and C2, after transoral craniovertebral junction decompression, cranial settling in Down's syndrome and inflammatory disease such as Grisel's syndrome. Instability was seen in children with clivus chordoma and osteoblastoma. Atlantoaxial fusions were performed mainly with interlaminar rib graft fusion and more recently with the transarticular screw fixation in the older patient. In the teenager, lateral mass screws at C1 and rod fixation were made; C2 pars interarticular screw fixation and C2 pedicle screw fixation. A C2 translaminar screw fixation is described. Occipitocervical fusions were made utilizing rib grafts below the age of 6. A contoured loop fixation was made in children above the age of 7, and recently, rod and screw fixation was also utilized. RESULTS: Abnormal cervical spine growth was not seen in children who underwent craniocervical stabilization below the age of 5. The authors have reserved rigid instrumentation for children above the age of 10 years and dependent on the anatomy.     

A case of Collet-Sicard syndrome associated with traumatic atlas fractures and congenital basilar invagination

An 18 year old man with congenital basilar invagination developed multiple lower cranial nerve (CN) palsies including CN IX to XII after a traffic accident. Computed tomography of his skull base revealed a two part atlas Jefferson fracture. Normally, lower cranial nerves (CN IX-XII) pass through a space between the styloid process and the atlas transverse process. Atlas burst fractures rarely cause neurological deficits because of a greater transverse and sagittal diameter of the spinal canal at the atlas, and a tendency of the lateral masses to slide away from the cord after injury. However, when associated with a rare condition-congenital basilar invagination-atlas fractures can compromise the space and make CN IX-XII more vulnerable to compression injury. This report discusses the correlation between the anatomical lesions and clinical features of this patient.     

Craniocervical developmental anatomy and its implications

Introduction  Congenital and developmental osseous abnormalities and anomalies that affect the craniocervical junction complex can result in neural compression and vascular compromise and can manifest itself with abnormal cerebrospinal fluid dynamics. An understanding of the development of the craniocervical junction is essential to recognize the pathological abnormalities. Materials and methods  Atlas assimilation, segmentation failures, os odontoideum, basilar invagination, and the various syndromes that affect the craniocervical junction have been analyzed. The natural history provides an added insight into its treatment. Results  Proatlas segmentation abnormalities surrounded the foramen magnum and the posterior arch of C1. Hindbrain herniation was associated in 33 of the 90 children involved. Spastic quadriparesis presented in 80% and lower cranial nerve abnormalities in 33%. Vertebrobasilar dysfunction was observed in 40% and trauma presentation seen in 60% of individuals. Atlas assimilation was present in 550 individuals who were evaluated for craniovertebral junction abnormalities. Hindbrain herniation occurred in 38%. Segmentation failure of C2 and C3 vertebrae compounded the abnormal dynamics resulting in atlantoaxial instability. This was a reducible instability with formation of pannus around the odontoid process until it became irreducible at approximately 14 years of age. Unilateral atlas assimilation caused torticollis in children. Os odontoideum was investigated regarding craniocervical trauma at a young age. Conclusion  The conclusion was that os odontoideum was associated with an unrecognized fracture in children below the age of 5 with a previously normal odontoid structure as observed in our series. Atlas and axis abnormalities were reviewed in this series. This large database has provided an understanding of the natural history of many entities and allowed treatment protocols to be established that have stood the test of time.     

Odontoid compression of the brainstem without basilar impression-- "odontoid invagination".

We report five patients with odontoid invagination, in which the odontoid process bulges upward into the foramen magnum and compresses the brainstem without deformity of the occipital bone. Two patients had a craniovertebral abnormality associated with Chiari malformation without instability of the craniovertebral junction (stable odontoid invagination). The other three patients had dislocation of the craniovertebral junction due to iatrogenic destruction of the occipital condyle, rheumatoid arthritis or an anomaly of C2 (unstable odontoid invagination). Patients with stable odontoid invagination underwent a transoral odontoidectomy followed by occipitocervical fixation. Those with unstable odontoid invagination underwent cervical traction followed by posterior fixation in reducible cases, while in irreducible cases odontoidectomy with subsequent occipitocervical fixation was performed. Decompression of the neuraxis together with symptomatic improvement was achieved in all patients and none became unstable or developed new symptoms during follow-up ranging from 3 to 15 years.     

Atlantoaxial joint distraction as a treatment for basilar invagination: a report of an experience with 11 cases

Objective: A novel method of treatment of basilar invagination that involves distraction of the atlantoaxial joint using specially designed spiked spacers is described. Bone graft that is additionally placed within the appropriately prepared atlantoaxial joint and posterior to the arch of atlas and lamina of C2 provides bony fusion. Materials and Methods: Between December 2002 and April 2007, 11 patients underwent the discussed method of fixation at the Department of Neurosurgery, King Edward Memorial Hospital in Mumbai, India. All 11 patients had "congenital" basilar invagination and the symptoms were progressive in nature. Results: The mean follow-up period was 21 months (range 8-40 months). Neurological improvement and successful distraction with atlantoaxial stabilization and ultimate bone fusion was achieved in all the patients and was documented with dynamic radiography. There were no neurological, vascular, or infective complications. Conclusions: We conclude that the described method of atlantoaxial joint distraction and fixation provides an alternative treatment strategy for cases with basilar invagination. "Joint distraction" as a stand-alone method could provide reduction of basilar invagination and firm stabilization in such cases.     

经口齿状突切除联合后路枕颈融合治疗颅底凹陷畸形

目的探讨显微镜下经口齿状突切除联合枕颈融合治疗颅底凹陷畸形的方法、疗效以及并发症。方法回顾性分析昆明医科大学第二附属医院神经外科从2012年9月至2017年5月收治的12例齿状突突压迫延髓及上颈髓腹侧病人的临床资料,其中单纯颅底凹陷1例,颅底凹陷伴Chiari畸形7例,颅底凹陷伴寰枕融合4例,12例患者均行经口齿状突切除联合枕颈植骨融合手术治疗,术后长期跟踪随访,根据影像学参考数值作统计学分析。结果经过6月至2年的随访,术后症状明显缓解8例,肢体感觉无变化3例,1例2月后出现脑脊液漏,经过修补和皮瓣转移治愈,无1例患者出现伤口感染,同时测量每例患者术前及术后影像学上钱氏线,麦氏线,韦氏线,Klaus高度指数、延颈髓角及颅底角的影像学参数值变化,并将影像学数值进行统计学分析,结果提示达到显著统计学意义(P0.01)。结论经口齿状突切除术是治疗齿状突压迫延髓及上颈髓腹侧病变直接有效的手术方法,术中充分磨除齿状突和必要的固定能够促进患者的治愈,提高患者的生活质量。     

Atlantoaxial manual realignment in a patient with traumatic atlantoaxial joint disruption

We report a patient with complex traumatic translatory atlantoaxial dislocation, who we treated by joint exposure and reduction of the dislocation by facet manipulation and subsequent plate and screw atlantoaxial fixation. A 28-year-old male had fallen 7.6 m (25 feet), and following the fall had severe neck pain but no neurological deficit. Investigations revealed a fracture at the base of the odontoid process and posterior displacement of the entire atlas over the axis, resulting in a translatory atlantoaxial dislocation. Head traction failed as he developed severe vertigo following its application. The patient was operated upon in a prone position. We opened the atlantoaxial joint and realigned the facets using distraction and manipulation techniques and secured the joint using a plate and screw interarticular method. The patient tolerated the treatment well and was symptom-free after 28 months. Postoperative images showed good craniovertebral alignment. Although technically challenging, direct manipulation of the facets of the atlas and axis can result in excellent craniovertebral realignment.     

Tactics of surgical treatment for an inflammatory process of C0-C(I)-C(II) segments in the craniovertebral joint instability

Pathological processes of C0-C(I)-C(II) segments, such as the clivus, atlas arch, dens, and body of the C, vertebra pose major problems for diagnosis and treatment. On removal of a sizable pathological focus, there may be instability of the craniovertebral segment, secondary displacement, and spinal compression syndrome. Therefore these patients frequently need stabilization of the craniovertebral transition. Patients with initial instability of the craniovertebral junction and subluxation of C(I)-C(II) segments are an intricate problem. The authors describe a rare case of an inflammatory process of C0-C(I)-C(II) segments with craniovertebtal junction instability. A differential diagnosis was made between chordoma, osteoblastoma, and an inflammatory focus at the above site. The following tactics was undertaken: the first stage was occipitospondylosynthesis with "Vertex" system with osteoplasty under Halo-traction; the second stage included transoral removal of a pathological removal of the dens and body of the C(II) vertebra, left lateral mass of the CI vertebra, and lower clivus. After removal of the pathological focus, there were portions of the abnormally changed bone with rarefaction without tumor tissue. Histologic studies revealed the signs of a chronic inflammatory process. A five-month follow-up showed that neurological symptoms and craniovertebral junction instability regressed. The control computed tomography made 5 months after surgery demonstrated the radical elimination of the pathology and the absence of C, vertebral subluxation. Thus, there is evidence for the tactics of successive operations (a stabilizing operation--posterior occipitospondylosynthesis (desirably under Halo-traction), followed by removal of a pathological focus via transoral access) in pathological processes of the craniovertebral C0-C(I)-C(II) in cases of initial craniovertebral junction instability.     

Management of craniocervical junction dislocation

The discovery of a craniocervical junction malformation requires management in three steps: (1) The patterns must be recognized using tomographic measurements (Chamberlain's line, Wackenheim's line). Dynamic flexion-extension studies are necessary to assess stability or instability. Stable patterns range from platybasia to basilar invagination, with gradual deformation, and are frequently associated with Chiari malformation. Unstable patterns characterized by odontoid instability are the equivalent of an odontoid fracture. The origin is malformative (hypoplasia, aplasia of the dens, os odontoidum), but the last may be difficult to distinguish from an old odontoid fracture. They are found in many syndromes (Down, Morquio, etc.). Unstable atlantoaxial patterns with atlas assimilation are hardly reducible; they evolve toward progressive instability. (2) The neurological consequences must be defined from the clinical features of the spinal cord and the cranial nerves. Both static and dynamic MRI scans must be performed; in this way identification of the neural abnormalities (hydromyelia, Chiari, etc.) and of the osseous compression is possible. (3) The most appropriate operative procedure must be selected: stable platybasia with a nervous compression by Chiari is cured only by posterior decompression; odontoid instability is cured by reduction and posterior fixation, using hooks and autologous bone grafts on the posterior arches of C-1 and C-2. Sometimes a transarticular screw fixation of C1-2 is necessary if there is a defect on the C-1 posterior arch. Craniocervical dislocations with assimilation of the atlas require posterior occipito-vertebral bony fixation with grafts and external halo immobilization or internal fixation with hooks or screws, with anterior transoral decompression in a second step.     

颅颈交界区后路螺钉内固定

目的 报告C2椎弓根螺钉结合C1侧块或枕骨螺钉用于颅颈交界区后路内固定的解剖研究及临床应用结果.方法 福尔马林固定的头颈标本4个,根据解剖标志分别植入C2椎弓根及C1侧块螺钉,然后行CT扫描及重建,观察螺钉位置.2004年5月至2007年1月,利用C2椎弓根一C1侧块/枕骨螺钉内同定9例病人,男4例,女5例,年龄12～68岁,平均38岁;各种原因引起的C1～C2半脱位6例,因颅底凹陷经口腔齿状突切除后1例,斜坡脊索瘤经口腔切除手术前2例;采用C2椎弓根-C1侧块螺钉技术4例,C2椎弓根一枕骨螺钉技术5例,手术后均行CT扫描观察螺钉位置.结果 手术中直接显露C2椎弓根内上缘,并以此确立进钉方向,在椎弓根峡部后缘确定进钉点,可保证C2椎弓根螺钉的安全植入;直接显露C1侧块后正中确立进钉点,可避免螺钉植入过程中的椎动脉损伤.9例病人中,手术后CT复查有2例病人两颗螺钉穿破骨皮质,但末造成血管及神经的压迫,其余螺钉位置均较好;随访4-32个月,1例临床症状较术前无变化,其余8例均改善.结论 C2椎弓根-C1侧块/枕骨螺钉技术可安全有效地用于颅颈交界区内固定.