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.     

High cervical C3-4 'disc' compression associated with basilar invagination

A 20-year-old male had torticollis and short neck since birth. He presented with symptom of progressive quadriparesis over a two-year period. Investigations revealed basilar invagination with marked rotation in the craniovertebral region and relatively large C3-4 region osteophytes. Serial MRI over two years showed persistent signal opposite C3-4 disc space suggestive of cord compression. Although the cord was humped over the odontoid process, there was no clear radiological evidence that the cord was compromised at this level. During surgery, instability was identified only at the craniovertebral region and not at the level of C3-4. Distraction of the lateral masses of atlas and axis and fixation using interarticular spacers and bone graft and direct screw implantation in the lateral mass of the atlas and pars of the axis resulted in reduction of the basilar invagination and of atlantoaxial dislocation. The patient had marked clinical recovery, despite the fact that no direct procedure was done for C3-4 disc decompression. The case suggests that C3-4 disc changes could be secondary to primary instability at the craniovertebral junction.     

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.     

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.     

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。     

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.     

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.     

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.     

复杂颅底凹陷畸形的外科治疗

目的分析总结复杂颅底凹陷畸形的临床表现及治疗方法。方法根据临床表现和影像学特征,对我院近9年经手术治疗的30例复杂颅底凹陷畸形病例分为Ⅰ组、Ⅱ组,Ⅰ组行后方入路枕下减压术和／或枕颈植骨融合内固定术,Ⅱ组行前路经口齿状突切除术和枕颈植骨融合内固定术。结果Ⅰ组17例有效率85％,Ⅱ组13例有效率83％。结论对于不同类型的复杂颅底凹陷畸形患者,选择不同的手术方式,对于提高术后疗效有重要作用。     

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.     

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.     

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.     

后路复位内固定并颅后窝小骨窗减压治疗合并颅底凹陷、寰枢椎脱位和脊髓空洞症的ChiariⅠ型畸形

研究背景ChiariⅠ型畸形为颅颈交界区软组织畸形,可合并其他复杂骨性畸形如寰枢椎脱位、颅底凹陷、扁平颅底及寰枕融合等.对这些复杂畸形,目前尚无成熟的治疗方法.本文探讨颅后窝小骨窗减压并Ⅰ期经后路复位内固定术治疗合并颅底凹陷、寰枢椎脱位和脊髓空洞症的ChiariⅠ型畸形的临床疗效.方法 回顾分析2004 年7 月-2011 年9 月治疗的寰枢椎脱位和颅底凹陷患者临床资料,分别采用日本骨科协会(JOA)17 分评分系统和MRI 影像学数据评价颈脊髓功能和脊髓空洞改善程度.结果 根据纳入标准,共筛选14 例符合入组条件的患者,男性4 例,女性10 例;平均年龄为(31.86 ±11.36)岁.术前JOA 评分平均为13.07 ± 1.59,术后增加至15.57 ± 1.02,二者比较差异具有统计学意义(t = 9.946,P = 0.000);术前脊髓空洞大小平均为(7.05 ± 1.98)mm,术后缩小至(2.21 ± 1.91)mm,手术前后比较差异亦有统计学意义(t = 7.271,P = 0.000).手术后无一例发生并发症或死亡.结论 经后路复位内固定联合颅后窝小骨窗减压术治疗合并脊髓空洞症、寰枢椎脱位及颅底凹陷的ChiariⅠ型畸形能够显著改善患者预后、缩小脊髓空洞.     

寰枕融合畸形患者寰枢侧块关节形态变化与寰枢椎脱位的三维特征

目的 分析寰枕融合畸形伴寰枢椎脱位时侧块关节的形态学变化与脱位的三维特征. 方法 寰枕融合畸形伴寰枢椎脱位患者36例行螺旋CT扫描后.数据以DICOM格式传送至三维可视化工作站.重建颅颈交界区三维模型,按照骨性畸形、寰齿关节、侧块关节的次序观察骨性畸形及寰枢椎脱位的三维特征. 结果 寰枢侧块关节呈关节滑脱者57侧(79%)、关节整体变形前倾者61侧(85%)和关节面分离者11侧(15%).对照两侧对称或不对称侧块关节的形态变化与脱位时寰椎与枢椎的三维位置关系,本组寰枢椎脱位的三维分型可归纳为三种:对称N(14/36例,39%),为两侧寰枢椎侧块关节呈大致对称的关节滑脱和关节整体变形前倾;旋转型(13/36例,36%),为两侧寰枢侧块关节呈显著不对称的关节滑脱和关节整体变形前倾;分离型(9/36例,25%),为至少一侧侧块关节出现关节面的完全分离. 结论 寰枕融合畸形时先天性的关节发育异常、继发的关节变形以及韧带的疲劳拉伸等多种因素及其相互作用是寰枢椎脱位发生的根本原冈.采用三维可视化方法直观地观察和分析寰枢椎脱位及寰枢侧块关节形态,对于手术决策和内固定方案选择等具有重要价值.     

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.     

后路复位内固定并颅后窝小骨窗减压治疗合并颅底凹陷、寰枢椎脱位和脊髓空洞症的ChiariI型畸形

研究背景ChiariI型畸形为颅颈交界区软组织畸形,可合并其他复杂骨性畸形如寰枢椎脱位、颅底凹陷、扁平颅底及寰枕融合等。对这些复杂畸形,目前尚无成熟的治疗方法。本文探讨颅后窝小骨窗减压并I期经后路复位内固定术治疗合并颅底凹陷、寰枢椎脱位和脊髓空洞症的ChiariI型畸形的临床疗效。方法回顾分析2004年7月-2011年9月治疗的寰枢椎脱位和颅底凹陷患者临床资料,分别采用日本骨科协会（JOA）17分评分系统和MRI影像学数据评价颈脊髓功能和脊髓空洞改善程度。结果根据纳入标准,共筛选14例符合入组条件的患者,男性4例,女性10例;平均年龄为（31．86±11．36）岁。术前JOA评分平均为13．07±1．59,术后增加至15．57±1．02,二者比较差异具有统计学意义（t=9．946,P=0．000）;术前脊髓空洞大小平均为（7．05±1．98）mm,术后缩小至（2．21±1．91）mm,手术前后比较差异亦有统计学意义（t=7．271,P=0．000）。手术后无一例发生并发症或死亡。结论经后路复位内固定联合颅后窝小骨窗减压术治疗合并脊髓空洞症、寰枢椎脱位及颅底凹陷的ChiariI型畸形能够显著改善患者预后、缩小脊髓空洞。     

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。     

Somatosensory and brainstem auditory evoked potential in congenital craniovertebral anomaly; effect of surgical management.

Clinical features and evoked potential recordings were analysed in 32 patients with congenital atlantoaxial dislocation before and after surgery. Seven patients (group 1) had atlantoaxial dislocation, while 22 patients had associated basilar invagination (group 2). In both groups, pyramidal tract signs, posterior column signs, wasting of the upper limbs, and abnormality of somatosensory evoked potentials (SSEP) were similar. Conversely, lower cranial nerve involvement and abnormal brainstem auditory evoked potentials (BAEP) were significantly more in patients with basilar invagination (p less than 0.05). All seven patients in group 1 and 17 patients in group 2 were operated upon. Clinical and electrophysiological deterioration were significant in patients with basilar invagination (group 2), following posterior fixation compared with group 1. Among the patients in group 2, who clinically deteriorated following posterior fixation, seven had transoral excision of odontoid and six of them improved both clinically and electrophysiologically. Two patients in group 2 had odontoid excision before posterior fixation, and in both the evoked potentials improved postoperatively. In group 1 the patient's BAEP remained unaffected following posterior fixation, however, in group 2, eight patients over 53% showed improvement in brainstem function following posterior fixation. This study shows the value of evoked potentials in congenital atlantoaxial dislocation, and rationalizes the surgical procedure in these patients. In patients with basilar invagination, odontoid excision is the preferred first stage procedure.     

Chiari畸形合并颅颈交界畸形的处理策略

目的 探讨Chiari畸形合并颅颈交界畸形的临床特点及治疗方法.方法 回顾性分析56例Chiari畸形合并颅颈交界畸形的临床资料,其中合并颅底陷入35例,寰枕融合25例,颈椎分节不全6例.病人均行颅后窝减压硬脑膜扩大修补术,行小脑扁桃体部分切除术21例.固定方式采用钛缆固定和自体骨移植41例,C<,1>侧块～C<,2>椎弓根螺钉固定和自体骨移植15例.结果 术后发生颅内感染2例,脑脊液切口漏1例.55例随访6～60个月,平均42个月;植骨融合满意52例,钛缆固定和自体骨移植植骨未能融合3例;症状改善51例(92.7%),无变化4例(7.3%);随访期间无死亡病例.结论 Chiari畸形合并颅颈交界畸形应行颅颈交界关节稳定性检查及评估,对有潜在颅颈交界不稳定病人应行后路减压并枕颈植骨固定融合术,单纯后路减压可能加重颅颈交界不稳定,症状难以缓解甚至加重.