Complete reduction of retro-odontoid soft tissue mass in os odontoideum following the posterior C1-C2 tranarticular screw fixation.

STUDY DESIGN: A case report of os odontoideum with retro-odontoid soft tissue hypertrophy treated by the transarticular screw fixation. OBJECTIVES: To present a case of os odontoideum that showed complete reduction of retro-odontoid soft tissue mass caused by atlantoaxial subluxation after the C1-C2 transarticular screw fixation. SUMMARY OF BACKGROUND DATA: Hypertrophy of the periodontoid soft tissue has been reported to be associated with chronic atlantoaxial subluxation and progressive myelopathy. While the rheumatoid pannus has been reported to become reduced of disappear after fixation of the unstable segment, the reduction of the hypertrophied soft tissue mass has never been reported in atlantoaxial subluxation of nonrheumatoid origin, especially in the case of os odontoideum. METHODS: Posterior C1-C2 transarticular screw fixation was performed in a patient with os odontoideum, who showed signs of progressive myelopathy by the compression of retro-odontoid soft tissue mass and atlantoaxial subluxation. RESULTS: The fixation of atlantoaxial subluxation achieved not only the complete reduction of the retro-odontoid soft tissue mass, but also clinical improvement of the myelopathy. CONCLUSIONS: Posterior atlantoaxial fixation is worth trying in slow progressing myelopathy by the compression of hypertrophy of the soft tissue even in nonrheumatoid atlantoaxial subluxation, thereby obviating the need for direct removal of the mass via the transoral route.     

Os odontoideum with bipartite atlas and segmental instability: a case report

We report on the case of a 15-year-old adolescent who presented with a transient paraplegia and hyposensibility of the upper extremities after sustaining a minor hyperflexion trauma to the cervical spine. Neuroimaging studies revealed atlantoaxial dislocation and ventral compression of the rostral spinal cord with increased cord signal at C1/C2 levels caused by an os odontoideum, as well as anterior and posterior arch defects of the atlas. The patient underwent closed reduction and posterior atlantoaxial fusion. We describe the association of an acquired instability secondary to an os odontoideum with an anteroposterior spondyloschisis of the atlas and its functional result after 12 months. The rare coincidence of both lesions indicates a multiple malformation of the upper cervical spine and supports the theory of an embryologic genesis of os odontoideum.

     

寰椎后弓椎板钩联合枢椎椎弓根螺钉固定治疗游离齿状突并可复性寰枢椎脱位

背景：游离齿状突并可复性寰枢椎脱位常需要手术治疗,但目前缺乏操作简单且安全有效的寰枢椎内固定方式。 目的：评估寰椎后弓椎板钩联合枢椎椎弓根螺钉固定植骨融合治疗游离齿状突并可复性寰枢椎脱位的疗效。 方法：回顾性分析2005年7月至2012年6月采用寰椎后弓椎板钩联合枢椎椎弓根螺钉固定自体髂骨植骨融合术治疗游离齿状突并可复性寰枢椎脱位患者l1例。对脱位复位情况、内固定植骨融合率、JOA功能评分、影像学评估及术后并发症等进行分析。 结果：11例术中均未发生椎动脉和脊髓损伤。术后均获得随访,随访时间为12~37个月,平均25个月,均未发生内固定物松动、断裂,术后疼痛和神经症状均得到缓解,术后JOA评分较术前明显改善（P＜0.01）,寰枢椎均融合。 结论：寰椎后弓椎板钩联合枢椎椎弓根螺钉固定植骨融合术治疗游离齿状突并可复性寰枢椎脱位是一种安全有效的方法。     

Classification of thoracolumbar fractures and dislocations

To achieve stable fixation of the upper cervical spine in posterior fusions, the occiput is often included. With the newer techniques, excluding fixation to the occiput will retain the occiput–cervical motion, while still allowing a stable fixation. Harms’s technique has been adapted at our institution and its effectiveness for indications such as C2 complex fractures and tumors using C1 or C2 as endpoints of a posterior fixation are reviewed. Fourteen cases were identified, consisting of one os odontoideum; four acute fractures and four non-unions of the odontoid; three tumors and two complex fractures of C2 vertebral body, and one C2–C3 post-traumatic instability. One misplaced screw without clinical consequences was the only complication recorded. Screw loosening or migration was not observed at follow-up, showing a stable fixation.

     

Posterior C1-2 fusion using a polyaxial screw/rod system for os odontoideum with bilateral persistence of the first intersegmental artery

The authors report the case of a patient with os odontoideum, myelopathy secondary to atlantoaxial instability, and bilaterally persistent first intersegmental artery at the craniovertebral junction. Instead of occipitocervical fusion, C1-2 posterior fusion was performed using a polyaxial screw/rod system. The information obtained from 3D CT angiography studies may highlight the potential risk of vertebral artery injury in advance and reduce the risk of an intraoperative vertebral artery injury. In addition, C-1 lateral mass screw placement may be a safe procedure for cases of atlantoaxial subluxation in which there are persistent C-1 intersegmental arteries.     

The options of C2 fixation for os odontoideum: a radiographic study for the C2 pedicle and lamina anatomy

Introduction  

Patients with os odontoideum always present instability in atlantoaxial joint and need atlantoaxial fixation. C2 pedicle or laminar screws fixation has proven to be efficient and reliable for atlantoaxial instability. However, os odontoideum is a congenital or developmental disease, featured with anomalous bony anatomies. The anatomic measurements and guidelines for C2 pedicle screw placement in general population tends to differ with those of os odontoideum patients, for whom C2 pedicle screws are often needed. The option and techniques of C2 fixation are still challenging and yet to be fully explored.     

后路融合术治疗齿状突游离小骨并寰枢椎不稳

目的通过临床病例回顾,分析后路融合内固定术治疗齿状突游离小骨合并寰枢椎不稳的临床特点及疗效,为临床诊疗提供参考。方法 2006年10月至2008年12月,采用后路寰枢椎融合或枕颈融合术治疗合并寰枢椎不稳的齿状突游离小骨57例,男34例,女23例。年龄13～71岁,平均37.4岁。有明确外伤病史者41例。55例存在不同程度的脊髓压迫症状。术前ASIA（American Spinal Injury Association）脊髓神经功能分级：B级3例,C级33例,D级19例,E级2例。结果随访时间6～60个月,平均26个月。51例获得骨性融合,6例发生延迟愈合。无因手术操作致椎动脉和脊髓损伤病例。无内固定脱落、断裂、退钉等并发症。所有病例枕颈部症状消失,术后ASIA脊髓神经功能分级：C级5例,D级35例,E级17例。结论术前认真分析,选择合适的后路融合术式能有效治疗齿状突游离小骨合并寰枢椎不稳,减少手术并发症。     

A retrospective study of congenital osseous anomalies at the craniocervical junction treated by occipitocervical plate-rod systems

Purpose

To evaluate the effectiveness of posterior occipitocervical reconstruction using the anchors of cervical pedicle screws and plate-rod systems for patients with congenital osseous anomalies at the craniocervical junction.

Methods

Twenty patients with congenital osseous lesions who underwent posterior occipitocervical fusion using the anchors of cervical pedicle screws and plate-rod systems for reduction and fixation from 1996 to 2009 were reviewed. The lesions included os odontoideum, occipitalization of the atlas, congenital C2–3 fusion, congenital atlantoaxial subluxation, congenital basilar invagination and combined anomalies. The clinical assessment and the measurements of the images were performed preoperatively, postoperatively and at most recent follow-up.

Results

The combined deformity of flexion of the occipitoatlantoaxial complex and invagination of the odontoid process associated with congenital osseous lesions at the craniocervical junction was corrected by application of combined forces of extension and distraction between the occiput and the cervical pedicle screws. Preoperative myelopathy improved in 94.7 % patients. The mean Ranawat value, Redlund-Johnnell value, atlantodental distance, occiput (O)–C2 angle, and C2–C7 lordosis angle improved postoperatively and was sustained at most recent follow-up. The mean cervicomedullary angle improved from 129.3° preoperatively to 153.3° postoperatively. The mean range of motion at the lower adjacent motion segment remained unchanged at most recent follow-up. The fusion rate was 95 %.

Conclusions

The results of the present study indicate that posterior occipitocervical reconstruction using the anchors of cervical pedicle screws and plate-rod systems is an effective technique for treatment of deformities and/or instability caused by congenital osseous anomalies at the craniocervical junction.     

Ⅰ期前后路联合手术治疗游离齿突继发的难复性寰枢椎脱位

目的探讨颈高位咽后入路前路松解、Ⅰ期后路融合治疗游离齿突继发的难复性寰枢椎脱位的临床效果。方法本组19例均为游离齿突继发的难复性寰枢椎脱位,X线片动态位不能自行复位,且术前颅骨牵引均未获得满意复位。采用颈高位咽后入路显露C1～C3,行寰枢椎前方松解复位,Ⅰ期后路寰枢融合内固定。结果 19例患者采用颈高位前方咽后入路均成功显露C1前弓～C3椎体,前路松解后复位良好,Ⅰ期行后路寰枢融合内固定,全组无一例出现脊髓损伤加重、咽喉部阻塞或窒息。1例颈后部伤口积液感染,经换药引流后痊愈;2例出现舌下神经牵拉症状,1例出现面神经刺激症状,均在1个月后恢复正常。脊髓功能正常者无神经功能损害,不全瘫患者神经功能均有部分恢复。随访植骨均获骨性融合,无内固定松脱。结论颈高位咽后入路行前方松解能够复位游离齿突继发的难复性寰枢椎脱位患者,Ⅰ期后路寰枢融合可获良好的植骨融合。     

Fusion of the upper cervical spine in children and adolescents. An analysis of 17 patients.

A retrospective review of 17 immature patients who underwent posterior spinal fusion of C1-C2 or C1-C3 was performed to establish the efficacy of the procedure, to determine the incidence of complications, and to identify those at high risk for complications. All had radiographic C1-C2 instability or dislocation. Etiologies included os odontoideum, fixed rotatory subluxation, atlantoaxial subluxation, type II dens fracture nonunion, and nonunion of a Hangman's fracture. Before surgery, 10 patients were neurologically intact, and seven had neurologic findings. Associated diagnosis included Down's syndrome in three and Ehler-Danhlos in one. Follow-up averaged 25 months. One neurologically intact patient had a C2 radiculopathy that resolved by 1 year. Three patients with Down's syndrome had complications: one with a preoperative Brown-Sequard syndrome had transient worsening in the immediate postoperative period, one with a preoperative myelopathy developed a late recurrence of a severe myelopathy that required odontectomy, and another sustained an intraoperative spinal cord contusion followed by postoperative quadriplegia and death due to respiratory failure. Of seven reporting neurologic symptoms before surgery, two had residual deficit in the late postoperative period. These two represented preventable technical errors. There were two nonunions, one of which required occiput to C2 fusion. In general, posterior spinal fusion of the upper cervical spine was found to be a reliable, safe, and predictable procedure, but extra caution should be employed when considering arthrodesis in patients with ongoing spinal cord compression, fixed dislocations, and inherited ligamentous laxity.     

Multidirektionale atlantoaxiale Instabilität bei adultem Os odontoideum

Increasing neck pain in a 29 year old woman after a frontal car collision gave reason for a conventional x-ray that presented a traumatically displaced os odontoideum positioned at the top of the dens axis. No neurological defect was seen. Dynamic flexion/extension film showed a movement to an atlantoaxial dislocation with a shift of the os odontoideum. The sclerotic structure of the corresponding bony surfaces was confirmed by computed tomography, whereas magnetic resonance imaging demonstrated a posttraumatic signal change in front of the base of dens axis and os odontoideum.Fusion was achieved by computed navigation with C1/C2 transfacetal screws as described by Magerl and interspinal fusion with a bicortical autologous iliac crest graft and a posterior tension band as described by Brooks. An exact positioning of screws past the asymmetric course of both arteria vertebrales was possible by navigation. The patient was free of pain 5 months after the fusion.     

Os odontoideum with posterior atlantoaxial instability

Nine patients who had os odontoideum with posterior atlantoaxial instability are reviewed. Three parameters were measured on the lateral radiographs: the distance from the os odontoideum to the spinous process of the axis in extension (Dext), the distance from the os odontoideum to the posterior arch of the atlas (Datl), and the degree of instability (Inst). Patients were classified into four groups: Group I, local symptoms (N = 3); Group II, transient myelopathy (N = 0); Group III, progressive myelopathy (N = 6); and Group IV, cerebral symptoms (N = 0). The development of cervical myelopathy was not related to degree of instability but to distance from the os to the spinous process of the axis (Dext). Dext was more than 16 mm in Group I and less than or equal to 16 mm in Group III. Five of six patients in Group III underwent myelography. Based on myelographic findings, Group III was further subdivided into two groups, Group IIIA (N = 2) and Group IIIB (N = 3), according to the following characteristics: In Group IIIA, the distance from the os to the posterior arch of the atlas was more than 13 mm, and the spinal cord was impinged between the os odontoideum and the lamina of the axis in extension and reduced in flexion. In Group IIIB, Datl was less than or equal to 13 mm, and the spinal cord was compressed at the level of the atlas during flexion and extension. Stenotic Datl of 13 mm or less specifically defined severe cervical myelopathy. Surgical treatment for cervical myelopathy in os odontoideum with posterior instability is suggested as follows: in the absence of canal stenosis of the atlas (Group IIIA), atlantoaxial fusion in a reduced position is indicated; when associated with canal stenosis of the atlas (Group IIIB), laminectomy of the atlas followed by occiput-to-C2 arthrodesis is indispensable.     

Synovial cyst of the transverse ligament of the atlas in a patient with os odontoideum and atlantoaxial instability

STUDY DESIGN: A case report and review of the literature. OBJECTIVE: To describe the diagnosis and successful treatment of a synovial cyst arising from the transverse ligament in a patient with os odontoideum and atlantoaxial instability. SUMMARY OF BACKGROUND DATA: Synovial cysts arising from the transverse ligament of the atlas are extremely rare. Development of a synovial cyst is thought to be attributable to degenerative changes of the C1-C2 facet joints or to microtrauma. Direct excision of the cyst is the only treatment cited in previous reports. METHODS: A synovial cyst arising from the transverse ligament of the atlas in a 45-year-old man with os odontoideum and atlantoaxial instability was treated surgically with posterior atlantoaxial fusion alone. The magnetic resonance images, surgical treatment, and related literature are reviewed. RESULTS: Preoperative magnetic resonance images of the cervical spine showed a large cystic mass located ventral to the cord arising at the level of the transverse ligament of the atlas: the mass was of low signal intensity on T1-weighted images, was of high signal intensity on T2-weighted images, and was enhanced marginally with gadolinium-DTPA on T1-weighted images. Spontaneous regression of the cyst was identified on the follow-up magnetic resonance images taken 3 months after C1-C2 posterior wiring and fusion. CONCLUSIONS: A patient with a synovial cyst arising at the C1-C2 junction ventrally at the level of the transverse ligament showed spontaneous regression of the lesion after C1-C2 posterior wiring and fusion.     

Os odontoideum with cerebellar infarction: a case report

STUDY DESIGN: A case report. OBJECTIVES: To report the case of a child with os odontoideum associated with cerebellar infarction and to discuss the correlation between atlantoaxial instability with os odontoideum and vertebrobasilar artery insufficiency. SUMMARY OF BACKGROUND DATA: Knowledge of the influence of atlantoaxial instability on vertebrobasilar artery insufficiency remains limited despite the publication of several reports. METHODS: A 5-year-old boy with ataxic gait disturbance was hospitalized in the pediatric ward. Magnetic resonance imaging revealed multiple cerebellar infarctions, and cerebral angiogram showed occlusions of several branches of the basilar artery and a winding of the left vertebral artery. Stress lateral radiographs of the cervical spine showed atlantoaxial instability with os odontoideum. Posterior C1-C2 transarticular screw fixation with iliac bone graft was applied to obtain firm stability and fusion. RESULTS: There was no damage to the vertebral arteries or spinal nerves in the perioperative period. Solid union of the grafted bone and rigid stability of the atlantoaxial joint were seen on lateral flexion-extension radiographs 1 year after the operation. There has been no sign of recurrent arterial insufficiency, and the patient has been free from cerebellar dysfunction to date. CONCLUSIONS: Atlantoaxial instability may cause insufficiency of the vertebral artery as well as spinal cord injury. More attention should be paid to the possible relation between atlantoaxial instability and vertebrobasilar artery insufficiency.     

前路松解复位后路融合治疗游离齿突继发环枢椎脱位

目的: 探讨经高位咽后入路前路松解、后路融合治疗游离齿突继发的难复性环枢椎脱位。方法: 本组 3例, 均为男性, 年龄 17~36岁, 无明显创伤史, 颅骨牵引 2~3周, 采用高位咽后入路显露C1~3, 行环枢前方松解复位, Ⅰ期后路环枢融合, Brooks法钛缆内固定。结果: 3例游离齿突继发的难复性环枢椎脱位, 术前颅骨牵引不能复位, 经前路手术松解达到良好复位, 后路环枢融合良好, 内固定无松脱, 无伤口感染。3例患者神经症状均明显改善。结论: 经高位咽后入路行前方松解, 能够复位游离齿突继发的难复性环枢椎脱位, Ⅰ期后路环枢融合可获良好的植骨融合。     

Ossification of the posterior atlantoaxial membrane associated with an os odontoideum: a case report

We report a case of ossification of the posterior atlantoaxial membrane associated with an os odontoideum in a 46-year-old woman. She developed myelopathy following a minor motor vehicle accident. The patient underwent posterior atlantoaxial arthrodesis and resection of the ossified lesion and recovered uneventfully. Long-standing atlantoaxial instability might have played a role in ectopic ossification of the posterior atlantoaxial membrane.     

Os odontoideum: Etiology, symptoms and therapy

Summary The etiology of os odontoideum is still controversial. In most patients, it is found by accident because of neurological symptoms and/or painful range of motion of the cervical spine. Upon recognition of the os odontoideum, it is unknown whether or not immediate surgery is beneficial. This is in contrast to an “unstable” os odontoideum, which could result in atlantoaxial instability or compression of the myelon. In this study, we present the results of our treatment of four patients with an unstable os odontoideum. In all four cases, a C1-2 fusion was performed (3 × Magerl/Seemann, 1 Gallie-Brooks). Postoperatively, we found a complete regression of neurological symptoms in three patients and one was significantly improved. The range of motion of the cervical spine was free of pain in all patients. As a result, we strongly support immediate surgical treatment of an unstable os odontoideum in order to prevent severe and life-threatening neurological complications.      

游离齿状突并发寰枢关节脱位的治疗策略及疗效分析

目的:探讨游离齿状突并发寰枢关节脱位的治疗策略并观察其临床疗效.方法:回顾性分析2006年1月至2015年1月手术治疗的17例齿状突游离小骨并发寰枢关节脱位患者的相关资料,其中男7例,女10例;年龄17～53(43.1±11.3)岁;病程3～27(10.2±6.9)个月.所有患者术前予颅骨牵引,14例可复性脱位患者中1...     

Outcomes of C1 and C2 posterior screw fixation for upper cervical spine fusion

To achieve stable fixation of the upper cervical spine in posterior fusions, the occiput is often included. With the newer techniques, excluding fixation to the occiput will retain the occiput–cervical motion, while still allowing a stable fixation. Harms’s technique has been adapted at our institution and its effectiveness for indications such as C2 complex fractures and tumors using C1 or C2 as endpoints of a posterior fixation are reviewed. Fourteen cases were identified, consisting of one os odontoideum; four acute fractures and four non-unions of the odontoid; three tumors and two complex fractures of C2 vertebral body, and one C2–C3 post-traumatic instability. One misplaced screw without clinical consequences was the only complication recorded. Screw loosening or migration was not observed at follow-up, showing a stable fixation.     

Os odontoideum with cervical mylopathy due to posterior subluxation of C1 presenting sleep apnea

Sleep apnea is a breathing disorder that manifests as repetitive cessation of breathing during sleep. It has been reported that patients with upper cervical lesions caused by rheumatoid arthritis [1–5], Arnold-Chiari type 1 malformation [6] and anterior C1-2 osteochondroma [7] have sleep apnea. Os odontoideum is characterized by the radiolucent defect between the dens and the body of the axis. In some cases with os odontoideum, C1 is very unstable and causes compression of the spinal cord at the upper cervical level. We encountered a patient with os odontoideum presenting as sleep apnea. The patient had cervical myelopathy caused by posterior subluxation of C1. Spinal cord atrophy due to the compression was marked at the C1–2 level. To our knowledge, there are no reports of such a case. Here, we present the clinical findings of this patient, and the pathogenesis of sleep apnea is discussed.