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.     

Posterior atlantoaxial subluxation due to os odontoideum combined with cervical spondylotic myelopathy : a case report

In patients with os odontoideum and posterior atlantoaxial subluxation are extremely rare. No reports have described posterior atlantoaxial subluxation associated with os odontoideum combined with cervical spondylotic canal stenosis, both of which require surgical treatment. We report one case of a 75-year-old female who underwent arthrodesis between the occiput and C3 using a hook-and-rod system and also a double-door laminoplasty from levels C3 to C7. The claw mechanism was applied between the C2 lamina and the C3 inferior articular process. The posterior atlantoaxial subluxation was completely reduced by the method that the rod gradually pushed the posterior arch of C1 anteriorly during connection to the occiput. Twelve months after surgery, the patient showed improvement in preoperative clumsiness and gait disturbance, and the latest plain radiographs showed solid osseous fusion, with no loss of correction or instrumentation failure.

     

Upper cervical spine instability in pseudoachondroplasia

BACKGROUND: Pseudoachondroplasia (PSACH) is a rare autosomal dominant skeletal dysplasia associated with os odontoideum and atlantoaxial instability. This study aims to define the characteristics of upper cervical spine instability in patients with PSACH and analyze the relation between the incidence of upper cervical instability and os odontoideum. METHODS: Fifteen patients (10 women and 5 men) with PSACH of Korean ethnicity with mean age of 23.7 years (range, 3-44 years) at presentation to our hospital with varied complaints, including short stature, limb deformity, neck pain, and neurological symptoms, were evaluated clinicoradiologically for upper cervical spine instability. The patients were separated into group 1 (n = 9) with os odontoideum and group 2 (n = 6) without os odontoideum. Comparisons were made using parameters such as instability index, rotational instability, atlantodens interval and space available for cord, and analysis done to correlate cervical instability with age and Japanese Orthopedic Association (JOA) score. RESULTS: Significant differences were found statistically when the 2 groups were compared on the basis of the space available for the cord (SAC), JOA scoring, and rotational instability. Linear relationship was found between instability and age and JOA score. Incidence of os odontoideum was 60% in our study group. CONCLUSIONS: Os odontoideum led to an increase in the incidence of upper cervical spine instability. Instability increased with the age. The presence of os odontoideum and atlantoaxial instability did not warrant for surgery because no signs of cervical myelopathy developed or progressed in our patients during the follow-up period, but these patients should undergo regular clinical and radiological evaluation. LEVEL OF EVIDENCE: Level IV prognostic study.     

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。     

Symptomatic cervical synovial cyst associated with an os odontoideum diagnosed by magnetic resonance imaging: case report and review of the literature

STUDY DESIGN: The first case of a synovial cyst of the upper cervical spine associated with os odontoideum diagnosed by magnetic resonance imaging is presented. OBJECTIVES: To evaluate distinct magnetic resonance imaging findings of a cervical synovial cyst located anterior to the cord and discuss its association with os odontoideum. These findings may guide further investigations. BACKGROUND: Synovial cysts of the spine are uncommon findings. They occur mostly dorsolaterally and with greatest frequency in the lumbar spine and are rarely symptomatic. No association with os odontoideum has been reported before. METHODS: A single subject with symptoms of deterioration in his hand functions was examined by a 2. 0-T magnetic resonance imager. RESULTS: Magnetic resonance imaging of the cervical spine showed an os odontoideum connected to the body of C2 by a synovial joint that had a cystic extension posteriorly compressing the cord. CONCLUSION: Synovial cysts should be considered in the differential diagnosis of an extradural mass of the upper cervical spine. Magnetic resonance imaging should be the choice in the investigation of such cases.     

高位颈椎的前路手术治疗

目的观察高位颈椎前路手术的临床效果,方法本组15例．男10例,女5例．年龄12—67岁。C1,2椎体结核3例．Hangman 7例,先天性齿状突不连伴难复性环椎脱位3例,齿状突骨折2例。本组经高位前方咽后入路显露C2-3,椎体结核患者行病灶清除术．先天性齿状突不连者行前路松解复位．后路环枢融合;Hangman骨折。复位后行C2,3椎间植骨融合术．放自锁钛板内固定,齿状突骨折行前路中空螺钉内固定。结果15例患者均成功地显露C1前弓至C3椎体,并完成病灶清除、复位、减压融合内固定：无颈部重要血管神经损伤,无伤口感染．9例不全瘫有部分恢复。结论高位前方咽后入路可充分显露上颈椎．高位颈椎前路术式能有效复位、减压和稳定,并可最大程度重建颈椎生理功能。     

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.      

Pediatric atlantoaxial instability presenting as cerebral and cerebellar infarcts

Atlantoaxial instability can lead to severe, permanent neurologic compromise and death if not treated by cervical fusion. However, identification of atlantoaxial subluxation can be difficult owing to the often confusing signs and symptoms. We describe a patient with unexplained transient repeated cerebral and cerebellar signs who had 10 mm of translation of the atlas on the axis owing to os odontoideum with infarcts in the cerebellum and occipital parietal lobes. These correlated with angiographically documented vertebral artery narrowing at the level of the axis and the subsequent low flow to the posterior cerebellum. After stabilization and fusion of the cervical spine, the patient regained normal neurologic function and has remained symptom-free at 2 years of follow-up.     

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。     

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.     

Cervical instability presenting as thoracic pain: case report and literature review

Study design

Case report.

Objective

To report a case of cervical instability from an os odontoideum that presented as posterior thoracic pain and to present a review of the literature.

Background

Thoracic posterior paraspinal spasms and pain are common chief complaints in individuals with spinal abnormalities.

Methods

A 19-year-old man presented with posterior thoracic pain for nearly 1 year following a college sports-related injury (lacrosse). Computed tomography and magnetic resonance imaging did not reveal any significant thoracic or lumbar spinal cord or nerve root pathology, but did reveal an incidental finding of an os odontoideum.

Results

Surgical stabilization of the atlantoaxial instability resulting from the os odontoideum resulted in complete resolution of the patient''s thoracic pain.

Conclusions

Thoracic back pain without a clear thoracic spine etiology warrants further workup to rule out the possibility of spinal instability.     

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.     

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.

     

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。     

难复性寰枢关节脱位的手术治疗

目的探讨难复性寰枢关节脱位的手术治疗方法。方法54例难复性寰枢关节脱位患者,男32例,女22例;年龄7～63岁,平均32岁。其中齿突不连18例,寰椎枕骨化畸形22例,齿突骨折畸形愈合5例,寰椎横韧带松弛9例。40例有脊髓病或脊髓损伤的症状、体征。先行经口咽入路的寰枢关节松解复位术,术中横断挛缩的椎前肌、前纵韧带和侧块关节囊,借助于牵引和器械撬拨的力量使寰枢关节复位;同期行后路寰枢或枕颈固定植骨融合术,后路固定方法包括经寰枢侧块关节螺钉固定5例、寰枢侧块钉板固定12例和借助于枢椎椎弓根螺钉与枕颈固定板的枕颈固定37例。术后不用外固定。结果41例获得解剖复位;13例部分复位,其中2例行部分齿突切除,另11例术前颈髓角平均104.1°,术后120.2°。48例随访4～40个月,平均15.7个月,全部病例均获骨性融合。术前有脊髓症状的38例术后功能评价(Odom标准)为优15例,良14例,可8例,差1例。术中出现硬膜破裂1例,椎弓根钉切割1例;术后出现呼吸衰竭1例,发音不正常3例,吞咽不利1例,术后2周发生败血症脊髓炎致瘫痪1例,术后2个月内固定松动1例。结论经口咽入路寰枢关节松解复位结合后路坚强内固定及植骨融合,对难复性寰枢关节脱位有良好的治疗效果。     

Os Odontoideum: A Cause of Atlanto-Axial Instability

Os odontoideum is a rare condition in which instability may damage the upper cervical cord. A delay in diagnosis is not uncommon. This paper describes a series of 11 patients with os odontoideum. The presenting symptoms were divided into three groups: posttraumatic neck-pain, gradually appearing signs of medullary compression and an asymptomatic group. Eight patients had atlanto-axial instability. Six had interlaminar fusion between atlas and axis. No serious complications were seen. Stability was obtained in all patients postoperatively. In case of significant instability, fusion is indicated. In patients with cerebral palsy a closer examination of the upper cervical cord is recommended.     

Atlantoaxial Subluxation in Different Intraoperative Head Positions in Patients with Rheumatoid Arthritis

Background: Disorders of the cervical spine are often observed in patients with rheumatoid arthritis (RA). However, the best head position for RA patients with atlantoaxial subluxation in the perioperative period is unknown. This study investigated head position during general anesthesia for the patients with RA and proven atlantoaxial subluxation.

Methods: During anesthesia of patients with RA and proven atlantoaxial subluxation, the authors used fluoroscopy to obtain a lateral view of the upper cervical spine in four different positions: the mask position, the intubation position, the flat pillow position, and the protrusion position. Copies of the still fluoroscopic images were used to determine the anterior atlantodental interval, the posterior atlantodental interval, and the angle of atlas and axis (C1-C2 angle).

Results: The anterior atlantodental interval was significantly smaller in the protrusion position (2.3 mm) than in the flat pillow position (5.1 mm) (P < 0.05). The posterior atlantodental interval was significantly greater in the protrusion position (18.9 mm) than in the flat pillow position (16.2 mm) (P < 0.05). The C1-C2 angle was, on average, 9.3[degrees] greater in the protrusion position than in the flat pillow position (P < 0.05).     

Surgical management of symptomatic os odontoideum with posterior screw fixation performed using the magerl and harms techniques with intraoperative 3-dimensional fluoroscopy-based navigation

STUDY DESIGN.: Retrospective case series. OBJECTIVE.: To evaluate the accuracy of screw fixation using intraoperative three-dimensional fluoroscopy-based navigation (ITFN) and to assess the clinical outcomes of this treatment regimen. SUMMARY OF BACKGROUND DATA.: The surgical management of symptomatic os odontoideum poses considerable difficulties due to the highly variable anatomy of the upper cervical spine and surrounding neurovascular structures. Various methods have been described for the treatment of symptomatic os odontoideum, all of which have limitations. METHODS.: Nineteen patients with symptomatic os odontoideum were investigated. Pain scores were assessed using the visual analogue scale. Myelopathy was assessed using the Nurick scale and Odom's criteria. Radiological imaging was carried out in all patients for diagnosis and to assess the atlantodens interval, space available for cord, and presence of intramedullary hyperintensity signals on T2-weighted images at the C1-C2 level. Posterior stabilization was performed for all patients by using ITFN. RESULTS.: The mean Nurick score improved from 2.3 before surgery to 0.7 at the time of follow-up. The mean follow-up period was 34.7 months (range, 12-65 mo). According to Odom's criteria, outcomes were as follows: excellent, 47%; good, 37%; fair, 11%; and poor, 5%. All patients with preoperative neck pain had symptom relief or improvement, with all of these patients having more than 83.7% improvement in visual analogue scale scores. The mean preoperative space available for cord value of 9.3 mm improved to 17.7 mm. Solid fusion and reduction of atlantoaxial dislocation were achieved in every patient without screw failure. Sixty screws were placed in 19 patients. Two C2 polyaxial screws in 2 patients and 1 transarticular screw in 1 patient slightly penetrated the transverse foramen with no vascular injury and clinical sequelae. CONCLUSION.: ITFN is a safe, accurate, and effective tool for screw placement in patients with symptomatic os odontoideum.     

枢椎椎板螺钉在上颈椎后路固定术中的应用

目的探讨枢椎椎板螺钉固定术应用于上颈椎后路融合内固定术中的可行性。方法回顾性分析本院2012年1月—2014年12月在上颈椎后路融合固定术中采用枢椎椎板螺钉固定的19例患者资料,术中根据枢椎椎弓根是否存在缺如、细小等情况,选择置入双侧枢椎椎板螺钉或单侧枢椎椎板螺钉并对侧椎弓根螺钉,联合枕骨板螺钉和/或寰椎侧块螺钉。15例上颈椎畸形患者均有不同程度脊髓功能损害表现,日本骨科学会(JOA)评分为5~15分,平均11.5分。4例外伤性寰枢椎骨折患者有后颈部疼痛及活动障碍,疼痛视觉模拟量表(VAS)评分为2~7分,平均4.5分。术后复查患者影像学资料,观察内固定位置及植骨融合情况。结果所有手术顺利完成,未发生椎动脉、脊髓等损伤。术后复查CT,显示所有枢椎椎板螺钉位置良好,均未突破内侧皮质骨。随访时X线、CT示螺钉位置良好,无松动及断钉。所有患者术后12个月植骨均融合,上颈椎畸形患者神经功能均有不同程度改善,JOA评分为13~17分,平均15.3分。外伤性寰枢椎骨折患者颈部疼痛及活动障碍明显改善,VAS评分为0~2分,平均1.0分。结论枢椎椎板螺钉固定在上颈椎后路固定手术中方法简单安全、效果良好,对于无法行枢椎椎弓根螺钉固定的患者,枢椎椎板螺钉固定是一种安全有效的替代方法。