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.     

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。     

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 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.     

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。     

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.

     

Rotational stenosis of the vertebral artery at the atlantoaxial joint: report of three cases

Three cases of vertebral artery stenosis or occlusion at the level of the atlantoaxial joint during head rotation were reported. The vertebral artery was mechanically compressed on the side of the head opposite to the direction in which the heads was turned. One case was associated with atlantoaxial dislocation due to rheumatoid arthritis. Posterior fixations of C1 - C2 or C1 - C3 using iliac bone and wire were performed in two cases, and a neck collar was applied in another case. All of the three cases have been free from vertebrobasilar insufficiency since the treatment. The pathogenesis and treatment of vertebral artery occlusion at the atlantoaxial joint are discussed.     

Retro-dental reactive lesions related to development of myelopathy in patients with atlantoaxial instability secondary to Os odontoideum

STUDY DESIGN: A retrospective analysis of 13 patients with atlantoaxial instability secondary to Os odontoideum who underwent posterior atlantoaxial fusion. OBJECTIVE: To assess the relationships between the development of myelopathy and plain radiographic parameters in patients with atlantoaxial instability secondary to Os odontoideum and to determine whether the pathologic structures, which compress the spinal cord, are visualized using magnetic resonance imaging. SUMMARY OF BACKGROUND DATA: The development of myelopathy, which is the most serious complication associated with Os odontoideum, was thought to be related to either the degree of instability or direction of instability, or a decrease in the space available for the cord. However, such indirect radiographic parameters measured using plain radiographs cannot provide direct information concerning the causes of myelopathy in patients with atlantoaxial instability secondary to Os odontoideum. METHODS: Thirteen patients who underwent posterior atlantoaxial fusion for clinical symptoms due to Os odontoideum were classified into two groups depending on whether they had (n = 9) or did not have (n = 4) myelopathy. Four radiographic parameters were measured using flexion and extension lateral radiographs; the degree of instability, the direction of instability, and the space available for the cord in flexion and extension. MRI was performed on all patients in the myelopathy group. The radiologic and clinical data were compared for the two groups. RESULTS: There were no significant statistical differences in the degree of instability (6.83 vs. 7.38, P = 0.816), space available for the cord in flexion (6.94 vs. 7.13, P = 0.938), and space available for cord in extension (7.56 vs. 5.75, P = 0.434) between the two groups. There was a poor agreement between the direction of instability and the development of myelopathy (kappa = 0.268, P = 0.308). Magnetic resonance imaging did demonstrate, however, cord compression caused by retro-dental reactive lesions in the myelopathy; cystic masses were present in two patients; and fibrocartilaginous masses were present in seven. CONCLUSION: The current study suggests that the value of plain radiographic parameters should be reevaluated as a means of evaluating myelopathy in patients with atlantoaxial instability secondary to Os odontoideum, and that retro-dental reactive lesions should be considered as the potential cause of myelopathy.     

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.     

难复性寰枢脱位的影像学表现与前方减压术式选择初探

目的：研究难复性寰枢脱位的影像学特征,探讨延、脊髓前方减压术式的选择。方法：回顾性分析了36例难复性寰枢脱位患者颅颈区X光片、CT和MRI,其中27例作了经后外侧入路前方减压术。结果：23例为枢椎完整型寰枢脱位,其寰椎侧块前移,有3例并寰椎前下旋转,4例并侧方移位,3例单侧关节脱位较严重;21例合并寰椎桃化,其中2例有枕大孔（即枕化的寰椎孔）不规则狭窄,1例有齿突椎体化畸形。13例为齿突不连型寰枢脱位,其中寰椎后脱位1例;寰椎前脱位为半脱位者8例（其中1例为“齿突骨”）,全脱位者4例。术后CT显示,经后外侧入路前方减压的27例中23例骨性减压满意。结论：就前方减压而言,经后外侧入路的治疗有寰椎“旋转”,齿突畸形（如齿突椎体化、“齿突骨”等）或枕大孔不规则狭窄等的寰枢脱位有其优势,经口入路松解并牵引复位治疗齿突不连的寰枢椎全脱位较合理。     

C1-C2 transarticular screw fixation: technical aspects.

OBJECTIVE: I review posterior atlantoaxial fusion with transarticular screw fixation, including indications, complications, and operative technique, emphasizing my experience. METHODS: The indications for C1-C2 transarticular screw fixation include traumatic injuries to the atlantoaxial complex, instability resulting from inflammatory disease (rheumatoid arthritis), and congenital abnormalities (os odontoideum). All patients underwent stabilization using cannulated C1-C2 transfacetal screws by the method described by Magerl. Supplemental interspinous fusion with bicortical autologous iliac crest graft and titanium cable was used to restore the posterior tension band by use of the method described by Sonntag's group. Preoperatively, all patients underwent imaging with plain radiographs, magnetic resonance imaging, and axial computed tomography. Patients were maintained in a rigid cervical orthosis postoperatively. RESULTS: Measures used to improve safety and efficacy include patient positioning, fluoroscopic guidance, preoperative magnetic resonance imaging, axial computed tomography, and open reduction of C1-C2 subluxation before screw passage. In this series of 75 patients, fusion was obtained in 72 patients (96%). There were no instances of vertebral artery injury, errant screw placement, instrumentation failure, dural laceration, spinal cord injury, or hypoglossal nerve injury. CONCLUSION: C1-C2 transarticular screw fixation with a posterior tension band construct provides excellent fusion rates with few perioperative complications. Preoperative imaging and meticulous surgical technique improve outcomes.     

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.     

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.     

不稳定性齿突游离小骨的诊断及治疗：26例患者临床分析

目的通过临床病例分析探讨不稳定性齿突游离小骨的临床特点及后路融合手术的治疗效果。方法回顾性分析2005年5月-2012年5月本院采用手术治疗有临床症状的不稳定性齿突游离小骨患者26例。分析总结病史特点、临床表现、影像学表现及手术治疗效果。结果 26例患者中男16例,女10例。年龄36-66岁,平均43.3岁。15例既往有明确外伤史,21例患者有颈部症状,所有患者均有不同程度的神经损伤症状,术前神经功能日本骨科学会（Japanese Orthopaedic Association,JOA）评分8-15分,平均10.1分。所有患者影像学均有寰枢椎脱位表现,其中22例为可复性,有2例伴有上颈椎其他畸形。24例行后路寰枢椎融合术,2例行枕颈融合术,术中无椎动脉、脊髓损伤发生,术后平均随访26个月（12-36个月）,26例患者均达到骨性融合,无内固定松动、断裂等并发症。术后12个月,颈部症状及神经功能明显改善,JOA评分为12-17分,平均15.1分（P〈0.05）。结论不稳定性齿突游离小骨容易损伤脊髓,应尽早手术重建其稳定性,经后路融合手术安全有效。     

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.     

Atlanto-axial instability and spinal cord compression in children--diagnosis by computerized tomography

Five children who were at risk for atlanto-axial instability underwent computerized tomography scanning of the cervical spine in flexion and extension to document the degree of bone instability and the presence or absence of spinal cord compression. Two patients had Morquio's syndrome, two had os odontoideum , and one had Klippel-Feil syndrome, and in all five the lateral radiographs of the cervical spine in flexion and extension were equivocal with regard to instability or were difficult to interpret because of the bone anomalies. The computerized tomography scan then provided a diagnosis by a non-invasion technique and quantitated the amount of compromise of the spinal cord by delineating flattening of the cord. The scan therefore helped the surgeon to decide if the spinal cord was at significant risk and if atlanto-axial fusion was advisable.     

What is the best treatment option for cervical spinal cord injury by os odontoideum in a patient with athetoid dystonic cerebral palsy?

Context: Atlantoaxial instability in an athetoid dystonic cerebral palsy patient due to os odentoideum represents a rare cause of high-level cervical spinal cord injury. There is no evidence-based treatment protocol for this injury and a number of reports have debated whether nonsurgical or surgical treatment is the best option.Findings: Here, we report the case of a 32-year-old athetoid dystonic cerebral palsy patient with os odontoideum (OO) causing compressive myelopathy on the C1–2 levels. About two weeks after atlantoaxial fusion, the patient started an intensive rehabilitation program and maintained it for four weeks. He showed neurological and functional improvement at discharge after four weeks of training. There were further improvements in function and symptoms four weeks after discharge.Conclusion: Intensive rehabilitation programs are important for the recovery and good prognosis in spinal cord injury patients. However, rehabilitation of CP patients with spinal cord injury is often neglected. We provided intensive rehabilitation therapy to a patient for a cervical spinal cord injury by OO with athetoid dystonic cerebral palsy and achieved neurological and functional recovery.     

Multiple cerebellar hemorrhagic infarctions following surgery for a huge atlantoaxial neurinoma.

BACKGROUND CONTEXT: There have been only five reported cases with cerebellar hemorrhagic infarction after spinal surgery, and the underlying pathomechanism remains obscure. PURPOSE: To describe a case with multiple cerebellar hemorrhagic infarctions after surgery for a huge atlantoaxial neurinoma. STUDY DESIGN/SETTING: Case report METHODS: A 36-year-old man underwent uneventful surgery for a huge atlantoaxial neurinoma. After surgery, the patient was lethargic with slurred speech and subsequently developed cerebellar symptoms, although preoperative myelopathic symptoms did not worsen. The clinical and radiological findings are presented, and possible causes of the hemorrhages are discussed. RESULTS: Magnetic resonance imaging of the brain after surgery showed multiple cerebellar hemorrhagic infarctions. However, magnetic resonance angiography revealed no occlusion or stenosis in the vertebrobasilar system, and a duplex scan of the neck vessels confirmed normal flow in the vertebral arteries after surgery. In response to the conservative treatment, the patient exhibited neurological recovery with disappearance of cerebellar symptoms. CONCLUSIONS: In the present case with multiple cerebellar hemorrhagic infarctions, venous infarction appears more likely to be the cause of cerebellar hemorrhagic infarction than arterial infarction. The most likely underlying pathomechanism is a cerebellar venous disturbance precipitated by loss of a large amount of cerebrospinal fluid, although the exact etiology remains elusive.     

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.

     

前路经寰枢关节螺钉内固定植骨融合治疗寰枢关节不稳

目的探讨前路经寰枢关节螺钉内固定植骨融合治疗寰枢关节不稳的手术方法及临床疗效。方法对23例寰枢关节不稳患者行前路寰枢关节螺钉内固定植骨融合治疗。结果所有患者术后无脊髓、椎动脉和食道损伤等并发症发生。23例获4～45个月随访(平均18.4个月),随访期间所有患者寰枢关节稳定性良好,21例寰枢关节螺钉位置满意,17例获得植骨融合。结论前路经寰枢关节螺钉内固定植骨融合术是治疗寰枢关节不稳的有效方法,能使寰枢关节即刻稳定性获得良好恢复,同时达到植骨融合的目的。