先天性齿突小骨伴寰枢椎脱位1例报道

<正>齿突游离小骨(os odontoideum)是指表面光滑的小骨替代正常的枢椎齿突,并且与枢椎椎体相分离。齿突游离小骨容易诱发寰枢关节脱位产生脊髓压迫,进一步发展可造成四肢瘫痪、呼吸困难乃至危及生命。本院收治先天性齿突小骨伴寰枢椎脱位患者1例,经手术治疗后恢复良好,报道如下。     

游离齿突伴寰枢椎不稳引起的进行性脊髓损伤

齿突游离小骨(os odontoideum)是造成寰枢椎不稳的原因之一,随着对其研究的深入和影像学检查手段的不断进步及临床对此类畸形的重视,这类病变的的报道逐渐增多.游离齿突伴寰枢椎脱位引起的进行性脊髓损伤往往在创伤或症状出现后偶然被发现,门急诊仍有部分病例被漏诊或误诊.为此,对本院收治的22例齿突游离小骨伴寰枢椎不稳引起的进行性脊髓损伤临床特点进行分析并报告如下.     

齿突游离小骨的影像学测量与手术治疗

目的：对齿突游离小骨的影像学测量及其手术治疗进行研究。方法：对已治疗的45例齿突游离小骨进行分析，其中38例采用3种影像学测量方法来评价C1-2不稳程度。所有病人均行后路融合术，其中寰枢椎融合28例，枕颈融合17例。结果：测量分析发现，上颈椎最大椎管矢状径＜13mm时有脊髓损害的危险。所有手术病人平均随访6年，均取得牢固骨性愈合。38例临床症状改善，4例无变化，3例加重。结论：对于齿突游离小骨伴有脊髓压迫症状，或仅有枕颈部症状但影像学测量椎管矢状径减小接近13mm这一临界值，有脊髓损害危险时应施行手术治疗。     

齿状突游离小骨

齿状突游离小骨较少见到，但其可导致寰枢椎不稳与脊髓压迫。为引起临床医生的警惕，作者报告１７例齿状突游离小骨。除３例无症状者未行手术治疗外，１４例存在寰枢椎不稳者均行枕颈融合，术后均获骨性融合。本组病例术后随访２～１６年，临床症状消失或基本消失者９例，明显减轻者５例。３例非手术治疗者无变化。作者认为，对于齿状突游离小骨存在寰枢椎不稳者应行手术治疗     

游离齿突小骨及寰枢椎不稳

游离齿突小骨(Os odontoideum)是齿突畸形中最常见的一种，常导致寰枢椎不稳，引起脊髓压迫，严重者可导致瘫痪．本文综述了游离齿突小骨的发生原因、导致寰枢椎不稳的客观测量指标、齿突周围反应性软组织增生以及脊髓压迫程度等方面．以协助诊断、指导治疗。     

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。     

齿突游离小骨的影像学测量与手术治疗

目的对齿突游离小骨的影像学测量及其手术治疗进行研究.方法对已治疗的45例齿突游离小骨进行分析,其中38例采用3种影像学测量方法来评价C1～2不稳程度.所有病人均行后路融合术,其中寰枢椎融合28例,枕颈融合17例.结果测量分析发现,上颈椎最大椎管矢状径<13mm时有脊髓损害的危险.所有手术病人平均随访6年,均取得牢固骨性愈合.38例临床症状改善,4例无变化,3例加重.结论对于齿突游离小骨伴有脊髓压迫症状,或仅有枕颈部症状但影像学测量椎管矢状径减小接近13mm这一临界值,有脊髓损害危险时应施行手术治疗.     

单纯后路与前后联合入路手术治疗成年型齿突游离小骨并寰枢关节脱位

[目的]探讨成年型齿突游离小骨继发寰枢关节脱位手术方式及其疗效。[方法]回顾性分析2010年9月~2014年9月收治的13例成年齿突游离小骨继发寰枢椎脱位患者,其中9例可复性脱位患者行单纯后路复位+寰枢椎短节段固定融合术,4例难复性脱位者行前路经口咽减压联合后路寰枢椎融合术,随访术后临床表现及影像学改变。[结果]所有患者均获随访,随访时间1~5年,平均(2.5±1.1)年;术后影像学检查示患者均达到骨性融合,愈合时间3~9个月,平均(4.5±1.6)个月;无内固定松动、断裂等并发症,2例患者术后出现颈椎不适,但颈椎屈伸旋转功能无明显受限,对日常生活无明显影响。术后神经功能均得到明显改善,末次随访,JOA评分由术前平均(9.5±1.65)分提高到(14.2±1.6)分(P0.05)。[结论]后路短节段寰枢椎融合术是治疗成年型游离齿突伴寰枢关节脱位安全有效的治疗方法,可解除脊髓压迫,重建寰枢椎的稳定性,术后对枕颈部活动影响较小;难复性脱位患者,建议采用前路经口咽减压联合后路复位固定植骨融合术。     

寰枢关节类风湿性关节炎的影像学分析(附21例报告)

目的评估累及寰枢关节的21例RA患者经联合治疗的临床效果及其影像学特征。方法对平均病程为7．95年（2～26年）的21例患者行MTX＋其他DMARDs的联合治疗,同时行临床和影像学评估,明确16例存在寰枢椎前向半脱位、3例垂直半脱位、2例侧方半脱位。6例有明显枕颈部症状的寰枢不稳息者行后路寰枢或枕颈融合治疗。结果联合治疗的有效率为85．7％。RA病程越长,越易发生寰枢椎不稳和椎管矢状径减小,本组前向寰枢椎半脱位最常见。6例手术患者的齿突周围血管翳在随访中较术前明显减小。结论对累及寰枢关节的RA患者,无论有无寰枢椎不稳、有无症状或脊髓损伤的体征,均可成功行影像学评估且行MTX＋其他DMARDs的联合治疗可取得较好的疗效;为防止枕颈部脊髓压迫,宜对此类患者行常规、定期的临床和影像学评估。     

关节间隙螺钉加寰椎挂钩治疗齿状突游离小骨

目的评价C1～C2关节间隙螺钉加寰椎椎板钩治疗齿状突游离小骨合并寰枢椎不稳的临床特点及疗效。方法2004年10月至2007年2月,采用C1～C2关节间隙螺钉及寰椎椎板钩治疗合并寰枢椎不稳的齿状突游离小骨18例,男7例,女11例。年龄13-69岁,平均35．2岁。其中,有明确外伤病史11例。所有病例均存在枕颈部症状,15例存在不同程度的脊髓压迫症状。术前ASIA脊髓神经功能分级：B级2例;C级7例：D级6例;E级3例。术后定期随访,并对临床症状及影像学表现进行分析。结果随访时间6～58个月,平均21个月。术后3月所有病例枕颈部症状消失,X线及CT重建提示所有病例均获得良好骨性融合,寰枢椎序列良好,ASIA脊髓神经功能分级：C级4例,D级7例,E级7例。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、假关节形成或寰枢椎不稳等并发症。结论C1～C2关节间隙螺钉加寰椎椎板钩是治疗齿状突游离小骨合并寰枢椎不稳的有效方法。     

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.     

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.     

Transarticular screws in the management of C1-C2 instability in children

C1-C2 instability is a challenging problem in the pediatric population. Small patient size and poor healing potential in the at-risk groups, such as patients with Down syndrome and os odontoideum, make fixation difficult. Instability in patients with Down syndrome is a common problem, and traditional methods of fixation have a high complication rate and are a challenge given the frequent anatomic abnormalities such as an incomplete or hypoplastic arch, os odontoideum, and incomplete passive reduction. The purpose of this study was to review our experience of transarticular screw use in pediatric patients and to define the potential applications of this technique in pediatric C1-C2 instability. Twelve patients, with C1-C2 instability managed with transarticular screws at the authors' institution, were reviewed. The youngest patient treated was 5 years old with a mean age for the group of 11.5 years. The group consisted of 3 patients with Down syndrome and 9 patients with os odontoideum. Three of the patients with os odontoideum failed previous posterior wiring. Two patients presented with an acute spinal cord injury in the setting of chronic instability. Preoperative computed tomography or magnetic resonance imaging was used in all patients to define the vascular and bony anatomy. No further surgery has been required at a mean follow-up of 5.1 years in all patients. Although vertebral size and congenital anomalies may make screw positioning challenging, the technique allows fixation in the absence of a complete posterior arch of C1 and eliminates the need for instrumentation in the canal. This technique also provides a high fusion rate in a complicated patient population.     

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。     

Medical-insurance aspects of atlantoaxial instability in children]

INTRODUCTION: An os odontoideum is mostly diagnosed coincidentally on the basis of neurological symptoms or painful movement of the cervical spine. Diagnostic work-up and therapy are currently subjects of controversial discussion in the literature. CASE: Our report is about an eleven-year-old boy with an unknown os odontoideum, who developed neurological symptoms with tetraparesis after a fall from 1.5 m height. Conventional X-ray examination resulted in the diagnosis of a suspected dens fracture, MRI showed atlanto-axial instability and an os odontoideum with significant dural sack compression but no signs of acute bony or ligamentous lesion. CONCLUSION: Because of the importance concerning not only medical but also legal/insurance aspects, a possible coincidental finding of an os odontoideum versus a dens fracture must be included in the differential diagnosis. In the case of an os odontoideum without instability in children, conservative therapy is justified after due enlightenment regarding possible risks. In the event of neurological symptoms and/or persistent instability the authors advocate early surgical stabilization even in patients with little infirmity, particularly in view of the possible consequences.     

Fractures of the Odontoid in Children

Odontoid fractures are rare in children; they may, however, occur at any age with a prevalence in younger children. Below the age of 9, there is almost exclusively a separation of the subdental synchondrosis, whereas in children older than 9 years, the basal odontoid fracture resembles the adult type. Motor vehicle accidents (MVA) are the dominant trauma. Clinically, a substantial lesion of the upper cervical spine cannot be excluded the symptoms of odontoid fracture, such as neck pain or neck stiffness, being subtle and unspecific. Therefore, the diagnosis of odontoid fractures is based on radiographic screening of traumatized cervical spines with a standard three-view program (anteroposterior, lateral from the occiput on Th1, transoral dens view). Computed tomography (CT) and magnetic resonance imaging (MRI) are reserved to special indications. Acute odontoid fracture is mainly treated conservatively, preferably with a Minerva cast. In exceptional cases, operation with preservation of C1/C2 mobility may be indicated. The genesis of os odontoideum may be traumatic and is due to untreated odontoid fractures in children below the age of 2.5 years. Chronic atlanto-axial instability is treated by segmental fusion.     

Varied clinical presentation of os odontoideum: a case report

Objective:

To present a case of an os odontoideum and to provide insight into the varied clinical presentations.

Clinical Features:

A 54 year old man presented with chronic neck pain without headache. A clinical examination was performed and the chiropractor viewed his AP and lateral radiographs. Previous flexion/ extension radiographs and MRI imaging from 2009 were requested for review. The patient was diagnosed with grade II mechanical neck pain. Treatment was rendered that day which included spinal manipulation/ mobilization. Several days later the requested imaging reports were received and described the presence of an os odontoideum.

Conclusion:

In the presence of os odontoideum, familiarity with the signs and symptoms of potential cervical instability is imperative. Health care providers must remain diligent in their patient histories, physical exams, and imaging. This case highlights the importance of following up on imaging studies to rule out diagnoses that would involve treatment contraindications thus ensuring safe and effective treatment.     

Diagnosis of Os odontoideum using kinematic magnetic resonance imaging. A case report

STUDY DESIGN: A case of os odontoideum diagnosed using kinematic magnetic resonance imaging is presented. OBJECTIVES: To evaluate the kinematic magnetic resonance imaging findings of os odontoideum and the possible use these findings might have to guide treatment. BACKGROUND: Kinematic magnetic resonance imaging is a new imaging modality that is able to produce realtime images of a structure through a range of motion. This makes it well suited for investigating dynamic processes such as cervical instability. METHODS: A single subject with known os odontoideum was examined using a Sigma SPR Kinematic Magnetic Resonance Imager (General Electric, Florence, SC). RESULTS: Kinematic magnetic resonance imaging demonstrated cervical spinal cord impingement and cervical instability throughout flexion and extension, but not during lateral bending or rotation. CONCLUSIONS: Kinematic magnetic resonance imaging can evaluate the cervical spine in an axially loaded position throughout its range of motion. This modality may be a useful method for diagnosing and classifying abnormalities of the spine.     

Spondyloepiphyseal dysplasia congenita with absent femoral head

Spondyloepiphyseal dysplasia congenita (SEDC), an inherited chondrodysplasia, occurs through a mutation in the COL2A1 gene encoding the type II procollagen alpha1 chain, proalpha1 (II). Recently, the authors studied two Korean patients with SEDC. Both these patients had short stature, os odontoideum with or without atlantoaxial instability, platyspondyly, and epiphyseal dysplasia limited to the femoral heads. The more seriously affected patient had shorter height (125 cm), atlantoaxial instability associated with os odontoideum, flat feet, and cleft palate, absence of the femoral head on radiographic and magnetic resonance imaging (MRI), and dislocated proximal femur. The less seriously affected patient was taller (145 cm) and had no atlantoaxial instability, absence of the femoral head on radiography with visible cartilage anlage on MRI, and subluxated cartilaginous femoral head. A mutation analysis was performed using direct sequencing. Two novel dominant mutations were found in the COL2A1 gene of these two patients: G277V and G238S, respectively. Although glycine was substituted with valine and serine in the proalpha1 (II) of these two patients, their phenotypes were significantly different in physical and radiologic evaluations.