Os odontoideum and craniovertebral junction instability secondary to dystonia: case series and review of the literature.

INTRODUCTION: Os odontoideum refers to a rounded ossicle detached from a hypoplastic odontoid process at the body of the axis. The aetiology has been debated and believed to be either congenital or acquired (resulting from trauma). Os odontoideum results in incompetence of the transverse ligament and thus predisposes to atlantoaxial instability and spinal cord injury. METHODS/RESULTS: Three cases of children with severe dystonic cerebral palsy presenting with myelopathic deterioration secondary to atlantoaxial instability due to os odontoideum are presented. This observation supports the hypothesis of os odontoideum being an acquired phenomenon, secondary to chronic excessive movement with damage to the developing odontoid process. CONCLUSION: In children with cerebral palsy and dystonia, pre-existing motor deficits may conceal an evolving myelopathy and result in delayed diagnosis of clinically significant atlantoaxial subluxation.

The Rare Anomaly That Can Be Confused With Fracture: Os Odontoideum.

Os odontoideum is a rare anomaly of the second cervical vertebra. The odontoid process is separated by a wide gap from the vertebral body in this anomaly. It can be associated with atlantoaxial instability.

Stability-Sparing Endoscopic Endonasal Odontoidectomy in a Malformative Craniovertebral Junction: Case Report and Biomechanical Considerations.

BACKGROUND: The craniovertebral junction (CVJ) is often involved in a wide range of congenital, developmental and acquired pathologies that can create bony and ligamentous instability or cause direct compression on the medulla and cervical spine cord, resulting in significant impairment. Atlas assimilation is the most common malformation in the CVJ and can be frequently associated with basilar invagination (BI) and Chiari malformation (CM) type I. Posterior atlas assimilation more frequently leads to BI type II with a mass effect on neural structures but usually no signs of biomechanical instability. Operative approaches to the CVJ have undergone a remarkable evolution and can be divided into ventral, lateral and dorsal ones. In this kind of surgery, it is vital to detect and eventually treat any CVJ instability. CASE DESCRIPTION: We present a case of CVJ malformation comprising assimilation of the posterior arch of the atlas, BI type II and CM, treated by endoscopic endonasal odontoidectomy and partial clivus removal to spare CVJ stability. CONCLUSION: Neurological and biomechanical analysis of all CVJ malformations permits stratification and selection of those cases that can be managed by simple, direct, minimally invasive decompression with no need for surgical fusion.

Accidental or linked: separated odontoid process fused to the enlarged anterior arch of the atlas associated with atlantoaxial subluxation in a Kashin-Beck disease patient.

PURPOSE: KBD is an endemic disease affecting the epiphyseal growth plate and articular cartilage of multiple joints, resulting in extremities' deformation and skeletal dysplasia. More attention has been paid to the visible deformed extremities instead of inconspicuous spinal condition. There is a lack of reports concerning the spinal radiological features, especially for the atlantoaxial joint. The aim of this paper is to report a case of a Kashin-Beck disease (KBD) patient diagnosed with atlantoaxial subluxation, concomitant with separated odontoid process fused to the enlarged anterior arch of the atlas. METHODS: We report the case of a 60-year-old woman with 54 years' history of KBD complaining of occipitocervical pain, decreasing motor strength and sensory function of both upper and lower extremities. Subsequent radiological examinations of lateral plain radiography, computed tomography scans and magnetic resonance imaging were performed to reveal these rare characteristics of atlantoaxial joint in this patient. Then, we review the associated articles to postulate whether this anomaly is accidental or linked in a KBD patient. RESULTS: She had an extremely rare variant with three aspects of characteristics: atlantoaxial subluxation concurrent with severe spinal canal stenosis and spinal cord compression, odontoid process separating from the body of axis, and the enlarged anterior arch of the atlas fusion with odontoid process. Comparing with the congenital anomaly of atlantoaxial joint, we postulated that this aetiology of anomaly might be linked to the acquired form attributed to the histopathology of KBD, rather than an accidental event. CONCLUSIONS: The anomaly of atlantoaxial joint might occur in KBD patients. Larger numbers of KBD candidates with earlier symptoms are recommended for radiological examinations of atlantoaxial joint, especially for the adolescents. Spinal surgeons are suggested to involve the research of the spinal anatomy and variation for the prevention and earlier therapy for KBD patients.

Os Odontoideum Discovered After Minor Cervical Trauma.

Minor cervical spine injury is a common cause of pediatric emergency department visits. We present a case of a 10-year-old boy with transient paresthesia after minor cervical trauma found to have a rare cervical spine abnormality requiring surgical fusion. We present and discuss the management options for os odontoideum.

Bergmann's ossicle (ossiculum terminale persistens): a brief review and differentiation from other findings of the odontoid process.

PURPOSE: The purpose of this paper was to review the literature on Bergmann's ossicle and provide an overview on its development, etiology, and clinical presentation while also differentiating it from similar structural anomalies. METHODS: A thorough review of the literature available on Bergmann's ossicle was performed. RESULTS: Bergmann's ossicle, also referred to as ossiculum terminale persistens, was defined as a developmental anomaly of the odontoid process in which an ossification center that gives rise to the tip of the dens fails to fuse properly with the body of the axis. CONCLUSION: Bergmann's ossicle is most often a benign condition, although it rarely may present with clinical symptoms such as neck pain and neurological signs. It may be associated with Down's syndrome and contribute to atlantoaxial instability.

Intraoperative electrophysiological monitoring during posterior craniocervical distraction and realignment for congenital craniocervical anomaly.

PURPOSE: Congenital craniocervical segmentation anomaly associated with malalignment of the odontoid process causes progressive spinal cord compression with myelopathy. Recent literatures have reported that ventral decompression could be achieved with posterior craniocervical realignment through posterior instrumented reduction. The purpose of the present study is to show the efficacy of intraoperative electrophysiological monitoring during craniocervical realignment through screws and rod system for congenital craniocervical segmentation anomaly. METHODS: Consecutive ten patients with a congenital craniocervical segmentation anomaly and myelopathy due to a malaligned odontoid process, who underwent posterior craniocervical realignment, were included. Klippel-Feil syndrome (KFS) was combined in four patients. Gait disturbance and motor weakness were the main presentation. Craniocervical realignment was achieved by intraoperative distraction through a rod and screw system. Intraoperative neuromonitoring was performed with transcranial motor-evoked potential (TcMEP) and somatosensory-evoked potential (SSEP). RESULTS: Significant change in TcMEP occurred in two patients with KFS during surgery, but the change was reversed with release of distraction. All patients were awakened without neurological deficit. Motor weakness and gait disturbance were normalized within 6 months in all patients. Postoperative computed tomography scan and/or magnetic resonance imaging showed that the reduction was complete in all patients. CONCLUSIONS: Craniocervical realignment through screws and rod system may be safe and efficacious surgical technique for the treatment of congenital craniocervical anomaly with the help of intraoperative neuromonitoring. However, distraction should be cautiously monitored, especially when Klippel-Feil syndrome is combined.

VACTERL (vertebral defects, anal atresia, tracheoesophageal fistula with esophageal atresia, cardiac defects, renal and limb anomalies) association: disease spectrum in 25 patients ascertained for their upper limb involvement.

OBJECTIVE: To review the clinical characteristics in a series of 25 patients with VACTERL (vertebral defects, anal atresia, tracheoesophageal fistula with esophageal atresia, cardiac defects, renal and limb anomalies) association who were ascertained for upper limb involvement. STUDY DESIGN: The study involved a review of clinical and radiologic data from patients with VACTERL association collected by a hand surgery clinic between 2004 and 2013. RESULTS: Radial axis involvement was found in all 25 patients (100%), with severe thumb function impairment in 79% and complete absence of the radius in roughly 33%. Costovertebral anomalies were the most frequent feature, found in 23 patients (92%). All 3 core features (anal atresia, tracheoesophageal fistula with esophageal atresia, and costovertebral anomalies) were present in only 12% of the patients. Twelve patients (48%) had abnormalities not part of the VACTERL spectrum, showing a specific pattern of non-VACTERL-type malformations, including genitourinary abnormalities (12%), single umbilical artery (8%), and tethered cord (8%). Previously unreported clinical findings were concurrent hypoplasia of both the odontoid process and the coccyx in 2 patients and an isolated sacral dimple in 2 patients. CONCLUSION: Upper limb involvement in VACTERL association is a specific feature of the radial axis that occurs in monolateral form in approximately 75% of cases and, when bilateral, always occurs in a nonsymmetrical fashion. Odontoid and coccygeal hypoplasia and sacral dimple are newly reported malformations of the VACTERL phenotype.

Dysphagia as a primary manifestation of basilar impression: A case report.

Secondary basilar invagination or basilar impression is an anomaly at the craniovertebral junction where the odontoid process prolapses into the foramen magnum with the risk of compressing adjacent structures and obstructing the proper flow of cerebrospinal fluid (CSF). The incidence is less than 1% in the general population and occurs mainly in the first three decades of life when it is associated with malformations of the neuroaxis. In older age, the main aetiologies are diseases that alter bone mineral density. The clinical course is usually progressive and the most common symptoms are asthenia, cervical pain and restricted movement, but also dysphonia, dyspnoea and dysphagia. It is a progressive disease which, if left untreated, can cause severe neurological damage and death. We report the case of a 79-year-old woman with osteoporosis and progressive dysphagia leading to severe malnutrition, which conditioned the decision not to intervene due to the high perioperative risk.

Congenital axis dysmorphism in a medieval skeleton : secunda a vertendo epistropheus .

PURPOSE: We describe here the axis dysmorphism that we observed in the skeletal remains of a human child dug up from a fifteenth century cemetery located in north-eastern Italy. This bone defect is discussed in the light of pertinent literature. METHODS: We performed macroscopical examination and CT scan analysis of the axis. RESULTS: Axis structure was remarkably asymmetric. Whilst the left half exhibited normal morphology, the right one was smaller than normal, and its lateral articular surface showed horizontal orientation. In addition, the odontoid process appeared leftward deviated and displayed a supplementary articular-like facet situated on the right side of its surface. CONCLUSIONS: These findings suggest a diagnosis of unilateral irregular segmentation of atlas and axis, a rare dysmorphism dependent upon disturbances of notochordal development in early embryonic life. Likewise other malformations of the craniovertebral junction, this axis defect may alter the delicate mechanisms of upper neck movements and cause a complex series of clinical symptoms. This is an emblematic case whereby human skeletal remains may provide valuable information on the anatomical defects of craniovertebral junction.

Navigation-assisted Le Fort I osteotomy with midpalatal split to treat compressive pathologies of the craniovertebral junction.

This report describes the management of the case of an 11-year-old girl with serious compressive pathology of the craniocervical junction using a navigation-guided Le Fort I level maxillotomy and midline split. In this pediatric case, image guidance significantly enhanced intraoperative orientation and helped to determine the correct location of the horizontal osteotomy lines at the Le Fort I level.

Partial midfacial duplication.

A case of craniofacial duplication is presented. Details on this rare form are described, and its treatment is discussed with brief review of the pertinent literature. We excised the duplicate maxilla and also discovered bilateral macrostomia. A year later, a mass appeared again. By CT scan, we found that there was a mass in the skull base extruding to the superior wall of cavitas pharyngis. The mass below the sphenoid bone and the ethmoid bone connected with the skull base. CT scan also showed malformation of the first cervical vertebra and odontoid process had bifurcated. Once again, we excised the mass and found a cranial meningocele on the skull base, repaired the palate cleft, and closed the cerebral meningocele. The patient had a palate fistula after operation. A year later, the palate fistula and macrostomia were repaired. We think the patient should be operated on immediately after she was born so that we could relieve the dyspnea; furthermore, by one well-planned operation, we could repair the palate cleft and other deformity just after we excised the mass.

Transnasal endoscopic removal of malformation of the odontoid process in craniovertebral anomaly: a case report.

The endoscopic endonasal approach is emerging as a feasible alternative to the transoral route for the resection of the odontoid process, when the latter produces a compression of the brainstem and cervicomedullary junction. This type of approach has some advantages, such as excellent prevertebral exposure of the craniovertebral junction in patients with small oral cavities and the possibility to avoid the use of mouth retractors. In this article, we present a typical case of a 12-year-old female patient with a diagnosis of craniovertebral anomaly-basilar invagination into foramen magnum, suffering from an extreme posterior tilt of the odontoid process causing severe anterior compression of the cervicomedullary junction, is presented to stress the potential of this technique. Transnasal endoscopic removal of the odontoid process was performed and resolution of the ventral compression was achieved. This article demonstrates that in selected cases, a multidisciplinary team approach can help our patients.

Incidental os odontoideum: current management strategies.

Os odontoideum was first described in the late 1880s and still remains a mystery in many respects. The genesis of os odontoideum is thought to be prior bone injury to the odontoid, but a developmental cause probably also exists. The spectrum of presentation is striking and ranges from patients who are asymptomatic or have only neck pain to those with acute quadriplegia, chronic myelopathy, or even sudden death. By definition, the presence of an os odontoideum renders the C1-2 region unstable, even under physiological loads in some patients. The consequences of this instability are exemplified by numerous cases in the literature in which a patient with os odontoideum has suffered a spinal cord injury after minor trauma. Although there is little debate that patients with os odontoideum and clinical or radiographic evidence of neurological injury or spinal cord compression should undergo surgery, the dispute continues regarding the care of asymptomatic patients whose os odontoideum is discovered incidentally. The authors' clinical experience leads them to believe that certain subgroups of asymptomatic patients should be strongly considered for surgery. These subgroups include those who are young, have anatomy favorable for surgical intervention, and show evidence of instability on flexion-extension cervical spine x-rays. This recommendation is bolstered by the fact that surgical fusion of the C1-2 region has evolved greatly and can now be done with considerable safety and success. When atlantoaxial instrumentation is used, fusion rates for os odontoideum should approach 100%.

Two-Stage Approach for Unstable Pediatric Craniocervical Junction Anomalies with a Halo Vest and Delayed Occipitocervical Fusion: Technical Note, Case Series, and Literature Review.

OBJECTIVE: Malformations in the craniocervical junction (CCJ) are rare in the pediatric population but often need surgical treatment. We present a pediatric case series of patients treated with a 2-stage surgical approach with a halo vest and occipitocervical fusion and review complications and outcomes. METHODS: A retrospective analysis of a single-center case series was performed. Pediatric patients affected by congenital craniocervical junction anomalies and treated with a 2-stage approach were included. A halo vest was implanted in the first surgery, and ambulatory progressive reduction was performed. When a favorable anatomic situation was observed, arthrodesis was performed. Safety analysis was undertaken by analyzing the incidence of complications in both procedures. Effectivity analysis was carried out analyzing radiologic and clinical outcome (Goel grade and modified Japanese Orthopaedic Association score). Student t test was used for statistical analysis. RESULTS: Sixteen cases were included. Mean age of patients was 9.38 years. Safety analysis showed 2 halo loosenings, 1 pin infection, 2 wound infections, 1 cerebrospinal fluid leak, and 2 delayed broken rods. No major complications were observed. Radiologic analysis showed an improvement in the tip of the odontoid process to the McRae line distance (from -3.26 mm to -6.16 mm), atlantodental interval (from 3.05 mm to 1.88 mm), clival-canal angle (from 134.61° to 144.38°), and cervical kyphosis (from 6.39° to 1.54°). Clinical analysis also showed improvement in mean Goel grade (from 1.75 to 1.44) and modified Japanese Orthopaedic Association score (from 15.12 to 16.41). CONCLUSIONS: The 2-stage approach was a suitable and effective treatment for craniocervical junction anomalies in pediatric patients.

Variable morphology of the axis vertebrae in 100 specimens: implications for clinical palpation and diagnostic imaging.

OBJECTIVE: The purpose of this study was to investigate and measure the variable morphologies of axis vertebrae and explore the clinical significance of variations as it may pertain to clinical palpation and diagnostic imaging. METHODS: The common variable morphologies in 100 specimens of intact dry adult axis vertebrae (Chinese) were investigated and measured. The frequencies in deviation of odontoid processes, deviation of spinous processes, and presence of bifid spinous processes were observed. The distances between the apices of transverse processes and inferior articular facets were also measured. RESULTS: Variable morphologies of C2 that we observed were deviation of odontoid processes (14 cases, 14.0%), deviation of spinous processes (3 cases, 3.0%), and bifid spinous processes (95 cases, 95.0%). Of the bifid spinous processes, 56 had a process on the left side equal to the right side, 21 were longer on the left, and 18 were longer on the right. The distances between apices of transverse processes and inferior articular facets in the left side of C2 were 17.67 +/- 2.47 mm, and that of the right side were 17.81 +/- 2.55 mm. CONCLUSIONS: Because variable morphology of the axis is common, congenital deviation of the odontoid process, deviation of the spinous process, and asymmetrical bifid spinous processes should be taken into account during clinical palpation and diagnostic imaging.

Clinicoradiographic presentation of a girl with progressive pseudorheumatoid arthropathy.

We report the case of a girl-child who manifested the clinicoradiographic features of pseudorheumatoid arthritis. 3D-CT scan of the craniocervical junction showed distinctive features of dystopic type of os odontoideum. The report highlights the necessity to explore the craniocervical junction in patients with progressive pseudorheumatoid arthropathy.

Familial Os Odontoideum.

BACKGROUND: To add to the confusion in the debate on pathogenesis of os-odontoideum, an additional report of its occurrence in two members of the same family is reported. CASE DESCRIPTION: This is a report of a rare coincidence wherein both father (51 years old) and daughter (25 years old) were diagnosed to have os odontoideum and presented with crippling neurologic deficits. CONCLUSIONS: Following atlantoaxial fixation, both recovered in their symptoms. Investigations revealed no genetic abnormality. Literature on the subject is briefly reviewed.

The Retroverted Dens: A Review of its Anatomy, Terminology, and Clinical Significance.

BACKGROUND: Little attention has been given to the retroverted dens within the existing medical literature. However, this finding can have a clinical impact, especially in patients with Chiari malformation type I (CM1), as it can have consequences for further treatment. METHODS: Using standard search engines, we performed a literature review of anatomical, radiologic, and clinical studies as well as pathologic and surgical considerations related to the retroverted dens. Key words for our search included retroverted dens; retroflexed dens; odontoid retroflexion; posterior inclination; and tilted dens. RESULTS: A retroverted dens is most commonly found in the pediatric population in relation to CM1. Research has demonstrated that high degree of dens angulation can result in significant anterior brain stem compression with the need for both anterior and posterior decompression in patients with symptomatic CM1. CONCLUSIONS: A greater degree of dens angulation can lead to neurologic symptoms secondary to spinomedullary compression. Therefore, correct measurements are essential as such findings can influence presurgical planning.