Os Odontoideum

Arvin, B. Mak; Fournier‐Gosselin, Marie‐Pierre; Fehlings, Michael G.

doi:10.1227/01.neu.0000366113.15248.07

Cited by 120 publications

(66 citation statements)

References 75 publications

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“…More recently, abnormally flattened articulations between the occipital condyles and atlas lateral masses have also been identified, increasing the degrees of movement at the craniocervical junction [7, 17-20]. Furthermore, as we saw in our study, there is also an increased incidence of bony abnormalities in the atlas (e.g., nonsegmentation or incomplete arch) and axis (e.g., os odontoideum) [1, 7, 8, 11, 19]. The combination of these abnormalities allows abnormal movement across the atlantoaxial junction or may cause excessive motion across a single level resulting in potential injury to the neurologic structures.…”

Section: Discussionsupporting

confidence: 69%

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Dynamic MRI in the Evaluation of Atlantoaxial Stability in Pediatric Down Syndrome Patients

Melamed

Krieger

2019

Pediatr Neurosurg

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Background/Aims: Down syndrome is the most common inherited disorder. Some patients develop atlantoaxial instability. Existing screening guidelines were developed prior to availability of MRI. We present predictors for deficit using dynamic MRI of the craniocervical junction. Methods: A retrospective review of Down syndrome patients from 2001 to 2015 was carried out. Patients were considered symptomatic if they had clinical deficits or signal change on MRI. Measurements were taken at the atlantoaxial junction and structural abnormalities noted. Analysis was performed with SPSS. Results: A total of 36 patients were included. Patients averaged 93 months of age with a follow-up of 57 months. No asymptomatic patients developed myelopathy during follow-up. During dynamic imaging, symptomatic patients had greater changes in space available for the cord (SAC) (5.2 vs. 2.7 mm; p < 0.001) and atlantodental interval (ADI) (2.8 vs. 1.3 mm; p = 0.04). These patients were also more likely to have a bony anomaly (50 vs. 13%; p = 0.03). Conclusion: This study characterizes the range of motion seen on dynamic MRI and provides parameters that can be used to distinguish patients at risk for neurologic injury. Changes greater than 3 mm in ADI or 5 mm in SAC during dynamic MRI or any bony abnormality warrants further investigation. Patients without these features may be able to avoid an unnecessary intervention.

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Section: Discussionsupporting

confidence: 69%

“…Patients with Down syndrome face an increased incidence of radiographic instability, approaching 30% in some studies [1-5, 6, 7]. The actual number of symptomatic patients varies, however, but may be as few as 1.5% depending on how symptomatology is defined [7, 8, 9-13].…”

Section: Discussionmentioning

confidence: 99%

Dynamic MRI in the Evaluation of Atlantoaxial Stability in Pediatric Down Syndrome Patients

Melamed

Krieger

2019

Pediatr Neurosurg

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“…There is continued debate as to its etiology – congenital or traumatic – with studies and reports supporting the pathogenesis of both. [ 6 7 8 9 ] Whether congenital or post-traumatic, the anomaly occurs early enough in development of the spine for secondary findings to be seen, including a relatively foreshortened base of the dens and a hypertrophied anterior arch of C-1 [ Figure 3 ].…”

Section: Developmental Variants and Anomaliesmentioning

confidence: 99%

The Dens: Normal Development, Developmental Variants and Anomalies, and Traumatic Injuries

O’Brien

Shen

Lee

2015

Journal of Clinical Imaging Science

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Accurate interpretation of cervical spine imagining can be challenging, especially in children and the elderly. The biomechanics of the developing pediatric spine and age-related degenerative changes predispose these patient populations to injuries centered at the craniocervical junction. In addition, congenital anomalies are common in this region, especially those associated with the axis/dens, due to its complexity in terms of development compared to other vertebral levels. The most common congenital variations of the dens include the os odontoideum and a persistent ossiculum terminale. At times, it is necessary to distinguish normal development, developmental variants, and developmental anomalies from traumatic injuries in the setting of acute traumatic injury. Key imaging features are useful to differentiate between traumatic fractures and normal or variant anatomy acutely; however, the radiologist must first have a basic understanding of the spectrum of normal developmental anatomy and its anatomic variations in order to make an accurate assessment. This review article attempts to provide the basic framework required for accurate interpretation of cervical spine imaging with a focus on the dens, specifically covering the normal development and ossification of the dens, common congenital variants and their various imaging appearances, fracture classifications, imaging appearances, and treatment options.

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“…They have also been reported, on occasion, to be a preventive treatment for spinal cord injury in patients without neurological symptoms. [ 1 3 4 ] Although the choice of surgical procedures for patients with atlantoaxial instability depends on the pathology of the instability, the patients' individual anatomical features, and their comorbidity, pre-operative imaging in the craniovertebral junction may often show concomitant diseases or conditions, such as osseous anomalies,[ 5 6 ] vertebral artery anomalies,[ 7 ] and congenital disease. [ 8 ] Knowledge of the treatments for these coexisting states can help the surgeon to prevent intra-or post-operative complications.…”

Section: Discussionmentioning

confidence: 99%

Occipitalized os odontoideum: A case report

Ohya

Miyoshi

Kitagawa

et al. 2014

J Craniovert Jun Spine

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We report on a 36-year-old man presenting with a sudden onset of motor weakness and numbness in the upper extremities following a fall from a truck bed. Radiological findings demonstrated an os odontoideum and osseous continuity between the occiput and an ossicle, termed an “occipitalized os odontoideum.” The occipitalized ossicle and atlas moved as a functional unit from the body of the axis. He underwent atlantoasxial stabilization with an atlas lateral mass screw and axis pedicle screw. Eighteen months later, he remained free of symptoms and showed solid bone fusion. Atlantoaxial stabilization resulted in an excellent clinical outcome for this condition. Our report provides useful knowledge regarding treatment of extremely rare osseous anomalies in the craniovertebral junction.

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Os Odontoideum

Cited by 120 publications

References 75 publications

Dynamic MRI in the Evaluation of Atlantoaxial Stability in Pediatric Down Syndrome Patients

Dynamic MRI in the Evaluation of Atlantoaxial Stability in Pediatric Down Syndrome Patients

The Dens: Normal Development, Developmental Variants and Anomalies, and Traumatic Injuries

Occipitalized os odontoideum: A case report

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