Citation, DOI & article data
Citation:
Iqbal, S., Knipe, H. Odontoid process agenesis. Reference article, Radiopaedia.org. (accessed on 03 Jul 2022) https://doi.org/10.53347/rID-87627
Odontoid process agenesis is rare, occuring due to a lack of failure of ossification of the odontoid process. It is seen in patients with spondyloepiphyseal and spondylometaphyseal dysplasia 1,2.
Plain radiograph
On plain film, odontoid process agenesis appears small, as a slight depression on the superior articular facet on open mouth view or hypo genesis of basal segment of odontoid with floating apical process. Both of these conditions are associated with atlantoaxial instability.
CT
On dynamic CT scan both flexion and extension views should be performed, to identify posterior subluxation.
Treatment and prognosis
Atlantoaxial instability will lead to vascular compression and stroke because of ischemia 2,4. Treatment options include a surgical fusion of C1 and C2.
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- 2. Cormier DV, Cormier. Spondylo-epi-metaphyseal dysplasia. (2008) Best practice & research. Clinical rheumatology. doi:10.1016/j.berh.2007.12.009 - Pubmed
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- 4. Kyoshima K, Kyoshima KY, Kyoshima TK, Kyoshima AK, Kyoshima KM, Kyoshima KT, Kyoshima. Odontoid compression of the brainstem without basilar impression-- "odontoid invagination". (2005) Journal of clinical neuroscience : official journal of the Neurosurgical Society of Australasia. doi:10.1016/j.jocn.2004.07.022 - Pubmed
- 5. Sureisen M, Achannan R, Chong KC, Wong CC. What the mind does not know, the eyes do not see: a rare congenital fusion of the odontoid process to the atlantal hemiarch. (2015) BMJ case reports. doi:10.1136/bcr-2015-212748 - Pubmed
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