Atlanto-occipital dissociation injuries
Citation, DOI, disclosures and article data
At the time the article was created Frank Gaillard had no recorded disclosures.
View Frank Gaillard's current disclosuresAt the time the article was last revised Liz Silverstone had no financial relationships to ineligible companies to disclose.
View Liz Silverstone's current disclosures- Atlanto-occipital dissociation (AOD)
- Atlanto-occipital dislocations
- Atlanto-occipital subluxations
- Atlanto-occipital dissociation
Atlanto-occipital dissociation injuries are severe and include both atlanto-occipital dislocations and atlanto-occipital subluxations.
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Pathology
The tectorial membrane and alar ligaments provide most of the stability to the atlanto-occipital joint, and injury to these ligaments results in instability due to low inherent osseous stability 3.
Classification
The Traynelis classification describes injuries according to the displacement of the occipital condyles relative to the atlas.
The AO Spine classification of upper cervical injuries is another classification system split into location-specific patterns and then further subdivided according to injury type and presence of neurological signs and/or modifying factors.
Radiographic features
The key to the diagnosis, in addition to identifying gross disruption of the normal alignment of the atlanto-occipital joint, hinges on using a number of lines on the lateral horizontal shoot-through cervical spine film 1:
basion-dens interval (BDI) >10 mm in adults 3
basion-axial interval (BAI) >12 mm in adults
Powers ratio >1 (insensitive to a vertical distraction injury or posterior dissociation)
-
>3 mm in adult males
>2.5 mm in adult females
CT
For pediatric patients, the condyle-C1 interval (CCI) has been shown to provide the highest diagnostic accuracy 4.
condyle-C1 interval (CCI) >4 mm in children
Differential diagnosis
Jefferson fracture: anterior and posterior C1 ring fracture, possible lateral masses displacement
odontoid fracture: type 2 will cause posterior dens displacement and will disrupt Powers ratio
atlanto-axial subluxation: atlantoaxial rotatory fixation will cause C1 lateral mass asymmetry relative to the dens
Down syndrome: atlanto-occipital instability due to laxity of the alar ligament
rheumatoid arthritis: CT/MRI will show atlantooccipital instability due to pannus destabilisation of joints and ligaments, and x-ray will show erosions
References
- 1. Rojas C, Bertozzi J, Martinez C, Whitlow J. Reassessment of the Craniocervical Junction: Normal Values on CT. AJNR Am J Neuroradiol. 2007;28(9):1819-23. doi:10.3174/ajnr.A0660 - Pubmed
- 2. Hall G, Kinsman M, Nazar R et al. Atlanto-Occipital Dislocation. World J Orthop. 2015;6(2):236-43. doi:10.5312/wjo.v6.i2.236 - Pubmed
- 3. Riascos R, Bonfante E, Cotes C, Guirguis M, Hakimelahi R, West C. Imaging of Atlanto-Occipital and Atlantoaxial Traumatic Injuries: What the Radiologist Needs to Know. Radiographics. 2015;35(7):2121-34. doi:10.1148/rg.2015150035 - Pubmed
- 4. Pang D, Nemzek W, Zovickian J. Atlanto-Occipital Dislocation--Part 2: The Clinical Use of (Occipital) Condyle-C1 Interval, Comparison with Other Diagnostic Methods, and the Manifestation, Management, and Outcome of Atlanto-Occipital Dislocation in Children. Neurosurgery. 2007;61(5):995-1015; discussion 1015. doi:10.1227/01.neu.0000303196.87672.78 - Pubmed
- 5. Kasliwal M, Fontes R, Traynelis V. Occipitocervical Dissociation-Incidence, Evaluation, and Treatment. Curr Rev Musculoskelet Med. 2016;9(3):247-54. doi:10.1007/s12178-016-9347-6 - Pubmed
- 6. Divi S, Schroeder G, Oner F et al. AOSpine-Spine Trauma Classification System: The Value of Modifiers: A Narrative Review With Commentary on Evolving Descriptive Principles. Global Spine J. 2019;9(1 Suppl):77S-88S. doi:10.1177/2192568219827260 - Pubmed
Incoming Links
- Atlas (C1)
- Occipital condyle fracture
- Basion
- Opisthion
- Basion-dens interval
- Atlanto-occipital articulation
- Torticollis
- AO Spine classification of upper cervical injuries
- Cervical spine fractures
- Cervical spine injury
- Powers ratio
- Wackenheim line
- Basion-axial interval
- Musculoskeletal curriculum
- Medical abbreviations and acronyms (A)
- Traynelis classification of atlanto-occipital dislocations
- Condyle-C1 interval (CCI)
- Atlantodental interval
- Atlanto-occipital dissociation
- Craniocervical dissociation
- Atlanto-occipital dissociation with vertebral artery transection
- Atlanto-occipital dissociation (Traynelis type 1), C2 teardrop fracture, C6/7 facet joint dislocation
- Atlanto-occipital dissociation - Traynelis type 1
- Traynelis classification of atlanto-occipital dissociation (diagrams)
- Craniocervical dissociation with basilar artery transection
- Atlanto-occipital and atlantoaxial distraction
- Craniocervical dissociation
- Hypoxic ischaemic injury, diffuse axonal injury and atlanto-occipital dislocation
- Atlanto-occipital dislocation
- Base of skull lines (annotated images)
- Atlanto-occipital dissociation
- Craniocervical junction distraction injury
- Atlantooccipital dissociation
- Atlanto-occipital disassociation
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