Atlanto-occipital dissociation injuries
Neuroimaging
assessment in Down syndrome: a pictorial review. a Sagittal T2/TSE of a 12-year-old Down syndrome patient showing a small and flattened shape of the occipital condyle as well as the C1 superior articular facet, with some degree of anterior luxation of C1. b Sagittal T2/TSE of a normal 12-year-old boy for comparison; there is normal curved shape of articular facets
School ager
with Trisomy 21. Lateral radiograph of the cervical spine in flexion (left) shows a normal atlanto dens interval and normal relationship of the occipital condyles to the lateral masses of C1 while on extension (right) there is posterior translation of the occipital condyles in relation to the lateral masses of C1.The diagnosis was atlanto occipital instability in a patient with Trisomy 21.
Atlanto-occipital
dissociation injuries • Traynelis classification of atlanto-occipital dissociation (diagrams) - Ganzer Fall bei Radiopaedia
Atlanto-occipital
dissociation injuries • Atlantooccipital dissociation - Ganzer Fall bei Radiopaedia
Atlanto-occipital
dissociation injuries • Base of skull lines (annotated images) - Ganzer Fall bei Radiopaedia
Atlanto-occipital
dissociation injuries • Atlanto-occipital disassociation - Ganzer Fall bei Radiopaedia
Atlanto-occipital
dissociation injuries • Atlanto-occipital dissociation injury - Ganzer Fall bei Radiopaedia
Atlanto-occipital
dissociation injuries • Atlanto-occipital dislocation - Ganzer Fall bei Radiopaedia
Atlanto-occipital
dissociation injuries • Atlanto-occipital and atlantoaxial distraction - Ganzer Fall bei Radiopaedia
Atlanto-occipital
dissociation injuries • Craniocervical dissociation with basilar artery transection - Ganzer Fall bei Radiopaedia
Atlanto-occipital
dissociation injuries • Craniocervical dissociation - Ganzer Fall bei Radiopaedia
Atlanto-occipital
dissociation injuries • Atlanto-occipital dissociation - Traynelis type 1 - Ganzer Fall bei Radiopaedia
Atlanto-occipital
dissociation injuries • Atlanto-occipital dissociation (Traynelis type 1), C2 teardrop fracture, C6/7 facet joint dislocation - Ganzer Fall bei Radiopaedia
Atlanto-occipital
dissociation injuries • Atlanto-occipital dissociation with vertebral artery transection - Ganzer Fall bei Radiopaedia
Teenager hit
by a car. Coronal CT without contrast of the cervical spine (above left) shows a fracture through the left occipital condyle with the fracture fragment displaced inferiorly. Additionally, the occipital condyles do not articulate with the lateral masses of the C1 vertebral body. Left sagittal CT (above middle) again shows the left occipital condyle fracture and increased space between the left occipital condyle and the left lateral mass of C1. Right sagittal CT (above right) shows even more clearly the increased space between the right occipital condyle and the right lateral mass of C1. Midline sagittal CT (below) shows the basion-dens interval to be abnormally increased.The diagnosis was atlanto-occipital dissociation.
Atlanto-occipital dissociation injuries are severe and include both atlanto-occipital dislocations and atlanto-occipital subluxations.
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 .
Radiographic features
The key to the diagnosis, in addition to visualizing 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 :
- basion-dens interval (BDI) >10 mm in adults
- basion-axial interval (BAI) >12 mm in adults
- Powers ratio >1 (insensitive to a vertical distraction injury or posterior dissociation)
- atlantodental interval (ADI)
- >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.
- condyle-C1 interval (CCI) > 4 mm in children
Differential diagnosis
- occipital condyle fracture
- 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 alar ligament
- rheumatoid arthritis: CT/MRI will show atlantooccipital instability due to pannus destabilisation of joints and ligaments, and x-ray will show erosions
Siehe auch:
Assoziationen und Differentialdiagnosen zu atlantookzipitale Subluxation:
