Atlanto-occipital dissociation injuries

Atlanto-occipital dissociation (AOD) injuries are severe and include both atlanto-occipital dislocations and atlanto-occipital subluxations.

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.

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.

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:

For pediatric patients the condyle-C1 interval (CCI) has been shown to provide the highest diagnostic accuracy 4.

Fractures

Article information

rID: 23151
Synonyms or Alternate Spellings:
  • Atlanto-occipital dissociation (AOD)
  • Atlanto-occipital dislocations
  • Atlanto-occipital subluxations
  • Atlanto-occipital dissociation

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Cases and figures

  • Figure 1a: Traynelis type 1
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  • Figure 1b: Traynelis type 2
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  • Figure 1c: Traynelis type 3
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  • Figure 2: base of skull lines (annotated images)
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  • Case 1: type 2
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  • Case 2: type 1
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  • Case 3: widened basion-dens interval
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  • Case 4
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  • Case 5
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  • Case 6: with basilar artery transection
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  • Case 7: type 1
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  • Case 8: type 1
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  • Case 9: type 1
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