mercoledì 16 luglio 2008

Atlanto-occipital dislocation


The scout view of the head CT shows marked prevertebral soft tissue swelling. There is also subjective increased interspinous distance between C1 and C2. The cervical spine CT coronal view demonstrates irregularity of the occipital condyle joint spaces with the lateral masses of C1. The cervical spine CT sagittal view demonstrates separation of the basion from the odontoid process, measuring approximately 15mm. The cervical spine MRI demonstrates significant abnormal signal in the paraspinous soft tissues. It also demonstrates increased basion - odontoid space.

Differential diagnosis:
- Atlanto-occipital dislocation
- Ligamentous injury
- Cervical spine fracture(s)
- Artifact due to patient rotation

Diagnosis: Atlanto-occipital dislocation

Key points

Atlanto-occipital dislocation is a true neurological emergency, often associated with direct spinal cord injury, quadriplegia, respiratory arrest, and death.
Injury results from rapid deceleration with either hyper flexion or hyperextension.
Vascular injuries are common, ranging from carotid and vertebral artery dissection to complete transection.
Patient survival depends on immediate on-scene resuscitation, spinal immobilization, rapid transportation, rapid diagnosis, and a high index of suspicion.
Occurs more often in children, partly due to larger relative head size, and ligamentous laxity.
Non-traumatic causes include Down's syndrome and rheumatoid arthritis.
Lateral X-Ray findings can include prevertebral soft tissue swelling (usually marked), increased basion-dens interval (more than 12mm).
If plain films are inconclusive, cervical spine CT findings can include prevertebral soft tissue swelling, occipital condyle fracture, irregularity of the articulation between the occipital condyles and the lateral masses of C1.
Cervical spine MRI findings can include abnormal fluid signal in the region of the interspinous ligament or nuchal ligament.

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