Atlanto-occipital dissociation with vertebral artery transection

• craniocervical dissociation with anterior displacement of the occipital condyles
• significant prevertebral edema
• marked increase in the basion-dens interval and the basion-axial interval
• ETT and enteric tube in situ. Pelvic binder noted. No chest or abdominal injury identified on the X-ray

Brain

• large volume sub-arachnoid hemorrhage, most pronounced within the basal cisterns and Sylvian fissures
• preserved grey-white matter differentiation

Cervical spine

• craniocervcial dissociation with significant inferior and posterior translation of C1 relative to the skull base
• transverse right occipital condyle fracture. Further occipital bone fractures
• mild widening of the right atlanto-axial joint - dens interval suggesting atlanto-axial articulation disruption
• gross prevertebral edema without cervical spine fracture

Carotid/circle of Willis angiogram

• transection of both vertebral arteries with non-opacification of the right vertebral artery at the level of C1 and the left vertebral artery at the skull base
• contrast blush / extravasation of the left vertebro-basilar junction in keeping with active hemorrhage (causing large volume SAH)
• minor luminal irregularity of both internal carotid arteries in keeping with low grade carotid blunt cerebrovascular injury
• normal opacification of the major circle of Willis branches with reconstitution of flow to the posterior circulation via the circle of Willis