Atlanto-Occipital Dissociations

Atlanto-occipital dissociations secured the #1 pole position for CVJ abnormalities because these injuries seriously threaten the adjacent critical neurovascular structures and life itself with atlanto-occipital dislocation usually being fatal. Definition: Traumatic dislocation of the craniovertebral junction involves disruption of strong ligamentous attachments holding the atlas, axis, and occiput together. Atlanto-occipital dissociations (AODs) are severe injuries which include atlanto-occipital dislocation and atlanto-occipital subluxation. The Classic Clue section reminds us when the trauma service requests head and neck imaging of patient who received multiple traumas as a pedestrian hit by a motor vehicle, who continues to complain of neck pain, although “no fracture” was identified on examination at the outside hospital which treated the patients other not insignificant injuries. AOD is often difficult to diagnose on initial imaging studies. Normal measurements for CT studies are distinctly different than for plain films, particularly in children. If you even suspect a problem, get a CT. AOD is a rare medical condition accounting for ~1% of cervical spine injuries but ~15% of fatal spine trauma. AOD is more common in children, probably because their small, horizontally oriented occipital condyles, the flat surface of the C1 lateral masses, and a relatively “loose” ligamentous capsule.