What is atlanto-occipital assimilation?
Atlantooccipital assimilation is a partial or complete congenital fusion between the atlas and the base of the occiput [2]. This occurs due to the failure of segmentation between the fourth occipital sclerotome and the first spinal sclerotome [3].
How does atlanto-occipital dislocation happen?
When severe flexion or extension exists at the upper cervical level, atlanto-occipital dislocation may occur. Atlanto-occipital dislocation involves complete disruption of all ligamentous relationships between the occiput and the atlas.
Which movement is minimally permitted at the atlanto-occipital joint?
The atlanto-occipital joints allow flexion-extension. Minimal degree of lateral bending, coupled with minimal rotation, is allowed. Most cervical rotation occurs about the OC-C1-2 complex. The movements allowed in the craniocervical region are shown in Table 7.7.
Is C1 fused to the skull?
Atlanto-occipital assimilation is the fusion of the atlas (C1) to the occiput and is one of the transitional vertebrae.
Can you survive atlanto-occipital dislocation?
Prognosis. The injury is immediately fatal in 70% of cases, with an additional 15% surviving to the emergency room but dying during the subsequent hospital stay. A basion-dental interval of 16mm or greater is associated with mortality. In those with neurologic deficits, survival is unlikely.
Is atlanto-occipital dislocation common?
Abstract. Atlanto-occipital dislocation (AOD) is a devastating condition that frequently results in prehospital cardiorespiratory arrest and accounts for 15% of fatal spinal trauma. Atlanto-occipital dislocation occurs 5 times more commonly in children than adults, and is believed to be caused by hyperextension.
Which ligament checks atlanto-occipital side flexion and rotation?
Anterior atlantooccipital ligament (and membrane)