How does atlanto-occipital dislocation happen?
Atlanto-occipital dislocation involves complete disruption of all ligamentous relationships between the occiput and the atlas. Death usually occurs immediately from stretching of the brainstem, which causes respiratory arrest. Radiographically, disassociation between the base of the occiput and the arch of C1 is seen.
What are the classifications of atlanto-occipital injuries?
Three types of complete AOD have been described. Ventral dislocation (type I) is the most common, axial dislocation (type II) is typically the most unstable, and dorsal dislocation (type III) is the rarest. Incomplete forms of AOD represent subluxations of the atlanto-occipital junction.
What is atlanto-occipital instability?
Atlantoaxial instability (AAI) is characterized by excessive movement at the junction between the atlas (C1) and axis (C2) as a result of either a bony or ligamentous abnormality. Neurologic symptoms can occur when the spinal cord or adjacent nerve roots are involved.
How is atlantoaxial instability diagnosed?
An atlantoaxial distance greater than 4-5 mm, as demonstrated by lateral radiographs, is indicative of AAI. Occult instability can be identified on the flexion-extension view. Another marker of instability in the anteroposterior (AP) plane is displacement of 3.5 mm in flexion-extension films.
What is atlanto-occipital?
The atlanto-occipital articulation (also known as the C0-C1 joint/articulation) is comprised of a pair of condyloid synovial joints that connect the occipital bone (C0) to the first cervical vertebra (atlas/C1).
What is atlas and Axis?
The atlas and axis vertebrae are the two most superior bones in the vertebral column, and they are part of the seven cervical vertebrae. The atlas is the top-most bone, sitting just below the skull; it is followed by the axis. Together, they support the skull, facilitate neck movement, and protect the spinal cord.
How is atlantoaxial subluxation treated?
Treatment of Atlantoaxial Subluxation Treatment includes symptomatic measures and cervical immobilization, usually beginning with a rigid cervical collar. Urgency of treatment is generally based on symptoms or presence of cord abnormalities on MRI in susceptible patients.
How do you treat AAI?
Unless symptoms of spinal cord compression occur, AAI requires no treatment. Once symptoms arise, cervical spine stabilization is indicated until surgical stabilization is performed. In persons with rotatory displacement, the time of presentation dictates the treatment.
What is atlanto-occipital dislocation (AOD)?
Atlanto-occipital dislocation (AOD) is being increasingly recognized as a potentially survivable injury as a result of improved prehospital management of polytrauma patients and increased awareness of this entity, leading to earlier diagnosis and more aggressive treatment.
What is the anatomy of the atlanto-occipital articulation?
The atlanto-occipital articulation is comprised of a pair of condyloid synovial joints that connect the occiput (C0) to the first cervical vertebra (atlas/C1). Article:
Where does the Posterior atlanto-occipital membrane attach?
The posterior atlanto-occipital membrane attaches from the occipital bone to the posterior arch of the atlas. It is a continuation of the ligamentum flavum[12,13]. The ligamentum nuchae is a continuation of the supraspinous ligament and spans from the external occipital protuberance to the spinous process of C7.
What ligaments stabilize the atlanto-occipital joint?
A complex of ligaments stabilizes the atlanto-occipital and atlantoaxial joints, which are classified into the intrinsic and extrinsic ligaments ( 5 ). The intrinsic ligaments form three layers anterior to the dura matter and include the odontoid ligaments, the cruciate ligament, and the tectorial membrane ( 6 ).