What is atlanto-axial instability?

Atlanto-axial instability (AAI) is a condition that affects the bones in the upper spine or neck under the base of the skull. The joint between the upper spine and base of the skull is called the atlanto-axial joint. In people with Down syndrome, the ligaments (connections between muscles) are “lax” or floppy.

How do you assess for atlantoaxial instability?

The patient is asked to slowly flex the head performing a slight cervical nod, at the same time the examiner presses posteriorly on the patient’s forehead. A sliding motion of the head in relation to the axis indicates atlantoaxial instability.

What is atlanto-axial?

The atlanto-axial joint is a joint in the upper part of the neck between the atlas bone and the axis bone, which are the first and second cervical vertebrae. It is a pivot joint.

What is Grisel’s syndrome?

Grisel’s syndrome involves the subluxation of the atlantoaxial joint from inflammatory ligamentous laxity following an infectious process. Even though it was first described in 1830, it is a rare disease usually affecting children, but infrequent adult cases do occur.

How is atlantoaxial instability treated?

Surgery is most successful for treating patients with ligamentous instability and less successful in treating patients with osseous instability. Optimal results have been obtained in patients with severe pain and mild myelopathy. Thus, detecting symptoms early is preferable for the most successful treatment.

How are the lateral atlanto axial joints best classified?

It is classified as a pivot joint. The lateral atlantoaxial joints are bilateral joints formed between the lateral masses of the atlas and axis. These joints are classified as gliding, or plane joints. The primary movement of the atlantoaxial joint complex is rotation.

What causes cervicocranial syndrome?

The cause of cervicocranial syndrome is either due to a defect (genetic mutation or development of diseases later in life) or an injury pertaining to the neck: cervical area, that damages the spinal nerves traveling through the cervical region resulting in vertebral subluxation.

What does Craniocervical instability feel like?

Symptoms of craniocervical instability include occipital headache, neck pain and neurological abnormalities such as numbness, motor weakness, dizziness, and gait instability. Patients sometimes describe the feeling that their head is too heavy for their neck to support (“bobble-head”).

What is the definition of atlanto-axial instability?

atlanto-axial instability Abnormal mobility of the articulation of the ATLAS BONE with the AXIS BONE. This is demonstrable on X-ray by a separation of more than 3 mm, at the front, between the body of the atlas and the odontoid process of the axis.

How many dogs have atlanto-axial instability ( AAI )?

Lisa was also diagnosed with Atlanto-Axial Instability (AAI) which is a complication of EDS that results from excessive movement. The abnormalities documented in the cervical region were 8 hemivertebrae (C5 2x, C6 3x, C7 3x) followed by four dogs with atlanto-axial instability, and one dog with block vertebrae (C2-C3).

How is the Adi measured for atlantoaxial dislocation?

Atlantoaxial dislocation can be defined with radiographic measurements of atlantoaxial joint articulation using the atlantodental interval (ADI). The ADI is a small slitlike space between the posterior aspect of the anterior atlas ring and the anterior aspect of the odontoid process.

Which is the most common cause of atlantoaxial dislocation?

Atlantoaxial dislocation can be broadly categorized into separate traumatic, congenital, or inflammatory etiologies, although the cause is commonly multifactorial. A purely traumatic atlantoaxial dislocation in the absence of another predisposing risk factor is extremely rare.