What is Predental space?
Predental Space This is defined as the distance from the anterior aspect of the dens to the posterior-inferior margin of the anterior arch of the atlas. In adults, the predental space measures 2.5 mm or less. However, the measured distance on a lateral radiograph is up to 4.5 mm in normal children.
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.
What is Atlantoaxial?
Introduction. The atlantoaxial joint is a type of synovial joint that is classified as a biaxial, pivot joint. This joint resides in the upper part of the neck between the first and second cervical vertebrae, also known as the atlas and axis, respectively.
What is subluxation of C1 and C2?
(C1–C2 Subluxation) Atlantoaxial subluxation is misalignment of the 1st and 2nd cervical vertebrae, which may occur only with neck flexion.
What is Atlantoaxial interval?
AAI is defined as an atlantodental (or atlantodens or atlas-dens) interval (ADI) of greater than 3 mm in adults and of greater than 5 mm in children as measured on plain radiography. The ADI is the distance between the odontoid process and the posterior border of the anterior arch of the atlas.
What is atlantoaxial 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 is atlantoaxial instability measured?
The ADI is determined by measuring the distance between the posterior edge of the anterior arch of C1 and the anterior edge of the dens. A value less than three mm is considered normal in adults and a value less than 4.5 mm is considered normal in children.