What is Basion dens interval?
The basion-dens interval (BDI) is the distance between the basion and the tip of the dens, used in the diagnosis of atlanto-occipital dissociation injuries. It is the distance from the most inferior portion of the basion to the closest point of the superior aspect of the dens in the median (midsagittal) plane.
What is the Atlantodental space?
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 Basion?
basion. / (ˈbeɪsɪən) / noun. anatomy the midpoint on the forward border of the foramen magnum.
Where is Odontoid process found?
The odontoid process, or dens, is a superior projecting bony element from the second cervical vertebrae (C2, or the axis). The first cervical vertebrae (atlas) rotates around the odontoid process to provide the largest single component of lateral rotation of the cervical spine.
What is the normal Atlantodental interval?
The atlantodental interval (ADI) is a measurement used to evaluate the atlanto-axial relationship. This distance, described by Hinck et al,6 is conventionally held to be normal when it is less than 3 mm in men and 2.5 mm in women.
What is the Predental space?
Distance between the anterior surface of the dens and the posterior surface of the tubercle of C1 is usually 3 mm or less in adults and 5 mm or less in children. This space is called by many names: predentate space, predental space, atlantodental distance.
What is ADI value?
The acceptable daily intake (ADI) is an estimate of the amount of a substance in food or drinking water that can be consumed daily over a lifetime without presenting an appreciable risk to health.
What holds the odontoid process?
The alar ligaments attach the odontoid process to the medial surfaces of the occipital condyles, and they prevent excessive rotation of the atlas and head relative to the axis. Another ligament, the transverse ligament of the atlas, runs posterior to the odontoid process and this ligament holds the dens in position.
What is TDI and ADI?
The acceptable daily intake (ADI) is used widely to describe “safe” levels of intake; other terms that are used are the reference dose (RfD) and tolerable intakes that are expressed on either a daily (TDI or tolerable daily intake) or weekly basis.
How is ADI derived?
The ADI is an estimate of the amount of a chemical that can be ingested daily over a lifetime without appreciable health risk. It is derived from No-Observed-Adverse-Effect-Levels (NOAELs) determined in a battery of toxicity tests in animals and augmented by human data where available.
What is the normal range of the basion-dens interval?
Normal values of the basion-dens interval in the adult population have been well-described in the literature. In a study by Harris et al, the basion-dens interval was <12 mm in 95% of adult patients on lateral cervical spine radiographs.
Is basion-dens interval related to cranioverterbral junction injury in children?
BACKGROUND AND PURPOSE: Widening of the basion-dens interval is an important sign of cranioverterbral junction injury. The current literature on basion-dens interval in children is sparse and based on bony measurements with variable values.
What is the odontoid process?
Introduction The odontoid process is a part of the C2 or axis vertebra and forms pivot of the structures forming the craniovertebral junction (CVJ). The pathologies of odontoid can be congenital or acquired.
Is odontoid process normal in height?
The odontoid process is usually normal in height. On occasion, it may be confused with a type 1 odontoid fracture (avulsion of the terminal ossicle), and absolute differentiation between the two entities may be difficult [Figure 9]. Open in a separate window Figure 9