In normal conditions, the articulation of the odontoid process of C2 (axis) with the anterior arch of C1 (atlas) allows for 50% of cervical lateral rotation.
The liagments responsible for stability are transverse and alar ligaments. They maintain joint integrity and limit posterior motion of the odontoid process relative to the C1 anterior arch.
An acute injury to this area can cause cord compression and could be fatal.
Acute trauma, usually cervical hyperflexion, hyperextension, or a direct axial load on the head or cervical spine causes atlanto axial injuries. Certain conditions congenital odontoid anomalies, such as odontoid aplasia, odontoid hypoplasia, and a separate odontoid process or os odontoideum and inflammatory processes predispose an individual to these injuries.
Most of these injuries are the result of significant trauma to the head, although they may occur in older patients with a simple fall and striking of the occiput.
The individuals suffering from these injuries present with general symptoms of neck pain, limited range of motion, and torticollis. However, worsening of symptoms like headache, fatigue, transient upper-extremity paresthesias could be an indicator of this injury.
Quadriplegia due to cord compression may also be a presentation.
Examination
Standard protocol of spine injury examination must be followed. More Information on this available here
An assessment of the airway, breathing, and circulation (ABCs), with immediate stabilization of the cervical spine in a neutral position must be done. While placing airway, a compromise to the injured spine should be avoided.
High-dose intravenous steroids should be considered in patients with suspected cervical cord injuries to reduce spinal cord swelling.
The findings may be completely normal in asymptomatic patients with radiographically documented injury .
An MRI may be used to investigate the integrity of the ligamentous complex.
Types of Atlanto axial Injuries
There are three patterns of atlantoaxial instability. These can present as isolated or combined injury
Type A
These injuries cause are rotational displacement in an axial plane. Fine-cut CT scans are of utmost importance in diagnosis and measurement of this condition.
Type B
These injuries are translationally unstable in a sagittal plane due to insufficiency of the transverse atlantal ligament. These are inherently unstable injuries.
Type C
Injuries are characterized by a multiplanar vertical atlantoaxial dissociation. Atlantoaxial distractive injuries are also referred to as atlantoaxial dissociation and constitute a variant of atlanto-occipital dissociation. This injury is a result of vertical separation as in judicial hanging. Often there is traumatic separation of both alar ligaments, rendering this injury highly unstable,
Treatment
Treatment decisions should be always made on the basis of a comprehensive evaluation of the patient in general and the injury specifically.
Presence of a spinal cord injury usually requires definitive surgical decompression and instrumented fusion of the injury to maximize chances for neurologic recovery.
Ligament injuries heal poorly when treated nonoperatively.
Non operative treatments include bracing, halo vest and cervical traction.
Operative treatment consists of C1 -C2 fusion.
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